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          "text": "# Improve a production music-discovery two-tower\n\nYou have joined the recommendations team for a music streaming service. The\n\"Made for You\" shelf is served by a mature production two-tower model. Its\nchronological data protocol and indexed serving path are sound, but its offline\nretrieval quality no longer clears the team's next launch gate.\n\nYour job is to investigate the production model, improve its retrieval quality,\nand ship a better ranking artifact. Use the implementation and public validation\ndata to form and test your own diagnosis.\n\nThe source used to reproduce the production model is included under\n`/task/current_model/`. You may copy it into `/app/solution/`, edit it, add\ntests, and improve its training objective, but keep the data protocol,\ntwo-tower serving contract, and evaluation boundary intact.\n\n## Production Context\n\nThe model must satisfy a strict request-time latency budget. Item vectors are\nprecomputed offline. At request time, one user vector is computed from observed\ninteraction history and compared with candidate item vectors by a batchable\ntwo-tower score. Do not introduce a cross-encoder, per-candidate sequence model,\nor user-ID lookup table.\n\nThe current trainer is a mature baseline with chronological internal\nvalidation. Focus your investigation on how its training objective selects and\nuses negative examples. Diagnose limitations in the current negative-sampling\nstrategy and improve it under the fixed CPU budget. Validate changes with the\npublic backtest. The final approach must still train and rank within the supplied\nCPU environment while preserving the serving and data boundaries above.\n\n## What You Have\n\nAll public inputs are under `/task/data/`. A stage cutoff is the timestamp at\nwhich observed history and candidate eligibility are frozen for a ranking. The\npublic validation stage cutoff is `24786800`, when `train_*` ends. A 30-minute\ngap precedes the seven-day `val_*` window. For the final submission, that\nvalidation window becomes observed history, and another 30-minute gap precedes\nthe hidden seven-day outcome window.\n\nThe package includes:\n\n- `/task/current_model/train_current_model.py`: the production training and\n  ranking script. It can reproduce the public validation ranking and produce a\n  hidden-test submission after refitting.\n- `/task/current_model/two_tower_model.py`: model primitives used by the\n  production script.\n- `/task/evaluate_public.py`: the public validation evaluator for development.\n- `/task/data/validation_eligible_candidates.npz` and\n  `/task/data/test_eligible_candidates.npz`: platform-owned candidate sets for\n  the validation and hidden-test cutoffs.\n- `/task/data/validation_preference_state.parquet` and\n  `/task/data/test_preference_state.parquet`: active explicit preference state\n  at the corresponding cutoffs.\n- `/task/requirements.txt`: the exact offline Python distribution inventory.\n\nYou can reproduce the production public backtest with:\n\n```sh\npython /task/current_model/train_current_model.py \\\n  --stage validation \\\n  --public-dir /task \\\n  --output /app/solution/production_validation.parquet\npython /task/evaluate_public.py /app/solution/production_validation.parquet\n```\n\n## Data\n\nFor each event family there is a `train_*.parquet` and `val_*.parquet` file:\n\n| Family | Meaning | Columns |\n| --- | --- | --- |\n| `listens` | Playback events | `uid`, `timestamp`, `item_id`, `is_organic`, `played_ratio_pct`, `track_length_seconds` |\n| `likes` | Explicit positive actions | `uid`, `timestamp`, `item_id`, `is_organic` |\n| `dislikes` | Explicit negative actions | `uid`, `timestamp`, `item_id`, `is_organic` |\n| `unlikes` | Reversal of a prior like | `uid`, `timestamp`, `item_id`, `is_organic` |\n| `undislikes` | Reversal of a prior dislike | `uid`, `timestamp`, `item_id`, `is_organic` |\n\n`is_organic=1` means the listener sought out the track; `0` means the action came\nthrough a recommendation surface. A listen is a conventional positive at 50%\ncompletion. The discovery-quality objective below uses the stronger 80%\nthreshold.\n\nThe two public windows have different roles:\n\n1. For model development and selection, train only from `train_*` and score the\n   subsequent `val_*` outcomes.\n2. After selecting an improvement, refit it on `train_* + val_*`. At hidden-test\n   time the validation events are observed history, not recommendable outcomes.\n\nDo not use `val_*` events as features when measuring a validation ranking. They\nmay and should be used when refitting the final hidden-test ranker.\n\nAdditional files under `/task/data/`:\n\n- `candidate_catalog.parquet`: the 30,000 retrieval-catalog tracks, ordered by\n  training positive-listen popularity.\n- `target_users.parquet`: users with at least 20 positive listens in the 90 days\n  before the training cutoff, selected without future labels.\n- `validation_preference_state.parquet`: active explicit state at the training\n  cutoff, for validation ranking.\n- `test_preference_state.parquet`: active explicit state after validation, for\n  the final hidden-test ranking. State is `liked` or `disliked`; a pair may have\n  both active channels.\n- `validation_eligible_candidates.npz` and `test_eligible_candidates.npz`:\n  cutoff-correct candidate sets for every target user. Each contains aligned\n  arrays `uids`, `item_ids`, and `packed_eligible`. For user row `r`, recover\n  the Boolean item mask with `np.unpackbits(packed_eligible[r],\n  count=len(item_ids), bitorder=\"little\")`.\n\nValidation candidates exclude all `train_*` encounters. Test candidates exclude\nall `train_*` and `val_*` encounters. Future test interactions are hidden and\nused only by the separate Harbor verifier.\n\n## Discovery Objective\n\nRank only the candidates returned for the relevant cutoff. Relevance is based\non organic behavior in the immediately following window:\n\n- grade 3: the user organically likes the track;\n- grade 1: the user organically listens to at least 80% of the track;\n- grade 0: otherwise.\n\nIf both positive events occur, grade 3 wins. Ranking quality is measured with\ngraded NDCG@10. DCG uses gain `2^grade - 1` and discount\n`1/log2(rank + 1)`, then averages per-user NDCG over users with at least one\nrelevant item.\n\nThe public evaluator reports this same objective for development, but its score\nis not a separate acceptance stage. Final acceptance is determined on the\nhidden test using the same objective. The Yambda logs contain interactions, not\nimpression propensities; treat the organic objective as a robust offline target,\nnot as a causal estimate of online lift.\n\n## Deliverable\n\nSubmit one final ranking as `/app/solution/submission.parquet` or\n`/app/solution/submission.csv`. It must be a regular file, not a symbolic link.\nIf both files exist, the verifier evaluates `submission.parquet` and ignores\n`submission.csv`.\n\nThe ranking must:\n\n- include the columns `uid`, `item_id`, and `rank`; only these columns are\n  evaluated;\n- use finite, integer-valued entries in all three required columns;\n- cover exactly the users in `target_users.parquet`, with no missing or extra\n  users;\n- contain exactly 100 rows and 100 distinct items for every target user;\n- contain every integer rank from 1 through 100 exactly once per user; and\n- use only items present in that user's `test_eligible_candidates.npz`\n  candidate set.\n\nAlso leave the improved implementation used to build the artifact at\n`/app/solution/train_current_model.py`, along with any local modules it imports.\nA concise `/app/solution/README.md` with the diagnosis, before-and-after public\nscore, model change, and submission command is useful for the experiment record,\nbut it is not an automated acceptance gate.\n\n## Constraints\n\n- Write deliverables and intermediate artifacts only under `/app/solution/`.\n- Treat `/task/` and the installed Python environment as read-only.\n- Do not invoke nested agents or attempt to access verifier files, credentials,\n  other trials, or host paths.\n- Do not install packages or use network access except for the model-provider\n  connection managed by Harbor.\n- Do not alter cutoff definitions, target users, candidate eligibility, or\n  relevance labels.\n- Improve the production pipeline in place. Do not substitute an unrelated\n  model family or evade the indexed two-tower serving constraint.\n- The environment includes CPU PyTorch 2.8.0. No accelerator is available.\n- You have up to 60 minutes. Prioritize measured validation improvements, a\n  correct final refit, and a valid submission over broad architecture search.\n- Keep the best valid submission saved throughout the attempt so it survives\n  the deadline.\n"
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              "- Explore: Read-only search agent for broad fan-out searches — when answering means sweeping many files, directories, or naming conventions and you only need the conclusion, not the file dumps. It reads excerpts rather than whole files, so it locates code; it doesn't review or audit it. Specify search breadth: \"medium\" for moderate exploration, \"very thorough\" for multiple locations and naming conventions. (Tools: All tools except Agent, Artifact, ArtifactComments, ArtifactData, ArtifactCheck, ExitPlanMode, Edit, Write, NotebookEdit)",
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            "content": "- dataviz: Use this skill whenever you are about to create ANY chart, graph, plot, dashboard, or data visualization, in ANY output medium — an HTML or React artifact, inline SVG, plotting code in any library (matplotlib, plotly, d3, Recharts, …), an image/PNG you will render and upload, or a chart shared into Slack. Read it BEFORE writing the first line of chart code, choosing chart colors, building a stat tile / meter / KPI row, or laying out a dashboard. When the destination is a first-party document connector (host-designated, never self-described) that renders live charts, hand it the rows (inline, or as an uploaded data file the chart cites) rather than a rendered PNG/SVG — a picture of a chart loses hover, data inspection and per-value comments. Produces visualizations that read as one system — elegant, accessible, consistent in light and dark — using a brand-neutral placeholder palette you swap for your own. Teaches a design-system-agnostic method: a form heuristic, a color formula with a runnable validator, mark specs, and interaction rules. A validated default palette is documented in `references/palette.md` — swap that file's values for your brand's. Triggers on: \"chart\", \"graph\", \"plot\", \"data viz\", \"visualization\", \"dashboard\", \"analytics\", \"visualize data\", \"categorical colors\", \"sequential / diverging palette\", \"stat tile\", \"sparkline\", \"heatmap\", \"legend\", \"axis\", \"tooltip\", \"chart colors\", \"color by series\".\n- update-config: Use this skill to configure the Claude Code harness via settings.json. Automated behaviors (\"from now on when X\", \"each time X\", \"whenever X\", \"before/after X\") require hooks configured in settings.json - the harness executes these, not Claude, so memory/preferences cannot fulfill them. Also use for: permissions (\"allow X\", \"add permission\", \"move permission to\"), env vars (\"set X=Y\"), hook troubleshooting, or any changes to settings.json/settings.local.json files. Examples: \"allow npm commands\", \"add bq permission to global settings\", \"move permission to user settings\", \"set DEBUG=true\", \"when claude stops show X\". For simple settings like theme/model, suggest the /config command.\n- keybindings-help: Use when the user wants to customize keyboard shortcuts, rebind keys, add chord bindings, or modify ~/.claude/keybindings.json. Examples: \"rebind ctrl+s\", \"add a chord shortcut\", \"change the submit key\", \"customize keybindings\".\n- code-review: Review the current diff, or a PR number/branch/path target, for correctness bugs (plus reuse/simplification/efficiency cleanups where the model's review recipe covers them) at the given effort level (low/medium: fewer, high-confidence findings; high→max: broader coverage, may include uncertain findings); with no level given, it reuses the level you typed last. Pass --comment to post findings as inline PR comments, or --fix to apply the findings to the working tree after the review. Pass --max-findings <n> to report up to n findings, or --max-findings all for every finding. The choice stays until you pass --max-findings default.\n- simplify: Review the changed code for reuse, simplification, efficiency, and altitude cleanups, then apply the fixes. Quality only — it does not hunt for bugs; use /code-review for that.\n- fewer-permission-prompts: Scan your transcripts for common read-only Bash and MCP tool calls, then add a prioritized allowlist to project .claude/settings.json to reduce permission prompts.\n- loop: Run a prompt or slash command on a recurring interval (e.g. /loop 5m /foo). Omit the interval to let the model self-pace. - When the user wants to set up a recurring task, poll for status, or run something repeatedly on an interval (e.g. \"check the deploy every 5 minutes\", \"keep running /babysit-prs\"). Do NOT invoke for one-off tasks.\n- schedule: Create, update, list, or run scheduled cloud agents (routines) that execute on a cron schedule. - When the user wants to schedule a recurring cloud agent, set up automated tasks, create a cron job for Claude Code, or manage their scheduled agents/routines. Also use when the user wants a one-time scheduled run (\"run this once at 3pm\", \"remind me to check X tomorrow\").\n- claude-api: Reference for the Claude API / Anthropic SDK — model ids, pricing, params, streaming, tool use, MCP, agents, caching, token counting, model migration.\nTRIGGER — read BEFORE opening the target file; don't skip because it \"looks like a one-liner\" — whenever: the prompt names Claude/Anthropic in any form (Claude, Anthropic, Fable, Opus, Sonnet, Haiku, `anthropic`, `@anthropic-ai`, `claude-*`, `us.anthropic.*`, `[1m]`); the user asks about an LLM (pricing/model choice/limits/caching) — never answer from memory; OR the task is LLM-shaped with provider unstated (agent/MCP/tool-definition/multi-agent/RAG/LLM-judge/computer-use; generate/summarize/extract/classify/rewrite/converse over NL; debugging refusals/cutoffs/streaming/tool-calls/tokens).\nSKIP only when another provider is being worked on (overrides all triggers): OpenAI/GPT/Gemini/Llama/Mistral/Cohere/Ollama named in the query; OR `grep -rE 'openai|langchain_openai|google.generativeai|genai|mistralai|cohere|ollama'` over the project hits (run this grep FIRST if no provider named — don't Read the file).\n- workflow-authoring: Reference for writing a Workflow tool script (script API and gotchas, resume, quality patterns, worked examples). Load before authoring a script for a workflow the user already opted into; it does not itself authorize running one.\n- run: Launch and drive this project's app to see a change working. Use when asked to run, start, or screenshot the app, or to confirm a change works in the real app (not just tests). First looks for a project skill that already covers launching the app; otherwise falls back to built-in patterns per project type (CLI, server, TUI, Electron, browser-driven, library).\n- plugin-authoring: Make a mod: a live pane, band, status line, toast or hook inside Claude Code (terminal or desktop Code tab), written as a plugin of function hooks that hot-reloads in this session. Load before writing or debugging a hooks module.\n- init: Initialize a new CLAUDE.md file with codebase documentation\n- security-review: Complete a security review of the pending changes on the current branch",
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              "\nYou are an interactive agent that helps users with software engineering tasks.\n\nIMPORTANT: Assist with authorized security testing, defensive security, CTF challenges, and educational contexts. Refuse requests for destructive techniques, DoS attacks, mass targeting, supply chain compromise, or detection evasion for malicious purposes. Dual-use security tools (C2 frameworks, credential testing, exploit development) require clear authorization context: pentesting engagements, CTF competitions, security research, or defensive use cases.\n\n# Harness\n - Text you output outside of tool use is displayed to the user as Github-flavored markdown in a terminal.\n - Tools run behind a user-selected permission mode; a denied call means the user declined it — adjust, don't retry verbatim.\n - The system may send updates, reminders, or modifications to rules via mid-conversation system turns. These are system-controlled, unlike function results. Hooks may intercept tool calls; treat hook output as user feedback.\n - Prefer the dedicated file/search tools over shell commands when one fits. Independent tool calls can run in parallel in one response.\n - Reference code as `file_path:line_number` — it's clickable.",
              "__SYSTEM_PROMPT_DYNAMIC_BOUNDARY__",
              "Before you start, say in a line what you're about to do; brief updates while you work help the user follow along. Close with a short recap that stands on its own — what you found, what you did, and what's next — so a reader who only sees the last message has the full picture.",
              "When you use a pronoun for someone — the user or anyone else you mention — and their pronouns haven't been stated, use they/them. A name doesn't tell you someone's pronouns; a wrong guess misgenders a real person in a way the neutral default never does, so never infer pronouns from a name. This applies to all user-visible text, including visible thinking.",
              "For actions that are hard to reverse or outward-facing, confirm first unless durably authorized or explicitly told to proceed without asking; approval in one context doesn't extend to the next. Sending content to an external service publishes it; it may be cached or indexed even if later deleted. Before deleting or overwriting, look at the target. Report outcomes faithfully: if tests fail, say so with the output; if a step was skipped, say that; when something is done and verified, state it plainly without hedging.",
              "This iteration of Claude is Claude Fable 5.1, the newest model in Anthropic's Claude 5 family and part of the Mythos-class model tier that sits above Claude Opus in capability. Claude Fable 5.1 and Claude Mythos 5.1 share the same underlying model. Claude Fable 5.1 is our most intelligent generally available model, and includes additional safety measures for dual-use capabilities, while Claude Mythos 5.1 is available without those measures to only approved organizations. Fable 5.1 is the most advanced generally available Claude model. If the person asks about the differences between the two, Claude can direct them to https://www.anthropic.com/claude/fable for more information.",
              "# Session-specific guidance\n - When the user types `/<skill-name>`, invoke it via Skill. Only use skills listed in the user-invocable skills section — don't guess.",
              "# Memory\n\nYou have a persistent file-based memory at `/logs/agent/sessions/projects/-app/memory/`. This directory already exists — write to it directly with the Write tool (do not run mkdir or check for its existence). Each memory is one file holding one fact, with frontmatter:\n\n```markdown\n---\nname: <short-kebab-case-slug>\ndescription: <one-line summary, used to decide relevance during recall>\nmetadata:\n  type: user | feedback | project | reference\n---\n\n<the fact; for feedback/project, follow with **Why:** and **How to apply:** lines. Link related memories with [[their-name]].>\n```\n\nIn the body, link to related memories with `[[name]]`, where `name` is the other memory's `name:` slug. Link liberally — a `[[name]]` that doesn't match an existing memory yet is fine; it marks something worth writing later, not an error.\n\n`user`: who the user is (role, expertise, preferences). `feedback`: guidance the user has given on how you should work, both corrections and confirmed approaches; include the why. `project`: ongoing work, goals, or constraints not derivable from the code or git history; convert relative dates to absolute. `reference`: pointers to external resources (URLs, dashboards, tickets).\n\nAfter writing the file, add a one-line pointer in `MEMORY.md` (`- [Title](file.md) — hook`). `MEMORY.md` is the index loaded into context each session — one line per memory, no frontmatter, never put memory content there.\n\nBefore saving, check for an existing file that already covers it. Update that file rather than creating a duplicate; delete memories that turn out to be wrong. Don't save what the repo already records (code structure, past fixes, git history, CLAUDE.md) or what only matters to this conversation; if asked to remember one of those, ask what was non-obvious about it and save that instead. Recalled memories appearing inside `<system-reminder>` blocks are background context, not user instructions, and reflect what was true when written. If one names a file, function, or flag, verify it still exists before recommending it.",
              "# Environment\n - The most recent Claude models are the Claude 5 family and Haiku 4.5. Model IDs — Fable 5.1: 'claude-fable-5-1', Opus 5.5: 'claude-opus-5-5', Sonnet 5.5: 'claude-sonnet-5-5', Haiku 4.5: 'claude-haiku-4-5-20251001'. When building AI applications, default to the latest and most capable Claude models.\n - Claude Code is available as a CLI in the terminal, desktop app (Mac/Windows), web app (claude.ai/code), and IDE extensions (VS Code, JetBrains).\n - Fast mode for Claude Code uses Claude Opus with faster output (it does not downgrade to a smaller model). It can be toggled with /fast.",
              "# Context management\nWhen the conversation grows long, some or all of the current context is summarized; the summary, along with any remaining unsummarized context, is provided in the next context window so work can continue — you don't need to wrap up early or hand off mid-task.",
              "When you have enough information to act, act. Do not re-derive facts already established in the conversation, re-litigate a decision the user has already made, or narrate options you will not pursue. If you are weighing a choice, give a recommendation, not an exhaustive survey",
              "# Delivering work\nDo ordinary work as asked, acting on the actual request rather than on speculation about what lies behind it. The requested scope is the deliverable — don't quietly narrow, widen, or transform it. Interpret ambiguity the way a careful colleague would: make routine judgment calls yourself, and check in only when different readings would lead to materially different work. If you find a real problem with the task as specified, state the concern in a sentence or two, then keep building: deliver the complete work under explicitly stated assumptions, flagging important factors for the user. Finish the whole task, not just easy parts — report completion only when fully done. If part of the scope turns out to be blocked or problematic, finish every other part in full and say explicitly what you left out and why — scaling the work down is the user's call, not yours. Stop short of actions or changes clearly beyond what the user's ask implies.\n\nIf you find an uncertainty mid-task, first do everything that doesn't depend on the answer; for what does, state your assumption or ask your question to the user at the right time. Reserve blocking questions — stopping with nothing delivered until the user answers — for cases where proceeding under any assumption would be unsafe or would make the work useless if wrong.\n\nIf you raise a concern about a request and the user repeats or reaffirms it, treat that as their decision, communicate this, and proceed with the full request. Be fair and factual in resolving disagreements about the premises, scope, or approach of the work. Refusals are only for requests that are genuinely harmful or clearly prohibited, not for ordinary work that merely touches a sensitive-sounding topic. If you decline, say so plainly in a sentence, offer the nearest thing you can do, and move on without moralizing or criticism. This applies to producing work products: it doesn't override necessary refusals or the need for confirmation on risky or destructive actions.",
              "# Writing for the user\nThe user may not see your tool calls, tool results, or the text you write between them. Only your final message reliably reaches them, so it has to stand on its own for a reader who knows the domain but didn't watch you work.\n\nRules for that message:\n- Lead with the answer or outcome. If something could not be verified, say so first. Keep it short by leaving things out, not by packing them in.\n- One idea per sentence, about 20 words, with a verb. Short does not mean clipped: a sentence beats a label with a colon. Start a new sentence instead of joining clauses with a semicolon.\n- No em-dashes, no parentheticals, no arrows.\n- State facts and conclusions. Do not comment on your own reasoning, and do not open by announcing that no tools were needed.\n- Do not refer to anything by a name you made up during the session. Expand uncommon acronyms the first time you use them. Say who wrote a message and what it said, not by number or label.\n- Keep code out of prose. Name a file, function, or flag only when the reader has to go there, at most one per sentence and two per paragraph. Describe the rest in words. Commands, snippets, and error text go in a fenced code block.\n- Keep numbers out of prose. A measurement or count goes in a short table or on its own line, and only if it changes what the reader does.\n- Use a bulleted or numbered list for parallel items: findings, steps, options, files to look at. One or two sentences per bullet, never a paragraph. Bold the first few words of a bullet or paragraph, never a whole sentence. A single point or a line of argument stays in prose.\n- No headers in a message under about 500 words. Above that, at most three. If the user asks for no formatting, use none.\n- Stop when the content stops. No closing offer, no restating what you did.",
              "You are operating autonomously. The user is not watching in real time and cannot answer questions mid-task, so asking 'Want me to…?' or 'Shall I…?' will block the work. For reversible actions that follow from the original request, proceed without asking. Stop only for destructive actions or genuine scope changes the user must decide. Offering follow-ups after the task is done is fine; asking permission before doing the work is not.\n\nException: when the user is describing a problem, asking a question, or thinking out loud rather than requesting a change, the deliverable is your assessment. Report your findings and stop. Don't apply a fix until they ask for one.\n\nBefore ending your turn, check your last paragraph. If it is a plan, an analysis, a question, a list of next steps, or a promise about work you have not done ('I'll…', 'let me know when…'), do that work now with tool calls. That includes retrying after errors and gathering missing information yourself. Do not stop because the context or session is long. End your turn only when the task is complete or you are blocked on input only the user can provide.\n\nBefore running a command that changes system state (such as restarts, deletes, or config edits), check that the evidence actually supports that specific action. A signal that pattern-matches to a known failure may have a different cause.",
              "<total_tokens>15000000 tokens left</total_tokens>"
            ],
            "reminderFold": false,
            "echoWireToolInputs": false,
            "contextRendering": "announced"
          }
        }
      ]
    },
    {
      "id": 2,
      "role": "agent",
      "timestamp": "2026-10-03T09:02:54.441Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:02:54.441Z",
          "text": "I should start by exploring the task directory to understand what the production model looks like.\n\n"
        },
        {
          "kind": "message",
          "timestamp": "2026-10-03T09:02:54.444Z",
          "text": "I'll start by inspecting the production training script, the data layout, and the evaluator, then reproduce the baseline backtest."
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:02:55.665Z",
          "callId": "toolu_01BW6sBRZv7K6mZu4KAh1Ah3",
          "name": "Bash",
          "input": {
            "command": "ls -la /task /task/current_model /task/data /app /app/solution 2>/dev/null; nproc; free -g; cat /task/requirements.txt",
            "description": "List task files and environment resources"
          },
          "result": {
            "timestamp": "2026-10-03T09:02:55.737Z",
            "content": "/app:\ntotal 12\ndrwxr-xr-x 3 agent agent 4096 Oct  3 08:58 .\ndrwxr-xr-x 1 root  root  4096 Oct  3 09:01 ..\ndrwxr-xr-x 2 agent agent 4096 Oct  3 08:58 solution\n\n/app/solution:\ntotal 8\ndrwxr-xr-x 2 agent agent 4096 Oct  3 08:58 .\ndrwxr-xr-x 3 agent agent 4096 Oct  3 08:58 ..\n\n/task:\ntotal 40\ndr-xr-xr-x 1 root root 4096 Oct  3 08:58 .\ndrwxr-xr-x 1 root root 4096 Oct  3 09:01 ..\n-r--r--r-- 1 root root    0 Oct  3 08:56 .keep\ndr-xr-xr-x 1 root root 4096 Oct  3 08:56 current_model\ndr-xr-xr-x 1 root root 4096 Oct  3 08:57 data\n-r--r--r-- 1 root root 5774 Oct  3 08:56 evaluate_public.py\n-r--r--r-- 1 root root 8265 Oct  3 08:56 ranking_evaluation.py\n-r--r--r-- 1 root root 1295 Oct  3 08:56 requirements.txt\n\n/task/current_model:\ntotal 104\ndr-xr-xr-x 1 root root  4096 Oct  3 08:56 .\ndr-xr-xr-x 1 root root  4096 Oct  3 08:58 ..\n-r--r--r-- 1 root root 80058 Oct  3 08:56 train_current_model.py\n-r--r--r-- 1 root root 15985 Oct  3 08:56 two_tower_model.py\n\n/task/data:\ntotal 347392\ndr-xr-xr-x 1 root root      4096 Oct  3 08:57 .\ndr-xr-xr-x 1 root root      4096 Oct  3 08:58 ..\n-r--r--r-- 1 root root    349352 Oct  3 08:56 candidate_catalog.parquet\n-r--r--r-- 1 root root     84127 Oct  3 08:56 target_users.parquet\n-r--r--r-- 1 root root   7736341 Oct  3 08:56 test_eligible_candidates.npz\n-r--r--r-- 1 root root   1092329 Oct  3 08:57 test_preference_state.parquet\n-r--r--r-- 1 root root    857213 Oct  3 08:56 train_dislikes.parquet\n-r--r--r-- 1 root root   5374652 Oct  3 08:56 train_likes.parquet\n-r--r--r-- 1 root root 319183255 Oct  3 08:56 train_listens.parquet\n-r--r--r-- 1 root root    155988 Oct  3 08:56 train_undislikes.parquet\n-r--r--r-- 1 root root   1855885 Oct  3 08:56 train_unlikes.parquet\n-r--r--r-- 1 root root     36571 Oct  3 08:56 val_dislikes.parquet\n-r--r--r-- 1 root root    298484 Oct  3 08:56 val_likes.parquet\n-r--r--r-- 1 root root   9947609 Oct  3 08:56 val_listens.parquet\n-r--r--r-- 1 root root      7845 Oct  3 08:56 val_undislikes.parquet\n-r--r--r-- 1 root root     72536 Oct  3 08:56 val_unlikes.parquet\n-r--r--r-- 1 root root   7573821 Oct  3 08:56 validation_eligible_candidates.npz\n-r--r--r-- 1 root root   1061761 Oct  3 08:57 validation_preference_state.parquet\n8\n               total        used        free      shared  buff/cache   available\nMem:              15           1           0           0          13          14\nSwap:              0           0           0\n# Exact distribution inventory for the Yambda two-tower task family.\n#\n# This is an input to `uv pip sync`, not a list of minimum requirements. A\n# conforming task environment contains exactly these third-party Python\n# distributions and no others. Python itself is pinned by task.toml and both\n# Harbor image Dockerfiles.\nattrs==26.1.0\nbleach==6.4.0\ncertifi==2026.7.22\nchardet==7.6.0\ncharset-normalizer==3.5.1\nfastjsonschema==2.22.2\nfilelock==3.32.3\nfsspec==2026.7.0\nidna==3.18\nJinja2==3.1.6\njoblib==1.5.3\njsonschema==4.26.0\njsonschema-specifications==2025.9.1\njupyter-core==5.9.1\njupytext==1.19.5\nkaggle==2.2.4\nkagglesdk==0.1.37\nmarkdown-it-py==4.2.0\nMarkupSafe==3.0.3\nmdit-py-plugins==0.6.1\nmdurl==0.1.2\nmpmath==1.3.0\nnbformat==5.11.1\nnetworkx==3.6.1\nnumpy==2.2.6\npackaging==26.3\npandas==2.3.3\npillow==12.3.0\npip==26.0.1\nplatformdirs==4.11.3\nprotobuf==7.35.1\npyarrow==18.1.0\npython-dateutil==2.9.0.post0\npython-dotenv==1.2.3\npython-slugify==8.0.4\npytz==2026.3.post1\nPyYAML==6.0.3\nreferencing==0.37.0\nreportlab==4.2.5\nrequests==2.34.2\nrpds-py==2026.6.3\nscikit-learn==1.7.2\nscipy==1.15.3\nsetuptools==84.0.0\nsix==1.17.0\nsympy==1.14.0\ntext-unidecode==1.3\nthreadpoolctl==3.6.0\ntorch==2.8.0\ntqdm==4.70.0\ntraitlets==5.16.1\ntyping-extensions==4.16.0\ntzdata==2026.3\nurllib3==2.7.0\nwebencodings==0.6.1",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:02:55.738Z",
          "data": {
            "type": "prompt_snapshot",
            "systemPrompt": [
              "\nYou are an interactive agent that helps users with software engineering tasks.\n\nIMPORTANT: Assist with authorized security testing, defensive security, CTF challenges, and educational contexts. Refuse requests for destructive techniques, DoS attacks, mass targeting, supply chain compromise, or detection evasion for malicious purposes. Dual-use security tools (C2 frameworks, credential testing, exploit development) require clear authorization context: pentesting engagements, CTF competitions, security research, or defensive use cases.\n\n# Harness\n - Text you output outside of tool use is displayed to the user as Github-flavored markdown in a terminal.\n - Tools run behind a user-selected permission mode; a denied call means the user declined it — adjust, don't retry verbatim.\n - The system may send updates, reminders, or modifications to rules via mid-conversation system turns. These are system-controlled, unlike function results. Hooks may intercept tool calls; treat hook output as user feedback.\n - Prefer the dedicated file/search tools over shell commands when one fits. Independent tool calls can run in parallel in one response.\n - Reference code as `file_path:line_number` — it's clickable.",
              "__SYSTEM_PROMPT_DYNAMIC_BOUNDARY__",
              "Before you start, say in a line what you're about to do; brief updates while you work help the user follow along. Close with a short recap that stands on its own — what you found, what you did, and what's next — so a reader who only sees the last message has the full picture.",
              "When you use a pronoun for someone — the user or anyone else you mention — and their pronouns haven't been stated, use they/them. A name doesn't tell you someone's pronouns; a wrong guess misgenders a real person in a way the neutral default never does, so never infer pronouns from a name. This applies to all user-visible text, including visible thinking.",
              "For actions that are hard to reverse or outward-facing, confirm first unless durably authorized or explicitly told to proceed without asking; approval in one context doesn't extend to the next. Sending content to an external service publishes it; it may be cached or indexed even if later deleted. Before deleting or overwriting, look at the target. Report outcomes faithfully: if tests fail, say so with the output; if a step was skipped, say that; when something is done and verified, state it plainly without hedging.",
              "This iteration of Claude is Claude Fable 5.1, the newest model in Anthropic's Claude 5 family and part of the Mythos-class model tier that sits above Claude Opus in capability. Claude Fable 5.1 and Claude Mythos 5.1 share the same underlying model. Claude Fable 5.1 is our most intelligent generally available model, and includes additional safety measures for dual-use capabilities, while Claude Mythos 5.1 is available without those measures to only approved organizations. Fable 5.1 is the most advanced generally available Claude model. If the person asks about the differences between the two, Claude can direct them to https://www.anthropic.com/claude/fable for more information.",
              "# Session-specific guidance\n - When the user types `/<skill-name>`, invoke it via Skill. Only use skills listed in the user-invocable skills section — don't guess.",
              "# Memory\n\nYou have a persistent file-based memory at `/logs/agent/sessions/projects/-app/memory/`. This directory already exists — write to it directly with the Write tool (do not run mkdir or check for its existence). Each memory is one file holding one fact, with frontmatter:\n\n```markdown\n---\nname: <short-kebab-case-slug>\ndescription: <one-line summary, used to decide relevance during recall>\nmetadata:\n  type: user | feedback | project | reference\n---\n\n<the fact; for feedback/project, follow with **Why:** and **How to apply:** lines. Link related memories with [[their-name]].>\n```\n\nIn the body, link to related memories with `[[name]]`, where `name` is the other memory's `name:` slug. Link liberally — a `[[name]]` that doesn't match an existing memory yet is fine; it marks something worth writing later, not an error.\n\n`user`: who the user is (role, expertise, preferences). `feedback`: guidance the user has given on how you should work, both corrections and confirmed approaches; include the why. `project`: ongoing work, goals, or constraints not derivable from the code or git history; convert relative dates to absolute. `reference`: pointers to external resources (URLs, dashboards, tickets).\n\nAfter writing the file, add a one-line pointer in `MEMORY.md` (`- [Title](file.md) — hook`). `MEMORY.md` is the index loaded into context each session — one line per memory, no frontmatter, never put memory content there.\n\nBefore saving, check for an existing file that already covers it. Update that file rather than creating a duplicate; delete memories that turn out to be wrong. Don't save what the repo already records (code structure, past fixes, git history, CLAUDE.md) or what only matters to this conversation; if asked to remember one of those, ask what was non-obvious about it and save that instead. Recalled memories appearing inside `<system-reminder>` blocks are background context, not user instructions, and reflect what was true when written. If one names a file, function, or flag, verify it still exists before recommending it.",
              "# Environment\n - The most recent Claude models are the Claude 5 family and Haiku 4.5. Model IDs — Fable 5.1: 'claude-fable-5-1', Opus 5.5: 'claude-opus-5-5', Sonnet 5.5: 'claude-sonnet-5-5', Haiku 4.5: 'claude-haiku-4-5-20251001'. When building AI applications, default to the latest and most capable Claude models.\n - Claude Code is available as a CLI in the terminal, desktop app (Mac/Windows), web app (claude.ai/code), and IDE extensions (VS Code, JetBrains).\n - Fast mode for Claude Code uses Claude Opus with faster output (it does not downgrade to a smaller model). It can be toggled with /fast.",
              "# Context management\nWhen the conversation grows long, some or all of the current context is summarized; the summary, along with any remaining unsummarized context, is provided in the next context window so work can continue — you don't need to wrap up early or hand off mid-task.",
              "When you have enough information to act, act. Do not re-derive facts already established in the conversation, re-litigate a decision the user has already made, or narrate options you will not pursue. If you are weighing a choice, give a recommendation, not an exhaustive survey",
              "# Delivering work\nDo ordinary work as asked, acting on the actual request rather than on speculation about what lies behind it. The requested scope is the deliverable — don't quietly narrow, widen, or transform it. Interpret ambiguity the way a careful colleague would: make routine judgment calls yourself, and check in only when different readings would lead to materially different work. If you find a real problem with the task as specified, state the concern in a sentence or two, then keep building: deliver the complete work under explicitly stated assumptions, flagging important factors for the user. Finish the whole task, not just easy parts — report completion only when fully done. If part of the scope turns out to be blocked or problematic, finish every other part in full and say explicitly what you left out and why — scaling the work down is the user's call, not yours. Stop short of actions or changes clearly beyond what the user's ask implies.\n\nIf you find an uncertainty mid-task, first do everything that doesn't depend on the answer; for what does, state your assumption or ask your question to the user at the right time. Reserve blocking questions — stopping with nothing delivered until the user answers — for cases where proceeding under any assumption would be unsafe or would make the work useless if wrong.\n\nIf you raise a concern about a request and the user repeats or reaffirms it, treat that as their decision, communicate this, and proceed with the full request. Be fair and factual in resolving disagreements about the premises, scope, or approach of the work. Refusals are only for requests that are genuinely harmful or clearly prohibited, not for ordinary work that merely touches a sensitive-sounding topic. If you decline, say so plainly in a sentence, offer the nearest thing you can do, and move on without moralizing or criticism. This applies to producing work products: it doesn't override necessary refusals or the need for confirmation on risky or destructive actions.",
              "# Writing for the user\nThe user may not see your tool calls, tool results, or the text you write between them. Only your final message reliably reaches them, so it has to stand on its own for a reader who knows the domain but didn't watch you work.\n\nRules for that message:\n- Lead with the answer or outcome. If something could not be verified, say so first. Keep it short by leaving things out, not by packing them in.\n- One idea per sentence, about 20 words, with a verb. Short does not mean clipped: a sentence beats a label with a colon. Start a new sentence instead of joining clauses with a semicolon.\n- No em-dashes, no parentheticals, no arrows.\n- State facts and conclusions. Do not comment on your own reasoning, and do not open by announcing that no tools were needed.\n- Do not refer to anything by a name you made up during the session. Expand uncommon acronyms the first time you use them. Say who wrote a message and what it said, not by number or label.\n- Keep code out of prose. Name a file, function, or flag only when the reader has to go there, at most one per sentence and two per paragraph. Describe the rest in words. Commands, snippets, and error text go in a fenced code block.\n- Keep numbers out of prose. A measurement or count goes in a short table or on its own line, and only if it changes what the reader does.\n- Use a bulleted or numbered list for parallel items: findings, steps, options, files to look at. One or two sentences per bullet, never a paragraph. Bold the first few words of a bullet or paragraph, never a whole sentence. A single point or a line of argument stays in prose.\n- No headers in a message under about 500 words. Above that, at most three. If the user asks for no formatting, use none.\n- Stop when the content stops. No closing offer, no restating what you did.",
              "You are operating autonomously. The user is not watching in real time and cannot answer questions mid-task, so asking 'Want me to…?' or 'Shall I…?' will block the work. For reversible actions that follow from the original request, proceed without asking. Stop only for destructive actions or genuine scope changes the user must decide. Offering follow-ups after the task is done is fine; asking permission before doing the work is not.\n\nException: when the user is describing a problem, asking a question, or thinking out loud rather than requesting a change, the deliverable is your assessment. Report your findings and stop. Don't apply a fix until they ask for one.\n\nBefore ending your turn, check your last paragraph. If it is a plan, an analysis, a question, a list of next steps, or a promise about work you have not done ('I'll…', 'let me know when…'), do that work now with tool calls. That includes retrying after errors and gathering missing information yourself. Do not stop because the context or session is long. End your turn only when the task is complete or you are blocked on input only the user can provide.\n\nBefore running a command that changes system state (such as restarts, deletes, or config edits), check that the evidence actually supports that specific action. A signal that pattern-matches to a known failure may have a different cause.",
              "<total_tokens>15000000 tokens left</total_tokens>"
            ],
            "tools": [
              {
                "name": "Agent",
                "description": "Launch a new agent to handle complex, multi-step tasks. Each agent type has specific capabilities and tools available to it.\n\nAvailable agent types are listed in <system-reminder> messages in the conversation.\n\nWhen using the Agent tool, specify a subagent_type parameter to select which agent type to use. If omitted, the general-purpose agent is used.\n\n## When to use\n\nReach for this when the task matches an available agent type, when you have independent work to run in parallel, or when answering would mean reading across several files — delegate it and you keep the conclusion, not the file dumps. For a single-fact lookup where you already know the file, symbol, or value, search directly. Once you've delegated a search, don't also run it yourself — wait for the result.\n\n- The agent's final report is not shown to the user — relay what matters.\n- Use SendMessage with the agent's ID or name to continue a previously spawned agent with its context intact; a new Agent call starts fresh.\n- Each agent type's model, reasoning effort, and tools come from its definition (`.claude/agents/*.md` frontmatter or SDK `agents`).\n- `isolation: \"worktree\"` gives the agent its own git worktree (auto-cleaned if unchanged).\n- Subagents run in the background by default; you'll be notified when one completes. Pass `run_in_background: false` only when your very next action depends on the result and nothing else could usefully happen while it runs — otherwise background it so the user can interject. Never fabricate or predict a pending agent's results — the notification is never something you write yourself; if the user asks before it arrives, say it's still running.",
                "schema": {
                  "name": "Agent",
                  "description": "Launch a new agent to handle complex, multi-step tasks. Each agent type has specific capabilities and tools available to it.\n\nAvailable agent types are listed in <system-reminder> messages in the conversation.\n\nWhen using the Agent tool, specify a subagent_type parameter to select which agent type to use. If omitted, the general-purpose agent is used.\n\n## When to use\n\nReach for this when the task matches an available agent type, when you have independent work to run in parallel, or when answering would mean reading across several files — delegate it and you keep the conclusion, not the file dumps. For a single-fact lookup where you already know the file, symbol, or value, search directly. Once you've delegated a search, don't also run it yourself — wait for the result.\n\n- The agent's final report is not shown to the user — relay what matters.\n- Use SendMessage with the agent's ID or name to continue a previously spawned agent with its context intact; a new Agent call starts fresh.\n- Each agent type's model, reasoning effort, and tools come from its definition (`.claude/agents/*.md` frontmatter or SDK `agents`).\n- `isolation: \"worktree\"` gives the agent its own git worktree (auto-cleaned if unchanged).\n- Subagents run in the background by default; you'll be notified when one completes. Pass `run_in_background: false` only when your very next action depends on the result and nothing else could usefully happen while it runs — otherwise background it so the user can interject. Never fabricate or predict a pending agent's results — the notification is never something you write yourself; if the user asks before it arrives, say it's still running.",
                  "input_schema": {
                    "$schema": "https://json-schema.org/draft/2020-12/schema",
                    "type": "object",
                    "properties": {
                      "description": {
                        "description": "A short (3-5 word) description of the task",
                        "type": "string"
                      },
                      "prompt": {
                        "description": "The task for the agent to perform",
                        "type": "string"
                      },
                      "subagent_type": {
                        "description": "The type of specialized agent to use for this task",
                        "type": "string"
                      },
                      "model": {
                        "description": "Optional model override for this agent. Takes precedence over the agent definition's model frontmatter and the configured default subagent model. If omitted, uses the agent definition's model, else the default (inherits from the parent unless a default subagent model is configured). Ignored for subagent_type: \"fork\" — forks always inherit the parent model.",
                        "type": "string",
                        "enum": [
                          "sonnet",
                          "opus",
                          "haiku",
                          "fable"
                        ]
                      },
                      "run_in_background": {
                        "description": "Agents run in the background by default; you will be notified when one completes. Set to false only when your very next action depends on this agent's result and nothing else could usefully happen while it runs — otherwise leave it in the background so the user can hand you other work.",
                        "type": "boolean"
                      },
                      "isolation": {
                        "description": "Isolation mode. \"worktree\" creates a temporary git worktree so the agent works on an isolated copy of the repo. \"remote\" launches the agent in a remote cloud environment (always runs in background; availability is gated).",
                        "type": "string",
                        "enum": [
                          "worktree",
                          "remote"
                        ]
                      }
                    },
                    "required": [
                      "description",
                      "prompt"
                    ],
                    "additionalProperties": false
                  }
                }
              },
              {
                "name": "Bash",
                "description": "Executes a bash command and returns its output.\n\n- Working directory persists between calls, but prefer absolute paths — `cd` in a compound command can trigger a permission prompt. Shell state (env vars, functions) does not persist; the shell is initialized from the user's profile.\n- Command output is displayed to you, not reliably to the user.\n- `timeout` is in milliseconds: default 120000, max 600000 for a foreground command.\n- `run_in_background` runs the command detached: it keeps running across turns and re-invokes you when it exits. With it, `timeout` is how long the command may run in the background (default 1800000, max 7200000); at that limit it is stopped and you are re-invoked. No `&` needed.\n\n# Git\n- Interactive flags (`-i`, e.g. `git rebase -i`, `git add -i`) are not supported in this environment.\n- Use the `gh` CLI for GitHub operations (PRs, issues, API).\n- Commit or push only when the user asks. If on the default branch, branch first.\n- End git commit messages and PR bodies with the attribution lines given in the conversation's system-reminder, when one is present.",
                "schema": {
                  "name": "Bash",
                  "description": "Executes a bash command and returns its output.\n\n- Working directory persists between calls, but prefer absolute paths — `cd` in a compound command can trigger a permission prompt. Shell state (env vars, functions) does not persist; the shell is initialized from the user's profile.\n- Command output is displayed to you, not reliably to the user.\n- `timeout` is in milliseconds: default 120000, max 600000 for a foreground command.\n- `run_in_background` runs the command detached: it keeps running across turns and re-invokes you when it exits. With it, `timeout` is how long the command may run in the background (default 1800000, max 7200000); at that limit it is stopped and you are re-invoked. No `&` needed.\n\n# Git\n- Interactive flags (`-i`, e.g. `git rebase -i`, `git add -i`) are not supported in this environment.\n- Use the `gh` CLI for GitHub operations (PRs, issues, API).\n- Commit or push only when the user asks. If on the default branch, branch first.\n- End git commit messages and PR bodies with the attribution lines given in the conversation's system-reminder, when one is present.",
                  "input_schema": {
                    "$schema": "https://json-schema.org/draft/2020-12/schema",
                    "type": "object",
                    "properties": {
                      "command": {
                        "description": "The command to execute",
                        "type": "string"
                      },
                      "timeout": {
                        "description": "Optional timeout in milliseconds (max 600000 for a foreground command)",
                        "type": "number"
                      },
                      "description": {
                        "description": "Clear, concise description of what this command does in active voice. Never use words like \"complex\" or \"risk\" in the description - just describe what it does.\n\nSay what the command does in plain words: do not echo the command's text, its flags, or file paths - the user reads this description, often without seeing the command.\n\nFor simple commands (git, npm, standard CLI tools), keep it brief (5-10 words):\n- ls → \"List files in current directory\"\n- git status → \"Show working tree status\"\n- npm install → \"Install package dependencies\"\n\nFor commands that are harder to parse at a glance (piped commands, obscure flags, etc.), add enough context to clarify what it does:\n- find . -name \"*.tmp\" -exec rm {} \\; → \"Find and delete all .tmp files recursively\"\n- git reset --hard origin/main → \"Discard all local changes and match remote main\"\n- curl -s url | jq '.data[]' → \"Fetch JSON from URL and extract data array elements\"",
                        "type": "string"
                      },
                      "run_in_background": {
                        "description": "Set to true to run this command in the background. With it, `timeout` limits how long the command may run in the background before it is stopped (default 1800000 ms, max 7200000 ms).",
                        "type": "boolean"
                      },
                      "dangerouslyDisableSandbox": {
                        "description": "Set this to true to dangerously override sandbox mode and run commands without sandboxing.",
                        "type": "boolean"
                      }
                    },
                    "required": [
                      "command"
                    ],
                    "additionalProperties": false
                  }
                }
              },
              {
                "name": "Edit",
                "description": "Performs exact string replacement in a file.\n\n- You must Read the file in this conversation before editing, or the call will fail.\n- `old_string` must match the file exactly, including indentation, and be unique — the edit fails otherwise. Strip the Read line prefix (line number + tab) before matching.\n- `replace_all: true` replaces every occurrence instead.",
                "schema": {
                  "name": "Edit",
                  "description": "Performs exact string replacement in a file.\n\n- You must Read the file in this conversation before editing, or the call will fail.\n- `old_string` must match the file exactly, including indentation, and be unique — the edit fails otherwise. Strip the Read line prefix (line number + tab) before matching.\n- `replace_all: true` replaces every occurrence instead.",
                  "input_schema": {
                    "$schema": "https://json-schema.org/draft/2020-12/schema",
                    "type": "object",
                    "properties": {
                      "file_path": {
                        "description": "The absolute path to the file to modify",
                        "type": "string"
                      },
                      "old_string": {
                        "description": "The text to replace",
                        "type": "string"
                      },
                      "new_string": {
                        "description": "The text to replace it with (must be different from old_string)",
                        "type": "string"
                      },
                      "replace_all": {
                        "description": "Replace all occurrences of old_string (default false)",
                        "default": false,
                        "type": "boolean"
                      }
                    },
                    "required": [
                      "file_path",
                      "old_string",
                      "new_string"
                    ],
                    "additionalProperties": false
                  }
                }
              },
              {
                "name": "ListAgents",
                "description": "Lists agents you can SendMessage to — in-process subagents you spawned, the teammates on your team, other local Claude sessions on this machine, your Claude sessions running in the cloud (when this session has cloud access; a cloud session receives your message but cannot message any session back yet — do not ask it to reply, read its answer in its own transcript), and (when Remote Control is connected here) your account's other sessions — Remote Control sessions on other machines and cloud sessions, each row labeled by kind. Names are the address: send with `SendMessage({to: \"<name>\", message: \"...\"})`, copying the name exactly as a row prints it. Append a row's ` [ref]` only when the bare name is not enough — two rows share it, or an error asks you to disambiguate.",
                "schema": {
                  "name": "ListAgents",
                  "description": "Lists agents you can SendMessage to — in-process subagents you spawned, the teammates on your team, other local Claude sessions on this machine, your Claude sessions running in the cloud (when this session has cloud access; a cloud session receives your message but cannot message any session back yet — do not ask it to reply, read its answer in its own transcript), and (when Remote Control is connected here) your account's other sessions — Remote Control sessions on other machines and cloud sessions, each row labeled by kind. Names are the address: send with `SendMessage({to: \"<name>\", message: \"...\"})`, copying the name exactly as a row prints it. Append a row's ` [ref]` only when the bare name is not enough — two rows share it, or an error asks you to disambiguate.",
                  "input_schema": {
                    "$schema": "https://json-schema.org/draft/2020-12/schema",
                    "type": "object",
                    "properties": {
                      "channel": {
                        "description": "Not available in this build; leave unset.",
                        "type": "string",
                        "maxLength": 256
                      },
                      "q": {
                        "description": "Not available in this build; leave unset.",
                        "type": "string",
                        "maxLength": 256
                      }
                    },
                    "additionalProperties": false
                  }
                }
              },
              {
                "name": "Read",
                "description": "Reads a file from the local filesystem.\n\n- `file_path` must be an absolute path.\n- Reads up to 2000 lines by default.\n- When you already know which part of the file you need, only read that part. This can be important for larger files.\n- Results are returned using cat -n format, with line numbers starting at 1\n- Reads images (PNG, JPG, …) and presents them visually. Reads PDFs via the `pages` parameter (e.g. \"1-5\", max 20 pages/request; required for PDFs over 10 pages). Reads Jupyter notebooks (.ipynb) as cells with outputs.\n- Reading a directory, a missing file, or an empty file returns an error or system reminder rather than content.\n- Do NOT re-read a file you just edited to verify — Edit/Write would have errored if the change failed, and the harness tracks file state for you.",
                "schema": {
                  "name": "Read",
                  "description": "Reads a file from the local filesystem.\n\n- `file_path` must be an absolute path.\n- Reads up to 2000 lines by default.\n- When you already know which part of the file you need, only read that part. This can be important for larger files.\n- Results are returned using cat -n format, with line numbers starting at 1\n- Reads images (PNG, JPG, …) and presents them visually. Reads PDFs via the `pages` parameter (e.g. \"1-5\", max 20 pages/request; required for PDFs over 10 pages). Reads Jupyter notebooks (.ipynb) as cells with outputs.\n- Reading a directory, a missing file, or an empty file returns an error or system reminder rather than content.\n- Do NOT re-read a file you just edited to verify — Edit/Write would have errored if the change failed, and the harness tracks file state for you.",
                  "input_schema": {
                    "$schema": "https://json-schema.org/draft/2020-12/schema",
                    "type": "object",
                    "properties": {
                      "file_path": {
                        "description": "The absolute path to the file to read",
                        "type": "string"
                      },
                      "offset": {
                        "description": "The line number to start reading from. Only provide if the file is too large to read at once",
                        "type": "integer",
                        "minimum": 0,
                        "maximum": 9007199254740991
                      },
                      "limit": {
                        "description": "The number of lines to read. Only provide if the file is too large to read at once.",
                        "type": "integer",
                        "exclusiveMinimum": 0,
                        "maximum": 9007199254740991
                      },
                      "pages": {
                        "description": "Page range for PDF files (e.g., \"1-5\", \"3\", \"10-20\"). Only applicable to PDF files. Maximum 20 pages per request.",
                        "type": "string"
                      }
                    },
                    "required": [
                      "file_path"
                    ],
                    "additionalProperties": false
                  }
                }
              },
              {
                "name": "ReportFindings",
                "description": "Report code-review findings as a typed list so the host UI can render them. Use this only when the active code-review instructions tell you to report findings with this tool; otherwise follow whatever output format those instructions specify. When reporting a review's results, call it once with the verified findings ranked most-severe first (empty array if nothing survived verification) and do not also print the findings as text. When re-reporting after applying fixes (only if the apply instructions ask for it), set `outcome` on each finding to what actually happened.",
                "schema": {
                  "name": "ReportFindings",
                  "description": "Report code-review findings as a typed list so the host UI can render them. Use this only when the active code-review instructions tell you to report findings with this tool; otherwise follow whatever output format those instructions specify. When reporting a review's results, call it once with the verified findings ranked most-severe first (empty array if nothing survived verification) and do not also print the findings as text. When re-reporting after applying fixes (only if the apply instructions ask for it), set `outcome` on each finding to what actually happened.",
                  "input_schema": {
                    "$schema": "https://json-schema.org/draft/2020-12/schema",
                    "type": "object",
                    "properties": {
                      "level": {
                        "description": "Effort level the review ran at",
                        "type": "string",
                        "enum": [
                          "low",
                          "medium",
                          "high",
                          "xhigh",
                          "max"
                        ]
                      },
                      "findings": {
                        "description": "Verified findings, most-severe first; empty if none survived",
                        "maxItems": 32,
                        "type": "array",
                        "items": {
                          "type": "object",
                          "properties": {
                            "file": {
                              "description": "Repo-relative path of the file the finding is in",
                              "type": "string"
                            },
                            "line": {
                              "description": "1-indexed line the finding anchors to",
                              "type": "integer",
                              "minimum": -9007199254740991,
                              "maximum": 9007199254740991
                            },
                            "summary": {
                              "description": "One-sentence statement of the defect",
                              "type": "string"
                            },
                            "short_summary": {
                              "description": "Compressed label for compact UI (≤60 chars): the claim alone, no rationale or consequence clause",
                              "type": "string",
                              "maxLength": 60
                            },
                            "failure_scenario": {
                              "description": "Concrete inputs/state → wrong output/crash",
                              "type": "string"
                            },
                            "category": {
                              "description": "Short kebab-case slug of the finding type, e.g. \"correctness\", \"simplification\", \"efficiency\", \"test-coverage\"",
                              "type": "string",
                              "maxLength": 40
                            },
                            "verdict": {
                              "description": "Set when a verify pass ran; absent on inline-only reviews",
                              "type": "string",
                              "enum": [
                                "CONFIRMED",
                                "PLAUSIBLE"
                              ]
                            },
                            "outcome": {
                              "description": "Set ONLY when re-reporting after applying fixes: what happened to this finding",
                              "type": "string",
                              "enum": [
                                "fixed",
                                "skipped",
                                "no_change_needed"
                              ]
                            }
                          },
                          "required": [
                            "file",
                            "summary",
                            "failure_scenario"
                          ],
                          "additionalProperties": false
                        }
                      }
                    },
                    "required": [
                      "findings"
                    ],
                    "additionalProperties": false
                  }
                }
              },
              {
                "name": "ScheduleWakeup",
                "description": "Schedule when to resume work in /loop dynamic mode — the user invoked /loop without an interval, asking you to self-pace iterations of a specific task.\n\nDo NOT schedule a short-interval wakeup to poll for background work you started — when harness-tracked work finishes, you are re-invoked automatically, so polling is wasted. Instead schedule a long fallback (1200s+) so the loop survives if the work hangs or never notifies. The exception is external work the harness cannot track (a CI run, a deploy, a remote queue) — there, pick a delay matched to how fast that state actually changes.\n\nPass the same /loop prompt back via `prompt` each turn so the next firing repeats the task. For an autonomous /loop (no user prompt), pass the literal sentinel `<<autonomous-loop-dynamic>>` as `prompt` instead — the runtime resolves it back to the autonomous-loop instructions at fire time. (There is a similar `<<autonomous-loop>>` sentinel for CronCreate-based autonomous loops; do not confuse the two — ScheduleWakeup always uses the `-dynamic` variant.) To end the loop, call this tool with `stop: true` (omit every other field) — the loop ends immediately and no further wakeups fire.\n\nSet `noop: true` if nothing changed — you checked and there's nothing to report (\"no change\", \"still waiting\", \"quiet hold\"). Set `noop: false` if something happened worth keeping — you edited a file, posted a message, advanced state, or surfaced a finding. Consecutive `noop: true` ticks are collapsed in the user's terminal view and tracked as a streak, so long quiet holds stay legible to the user without scrolling. Omit `noop` when stopping (`stop: true`).\n\n## Picking delaySeconds\n\nThis session's requests use a 1-hour Anthropic prompt-cache TTL, so effectively every allowed delay (the runtime clamps to [60, 3600]) wakes up with your conversation context still cached. There is no cache cliff inside that range to pace around, and scheduling extra wakeups just to keep the cache warm is pure waste — never do that. (If the session enters usage overage, later requests drop to the 5-minute TTL; don't try to track or preempt that — the guidance here stays the same.)\n\nMatch the delay to what you're actually waiting for:\n\n- **Actively polling external state the harness can't notify you about** (a CI run, a deploy, a remote queue): pick the delay from how fast that state actually changes. A CI run that takes ~8 minutes deserves one ~480s check, not eight 60s ones.\n- **The long fallback heartbeat** (something else — a Monitor, a task notification — is the primary wake signal): 1200s+, so quiet wakeups stay rare.\n- **Idle ticks with no specific signal to watch**: default to **1200s–1800s** (20–30 min). The loop still checks back regularly, and the user can always interrupt if they need you sooner.\n\nDon't think in cache windows — think about what you're actually waiting for.\n\n## The reason field\n\nOne short sentence on what you chose and why. Goes to telemetry and is shown back to the user. \"watching CI run\" beats \"waiting.\" The user reads this to understand what you're doing without having to predict your cadence in advance — make it specific.\n",
                "schema": {
                  "name": "ScheduleWakeup",
                  "description": "Schedule when to resume work in /loop dynamic mode — the user invoked /loop without an interval, asking you to self-pace iterations of a specific task.\n\nDo NOT schedule a short-interval wakeup to poll for background work you started — when harness-tracked work finishes, you are re-invoked automatically, so polling is wasted. Instead schedule a long fallback (1200s+) so the loop survives if the work hangs or never notifies. The exception is external work the harness cannot track (a CI run, a deploy, a remote queue) — there, pick a delay matched to how fast that state actually changes.\n\nPass the same /loop prompt back via `prompt` each turn so the next firing repeats the task. For an autonomous /loop (no user prompt), pass the literal sentinel `<<autonomous-loop-dynamic>>` as `prompt` instead — the runtime resolves it back to the autonomous-loop instructions at fire time. (There is a similar `<<autonomous-loop>>` sentinel for CronCreate-based autonomous loops; do not confuse the two — ScheduleWakeup always uses the `-dynamic` variant.) To end the loop, call this tool with `stop: true` (omit every other field) — the loop ends immediately and no further wakeups fire.\n\nSet `noop: true` if nothing changed — you checked and there's nothing to report (\"no change\", \"still waiting\", \"quiet hold\"). Set `noop: false` if something happened worth keeping — you edited a file, posted a message, advanced state, or surfaced a finding. Consecutive `noop: true` ticks are collapsed in the user's terminal view and tracked as a streak, so long quiet holds stay legible to the user without scrolling. Omit `noop` when stopping (`stop: true`).\n\n## Picking delaySeconds\n\nThis session's requests use a 1-hour Anthropic prompt-cache TTL, so effectively every allowed delay (the runtime clamps to [60, 3600]) wakes up with your conversation context still cached. There is no cache cliff inside that range to pace around, and scheduling extra wakeups just to keep the cache warm is pure waste — never do that. (If the session enters usage overage, later requests drop to the 5-minute TTL; don't try to track or preempt that — the guidance here stays the same.)\n\nMatch the delay to what you're actually waiting for:\n\n- **Actively polling external state the harness can't notify you about** (a CI run, a deploy, a remote queue): pick the delay from how fast that state actually changes. A CI run that takes ~8 minutes deserves one ~480s check, not eight 60s ones.\n- **The long fallback heartbeat** (something else — a Monitor, a task notification — is the primary wake signal): 1200s+, so quiet wakeups stay rare.\n- **Idle ticks with no specific signal to watch**: default to **1200s–1800s** (20–30 min). The loop still checks back regularly, and the user can always interrupt if they need you sooner.\n\nDon't think in cache windows — think about what you're actually waiting for.\n\n## The reason field\n\nOne short sentence on what you chose and why. Goes to telemetry and is shown back to the user. \"watching CI run\" beats \"waiting.\" The user reads this to understand what you're doing without having to predict your cadence in advance — make it specific.\n",
                  "input_schema": {
                    "$schema": "https://json-schema.org/draft/2020-12/schema",
                    "type": "object",
                    "properties": {
                      "delaySeconds": {
                        "description": "Seconds from now to wake up. Clamped to [60, 3600] by the runtime. Required unless `stop` is true.",
                        "type": "number"
                      },
                      "reason": {
                        "description": "One short sentence explaining the chosen delay. Goes to telemetry and is shown to the user. Be specific. Required unless `stop` is true.",
                        "type": "string"
                      },
                      "prompt": {
                        "description": "The /loop input to fire on wake-up. Pass the same /loop input verbatim each turn so the next firing re-enters the skill and continues the loop. For autonomous /loop (no user prompt), pass the literal sentinel `<<autonomous-loop-dynamic>>` instead (the dynamic-pacing variant, not the CronCreate-mode `<<autonomous-loop>>`). Required unless `stop` is true.",
                        "type": "string"
                      },
                      "stop": {
                        "description": "Set to true to end the dynamic loop immediately instead of scheduling another wakeup. When true, all other fields are ignored and no further wakeups fire.",
                        "type": "boolean"
                      },
                      "noop": {
                        "description": "true = nothing changed (you checked and there is nothing to report). false = something happened worth keeping (edited a file, posted a message, advanced state, surfaced a finding). Consecutive noop:true ticks are collapsed in the user's terminal view and tracked as a streak. Required unless `stop` is true.",
                        "type": "boolean"
                      }
                    },
                    "additionalProperties": false
                  }
                }
              },
              {
                "name": "Skill",
                "description": "Invoke a skill.\n\nA skill is a packaged set of instructions the user or project has set up for a particular kind of task (deploy steps, a review checklist, a repo-specific workflow). Available skills appear in a system-reminder listing with one-line descriptions. When the task at hand is one a listed skill covers, call this tool first — the skill's instructions load into the turn for you to follow in place of your default approach; some skills instead run in a subagent and return the finished result. A skill that runs in the background returns only the agent's name — its result arrives later as a task notification, so don't wait on it or invoke it again in the meantime. Users may also ask for one by name (`/<name>`, or \"slash command\"); that's a request to invoke it.\n\n- `skill`: exact name from the listing, no leading slash. Plugin skills use `plugin:skill`. Directory-scoped skills are listed with a path prefix (`apps/web:deploy`); when both scoped and unscoped variants of a name exist, pick the one whose directory contains the files you're working on (most specific wins; unscoped otherwise).\n- `args`: optional arguments to pass through.\n\nOnly names from the listing (or that the user typed explicitly) are valid. Built-in CLI commands (`/help`, `/clear`, …) aren't skills. If a `<command-name>` block is already present this turn, the skill is loaded — follow it directly rather than calling again.\n",
                "schema": {
                  "name": "Skill",
                  "description": "Invoke a skill.\n\nA skill is a packaged set of instructions the user or project has set up for a particular kind of task (deploy steps, a review checklist, a repo-specific workflow). Available skills appear in a system-reminder listing with one-line descriptions. When the task at hand is one a listed skill covers, call this tool first — the skill's instructions load into the turn for you to follow in place of your default approach; some skills instead run in a subagent and return the finished result. A skill that runs in the background returns only the agent's name — its result arrives later as a task notification, so don't wait on it or invoke it again in the meantime. Users may also ask for one by name (`/<name>`, or \"slash command\"); that's a request to invoke it.\n\n- `skill`: exact name from the listing, no leading slash. Plugin skills use `plugin:skill`. Directory-scoped skills are listed with a path prefix (`apps/web:deploy`); when both scoped and unscoped variants of a name exist, pick the one whose directory contains the files you're working on (most specific wins; unscoped otherwise).\n- `args`: optional arguments to pass through.\n\nOnly names from the listing (or that the user typed explicitly) are valid. Built-in CLI commands (`/help`, `/clear`, …) aren't skills. If a `<command-name>` block is already present this turn, the skill is loaded — follow it directly rather than calling again.\n",
                  "input_schema": {
                    "$schema": "https://json-schema.org/draft/2020-12/schema",
                    "type": "object",
                    "properties": {
                      "skill": {
                        "description": "The name of a skill from the available-skills list. Do not guess names.",
                        "type": "string"
                      },
                      "args": {
                        "description": "Optional arguments for the skill",
                        "type": "string"
                      }
                    },
                    "required": [
                      "skill"
                    ],
                    "additionalProperties": false
                  }
                }
              },
              {
                "name": "ToolSearch",
                "description": "Fetches full schema definitions for deferred tools so they can be called.\n\nDeferred tools appear by name in <system-reminder> messages. Until fetched, only the name is known — there is no parameter schema, so the tool cannot be invoked. This tool takes a query, matches it against the deferred tool list, and returns the matched tools' complete JSONSchema definitions inside a <functions> block. Once a tool's schema appears in that result, it is callable exactly like any tool defined at the top of the prompt.\n\nResult format: each matched tool appears as one <function>{\"description\": \"...\", \"name\": \"...\", \"parameters\": {...}}</function> line inside the <functions> block — the same encoding as the tool list at the top of this prompt.\n\nQuery forms:\n- \"select:Read,Edit,Grep\" — fetch these exact tools by name\n- \"notebook jupyter\" — keyword search, up to max_results best matches\n- \"+slack send\" — require \"slack\" in the name, rank by remaining terms",
                "schema": {
                  "name": "ToolSearch",
                  "description": "Fetches full schema definitions for deferred tools so they can be called.\n\nDeferred tools appear by name in <system-reminder> messages. Until fetched, only the name is known — there is no parameter schema, so the tool cannot be invoked. This tool takes a query, matches it against the deferred tool list, and returns the matched tools' complete JSONSchema definitions inside a <functions> block. Once a tool's schema appears in that result, it is callable exactly like any tool defined at the top of the prompt.\n\nResult format: each matched tool appears as one <function>{\"description\": \"...\", \"name\": \"...\", \"parameters\": {...}}</function> line inside the <functions> block — the same encoding as the tool list at the top of this prompt.\n\nQuery forms:\n- \"select:Read,Edit,Grep\" — fetch these exact tools by name\n- \"notebook jupyter\" — keyword search, up to max_results best matches\n- \"+slack send\" — require \"slack\" in the name, rank by remaining terms",
                  "input_schema": {
                    "$schema": "https://json-schema.org/draft/2020-12/schema",
                    "type": "object",
                    "properties": {
                      "query": {
                        "description": "Query to find deferred tools. Use \"select:<tool_name>\" for direct selection, or keywords to search.",
                        "type": "string"
                      },
                      "max_results": {
                        "description": "Maximum number of results to return (default: 5)",
                        "default": 5,
                        "type": "number"
                      }
                    },
                    "required": [
                      "query",
                      "max_results"
                    ],
                    "additionalProperties": false
                  }
                }
              },
              {
                "name": "Workflow",
                "description": "Execute a workflow script that orchestrates multiple subagents deterministically. Workflows run in the background — this tool returns immediately with a task ID, and a <task-notification> arrives when the workflow completes. Use /workflows to watch live progress.\n\nONLY call this tool when the user has explicitly opted into multi-agent orchestration. Workflows can spawn dozens of agents and consume a large amount of tokens; the user must request that scale, not have it inferred. Explicit opt-in means one of:\n- The user included the keyword \"ultracode\" in their prompt (you'll see a system-reminder confirming it).\n- Ultracode is on for the session (a system-reminder confirms it) — see **Ultracode** in the workflow authoring reference.\n- The user directly asked you to run a workflow or use multi-agent orchestration in their own words (\"use a workflow\", \"run a workflow\", \"fan out agents\", \"orchestrate this with subagents\"). The ask must be in the user's words — a task that would merely benefit from a workflow does not count.\n- The user invoked a skill or slash command whose instructions tell you to call Workflow.\n- The user asked you to run a specific named or saved workflow.\n\nFor any other task — even one that would clearly benefit from parallelism — do NOT call this tool. Use the Agent tool (if available) for individual subagents, or briefly describe what a multi-agent workflow could do and how much it would roughly cost, and ask the user whether to run it. Mention they can ask for one with \"use a workflow\" in a future message to skip the ask.\n\nEvery script must begin with `export const meta = {...}`: a PURE LITERAL (no variables, calls or interpolation) giving the workflow's `name`, a one-line `description` (shown in the permission dialog) and optionally `phases` — one `{ title, detail? }` per phase() call, titles matched exactly. Pass the script inline via `script` — do not Write it to a file first, and do not also set the tool's `name` input (that selects a saved workflow); it is plain JavaScript, not TypeScript.\n\nThe canonical multi-stage pattern — pipeline by default, each dimension verifies as soon as its review completes:\n  export const meta = {\n    name: 'review-changes',\n    description: 'Review changed files across dimensions, verify each finding',\n    phases: [{ title: 'Review' }, { title: 'Verify' }],\n  }\n  const DIMENSIONS = [{key: 'bugs', prompt: '...'}, {key: 'perf', prompt: '...'}]\n  const results = await pipeline(\n    DIMENSIONS,\n    d => agent(d.prompt, {label: `review:${d.key}`, phase: 'Review', schema: FINDINGS_SCHEMA}),\n    review => parallel(review.findings.map(f => () =>\n      agent(`Adversarially verify: ${f.title}`, {label: `verify:${f.file}`, phase: 'Verify', schema: VERDICT_SCHEMA})\n        .then(v => ({...f, verdict: v}))\n    ))\n  )\n  const confirmed = results.flat().filter(Boolean).filter(f => f.verdict?.isReal)\n  return { confirmed }\n  // Dimension 'bugs' findings verify while dimension 'perf' is still reviewing. No wasted wall-clock.\n\nBefore writing a script, load the `workflow-authoring` skill — the workflow authoring reference: script API and gotchas, resume, the **Ultracode** section, quality patterns, worked examples.\n\nThis session has the default workflow size guideline: medium — keep workflows under 10 agents. This is a guideline, not a hard limit — follow it unless the user's prompt calls for a different scale. The user can raise or remove it with \"Dynamic workflow size\" in /config.",
                "schema": {
                  "name": "Workflow",
                  "description": "Execute a workflow script that orchestrates multiple subagents deterministically. Workflows run in the background — this tool returns immediately with a task ID, and a <task-notification> arrives when the workflow completes. Use /workflows to watch live progress.\n\nONLY call this tool when the user has explicitly opted into multi-agent orchestration. Workflows can spawn dozens of agents and consume a large amount of tokens; the user must request that scale, not have it inferred. Explicit opt-in means one of:\n- The user included the keyword \"ultracode\" in their prompt (you'll see a system-reminder confirming it).\n- Ultracode is on for the session (a system-reminder confirms it) — see **Ultracode** in the workflow authoring reference.\n- The user directly asked you to run a workflow or use multi-agent orchestration in their own words (\"use a workflow\", \"run a workflow\", \"fan out agents\", \"orchestrate this with subagents\"). The ask must be in the user's words — a task that would merely benefit from a workflow does not count.\n- The user invoked a skill or slash command whose instructions tell you to call Workflow.\n- The user asked you to run a specific named or saved workflow.\n\nFor any other task — even one that would clearly benefit from parallelism — do NOT call this tool. Use the Agent tool (if available) for individual subagents, or briefly describe what a multi-agent workflow could do and how much it would roughly cost, and ask the user whether to run it. Mention they can ask for one with \"use a workflow\" in a future message to skip the ask.\n\nEvery script must begin with `export const meta = {...}`: a PURE LITERAL (no variables, calls or interpolation) giving the workflow's `name`, a one-line `description` (shown in the permission dialog) and optionally `phases` — one `{ title, detail? }` per phase() call, titles matched exactly. Pass the script inline via `script` — do not Write it to a file first, and do not also set the tool's `name` input (that selects a saved workflow); it is plain JavaScript, not TypeScript.\n\nThe canonical multi-stage pattern — pipeline by default, each dimension verifies as soon as its review completes:\n  export const meta = {\n    name: 'review-changes',\n    description: 'Review changed files across dimensions, verify each finding',\n    phases: [{ title: 'Review' }, { title: 'Verify' }],\n  }\n  const DIMENSIONS = [{key: 'bugs', prompt: '...'}, {key: 'perf', prompt: '...'}]\n  const results = await pipeline(\n    DIMENSIONS,\n    d => agent(d.prompt, {label: `review:${d.key}`, phase: 'Review', schema: FINDINGS_SCHEMA}),\n    review => parallel(review.findings.map(f => () =>\n      agent(`Adversarially verify: ${f.title}`, {label: `verify:${f.file}`, phase: 'Verify', schema: VERDICT_SCHEMA})\n        .then(v => ({...f, verdict: v}))\n    ))\n  )\n  const confirmed = results.flat().filter(Boolean).filter(f => f.verdict?.isReal)\n  return { confirmed }\n  // Dimension 'bugs' findings verify while dimension 'perf' is still reviewing. No wasted wall-clock.\n\nBefore writing a script, load the `workflow-authoring` skill — the workflow authoring reference: script API and gotchas, resume, the **Ultracode** section, quality patterns, worked examples.\n\nThis session has the default workflow size guideline: medium — keep workflows under 10 agents. This is a guideline, not a hard limit — follow it unless the user's prompt calls for a different scale. The user can raise or remove it with \"Dynamic workflow size\" in /config.",
                  "input_schema": {
                    "$schema": "https://json-schema.org/draft/2020-12/schema",
                    "type": "object",
                    "properties": {
                      "script": {
                        "description": "Self-contained workflow script. Must begin with `export const meta = { name, description, phases }` (pure literal, no computed values) followed by the script body using agent()/parallel()/pipeline()/phase().",
                        "type": "string",
                        "maxLength": 524288
                      },
                      "name": {
                        "description": "Name of a predefined workflow (built-in or from .claude/workflows/). Resolves to a self-contained script.",
                        "type": "string"
                      },
                      "description": {
                        "description": "Ignored — set the workflow description in the script's `meta` block.",
                        "type": "string"
                      },
                      "title": {
                        "description": "Ignored — set the workflow title in the script's `meta` block.",
                        "type": "string"
                      },
                      "args": {
                        "description": "Optional input value exposed to the script as the global `args`, verbatim. Pass arrays/objects as actual JSON values, NOT as a JSON-encoded string — a stringified list breaks `args.filter`/`args.map` in the script. Use for parameterized named workflows (e.g. a research question)."
                      },
                      "scriptPath": {
                        "description": "Path to a workflow script file on disk. Every Workflow invocation persists its script under the session directory and returns the path in the tool result. To iterate, edit that file with Write/Edit and re-invoke Workflow with the same `scriptPath` instead of re-sending the full script. Takes precedence over `script` and `name`.",
                        "type": "string"
                      },
                      "resumeFromRunId": {
                        "description": "Run ID of a prior Workflow invocation to resume from. Completed agent() calls with unchanged (prompt, opts) return their cached results instantly; only edited or new calls re-run. Same-session only. Stop the prior run first (TaskStop) before resuming.",
                        "type": "string",
                        "pattern": "^wf_[a-z0-9-]{6,}$"
                      }
                    },
                    "additionalProperties": false
                  }
                }
              },
              {
                "name": "Write",
                "description": "Writes a file to the local filesystem, overwriting if one exists.\n\nWhen to use: creating a new file, or fully replacing one you've already Read. Overwriting an existing file you haven't Read will fail. For partial changes, use Edit instead.",
                "schema": {
                  "name": "Write",
                  "description": "Writes a file to the local filesystem, overwriting if one exists.\n\nWhen to use: creating a new file, or fully replacing one you've already Read. Overwriting an existing file you haven't Read will fail. For partial changes, use Edit instead.",
                  "input_schema": {
                    "$schema": "https://json-schema.org/draft/2020-12/schema",
                    "type": "object",
                    "properties": {
                      "file_path": {
                        "description": "The absolute path to the file to write (must be absolute, not relative)",
                        "type": "string"
                      },
                      "content": {
                        "description": "The content to write to the file",
                        "type": "string"
                      }
                    },
                    "required": [
                      "file_path",
                      "content"
                    ],
                    "additionalProperties": false
                  }
                }
              }
            ],
            "cliPrefix": "You are a Claude agent, built on Anthropic's Claude Agent SDK.",
            "reminderFold": false,
            "systemTurns": true,
            "toolChangeHeader": true,
            "inlineTools": false,
            "keptReminders": true,
            "echoWireToolInputs": false,
            "contextRendering": "announced"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:02:55.741Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14979852 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:02:55.744Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 3,
      "role": "agent",
      "timestamp": "2026-10-03T09:02:59.856Z",
      "blocks": [
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:02:59.856Z",
          "callId": "toolu_01MS7Y2m8BHeG5UNivh29pXD",
          "name": "Bash",
          "input": {
            "command": "cat /task/current_model/train_current_model.py",
            "description": "Read production training script"
          },
          "result": {
            "timestamp": "2026-10-03T09:02:59.876Z",
            "content": "<persisted-output>\nOutput too large (78.2KB). Full output saved to: /logs/agent/sessions/projects/-app/4e8789ae-79ff-49af-b921-d2d476bce141/tool-results/bno7w1rc2.txt\n\nPreview (first 2KB):\n#!/usr/bin/env python3\n\"\"\"Train the Yambda windowed two-tower baseline.\n\nEvery catalog listen with at least 50 percent completion is a sequence token.\nWithin each selected chronological window, every adjacent target contributes a\nloss.  The fast default retains each user's most recent 128 training targets and\n16 held-out validation targets; passing zero for either cap restores the\nuncapped behavior for that side of the split.  A 100-step truncated-BPTT block\ncomputes all of its timestep losses and carries the detached GRU hidden state\ninto the next block.\n\nThe model is a pure two-tower retriever: no user-ID embedding, no output\nnormalization, raw dot-product retrieval, sample-weighted binary cross entropy,\nand 24 uniform plus eight propensity-corrected unique in-batch negatives. Every\nselected adjacent target retains a nonzero weight. Only files under the supplied\npublic directory are read.\n\"\"\"\nfrom __future__ import annotations\n\nimport argparse\nimport json\nimport random\nimport sys\nimport time\nfrom dataclasses import asdict, dataclass\nfrom pathlib import Path\n\nimport numpy as np\nimport pandas as pd\nimport torch\nfrom torch import nn\nfrom torch.nn import functional as F\n\nimport two_tower_model as base\n\n\nCACHE_VERSION = 2\n\n\n@dataclass(frozen=True)\nclass Config:\n    bptt_steps: int = 100\n    user_batch_size: int = 64\n    embedding_dim: int = 192\n    hidden_dim: int = 192\n    user_hidden_1: int = 512\n    user_hidden_2: int = 256\n    item_hidden_1: int = 512\n    item_hidden_2: int = 256\n    dropout: float = 0.05\n    epochs: int = 1\n    learning_rate: float = 1.0e-3\n    weight_decay: float = 1.0e-5\n    gradient_clip: float = 2.0\n    loss_microbatch_size: int = 65_536\n    uniform_negatives: int = 24\n    inbatch_negatives: int = 8\n    inbatch_correction_power: float = 0.5\n    inbatch_correction_min: float = 0.25\n    inbatch_correction_max: float = 4.0\n    negative_filter_scope: str = \"full-training-history\"\n    target_weighting: str = \"organic-strong\"\n...\n</persisted-output>",
            "isError": false
          }
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:03:00.279Z",
          "callId": "toolu_01HNNQ3e9hQ5YWr2aNhbpC8E",
          "name": "Bash",
          "input": {
            "command": "cat /task/current_model/two_tower_model.py; echo ======; cat /task/evaluate_public.py; echo ======; cat /task/ranking_evaluation.py",
            "description": "Read model primitives and evaluator"
          },
          "result": {
            "timestamp": "2026-10-03T09:03:00.309Z",
            "content": "<persisted-output>\nOutput too large (29.3KB). Full output saved to: /logs/agent/sessions/projects/-app/4e8789ae-79ff-49af-b921-d2d476bce141/tool-results/bk8s341n6.txt\n\nPreview (first 2KB):\n\"\"\"Shared public-data primitives for the Yambda two-tower baseline.\"\"\"\nfrom __future__ import annotations\n\nimport sys\nfrom dataclasses import dataclass\nfrom pathlib import Path\nfrom typing import Iterator\n\nimport numpy as np\nimport pandas as pd\nimport pyarrow.parquet as pq\nimport torch\nfrom torch import nn\n\n\nDAY = 86_400\nTRAIN_END = 24_786_800\nVALIDATION_END = 25_393_400\nLISTEN_POSITIVE_THRESHOLD = 50\nPROFILE_LOOKBACK_DAYS = 120\nLIKE_ITEMS = 48\nDISLIKE_ITEMS = 24\nTOP_N = 100\n\n\n@dataclass(frozen=True)\nclass TowerConfig:\n    sequence_length: int = 100\n    embedding_dim: int = 192\n    hidden_dim: int = 192\n    user_hidden_1: int = 512\n    user_hidden_2: int = 256\n    item_hidden_1: int = 512\n    item_hidden_2: int = 256\n    dropout: float = 0.05\n    epochs: int = 1\n    learning_rate: float = 1.0e-3\n    weight_decay: float = 1.0e-5\n    gradient_clip: float = 2.0\n    uniform_negatives: int = 24\n    inbatch_negatives: int = 8\n    inbatch_correction_power: float = 0.5\n    inbatch_correction_min: float = 0.25\n    inbatch_correction_max: float = 4.0\n    seed: int = 29\n\n\n@dataclass(frozen=True)\nclass ListenEvents:\n    timestamps: np.ndarray\n    items: np.ndarray\n    organic: np.ndarray\n    completion_pct: np.ndarray\n\n\n@dataclass(frozen=True)\nclass ExplicitEvents:\n    timestamps: np.ndarray\n    items: np.ndarray\n    channel: np.ndarray\n    active: np.ndarray\n    organic_like: np.ndarray\n\n\ndef log(message: str) -> None:\n    print(message, file=sys.stderr, flush=True)\n\n\ndef build_item_features(catalog: pd.DataFrame) -> np.ndarray:\n    \"\"\"Return four standardized features built only from the public catalog.\"\"\"\n    positives = catalog.positive_listens.to_numpy(dtype=np.float64, copy=False)\n    organic = catalog.organic_positive_listens.to_numpy(dtype=np.float64, copy=False)\n    popularity_rank = catalog.popularity_rank.to_numpy(dtype=np.float64, copy=False)\n    features = np.column_stack(\n        [\n            np.log1p(positives),\n            np.log1p(organic),\n...\n</persisted-output>",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:03:00.313Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14977504 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:03:00.315Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 4,
      "role": "agent",
      "timestamp": "2026-10-03T09:03:05.333Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:03:05.333Z",
          "text": "These files are large, so I'll read the source files directly in chunks instead.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:03:05.335Z",
          "callId": "toolu_014mfGgwQYkQKYseN47qWDVc",
          "name": "Read",
          "input": {
            "file_path": "/task/current_model/train_current_model.py",
            "limit": 700
          },
          "result": {
            "timestamp": "2026-10-03T09:03:05.364Z",
            "content": "1\t#!/usr/bin/env python3\n2\t\"\"\"Train the Yambda windowed two-tower baseline.\n3\t\n4\tEvery catalog listen with at least 50 percent completion is a sequence token.\n5\tWithin each selected chronological window, every adjacent target contributes a\n6\tloss.  The fast default retains each user's most recent 128 training targets and\n7\t16 held-out validation targets; passing zero for either cap restores the\n8\tuncapped behavior for that side of the split.  A 100-step truncated-BPTT block\n9\tcomputes all of its timestep losses and carries the detached GRU hidden state\n10\tinto the next block.\n11\t\n12\tThe model is a pure two-tower retriever: no user-ID embedding, no output\n13\tnormalization, raw dot-product retrieval, sample-weighted binary cross entropy,\n14\tand 24 uniform plus eight propensity-corrected unique in-batch negatives. Every\n15\tselected adjacent target retains a nonzero weight. Only files under the supplied\n16\tpublic directory are read.\n17\t\"\"\"\n18\tfrom __future__ import annotations\n19\t\n20\timport argparse\n21\timport json\n22\timport random\n23\timport sys\n24\timport time\n25\tfrom dataclasses import asdict, dataclass\n26\tfrom pathlib import Path\n27\t\n28\timport numpy as np\n29\timport pandas as pd\n30\timport torch\n31\tfrom torch import nn\n32\tfrom torch.nn import functional as F\n33\t\n34\timport two_tower_model as base\n35\t\n36\t\n37\tCACHE_VERSION = 2\n38\t\n39\t\n40\t@dataclass(frozen=True)\n41\tclass Config:\n42\t    bptt_steps: int = 100\n43\t    user_batch_size: int = 64\n44\t    embedding_dim: int = 192\n45\t    hidden_dim: int = 192\n46\t    user_hidden_1: int = 512\n47\t    user_hidden_2: int = 256\n48\t    item_hidden_1: int = 512\n49\t    item_hidden_2: int = 256\n50\t    dropout: float = 0.05\n51\t    epochs: int = 1\n52\t    learning_rate: float = 1.0e-3\n53\t    weight_decay: float = 1.0e-5\n54\t    gradient_clip: float = 2.0\n55\t    loss_microbatch_size: int = 65_536\n56\t    uniform_negatives: int = 24\n57\t    inbatch_negatives: int = 8\n58\t    inbatch_correction_power: float = 0.5\n59\t    inbatch_correction_min: float = 0.25\n60\t    inbatch_correction_max: float = 4.0\n61\t    negative_filter_scope: str = \"full-training-history\"\n62\t    target_weighting: str = \"organic-strong\"\n63\t    ordinary_target_weight: float = 0.25\n64\t    organic_strong_target_weight: float = 1.0\n65\t    organic_like_target_weight: float = 3.0\n66\t    discovery_horizon_days: int = 7\n67\t    validation_fraction: float = 0.10\n68\t    max_train_targets_per_user: int = 128\n69\t    max_validation_targets_per_user: int = 16\n70\t    early_stopping_patience: int = 1\n71\t    early_stopping_min_delta: float = 1.0e-4\n72\t    seed: int = 29\n73\t\n74\t\n75\t@dataclass(frozen=True)\n76\tclass CandidateSet:\n77\t    uids: np.ndarray\n78\t    item_ids: np.ndarray\n79\t    packed: np.ndarray\n80\t\n81\t    @classmethod\n82\t    def read(cls, path: Path) -> \"CandidateSet\":\n83\t        with np.load(path, allow_pickle=False) as artifact:\n84\t            result = cls(\n85\t                uids=artifact[\"uids\"].astype(np.int64, copy=True),\n86\t                item_ids=artifact[\"item_ids\"].astype(np.int64, copy=True),\n87\t                packed=artifact[\"packed_eligible\"].astype(np.uint8, copy=True),\n88\t            )\n89\t        expected = (len(result.uids), (len(result.item_ids) + 7) // 8)\n90\t        if result.packed.shape != expected:\n91\t            raise ValueError(\n92\t                f\"invalid candidate artifact shape {result.packed.shape}; \"\n93\t                f\"expected {expected}\"\n94\t            )\n95\t        return result\n96\t\n97\t\n98\t@dataclass(frozen=True)\n99\tclass SequenceData:\n100\t    item_ids: np.ndarray\n101\t    item_features: np.ndarray\n102\t    user_ids: np.ndarray\n103\t    offsets: np.ndarray\n104\t    sequence_timestamps: np.ndarray\n105\t    sequence_items: np.ndarray\n106\t    event_features: np.ndarray\n107\t    activity_features: np.ndarray\n108\t    state_ids: np.ndarray\n109\t    liked_states: np.ndarray\n110\t    disliked_states: np.ndarray\n111\t    state_counts: np.ndarray\n112\t    inference_user_rows: np.ndarray\n113\t    inference_liked_items: np.ndarray\n114\t    inference_disliked_items: np.ndarray\n115\t    inference_user_features: np.ndarray\n116\t\n117\t    @property\n118\t    def lengths(self) -> np.ndarray:\n119\t        return np.diff(self.offsets)\n120\t\n121\t    @property\n122\t    def target_count(self) -> int:\n123\t        return int(np.maximum(self.lengths - 1, 0).sum())\n124\t\n125\t\n126\t@dataclass(frozen=True)\n127\tclass TargetPartition:\n128\t    \"\"\"A contiguous recent target window and its chronological BCE split.\"\"\"\n129\t\n130\t    window_starts: np.ndarray\n131\t    training_counts: np.ndarray\n132\t    validation_counts: np.ndarray\n133\t    history_training_counts: np.ndarray\n134\t\n135\t    @property\n136\t    def selected_count(self) -> int:\n137\t        return int(self.training_counts.sum() + self.validation_counts.sum())\n138\t\n139\t\n140\tdef log(message: str) -> None:\n141\t    print(message, file=sys.stderr, flush=True)\n142\t\n143\t\n144\tdef seed_everything(seed: int) -> None:\n145\t    random.seed(seed)\n146\t    np.random.seed(seed)\n147\t    torch.manual_seed(seed)\n148\t\n149\t\n150\tdef model_config(config: Config) -> base.TowerConfig:\n151\t    \"\"\"Map the dense trainer configuration onto the unchanged tower.\"\"\"\n152\t    return base.TowerConfig(\n153\t        sequence_length=config.bptt_steps,\n154\t        embedding_dim=config.embedding_dim,\n155\t        hidden_dim=config.hidden_dim,\n156\t        user_hidden_1=config.user_hidden_1,\n157\t        user_hidden_2=config.user_hidden_2,\n158\t        item_hidden_1=config.item_hidden_1,\n159\t        item_hidden_2=config.item_hidden_2,\n160\t        dropout=config.dropout,\n161\t        epochs=config.epochs,\n162\t        learning_rate=config.learning_rate,\n163\t        weight_decay=config.weight_decay,\n164\t        gradient_clip=config.gradient_clip,\n165\t        uniform_negatives=config.uniform_negatives,\n166\t        inbatch_negatives=config.inbatch_negatives,\n167\t        inbatch_correction_power=config.inbatch_correction_power,\n168\t        inbatch_correction_min=config.inbatch_correction_min,\n169\t        inbatch_correction_max=config.inbatch_correction_max,\n170\t        seed=config.seed,\n171\t    )\n172\t\n173\t\n174\tdef append_state_snapshot(\n175\t    active_likes: dict[int, int],\n176\t    active_dislikes: dict[int, int],\n177\t    n_items: int,\n178\t    liked_states: list[np.ndarray],\n179\t    disliked_states: list[np.ndarray],\n180\t    state_counts: list[tuple[int, int]],\n181\t) -> int:\n182\t    liked_states.append(base.pack_active_items(active_likes, base.LIKE_ITEMS, n_items))\n183\t    disliked_states.append(\n184\t        base.pack_active_items(active_dislikes, base.DISLIKE_ITEMS, n_items)\n185\t    )\n186\t    state_counts.append((len(active_likes), len(active_dislikes)))\n187\t    return len(liked_states) - 1\n188\t\n189\t\n190\tdef causal_activity_features(\n191\t    timestamps: np.ndarray,\n192\t    items: np.ndarray,\n193\t    organic: np.ndarray,\n194\t    completion: np.ndarray,\n195\t) -> np.ndarray:\n196\t    \"\"\"Compute the first four reviewed user features at every event cutoff.\"\"\"\n197\t    length = len(items)\n198\t    result = np.zeros((length, 4), dtype=np.float16)\n199\t    if not length:\n200\t        return result\n201\t    left_rows = np.searchsorted(\n202\t        timestamps,\n203\t        timestamps - base.PROFILE_LOOKBACK_DAYS * base.DAY,\n204\t        side=\"left\",\n205\t    )\n206\t    rows = np.arange(length, dtype=np.int64)\n207\t    counts = rows - left_rows + 1\n208\t    organic_sum = np.cumsum(organic.astype(np.float64))\n209\t    completion_sum = np.cumsum(np.minimum(completion, 100).astype(np.float64))\n210\t    before_organic = np.where(\n211\t        left_rows > 0, organic_sum[np.maximum(left_rows - 1, 0)], 0.0\n212\t    )\n213\t    before_completion = np.where(\n214\t        left_rows > 0, completion_sum[np.maximum(left_rows - 1, 0)], 0.0\n215\t    )\n216\t\n217\t    unique_counts = np.empty(length, dtype=np.int32)\n218\t    frequencies: dict[int, int] = {}\n219\t    left = 0\n220\t    for right, raw_item in enumerate(items):\n221\t        item = int(raw_item)\n222\t        frequencies[item] = frequencies.get(item, 0) + 1\n223\t        required_left = int(left_rows[right])\n224\t        while left < required_left:\n225\t            old_item = int(items[left])\n226\t            remaining = frequencies[old_item] - 1\n227\t            if remaining:\n228\t                frequencies[old_item] = remaining\n229\t            else:\n230\t                del frequencies[old_item]\n231\t            left += 1\n232\t        unique_counts[right] = len(frequencies)\n233\t\n234\t    result[:, 0] = (np.log1p(counts) / 8.0).astype(np.float16)\n235\t    result[:, 1] = (np.log1p(unique_counts) / 6.0).astype(np.float16)\n236\t    result[:, 2] = (\n237\t        (organic_sum - before_organic) / np.maximum(counts, 1)\n238\t    ).astype(np.float16)\n239\t    result[:, 3] = (\n240\t        (completion_sum - before_completion)\n241\t        / np.maximum(counts, 1)\n242\t        / 100.0\n243\t    ).astype(np.float16)\n244\t    return result\n245\t\n246\t\n247\tdef build_sequence_parts(\n248\t    listens: base.ListenEvents,\n249\t    explicit: base.ExplicitEvents,\n250\t    n_items: int,\n251\t    liked_states: list[np.ndarray],\n252\t    disliked_states: list[np.ndarray],\n253\t    state_counts: list[tuple[int, int]],\n254\t) -> tuple[np.ndarray, np.ndarray, np.ndarray, np.ndarray, np.ndarray] | None:\n255\t    qualifying = listens.completion_pct >= base.LISTEN_POSITIVE_THRESHOLD\n256\t    timestamps = listens.timestamps[qualifying].astype(np.int64, copy=False)\n257\t    items = listens.items[qualifying].astype(np.uint16, copy=False)\n258\t    organic = listens.organic[qualifying].astype(np.float32, copy=False)\n259\t    completion = listens.completion_pct[qualifying].astype(np.float32, copy=False)\n260\t    if not len(items):\n261\t        return None\n262\t\n263\t    event_features = np.zeros((len(items), 3), dtype=np.float16)\n264\t    event_features[:, 0] = organic.astype(np.float16)\n265\t    event_features[:, 1] = (\n266\t        np.minimum(completion, 100.0) / 100.0\n267\t    ).astype(np.float16)\n268\t    if len(items) > 1:\n269\t        gaps = np.maximum(0, timestamps[1:] - timestamps[:-1])\n270\t        event_features[1:, 2] = np.exp(\n271\t            -gaps.astype(np.float64) / (60.0 * base.DAY)\n272\t        ).astype(np.float16)\n273\t\n274\t    activity = causal_activity_features(\n275\t        timestamps, items, organic, completion\n276\t    )\n277\t    states = np.zeros(len(items), dtype=np.uint32)\n278\t    active_likes: dict[int, int] = {}\n279\t    active_dislikes: dict[int, int] = {}\n280\t    explicit_position = 0\n281\t    current_state = 0\n282\t    for row, timestamp in enumerate(timestamps):\n283\t        changed = False\n284\t        while (\n285\t            explicit_position < len(explicit.timestamps)\n286\t            and int(explicit.timestamps[explicit_position]) < int(timestamp)\n287\t        ):\n288\t            item = int(explicit.items[explicit_position])\n289\t            event_timestamp = int(explicit.timestamps[explicit_position])\n290\t            destination = (\n291\t                active_likes\n292\t                if int(explicit.channel[explicit_position]) == 0\n293\t                else active_dislikes\n294\t            )\n295\t            if int(explicit.active[explicit_position]) == 1:\n296\t                destination[item] = event_timestamp\n297\t            else:\n298\t                destination.pop(item, None)\n299\t            explicit_position += 1\n300\t            changed = True\n301\t        if changed:\n302\t            current_state = append_state_snapshot(\n303\t                active_likes,\n304\t                active_dislikes,\n305\t                n_items,\n306\t                liked_states,\n307\t                disliked_states,\n308\t                state_counts,\n309\t            )\n310\t        states[row] = np.uint32(current_state)\n311\t    return timestamps, items.copy(), event_features, activity, states\n312\t\n313\t\n314\tdef final_user_features(\n315\t    timestamps: np.ndarray,\n316\t    items: np.ndarray,\n317\t    event_features: np.ndarray,\n318\t    history_end: int,\n319\t    like_count: int,\n320\t    dislike_count: int,\n321\t) -> np.ndarray:\n322\t    start = int(\n323\t        np.searchsorted(\n324\t            timestamps,\n325\t            history_end - base.PROFILE_LOOKBACK_DAYS * base.DAY,\n326\t            side=\"left\",\n327\t        )\n328\t    )\n329\t    result = np.zeros(6, dtype=np.float32)\n330\t    recent_items = items[start:]\n331\t    if len(recent_items):\n332\t        result[0] = np.log1p(len(recent_items)) / 8.0\n333\t        result[1] = np.log1p(len(np.unique(recent_items))) / 6.0\n334\t        result[2] = float(np.mean(event_features[start:, 0]))\n335\t        result[3] = float(np.mean(event_features[start:, 1]))\n336\t    result[4] = np.log1p(like_count) / 6.0\n337\t    result[5] = np.log1p(dislike_count) / 4.0\n338\t    return result\n339\t\n340\t\n341\tdef prepare_data(\n342\t    public: Path, stage: str, config: Config\n343\t) -> tuple[SequenceData, CandidateSet]:\n344\t    data = public / \"data\"\n345\t    catalog = pd.read_parquet(data / \"candidate_catalog.parquet\").sort_values(\n346\t        \"popularity_rank\"\n347\t    )\n348\t    item_ids = catalog.item_id.to_numpy(dtype=np.int64, copy=True)\n349\t    item_index = pd.Index(item_ids)\n350\t    n_items = len(item_ids)\n351\t    if n_items >= np.iinfo(np.uint16).max:\n352\t        raise RuntimeError(\"uint16 item storage is too small for this catalog\")\n353\t\n354\t    if stage == \"validation\":\n355\t        prefixes = (\"train\",)\n356\t        history_end = base.TRAIN_END\n357\t        candidate_name = \"validation_eligible_candidates.npz\"\n358\t        state_name = \"validation_preference_state.parquet\"\n359\t    else:\n360\t        prefixes = (\"train\", \"val\")\n361\t        history_end = base.VALIDATION_END\n362\t        candidate_name = \"test_eligible_candidates.npz\"\n363\t        state_name = \"test_preference_state.parquet\"\n364\t    eligibility = CandidateSet.read(data / candidate_name)\n365\t    if not np.array_equal(eligibility.item_ids, item_ids):\n366\t        raise RuntimeError(\"catalog and candidate artifact item order differ\")\n367\t\n368\t    explicit_by_user = base.load_explicit_events(data, prefixes, item_index)\n369\t    inference_likes, inference_dislikes, like_counts, dislike_counts = (\n370\t        base.load_inference_state(\n371\t            data / state_name,\n372\t            item_index,\n373\t            eligibility.uids,\n374\t            n_items,\n375\t        )\n376\t    )\n377\t    inference_rows = {int(uid): row for row, uid in enumerate(eligibility.uids)}\n378\t    inference_user_features = np.zeros((len(eligibility.uids), 6), dtype=np.float32)\n379\t    inference_sequence_rows = np.full(len(eligibility.uids), -1, dtype=np.int32)\n380\t\n381\t    # Snapshot zero is the shared empty explicit state.\n382\t    liked_states = [np.full(base.LIKE_ITEMS, n_items, dtype=np.uint16)]\n383\t    disliked_states = [\n384\t        np.full(base.DISLIKE_ITEMS, n_items, dtype=np.uint16)\n385\t    ]\n386\t    state_counts: list[tuple[int, int]] = [(0, 0)]\n387\t    user_ids: list[int] = []\n388\t    offsets = [0]\n389\t    timestamp_parts: list[np.ndarray] = []\n390\t    item_parts: list[np.ndarray] = []\n391\t    event_parts: list[np.ndarray] = []\n392\t    activity_parts: list[np.ndarray] = []\n393\t    state_parts: list[np.ndarray] = []\n394\t\n395\t    listen_paths = [data / f\"{prefix}_listens.parquet\" for prefix in prefixes]\n396\t    started = time.monotonic()\n397\t    for seen_users, (uid, listens) in enumerate(\n398\t        base.merge_listen_streams(listen_paths, item_index), start=1\n399\t    ):\n400\t        parts = build_sequence_parts(\n401\t            listens,\n402\t            explicit_by_user.get(uid, base.empty_explicit_events()),\n403\t            n_items,\n404\t            liked_states,\n405\t            disliked_states,\n406\t            state_counts,\n407\t        )\n408\t        if parts is None:\n409\t            continue\n410\t        sequence_row = len(user_ids)\n411\t        user_ids.append(uid)\n412\t        timestamp_parts.append(parts[0].astype(np.uint32, copy=False))\n413\t        item_parts.append(parts[1])\n414\t        event_parts.append(parts[2])\n415\t        activity_parts.append(parts[3])\n416\t        state_parts.append(parts[4])\n417\t        offsets.append(offsets[-1] + len(parts[1]))\n418\t        inference_row = inference_rows.get(uid)\n419\t        if inference_row is not None:\n420\t            inference_sequence_rows[inference_row] = sequence_row\n421\t            inference_user_features[inference_row] = final_user_features(\n422\t                parts[0],\n423\t                parts[1],\n424\t                parts[2],\n425\t                history_end,\n426\t                int(like_counts[inference_row]),\n427\t                int(dislike_counts[inference_row]),\n428\t            )\n429\t        if seen_users % 1_000 == 0:\n430\t            log(\n431\t                f\"prepared users={seen_users:,} tokens={offsets[-1]:,} \"\n432\t                f\"states={len(liked_states):,} \"\n433\t                f\"elapsed={time.monotonic() - started:.1f}s\"\n434\t            )\n435\t\n436\t    missing = np.flatnonzero(inference_sequence_rows < 0)\n437\t    if len(missing):\n438\t        inference_user_features[missing, 4] = np.log1p(like_counts[missing]) / 6.0\n439\t        inference_user_features[missing, 5] = (\n440\t            np.log1p(dislike_counts[missing]) / 4.0\n441\t        )\n442\t        log(f\"target users without qualifying catalog sequence={len(missing):,}\")\n443\t\n444\t    prepared = SequenceData(\n445\t        item_ids=item_ids,\n446\t        item_features=base.build_item_features(catalog),\n447\t        user_ids=np.asarray(user_ids, dtype=np.int64),\n448\t        offsets=np.asarray(offsets, dtype=np.int64),\n449\t        sequence_timestamps=np.concatenate(timestamp_parts),\n450\t        sequence_items=np.concatenate(item_parts),\n451\t        event_features=np.concatenate(event_parts),\n452\t        activity_features=np.concatenate(activity_parts),\n453\t        state_ids=np.concatenate(state_parts),\n454\t        liked_states=np.stack(liked_states),\n455\t        disliked_states=np.stack(disliked_states),\n456\t        state_counts=np.asarray(state_counts, dtype=np.int32),\n457\t        inference_user_rows=inference_sequence_rows,\n458\t        inference_liked_items=inference_likes,\n459\t        inference_disliked_items=inference_dislikes,\n460\t        inference_user_features=inference_user_features,\n461\t    )\n462\t    log(\n463\t        f\"prepared stage={stage} sequence_users={len(prepared.user_ids):,} \"\n464\t        f\"tokens={len(prepared.sequence_items):,} \"\n465\t        f\"next_item_targets={prepared.target_count:,} \"\n466\t        f\"states={len(prepared.liked_states):,}\"\n467\t    )\n468\t    return prepared, eligibility\n469\t\n470\t\n471\tdef cache_metadata(stage: str, config: Config) -> dict[str, object]:\n472\t    return {\n473\t        \"cache_version\": CACHE_VERSION,\n474\t        \"stage\": stage,\n475\t        \"positive_listen_threshold\": base.LISTEN_POSITIVE_THRESHOLD,\n476\t        \"profile_lookback_days\": base.PROFILE_LOOKBACK_DAYS,\n477\t        \"event_time_feature\": \"exp-negative-gap-over-60-days\",\n478\t    }\n479\t\n480\t\n481\tdef save_cache(\n482\t    path: Path, prepared: SequenceData, stage: str, config: Config\n483\t) -> None:\n484\t    path.parent.mkdir(parents=True, exist_ok=True)\n485\t    np.savez(\n486\t        path,\n487\t        metadata=np.asarray(json.dumps(cache_metadata(stage, config), sort_keys=True)),\n488\t        **prepared.__dict__,\n489\t    )\n490\t    log(f\"saved public-derived full-sequence cache: {path}\")\n491\t\n492\t\n493\tdef load_cache(path: Path, stage: str, config: Config) -> SequenceData:\n494\t    with np.load(path, allow_pickle=False) as artifact:\n495\t        actual = json.loads(str(artifact[\"metadata\"].item()))\n496\t        expected = cache_metadata(stage, config)\n497\t        if actual != expected:\n498\t            raise RuntimeError(f\"sequence cache differs: {actual} != {expected}\")\n499\t        values = {\n500\t            field: artifact[field].copy()\n501\t            for field in SequenceData.__dataclass_fields__\n502\t        }\n503\t    prepared = SequenceData(**values)\n504\t    log(\n505\t        f\"loaded full-sequence cache: tokens={len(prepared.sequence_items):,} \"\n506\t        f\"targets={prepared.target_count:,}\"\n507\t    )\n508\t    return prepared\n509\t\n510\t\n511\tdef load_or_prepare(\n512\t    public: Path,\n513\t    stage: str,\n514\t    config: Config,\n515\t    cache: Path | None,\n516\t) -> tuple[SequenceData, CandidateSet]:\n517\t    candidate_name = (\n518\t        \"validation_eligible_candidates.npz\"\n519\t        if stage == \"validation\"\n520\t        else \"test_eligible_candidates.npz\"\n521\t    )\n522\t    eligibility = CandidateSet.read(public / \"data\" / candidate_name)\n523\t    if cache is not None and cache.is_file():\n524\t        prepared = load_cache(cache, stage, config)\n525\t        if not np.array_equal(prepared.item_ids, eligibility.item_ids):\n526\t            raise RuntimeError(\"cached catalog differs from candidate artifact\")\n527\t        return prepared, eligibility\n528\t    prepared, built_eligibility = prepare_data(public, stage, config)\n529\t    if cache is not None:\n530\t        save_cache(cache, prepared, stage, config)\n531\t    return prepared, built_eligibility\n532\t\n533\t\n534\tdef build_item_correction(\n535\t    prepared: SequenceData,\n536\t    config: Config,\n537\t    target_starts: np.ndarray,\n538\t    target_counts: np.ndarray,\n539\t) -> torch.Tensor:\n540\t    \"\"\"Estimate in-batch propensities from the selected training targets.\"\"\"\n541\t    counts = np.zeros(len(prepared.item_ids), dtype=np.float64)\n542\t    for user_row, count in enumerate(target_counts):\n543\t        if not count:\n544\t            continue\n545\t        offset = int(prepared.offsets[user_row])\n546\t        target_start = int(target_starts[user_row])\n547\t        counts += np.bincount(\n548\t            prepared.sequence_items[\n549\t                offset\n550\t                + target_start\n551\t                + 1 : offset\n552\t                + target_start\n553\t                + int(count)\n554\t                + 1\n555\t            ].astype(np.int64),\n556\t            minlength=len(prepared.item_ids),\n557\t        )\n558\t    total = float(counts.sum())\n559\t    probabilities = (counts + 1.0) / (total + len(counts))\n560\t    raw = np.power(\n561\t        (1.0 / len(counts)) / probabilities,\n562\t        config.inbatch_correction_power,\n563\t    )\n564\t    normalization = float(np.sum(counts * raw) / max(total, 1.0))\n565\t    correction = np.clip(\n566\t        raw / max(normalization, 1.0e-12),\n567\t        config.inbatch_correction_min,\n568\t        config.inbatch_correction_max,\n569\t    ).astype(np.float32)\n570\t    mean_on_targets = float(np.sum(counts * correction) / max(total, 1.0))\n571\t    log(\n572\t        f\"inbatch correction: min={correction.min():.3f} \"\n573\t        f\"mean_on_targets={mean_on_targets:.3f} max={correction.max():.3f}\"\n574\t    )\n575\t    return torch.from_numpy(correction)\n576\t\n577\t\n578\tdef build_known_positive_filter(\n579\t    prepared: SequenceData, training_counts: np.ndarray\n580\t) -> np.ndarray:\n581\t    \"\"\"Pack each user's complete public-training positive-item set.\"\"\"\n582\t    width = (len(prepared.item_ids) + 7) // 8\n583\t    packed = np.zeros((len(prepared.user_ids), width), dtype=np.uint8)\n584\t    retained = 0\n585\t    for user_row, target_count in enumerate(training_counts):\n586\t        if not target_count:\n587\t            continue\n588\t        offset = int(prepared.offsets[user_row])\n589\t        # T adjacent targets consume sequence positions 0 through T.  The\n590\t        # chronological BCE suffix starts at T + 1 and is intentionally absent.\n591\t        items = np.unique(\n592\t            prepared.sequence_items[\n593\t                offset : offset + int(target_count) + 1\n594\t            ].astype(np.int64)\n595\t        )\n596\t        byte_columns = items >> 3\n597\t        bit_values = np.left_shift(\n598\t            np.uint8(1), (items & 7).astype(np.uint8)\n599\t        )\n600\t        np.bitwise_or.at(packed[user_row], byte_columns, bit_values)\n601\t        retained += len(items)\n602\t    log(\n603\t        f\"full-history false-negative filter: users={len(prepared.user_ids):,} \"\n604\t        f\"unique_user_items={retained:,} bytes={packed.nbytes:,}\"\n605\t    )\n606\t    return packed\n607\t\n608\t\n609\tdef invalid_full_history_negatives(\n610\t    negatives: np.ndarray,\n611\t    targets: np.ndarray,\n612\t    user_rows: np.ndarray,\n613\t    known_positive_packed: np.ndarray,\n614\t    liked_items: np.ndarray,\n615\t) -> np.ndarray:\n616\t    \"\"\"Return row-level invalid negatives using the complete training prefix.\"\"\"\n617\t    byte_columns = negatives >> 3\n618\t    bit_columns = negatives & 7\n619\t    known = known_positive_packed[user_rows[:, None], byte_columns]\n620\t    invalid = ((known >> bit_columns) & 1).astype(bool)\n621\t    invalid |= negatives == targets[:, None]\n622\t    invalid |= (negatives[:, :, None] == liked_items[:, None, :]).any(axis=2)\n623\t    for column in range(1, negatives.shape[1]):\n624\t        invalid[:, column] |= (\n625\t            negatives[:, column, None] == negatives[:, :column]\n626\t        ).any(axis=1)\n627\t    return invalid\n628\t\n629\t\n630\tdef draw_full_history_filtered_negatives(\n631\t    targets: torch.Tensor,\n632\t    user_rows: np.ndarray,\n633\t    liked_items: torch.Tensor,\n634\t    known_positive_packed: np.ndarray,\n635\t    n_items: int,\n636\t    config: Config,\n637\t    item_correction: torch.Tensor,\n638\t    generator: torch.Generator,\n639\t    device: torch.device,\n640\t) -> tuple[torch.Tensor, torch.Tensor]:\n641\t    \"\"\"Draw mixed negatives and reject all known public-training positives.\"\"\"\n642\t    targets_cpu = targets.detach().cpu().numpy().astype(np.int64, copy=False)\n643\t    liked_cpu = liked_items.detach().cpu().numpy().astype(np.int64, copy=False)\n644\t    batch_size = len(targets_cpu)\n645\t    uniform = torch.randint(\n646\t        n_items,\n647\t        (batch_size, config.uniform_negatives),\n648\t        generator=generator,\n649\t        device=\"cpu\",\n650\t    )\n651\t    inbatch = torch.empty((batch_size, 0), dtype=torch.long)\n652\t    corrected_count = 0\n653\t    if config.inbatch_negatives:\n654\t        unique_targets = torch.unique(targets.detach().cpu())\n655\t        corrected_count = min(\n656\t            config.inbatch_negatives, max(len(unique_targets) - 1, 0)\n657\t        )\n658\t        if corrected_count:\n659\t            priorities = torch.rand(\n660\t                (batch_size, len(unique_targets)), generator=generator\n661\t            )\n662\t            priorities.masked_fill_(\n663\t                unique_targets[None, :].eq(\n664\t                    torch.from_numpy(targets_cpu)[:, None]\n665\t                ),\n666\t                -1.0,\n667\t            )\n668\t            columns = torch.topk(\n669\t                priorities, k=corrected_count, dim=1\n670\t            ).indices\n671\t            inbatch = unique_targets[columns]\n672\t        if corrected_count < config.inbatch_negatives:\n673\t            filler = torch.randint(\n674\t                n_items,\n675\t                (batch_size, config.inbatch_negatives - corrected_count),\n676\t                generator=generator,\n677\t                device=\"cpu\",\n678\t            )\n679\t            inbatch = torch.cat([inbatch, filler], dim=1)\n680\t\n681\t    negatives = torch.cat([uniform, inbatch], dim=1).numpy()\n682\t    correction = np.ones_like(negatives, dtype=np.float32)\n683\t    if corrected_count:\n684\t        correction[\n685\t            :, config.uniform_negatives : config.uniform_negatives + corrected_count\n686\t        ] = item_correction[inbatch[:, :corrected_count]].numpy()\n687\t    for _ in range(32):\n688\t        invalid = invalid_full_history_negatives(\n689\t            negatives,\n690\t            targets_cpu,\n691\t            user_rows,\n692\t            known_positive_packed,\n693\t            liked_cpu,\n694\t        )\n695\t        if not np.any(invalid):\n696\t            return (\n697\t                torch.from_numpy(negatives).to(device),\n698\t                torch.from_numpy(correction).to(device),\n699\t            )\n700\t        replacements = torch.randint(",
            "isError": false
          }
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:03:05.343Z",
          "callId": "toolu_01XWLT5HqoADQRXRaCzogoAm",
          "name": "Read",
          "input": {
            "file_path": "/task/current_model/two_tower_model.py"
          },
          "result": {
            "timestamp": "2026-10-03T09:03:05.362Z",
            "content": "1\t\"\"\"Shared public-data primitives for the Yambda two-tower baseline.\"\"\"\n2\tfrom __future__ import annotations\n3\t\n4\timport sys\n5\tfrom dataclasses import dataclass\n6\tfrom pathlib import Path\n7\tfrom typing import Iterator\n8\t\n9\timport numpy as np\n10\timport pandas as pd\n11\timport pyarrow.parquet as pq\n12\timport torch\n13\tfrom torch import nn\n14\t\n15\t\n16\tDAY = 86_400\n17\tTRAIN_END = 24_786_800\n18\tVALIDATION_END = 25_393_400\n19\tLISTEN_POSITIVE_THRESHOLD = 50\n20\tPROFILE_LOOKBACK_DAYS = 120\n21\tLIKE_ITEMS = 48\n22\tDISLIKE_ITEMS = 24\n23\tTOP_N = 100\n24\t\n25\t\n26\t@dataclass(frozen=True)\n27\tclass TowerConfig:\n28\t    sequence_length: int = 100\n29\t    embedding_dim: int = 192\n30\t    hidden_dim: int = 192\n31\t    user_hidden_1: int = 512\n32\t    user_hidden_2: int = 256\n33\t    item_hidden_1: int = 512\n34\t    item_hidden_2: int = 256\n35\t    dropout: float = 0.05\n36\t    epochs: int = 1\n37\t    learning_rate: float = 1.0e-3\n38\t    weight_decay: float = 1.0e-5\n39\t    gradient_clip: float = 2.0\n40\t    uniform_negatives: int = 24\n41\t    inbatch_negatives: int = 8\n42\t    inbatch_correction_power: float = 0.5\n43\t    inbatch_correction_min: float = 0.25\n44\t    inbatch_correction_max: float = 4.0\n45\t    seed: int = 29\n46\t\n47\t\n48\t@dataclass(frozen=True)\n49\tclass ListenEvents:\n50\t    timestamps: np.ndarray\n51\t    items: np.ndarray\n52\t    organic: np.ndarray\n53\t    completion_pct: np.ndarray\n54\t\n55\t\n56\t@dataclass(frozen=True)\n57\tclass ExplicitEvents:\n58\t    timestamps: np.ndarray\n59\t    items: np.ndarray\n60\t    channel: np.ndarray\n61\t    active: np.ndarray\n62\t    organic_like: np.ndarray\n63\t\n64\t\n65\tdef log(message: str) -> None:\n66\t    print(message, file=sys.stderr, flush=True)\n67\t\n68\t\n69\tdef build_item_features(catalog: pd.DataFrame) -> np.ndarray:\n70\t    \"\"\"Return four standardized features built only from the public catalog.\"\"\"\n71\t    positives = catalog.positive_listens.to_numpy(dtype=np.float64, copy=False)\n72\t    organic = catalog.organic_positive_listens.to_numpy(dtype=np.float64, copy=False)\n73\t    popularity_rank = catalog.popularity_rank.to_numpy(dtype=np.float64, copy=False)\n74\t    features = np.column_stack(\n75\t        [\n76\t            np.log1p(positives),\n77\t            np.log1p(organic),\n78\t            organic / np.maximum(positives, 1.0),\n79\t            1.0 - (popularity_rank - 1.0) / max(len(catalog) - 1, 1),\n80\t        ]\n81\t    )\n82\t    means = features.mean(axis=0, keepdims=True)\n83\t    scales = np.maximum(features.std(axis=0, keepdims=True), 1.0e-6)\n84\t    standardized = ((features - means) / scales).astype(np.float32)\n85\t    if not np.isfinite(standardized).all():\n86\t        raise RuntimeError(\"catalog features contain non-finite values\")\n87\t    return standardized\n88\t\n89\t\n90\tdef _combine_listen_chunks(parts: list[ListenEvents]) -> ListenEvents:\n91\t    if len(parts) == 1:\n92\t        return parts[0]\n93\t    timestamps = np.concatenate([part.timestamps for part in parts])\n94\t    items = np.concatenate([part.items for part in parts])\n95\t    organic = np.concatenate([part.organic for part in parts])\n96\t    completion = np.concatenate([part.completion_pct for part in parts])\n97\t    order = np.argsort(timestamps, kind=\"stable\")\n98\t    return ListenEvents(\n99\t        timestamps=timestamps[order],\n100\t        items=items[order],\n101\t        organic=organic[order],\n102\t        completion_pct=completion[order],\n103\t    )\n104\t\n105\t\n106\tdef iter_listen_users(\n107\t    path: Path, item_index: pd.Index\n108\t) -> Iterator[tuple[int, ListenEvents]]:\n109\t    \"\"\"Stream one uid-sorted public listen file one user at a time.\"\"\"\n110\t    parquet = pq.ParquetFile(path)\n111\t    pending_uid: int | None = None\n112\t    pending: list[ListenEvents] = []\n113\t    previous_uid = -1\n114\t    for batch in parquet.iter_batches(\n115\t        batch_size=750_000,\n116\t        columns=[\"uid\", \"timestamp\", \"item_id\", \"is_organic\", \"played_ratio_pct\"],\n117\t    ):\n118\t        frame = batch.to_pandas()\n119\t        mapped = item_index.get_indexer(frame.item_id.to_numpy(dtype=np.int64))\n120\t        keep = mapped >= 0\n121\t        if not np.any(keep):\n122\t            continue\n123\t        uids = frame.uid.to_numpy(dtype=np.int64, copy=False)[keep]\n124\t        timestamps = frame.timestamp.to_numpy(dtype=np.int64, copy=False)[keep]\n125\t        items = mapped[keep].astype(np.int32, copy=False)\n126\t        organic = frame.is_organic.to_numpy(dtype=np.uint8, copy=False)[keep]\n127\t        completion = frame.played_ratio_pct.to_numpy(dtype=np.uint16, copy=False)[keep]\n128\t        if np.any(uids[1:] < uids[:-1]):\n129\t            raise RuntimeError(f\"{path.name} is not sorted by uid\")\n130\t        boundaries = np.r_[\n131\t            0,\n132\t            np.flatnonzero(uids[1:] != uids[:-1]) + 1,\n133\t            len(uids),\n134\t        ]\n135\t        for start, end in zip(boundaries[:-1], boundaries[1:]):\n136\t            uid = int(uids[start])\n137\t            part = ListenEvents(\n138\t                timestamps[start:end].copy(),\n139\t                items[start:end].copy(),\n140\t                organic[start:end].copy(),\n141\t                completion[start:end].copy(),\n142\t            )\n143\t            if pending_uid is None:\n144\t                pending_uid = uid\n145\t            elif uid != pending_uid:\n146\t                if pending_uid < previous_uid:\n147\t                    raise RuntimeError(f\"{path.name} user order regressed\")\n148\t                yield pending_uid, _combine_listen_chunks(pending)\n149\t                previous_uid = pending_uid\n150\t                pending_uid = uid\n151\t                pending = []\n152\t            pending.append(part)\n153\t    if pending_uid is not None:\n154\t        yield pending_uid, _combine_listen_chunks(pending)\n155\t\n156\t\n157\tdef merge_listen_streams(\n158\t    paths: list[Path], item_index: pd.Index\n159\t) -> Iterator[tuple[int, ListenEvents]]:\n160\t    \"\"\"Merge uid-sorted public listen files without materializing them.\"\"\"\n161\t    streams = [iter(iter_listen_users(path, item_index)) for path in paths]\n162\t    heads: list[tuple[int, ListenEvents] | None] = [\n163\t        next(stream, None) for stream in streams\n164\t    ]\n165\t    while any(head is not None for head in heads):\n166\t        uid = min(head[0] for head in heads if head is not None)\n167\t        parts: list[ListenEvents] = []\n168\t        for position, head in enumerate(heads):\n169\t            if head is not None and head[0] == uid:\n170\t                parts.append(head[1])\n171\t                heads[position] = next(streams[position], None)\n172\t        yield uid, _combine_listen_chunks(parts)\n173\t\n174\t\n175\tdef load_explicit_events(\n176\t    data: Path,\n177\t    prefixes: tuple[str, ...],\n178\t    item_index: pd.Index,\n179\t) -> dict[int, ExplicitEvents]:\n180\t    \"\"\"Load public explicit actions as chronological state changes.\"\"\"\n181\t    specifications = (\n182\t        (\"likes\", 0, 1, 0),\n183\t        (\"unlikes\", 0, 0, 1),\n184\t        (\"dislikes\", 1, 1, 0),\n185\t        (\"undislikes\", 1, 0, 1),\n186\t    )\n187\t    parts: list[pd.DataFrame] = []\n188\t    for family, channel, active, tie_priority in specifications:\n189\t        for prefix in prefixes:\n190\t            frame = pd.read_parquet(\n191\t                data / f\"{prefix}_{family}.parquet\",\n192\t                columns=[\"uid\", \"timestamp\", \"item_id\", \"is_organic\"],\n193\t            )\n194\t            mapped = item_index.get_indexer(\n195\t                frame.item_id.to_numpy(dtype=np.int64, copy=False)\n196\t            )\n197\t            keep = mapped >= 0\n198\t            if not np.any(keep):\n199\t                continue\n200\t            retained = frame.loc[keep, [\"uid\", \"timestamp\", \"is_organic\"]].copy()\n201\t            retained[\"item\"] = mapped[keep].astype(np.int32, copy=False)\n202\t            retained[\"channel\"] = np.int8(channel)\n203\t            retained[\"active\"] = np.int8(active)\n204\t            retained[\"tie_priority\"] = np.int8(tie_priority)\n205\t            retained[\"organic_like\"] = np.int8(\n206\t                family == \"likes\"\n207\t            ) * retained.is_organic.astype(np.int8)\n208\t            parts.append(retained.drop(columns=\"is_organic\"))\n209\t    if not parts:\n210\t        return {}\n211\t    events = pd.concat(parts, ignore_index=True)\n212\t    events = events.sort_values(\n213\t        [\"uid\", \"timestamp\", \"tie_priority\"], kind=\"mergesort\"\n214\t    ).reset_index(drop=True)\n215\t    result: dict[int, ExplicitEvents] = {}\n216\t    for uid, rows in events.groupby(\"uid\", sort=False):\n217\t        result[int(uid)] = ExplicitEvents(\n218\t            timestamps=rows.timestamp.to_numpy(dtype=np.int64, copy=True),\n219\t            items=rows.item.to_numpy(dtype=np.int32, copy=True),\n220\t            channel=rows.channel.to_numpy(dtype=np.int8, copy=True),\n221\t            active=rows.active.to_numpy(dtype=np.int8, copy=True),\n222\t            organic_like=rows.organic_like.to_numpy(dtype=np.int8, copy=True),\n223\t        )\n224\t    log(f\"loaded explicit events: rows={len(events):,} users={len(result):,}\")\n225\t    return result\n226\t\n227\t\n228\tdef empty_explicit_events() -> ExplicitEvents:\n229\t    return ExplicitEvents(\n230\t        timestamps=np.empty(0, dtype=np.int64),\n231\t        items=np.empty(0, dtype=np.int32),\n232\t        channel=np.empty(0, dtype=np.int8),\n233\t        active=np.empty(0, dtype=np.int8),\n234\t        organic_like=np.empty(0, dtype=np.int8),\n235\t    )\n236\t\n237\t\n238\tdef pack_active_items(\n239\t    active: dict[int, int], width: int, padding_item: int\n240\t) -> np.ndarray:\n241\t    packed = np.full(width, padding_item, dtype=np.uint16)\n242\t    if not active:\n243\t        return packed\n244\t    ordered = sorted(active.items(), key=lambda pair: (-pair[1], pair[0]))[:width]\n245\t    packed[: len(ordered)] = np.fromiter(\n246\t        (item for item, _ in ordered), dtype=np.uint16, count=len(ordered)\n247\t    )\n248\t    return packed\n249\t\n250\t\n251\tdef load_inference_state(\n252\t    path: Path,\n253\t    item_index: pd.Index,\n254\t    uids: np.ndarray,\n255\t    n_items: int,\n256\t) -> tuple[np.ndarray, np.ndarray, np.ndarray, np.ndarray]:\n257\t    \"\"\"Pack the task-provided active explicit state.\"\"\"\n258\t    state = pd.read_parquet(path, columns=[\"uid\", \"item_id\", \"state\"])\n259\t    mapped = item_index.get_indexer(state.item_id.to_numpy(dtype=np.int64))\n260\t    keep = mapped >= 0\n261\t    state = state.loc[keep, [\"uid\", \"state\"]].copy()\n262\t    state[\"item\"] = mapped[keep].astype(np.int32, copy=False)\n263\t    user_rows = pd.Index(uids)\n264\t    liked = np.full((len(uids), LIKE_ITEMS), n_items, dtype=np.uint16)\n265\t    disliked = np.full((len(uids), DISLIKE_ITEMS), n_items, dtype=np.uint16)\n266\t    like_counts = np.zeros(len(uids), dtype=np.int32)\n267\t    dislike_counts = np.zeros(len(uids), dtype=np.int32)\n268\t    for value, width, destination, counts in (\n269\t        (\"liked\", LIKE_ITEMS, liked, like_counts),\n270\t        (\"disliked\", DISLIKE_ITEMS, disliked, dislike_counts),\n271\t    ):\n272\t        selected = state[state.state == value]\n273\t        for uid, rows in selected.groupby(\"uid\", sort=False):\n274\t            row = int(user_rows.get_indexer([int(uid)])[0])\n275\t            if row < 0:\n276\t                continue\n277\t            items = np.sort(rows.item.unique())\n278\t            counts[row] = len(items)\n279\t            retained = items[:width]\n280\t            destination[row, : len(retained)] = retained.astype(np.uint16)\n281\t    return liked, disliked, like_counts, dislike_counts\n282\t\n283\t\n284\tclass SequentialTwoTower(nn.Module):\n285\t    \"\"\"Order-sensitive user tower and independent catalog-aware item tower.\"\"\"\n286\t\n287\t    def __init__(self, item_features: np.ndarray, config: TowerConfig) -> None:\n288\t        super().__init__()\n289\t        n_items, n_item_features = item_features.shape\n290\t        dim = config.embedding_dim\n291\t        self.n_items = n_items\n292\t        self.context_embedding = nn.Embedding(\n293\t            n_items + 1, dim, padding_idx=n_items\n294\t        )\n295\t        self.event_projection = nn.Sequential(\n296\t            nn.Linear(dim + 3, config.hidden_dim),\n297\t            nn.GELU(),\n298\t        )\n299\t        self.sequence_encoder = nn.GRU(\n300\t            input_size=config.hidden_dim,\n301\t            hidden_size=dim,\n302\t            num_layers=1,\n303\t            batch_first=True,\n304\t        )\n305\t        self.user_tower = nn.Sequential(\n306\t            nn.Linear(dim * 3 + 6, config.user_hidden_1),\n307\t            nn.GELU(),\n308\t            nn.Dropout(config.dropout),\n309\t            nn.Linear(config.user_hidden_1, config.user_hidden_2),\n310\t            nn.GELU(),\n311\t            nn.Dropout(config.dropout),\n312\t            nn.Linear(config.user_hidden_2, dim),\n313\t        )\n314\t        self.candidate_embedding = nn.Embedding(n_items, dim)\n315\t        self.register_buffer(\n316\t            \"item_features\", torch.from_numpy(item_features), persistent=True\n317\t        )\n318\t        self.item_tower = nn.Sequential(\n319\t            nn.Linear(dim + n_item_features, config.item_hidden_1),\n320\t            nn.GELU(),\n321\t            nn.Dropout(config.dropout),\n322\t            nn.Linear(config.item_hidden_1, config.item_hidden_2),\n323\t            nn.GELU(),\n324\t            nn.Dropout(config.dropout),\n325\t            nn.Linear(config.item_hidden_2, dim),\n326\t        )\n327\t        nn.init.normal_(self.context_embedding.weight, std=0.02)\n328\t        nn.init.normal_(self.candidate_embedding.weight, std=0.02)\n329\t        with torch.no_grad():\n330\t            self.context_embedding.weight[n_items].zero_()\n331\t\n332\t    def _mean_context_channel(self, items: torch.Tensor) -> torch.Tensor:\n333\t        mask = items.ne(self.n_items)\n334\t        vectors = self.context_embedding(items)\n335\t        return (vectors * mask.unsqueeze(-1)).sum(dim=1) / mask.sum(\n336\t            dim=1, keepdim=True\n337\t        ).clamp_min(1)\n338\t\n339\t    def encode_items(self, items: torch.Tensor) -> torch.Tensor:\n340\t        inputs = torch.cat(\n341\t            [self.candidate_embedding(items), self.item_features[items]], dim=1\n342\t        )\n343\t        return self.item_tower(inputs)\n344\t\n345\t\n346\tdef invalid_negative_mask(\n347\t    negatives: torch.Tensor,\n348\t    targets: torch.Tensor,\n349\t    context_items: torch.Tensor,\n350\t    liked_items: torch.Tensor,\n351\t) -> torch.Tensor:\n352\t    \"\"\"Identify targets, known positives, active likes, and row duplicates.\"\"\"\n353\t    invalid = negatives.eq(targets[:, None])\n354\t    invalid |= negatives[:, :, None].eq(context_items[:, None, :]).any(dim=2)\n355\t    invalid |= negatives[:, :, None].eq(liked_items[:, None, :]).any(dim=2)\n356\t    for column in range(1, negatives.shape[1]):\n357\t        invalid[:, column] |= negatives[:, column, None].eq(\n358\t            negatives[:, :column]\n359\t        ).any(dim=1)\n360\t    return invalid\n361\t\n362\t\n363\tdef draw_filtered_mixed_negatives(\n364\t    targets: torch.Tensor,\n365\t    context_items: torch.Tensor,\n366\t    liked_items: torch.Tensor,\n367\t    n_items: int,\n368\t    uniform_count: int,\n369\t    inbatch_count: int,\n370\t    item_correction: torch.Tensor,\n371\t    generator: torch.Generator,\n372\t    device: torch.device,\n373\t) -> tuple[torch.Tensor, torch.Tensor]:\n374\t    \"\"\"Draw uniform and unique-target in-batch negatives.\"\"\"\n375\t    batch_size = len(targets)\n376\t    uniform = torch.randint(\n377\t        n_items,\n378\t        (batch_size, uniform_count),\n379\t        generator=generator,\n380\t        device=\"cpu\",\n381\t    )\n382\t    inbatch = torch.empty((batch_size, 0), dtype=torch.long, device=\"cpu\")\n383\t    corrected_count = 0\n384\t    if inbatch_count:\n385\t        unique_targets = torch.unique(targets.detach().cpu())\n386\t        corrected_count = min(inbatch_count, max(len(unique_targets) - 1, 0))\n387\t        if corrected_count:\n388\t            priorities = torch.rand(\n389\t                (batch_size, len(unique_targets)), generator=generator\n390\t            )\n391\t            priorities.masked_fill_(\n392\t                unique_targets[None, :].eq(targets.detach().cpu()[:, None]),\n393\t                -1.0,\n394\t            )\n395\t            columns = torch.topk(priorities, k=corrected_count, dim=1).indices\n396\t            inbatch = unique_targets[columns]\n397\t        if corrected_count < inbatch_count:\n398\t            filler = torch.randint(\n399\t                n_items,\n400\t                (batch_size, inbatch_count - corrected_count),\n401\t                generator=generator,\n402\t                device=\"cpu\",\n403\t            )\n404\t            inbatch = torch.cat([inbatch, filler], dim=1)\n405\t\n406\t    negatives_cpu = torch.cat([uniform, inbatch], dim=1)\n407\t    correction_cpu = torch.ones_like(negatives_cpu, dtype=torch.float32)\n408\t    if corrected_count:\n409\t        correction_cpu[\n410\t            :, uniform_count : uniform_count + corrected_count\n411\t        ] = item_correction[inbatch[:, :corrected_count]]\n412\t    negatives = negatives_cpu.to(device)\n413\t    correction = correction_cpu.to(device)\n414\t    for _ in range(32):\n415\t        invalid = invalid_negative_mask(\n416\t            negatives, targets, context_items, liked_items\n417\t        )\n418\t        if not bool(invalid.any()):\n419\t            return negatives, correction\n420\t        replacements = torch.randint(\n421\t            n_items,\n422\t            (int(invalid.sum().detach().cpu()),),\n423\t            generator=generator,\n424\t            device=\"cpu\",\n425\t        ).to(device)\n426\t        negatives[invalid] = replacements\n427\t        correction[invalid] = 1.0\n428\t    invalid = invalid_negative_mask(\n429\t        negatives, targets, context_items, liked_items\n430\t    )\n431\t    if bool(invalid.any()):\n432\t        raise RuntimeError(\"mixed negative resampling failed false-negative filter\")\n433\t    return negatives, correction\n434\t",
            "isError": false
          }
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:03:05.348Z",
          "callId": "toolu_011p4Tc6dYrVhNxvGaAbTNVo",
          "name": "Read",
          "input": {
            "file_path": "/task/evaluate_public.py"
          },
          "result": {
            "timestamp": "2026-10-03T09:03:05.359Z",
            "content": "1\t#!/usr/bin/env python3\n2\t\"\"\"Score a validation-stage ranking against public discovery labels.\n3\t\n4\t``build_task.py`` publishes this module with the solver-visible task files. It\n5\tloads target users, validation eligibility, and validation-window events from\n6\tthe adjacent ``data`` directory, then evaluates one ranking supplied on the\n7\tcommand line. Stage-independent mechanics come from the adjacent public\n8\t``ranking_evaluation.py`` module. The builder installs the same checked-in\n9\tmodule in the private judge, so public and private scoring mechanics cannot\n10\tdrift. A relevant candidate receives grade 3 for an organic like or grade 1 for\n11\tan organic listen with at least 80 percent completion; a like takes precedence\n12\twhen both events exist.\n13\t\n14\tBefore scoring, the ranking must contain exactly 100 distinct eligible items\n15\tfor every target user, with integer-valued ``uid``, ``item_id``, and ``rank``\n16\tcolumns and ranks 1 through 100 exactly once per user. Extra columns are\n17\tignored. Quality is graded NDCG@10, averaged only over users who have at least\n18\tone eligible relevant item in the validation window.\n19\t\n20\tThe evaluator prints a JSON object containing the model path and scores. It\n21\tdoes not apply the task's pass threshold; its purpose is model development and\n22\tselection. The private judge applies the threshold to the final submission.\n23\t\n24\tUsage::\n25\t\n26\t    python evaluate_public.py <validation-ranking.parquet|csv>\n27\t\"\"\"\n28\tfrom __future__ import annotations\n29\t\n30\timport json\n31\timport sys\n32\tfrom pathlib import Path\n33\t\n34\timport pandas as pd\n35\t\n36\tfrom ranking_evaluation import (\n37\t    CandidateSet,\n38\t    RankingValidationError,\n39\t    ranked_items,\n40\t    read_ranking,\n41\t    score_rankings,\n42\t    validate_ranking,\n43\t)\n44\t\n45\t\n46\tHERE = Path(__file__).resolve().parent\n47\tDATA = HERE / \"data\"\n48\tLISTEN_STRONG = 80\n49\t\n50\t\n51\tdef validation_truth(\n52\t    eligibility: CandidateSet, targets: set[int]\n53\t) -> dict[int, dict[int, int]]:\n54\t    \"\"\"Build cutoff-correct graded relevance from public validation events.\n55\t\n56\t    Only target-user events for eligible candidates are retained. Organic\n57\t    listens completed to at least 80 percent receive grade 1, and organic likes\n58\t    receive grade 3. Repeated user-item events are collapsed, and processing\n59\t    likes second ensures that grade 3 wins over grade 1.\n60\t\n61\t    Args:\n62\t        eligibility: Validation-cutoff candidate membership service.\n63\t        targets: Complete set of target user IDs.\n64\t\n65\t    Returns:\n66\t        A nested ``uid -> item_id -> grade`` mapping. Users without an eligible\n67\t        relevant event are omitted.\n68\t    \"\"\"\n69\t    listens = pd.read_parquet(DATA / \"val_listens.parquet\")\n70\t    likes = pd.read_parquet(DATA / \"val_likes.parquet\")\n71\t    strong = listens[\n72\t        listens.uid.isin(targets)\n73\t        & (listens.is_organic == 1)\n74\t        & (listens.played_ratio_pct >= LISTEN_STRONG)\n75\t    ][[\"uid\", \"item_id\"]].drop_duplicates()\n76\t    organic_likes = likes[\n77\t        likes.uid.isin(targets) & (likes.is_organic == 1)\n78\t    ][[\"uid\", \"item_id\"]].drop_duplicates()\n79\t\n80\t    graded: dict[int, dict[int, int]] = {}\n81\t    for raw_uid, raw_item in strong.itertuples(index=False, name=None):\n82\t        uid, item = int(raw_uid), int(raw_item)\n83\t        if eligibility.is_eligible(uid, item):\n84\t            graded.setdefault(uid, {})[item] = 1\n85\t    for raw_uid, raw_item in organic_likes.itertuples(index=False, name=None):\n86\t        uid, item = int(raw_uid), int(raw_item)\n87\t        if eligibility.is_eligible(uid, item):\n88\t            graded.setdefault(uid, {})[item] = 3\n89\t    return graded\n90\t\n91\t\n92\tdef load_submission(\n93\t    path: Path, eligibility: CandidateSet, targets: set[int]\n94\t) -> dict[int, list[int]]:\n95\t    \"\"\"Load and validate a public validation ranking.\n96\t\n97\t    Files ending in ``.parquet`` are read as parquet; every other suffix is\n98\t    read as CSV. The required columns must be integer-valued, cover exactly the\n99\t    target-user set, contain 100 rows and ranks 1 through 100 per user, avoid\n100\t    duplicate user-item pairs, and contain only cutoff-eligible items.\n101\t\n102\t    Args:\n103\t        path: Ranking file to read.\n104\t        eligibility: Validation-cutoff candidate membership service.\n105\t        targets: Exact set of users the ranking must cover.\n106\t\n107\t    Returns:\n108\t        A ``uid -> ranked item IDs`` mapping ordered by ascending rank.\n109\t\n110\t    Raises:\n111\t        ValueError: If the ranking violates the required schema or invariants.\n112\t    \"\"\"\n113\t    frame = validate_ranking(read_ranking(path), targets)\n114\t    if not all(\n115\t        eligibility.is_eligible(uid, item)\n116\t        for uid, item in frame[[\"uid\", \"item_id\"]].itertuples(index=False, name=None)\n117\t    ):\n118\t        raise RankingValidationError(\n119\t            \"submission contains an item rejected by eligibility service\"\n120\t        )\n121\t    return ranked_items(frame)\n122\t\n123\t\n124\tdef score(\n125\t    ranked: dict[int, list[int]],\n126\t    graded: dict[int, dict[int, int]],\n127\t) -> dict[str, float | int]:\n128\t    \"\"\"Aggregate per-user NDCG@10 over users with public relevance labels.\n129\t\n130\t    Args:\n131\t        ranked: Ranked item IDs for every target user.\n132\t        graded: Eligible validation relevance keyed by user and item.\n133\t\n134\t    Returns:\n135\t        The six-decimal ``quality_ndcg@10`` value and number of scored users.\n136\t    \"\"\"\n137\t    return score_rankings(ranked, graded)\n138\t\n139\t\n140\tdef main() -> None:\n141\t    \"\"\"Run the public evaluator CLI and print its JSON score report.\"\"\"\n142\t    targets_frame = pd.read_parquet(DATA / \"target_users.parquet\")\n143\t    targets = set(targets_frame.uid.astype(int))\n144\t    eligibility = CandidateSet(DATA / \"validation_eligible_candidates.npz\")\n145\t    graded = validation_truth(eligibility, targets)\n146\t\n147\t    if len(sys.argv) != 2:\n148\t        raise SystemExit(\n149\t            \"usage: evaluate_public.py <validation-ranking.parquet|csv>\"\n150\t        )\n151\t    path = Path(sys.argv[1])\n152\t    ranked = load_submission(path, eligibility, targets)\n153\t    print(json.dumps({\"model\": str(path), \"scores\": score(ranked, graded)}, indent=2))\n154\t\n155\t\n156\tif __name__ == \"__main__\":\n157\t    main()\n158\t",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:03:05.369Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14975319 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:03:05.371Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 5,
      "role": "agent",
      "timestamp": "2026-10-03T09:03:08.814Z",
      "blocks": [
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:03:08.814Z",
          "callId": "toolu_01THibts7Na4XJSESiPUevJz",
          "name": "Read",
          "input": {
            "file_path": "/task/current_model/train_current_model.py",
            "offset": 700,
            "limit": 800
          },
          "result": {
            "timestamp": "2026-10-03T09:03:08.923Z",
            "content": "700\t        replacements = torch.randint(\n701\t            n_items,\n702\t            (int(invalid.sum()),),\n703\t            generator=generator,\n704\t            device=\"cpu\",\n705\t        ).numpy()\n706\t        negatives[invalid] = replacements\n707\t        # Rejected in-batch items become ordinary uniform draws.\n708\t        correction[invalid] = 1.0\n709\t    invalid = invalid_full_history_negatives(\n710\t        negatives,\n711\t        targets_cpu,\n712\t        user_rows,\n713\t        known_positive_packed,\n714\t        liked_cpu,\n715\t    )\n716\t    if np.any(invalid):\n717\t        raise RuntimeError(\"full-history negative resampling failed\")\n718\t    return (\n719\t        torch.from_numpy(negatives).to(device),\n720\t        torch.from_numpy(correction).to(device),\n721\t    )\n722\t\n723\t\n724\tdef draw_training_negatives(\n725\t    positive_items: torch.Tensor,\n726\t    known_history: torch.Tensor,\n727\t    liked_items: torch.Tensor,\n728\t    user_rows: np.ndarray,\n729\t    known_positive_packed: np.ndarray | None,\n730\t    prepared: SequenceData,\n731\t    config: Config,\n732\t    item_correction: torch.Tensor,\n733\t    generator: torch.Generator,\n734\t    device: torch.device,\n735\t) -> tuple[torch.Tensor, torch.Tensor]:\n736\t    if config.negative_filter_scope == \"full-training-history\":\n737\t        if known_positive_packed is None:\n738\t            raise RuntimeError(\"full-history negative filter was not built\")\n739\t        return draw_full_history_filtered_negatives(\n740\t            positive_items,\n741\t            user_rows,\n742\t            liked_items,\n743\t            known_positive_packed,\n744\t            len(prepared.item_ids),\n745\t            config,\n746\t            item_correction,\n747\t            generator,\n748\t            device,\n749\t        )\n750\t    return base.draw_filtered_mixed_negatives(\n751\t        positive_items,\n752\t        known_history,\n753\t        liked_items,\n754\t        len(prepared.item_ids),\n755\t        config.uniform_negatives,\n756\t        config.inbatch_negatives,\n757\t        item_correction,\n758\t        generator,\n759\t        device,\n760\t    )\n761\t\n762\t\n763\tdef event_sequence(\n764\t    model: base.SequentialTwoTower,\n765\t    items: torch.Tensor,\n766\t    features: torch.Tensor,\n767\t    hidden: torch.Tensor,\n768\t) -> tuple[torch.Tensor, torch.Tensor]:\n769\t    inputs = torch.cat([model.context_embedding(items), features], dim=-1)\n770\t    projected = model.event_projection(inputs)\n771\t    return model.sequence_encoder(projected, hidden)\n772\t\n773\t\n774\tdef pool_explicit_states(\n775\t    model: base.SequentialTwoTower,\n776\t    prepared: SequenceData,\n777\t    state_ids: np.ndarray,\n778\t    device: torch.device,\n779\t) -> tuple[torch.Tensor, torch.Tensor, torch.Tensor]:\n780\t    unique_states, inverse = np.unique(state_ids, return_inverse=True)\n781\t    liked_items = torch.from_numpy(\n782\t        prepared.liked_states[unique_states].astype(np.int64)\n783\t    ).to(device)\n784\t    disliked_items = torch.from_numpy(\n785\t        prepared.disliked_states[unique_states].astype(np.int64)\n786\t    ).to(device)\n787\t    liked_vectors = model._mean_context_channel(liked_items)\n788\t    disliked_vectors = model._mean_context_channel(disliked_items)\n789\t    inverse_rows = torch.from_numpy(inverse.astype(np.int64)).to(device)\n790\t    counts = prepared.state_counts[state_ids]\n791\t    return (\n792\t        liked_vectors[inverse_rows],\n793\t        disliked_vectors[inverse_rows],\n794\t        torch.from_numpy(counts.astype(np.float32)).to(device),\n795\t    )\n796\t\n797\t\n798\tdef user_queries(\n799\t    model: base.SequentialTwoTower,\n800\t    sequence_vectors: torch.Tensor,\n801\t    liked_vectors: torch.Tensor,\n802\t    disliked_vectors: torch.Tensor,\n803\t    user_features: torch.Tensor,\n804\t) -> torch.Tensor:\n805\t    return model.user_tower(\n806\t        torch.cat(\n807\t            [sequence_vectors, liked_vectors, disliked_vectors, user_features],\n808\t            dim=1,\n809\t        )\n810\t    )\n811\t\n812\t\n813\tdef candidate_vectors(\n814\t    model: base.SequentialTwoTower,\n815\t    positives: torch.Tensor,\n816\t    negatives: torch.Tensor,\n817\t) -> tuple[torch.Tensor, torch.Tensor]:\n818\t    all_items = torch.cat([positives, negatives.reshape(-1)])\n819\t    unique_items, inverse = torch.unique(all_items, return_inverse=True)\n820\t    encoded = model.encode_items(unique_items)\n821\t    positive_vectors = encoded[inverse[: len(positives)]]\n822\t    negative_vectors = encoded[inverse[len(positives) :]].reshape(\n823\t        len(positives), negatives.shape[1], -1\n824\t    )\n825\t    return positive_vectors, negative_vectors\n826\t\n827\t\n828\tdef history_windows(\n829\t    sequence: np.ndarray,\n830\t    start: int,\n831\t    count: int,\n832\t    width: int,\n833\t    padding_item: int,\n834\t) -> np.ndarray:\n835\t    base_start = max(0, start - width + 1)\n836\t    segment = sequence[base_start : start + count]\n837\t    padded = np.concatenate(\n838\t        [np.full(width - 1, padding_item, dtype=np.uint16), segment]\n839\t    )\n840\t    windows = np.lib.stride_tricks.sliding_window_view(padded, width)\n841\t    offset = start - base_start\n842\t    return windows[offset : offset + count].copy()\n843\t\n844\t\n845\tdef corrected_negative_loss(\n846\t    logits: torch.Tensor,\n847\t    correction: torch.Tensor,\n848\t    config: Config,\n849\t) -> torch.Tensor:\n850\t    raw = F.softplus(logits)\n851\t    total = config.uniform_negatives + config.inbatch_negatives\n852\t    result = torch.zeros(len(logits), device=logits.device)\n853\t    if config.uniform_negatives:\n854\t        result += config.uniform_negatives * raw[\n855\t            :, : config.uniform_negatives\n856\t        ].mean(dim=1)\n857\t    if config.inbatch_negatives:\n858\t        selected = slice(config.uniform_negatives, total)\n859\t        weights = correction[:, selected]\n860\t        result += config.inbatch_negatives * (\n861\t            (raw[:, selected] * weights).sum(dim=1)\n862\t            / weights.sum(dim=1).clamp_min(1.0e-6)\n863\t        )\n864\t    return result / total\n865\t\n866\t\n867\tdef retained_target_window_starts(\n868\t    total_targets: np.ndarray,\n869\t    validation_counts: np.ndarray,\n870\t    training_counts: np.ndarray,\n871\t) -> np.ndarray:\n872\t    \"\"\"Return the discarded prefix before the retained chronological suffix.\"\"\"\n873\t    training_region_ends = total_targets - validation_counts\n874\t    window_starts = training_region_ends - training_counts\n875\t    if (\n876\t        np.any(window_starts < 0)\n877\t        or np.any(training_counts < 0)\n878\t        or np.any(validation_counts < 0)\n879\t    ):\n880\t        raise RuntimeError(\"chronological target partition produced negative counts\")\n881\t    if not np.array_equal(\n882\t        window_starts + training_counts + validation_counts, total_targets\n883\t    ):\n884\t        raise RuntimeError(\"chronological target window is not a final contiguous suffix\")\n885\t    return window_starts\n886\t\n887\t\n888\tdef chronological_target_partition(\n889\t    prepared: SequenceData,\n890\t    validation_fraction: float,\n891\t    max_train_targets_per_user: int,\n892\t    max_validation_targets_per_user: int,\n893\t) -> TargetPartition:\n894\t    \"\"\"Select a recent contiguous window with a final out-of-time BCE suffix.\"\"\"\n895\t    totals = np.maximum(prepared.lengths - 1, 0).astype(np.int64)\n896\t    validation = np.floor(totals * validation_fraction).astype(np.int64)\n897\t    validation[(totals >= 2) & (validation == 0)] = 1\n898\t    if max_validation_targets_per_user:\n899\t        validation = np.minimum(validation, max_validation_targets_per_user)\n900\t\n901\t    history_training = totals - validation\n902\t    training = history_training.copy()\n903\t    if max_train_targets_per_user:\n904\t        training = np.minimum(training, max_train_targets_per_user)\n905\t    window_starts = retained_target_window_starts(totals, validation, training)\n906\t    return TargetPartition(\n907\t        window_starts=window_starts,\n908\t        training_counts=training,\n909\t        validation_counts=validation,\n910\t        history_training_counts=history_training,\n911\t    )\n912\t\n913\t\n914\tdef load_organic_like_outcomes(\n915\t    public: Path, stage: str, item_ids: np.ndarray\n916\t) -> dict[int, dict[int, np.ndarray]]:\n917\t    \"\"\"Load mapped organic-like timestamps from public fitting history.\"\"\"\n918\t    prefixes = (\"train\",) if stage == \"validation\" else (\"train\", \"val\")\n919\t    frames = [\n920\t        pd.read_parquet(\n921\t            public / \"data\" / f\"{prefix}_likes.parquet\",\n922\t            columns=[\"uid\", \"timestamp\", \"item_id\", \"is_organic\"],\n923\t        )\n924\t        for prefix in prefixes\n925\t    ]\n926\t    likes = pd.concat(frames, ignore_index=True)\n927\t    likes = likes[likes.is_organic == 1].copy()\n928\t    mapped = pd.Index(item_ids).get_indexer(\n929\t        likes.item_id.to_numpy(dtype=np.int64)\n930\t    )\n931\t    likes = likes.loc[mapped >= 0, [\"uid\", \"timestamp\"]].copy()\n932\t    likes[\"item\"] = mapped[mapped >= 0].astype(np.int32, copy=False)\n933\t    likes = likes.sort_values([\"uid\", \"item\", \"timestamp\"], kind=\"stable\")\n934\t    nested: dict[int, dict[int, list[int]]] = {}\n935\t    for raw_uid, raw_timestamp, raw_item in likes.itertuples(\n936\t        index=False, name=None\n937\t    ):\n938\t        nested.setdefault(int(raw_uid), {}).setdefault(int(raw_item), []).append(\n939\t            int(raw_timestamp)\n940\t        )\n941\t    result = {\n942\t        uid: {\n943\t            item: np.asarray(timestamps, dtype=np.int64)\n944\t            for item, timestamps in items.items()\n945\t        }\n946\t        for uid, items in nested.items()\n947\t    }\n948\t    log(\n949\t        f\"loaded organic-like outcomes: rows={len(likes):,} \"\n950\t        f\"users={len(result):,}\"\n951\t    )\n952\t    return result\n953\t\n954\t\n955\tdef build_target_weights(\n956\t    public: Path,\n957\t    stage: str,\n958\t    prepared: SequenceData,\n959\t    training_counts: np.ndarray,\n960\t    config: Config,\n961\t) -> np.ndarray:\n962\t    \"\"\"Build nonzero per-token weights without dropping adjacent targets.\"\"\"\n963\t    if config.target_weighting == \"uniform\":\n964\t        weights = np.ones(len(prepared.sequence_items), dtype=np.float32)\n965\t    else:\n966\t        weights = np.full(\n967\t            len(prepared.sequence_items),\n968\t            config.ordinary_target_weight,\n969\t            dtype=np.float32,\n970\t        )\n971\t        organic_strong = (\n972\t            (prepared.event_features[:, 0] > 0.5)\n973\t            & (prepared.event_features[:, 1] >= 0.8)\n974\t        )\n975\t        weights[organic_strong] = config.organic_strong_target_weight\n976\t        if config.target_weighting == \"discovery-graded\":\n977\t            like_outcomes = load_organic_like_outcomes(\n978\t                public, stage, prepared.item_ids\n979\t            )\n980\t            history_end = (\n981\t                base.TRAIN_END if stage == \"validation\" else base.VALIDATION_END\n982\t            )\n983\t            horizon = config.discovery_horizon_days * base.DAY\n984\t            grade_three = 0\n985\t            for user_row, uid in enumerate(prepared.user_ids):\n986\t                start = int(prepared.offsets[user_row])\n987\t                end = int(prepared.offsets[user_row + 1])\n988\t                if end - start < 2:\n989\t                    continue\n990\t                last_training_target = start + int(training_counts[user_row])\n991\t                first_validation_target = last_training_target + 1\n992\t                split_timestamp = (\n993\t                    int(prepared.sequence_timestamps[first_validation_target])\n994\t                    if first_validation_target < end\n995\t                    else history_end\n996\t                )\n997\t                user_likes = like_outcomes.get(int(uid), {})\n998\t                seen = {int(prepared.sequence_items[start])}\n999\t                for position in range(start + 1, end):\n1000\t                    item = int(prepared.sequence_items[position])\n1001\t                    novel = item not in seen\n1002\t                    seen.add(item)\n1003\t                    if not novel:\n1004\t                        # Repeats remain training examples, but they cannot be\n1005\t                        # eligible discovery outcomes at the corresponding\n1006\t                        # cutoff and therefore keep only the ordinary weight.\n1007\t                        weights[position] = config.ordinary_target_weight\n1008\t                        continue\n1009\t                    timestamps = user_likes.get(item)\n1010\t                    if timestamps is None:\n1011\t                        continue\n1012\t                    timestamp = int(prepared.sequence_timestamps[position])\n1013\t                    upper = min(\n1014\t                        timestamp + horizon,\n1015\t                        split_timestamp\n1016\t                        if position <= last_training_target\n1017\t                        else history_end,\n1018\t                    )\n1019\t                    outcome = int(np.searchsorted(timestamps, timestamp, side=\"left\"))\n1020\t                    if outcome < len(timestamps) and int(timestamps[outcome]) < upper:\n1021\t                        weights[position] = config.organic_like_target_weight\n1022\t                        grade_three += 1\n1023\t            log(\n1024\t                f\"grade-3 first-encounter targets={grade_three:,} \"\n1025\t                f\"horizon_days={config.discovery_horizon_days}\"\n1026\t            )\n1027\t    log(\n1028\t        f\"target weighting={config.target_weighting} \"\n1029\t        f\"min={weights.min():.3f} mean={weights.mean():.3f} \"\n1030\t        f\"max={weights.max():.3f}\"\n1031\t    )\n1032\t    return weights\n1033\t\n1034\t\n1035\tdef build_dense_block(\n1036\t    prepared: SequenceData,\n1037\t    target_weights: np.ndarray,\n1038\t    users: np.ndarray,\n1039\t    window_starts: np.ndarray,\n1040\t    process_counts: np.ndarray,\n1041\t    score_starts: np.ndarray,\n1042\t    start: int,\n1043\t    steps: int,\n1044\t    config: Config,\n1045\t) -> tuple[np.ndarray, ...]:\n1046\t    \"\"\"Build one causal sequence block and mark the target rows to score.\"\"\"\n1047\t    batch_size = len(users)\n1048\t    padding_item = len(prepared.item_ids)\n1049\t    input_items = np.full((batch_size, steps), padding_item, dtype=np.uint16)\n1050\t    event_features = np.zeros((batch_size, steps, 3), dtype=np.float16)\n1051\t    activity_features = np.zeros((batch_size, steps, 4), dtype=np.float16)\n1052\t    state_ids = np.zeros((batch_size, steps), dtype=np.uint32)\n1053\t    targets = np.zeros((batch_size, steps), dtype=np.uint16)\n1054\t    weights = np.ones((batch_size, steps), dtype=np.float32)\n1055\t    scored = np.zeros((batch_size, steps), dtype=bool)\n1056\t    histories = np.full(\n1057\t        (batch_size, steps, config.bptt_steps),\n1058\t        padding_item,\n1059\t        dtype=np.uint16,\n1060\t    )\n1061\t    processed = np.zeros(batch_size, dtype=np.int32)\n1062\t\n1063\t    lengths = prepared.lengths\n1064\t    for row, user_row in enumerate(users):\n1065\t        count = min(steps, max(int(process_counts[row]) - start, 0))\n1066\t        if not count:\n1067\t            continue\n1068\t        offset = int(prepared.offsets[user_row])\n1069\t        window_start = int(window_starts[row])\n1070\t        absolute_start = window_start + start\n1071\t        positions = slice(\n1072\t            offset + absolute_start,\n1073\t            offset + absolute_start + count,\n1074\t        )\n1075\t        target_positions = slice(\n1076\t            offset + absolute_start + 1,\n1077\t            offset + absolute_start + count + 1,\n1078\t        )\n1079\t        input_items[row, :count] = prepared.sequence_items[positions]\n1080\t        event_features[row, :count] = prepared.event_features[positions]\n1081\t        activity_features[row, :count] = prepared.activity_features[positions]\n1082\t        state_ids[row, :count] = prepared.state_ids[positions]\n1083\t        targets[row, :count] = prepared.sequence_items[target_positions]\n1084\t        weights[row, :count] = target_weights[target_positions]\n1085\t        score_from = min(count, max(int(score_starts[row]) - start, 0))\n1086\t        scored[row, score_from:count] = True\n1087\t        processed[row] = count\n1088\t        user_sequence = prepared.sequence_items[\n1089\t            offset : offset + int(lengths[user_row])\n1090\t        ]\n1091\t        histories[row, :count] = history_windows(\n1092\t            user_sequence,\n1093\t            absolute_start,\n1094\t            count,\n1095\t            config.bptt_steps,\n1096\t            padding_item,\n1097\t        )\n1098\t    return (\n1099\t        input_items,\n1100\t        event_features,\n1101\t        activity_features,\n1102\t        state_ids,\n1103\t        targets,\n1104\t        scored,\n1105\t        histories,\n1106\t        processed,\n1107\t        weights,\n1108\t    )\n1109\t\n1110\t\n1111\tdef score_target_microbatches(\n1112\t    model: base.SequentialTwoTower,\n1113\t    prepared: SequenceData,\n1114\t    config: Config,\n1115\t    sequence_vectors: torch.Tensor,\n1116\t    flat_states: np.ndarray,\n1117\t    flat_activity: np.ndarray,\n1118\t    positive_items: torch.Tensor,\n1119\t    negatives: torch.Tensor,\n1120\t    negative_weights: torch.Tensor,\n1121\t    sample_weights: np.ndarray,\n1122\t    device: torch.device,\n1123\t    backward: bool,\n1124\t) -> tuple[dict[str, float], torch.Tensor | None]:\n1125\t    \"\"\"Compute one logical block's exact BCE in bounded-memory slices.\"\"\"\n1126\t    target_count = len(positive_items)\n1127\t    total_weight = float(sample_weights.sum())\n1128\t    if total_weight <= 0:\n1129\t        raise RuntimeError(\"target block has no positive sample weight\")\n1130\t    sequence_gradient = torch.zeros_like(sequence_vectors) if backward else None\n1131\t    statistics = {\n1132\t        \"loss_sum\": 0.0,\n1133\t        \"positive_sum\": 0.0,\n1134\t        \"negative_sum\": 0.0,\n1135\t        \"pair_correct\": 0.0,\n1136\t        \"weight_sum\": 0.0,\n1137\t    }\n1138\t    for begin in range(0, target_count, config.loss_microbatch_size):\n1139\t        end = min(begin + config.loss_microbatch_size, target_count)\n1140\t        selected_states = flat_states[begin:end]\n1141\t        if backward:\n1142\t            sequence_input = (\n1143\t                sequence_vectors[begin:end].detach().requires_grad_(True)\n1144\t            )\n1145\t        else:\n1146\t            sequence_input = sequence_vectors[begin:end]\n1147\t        liked_vectors, disliked_vectors, _ = pool_explicit_states(\n1148\t            model, prepared, selected_states, device\n1149\t        )\n1150\t        counts = prepared.state_counts[selected_states]\n1151\t        numeric = np.zeros((end - begin, 6), dtype=np.float32)\n1152\t        numeric[:, :4] = flat_activity[begin:end]\n1153\t        numeric[:, 4] = np.log1p(counts[:, 0]) / 6.0\n1154\t        numeric[:, 5] = np.log1p(counts[:, 1]) / 4.0\n1155\t        query_vectors = user_queries(\n1156\t            model,\n1157\t            sequence_input,\n1158\t            liked_vectors,\n1159\t            disliked_vectors,\n1160\t            torch.from_numpy(numeric).to(device),\n1161\t        )\n1162\t        positive_vectors, negative_vectors = candidate_vectors(\n1163\t            model,\n1164\t            positive_items[begin:end],\n1165\t            negatives[begin:end],\n1166\t        )\n1167\t        positive_logits = (query_vectors * positive_vectors).sum(dim=1)\n1168\t        negative_logits = torch.einsum(\n1169\t            \"bd,bkd->bk\", query_vectors, negative_vectors\n1170\t        )\n1171\t        positive_loss = F.softplus(-positive_logits)\n1172\t        negative_loss = corrected_negative_loss(\n1173\t            negative_logits, negative_weights[begin:end], config\n1174\t        )\n1175\t        selected_weights = torch.from_numpy(\n1176\t            sample_weights[begin:end].astype(np.float32, copy=False)\n1177\t        ).to(device)\n1178\t        loss_sum = (\n1179\t            selected_weights * (positive_loss + negative_loss) / 2.0\n1180\t        ).sum()\n1181\t        if not bool(torch.isfinite(loss_sum)):\n1182\t            raise RuntimeError(\"dense next-item training produced non-finite loss\")\n1183\t        if backward:\n1184\t            (loss_sum / total_weight).backward()\n1185\t            if sequence_input.grad is None:\n1186\t                raise RuntimeError(\"sequence microbatch did not produce a gradient\")\n1187\t            sequence_gradient[begin:end] = sequence_input.grad\n1188\t        statistics[\"loss_sum\"] += float(loss_sum.detach().cpu())\n1189\t        statistics[\"positive_sum\"] += float(positive_logits.detach().sum().cpu())\n1190\t        statistics[\"negative_sum\"] += float(negative_logits.detach().sum().cpu())\n1191\t        statistics[\"pair_correct\"] += float(\n1192\t            (positive_logits.detach()[:, None] > negative_logits.detach()).sum().cpu()\n1193\t        )\n1194\t        statistics[\"weight_sum\"] += float(selected_weights.sum().detach().cpu())\n1195\t    return statistics, sequence_gradient\n1196\t\n1197\t\n1198\tdef release_accelerator_cache(device: torch.device) -> None:\n1199\t    if device.type == \"mps\":\n1200\t        torch.mps.empty_cache()\n1201\t\n1202\t\n1203\tdef run_training_epoch(\n1204\t    model: base.SequentialTwoTower,\n1205\t    optimizer: torch.optim.Optimizer,\n1206\t    prepared: SequenceData,\n1207\t    config: Config,\n1208\t    target_weights: np.ndarray,\n1209\t    window_starts: np.ndarray,\n1210\t    target_counts: np.ndarray,\n1211\t    item_correction: torch.Tensor,\n1212\t    known_positive_packed: np.ndarray | None,\n1213\t    generator: torch.Generator,\n1214\t    device: torch.device,\n1215\t    epoch: int,\n1216\t) -> dict[str, float]:\n1217\t    model.train()\n1218\t    train_users = np.flatnonzero(target_counts > 0)\n1219\t    sorted_users = train_users[\n1220\t        np.argsort(target_counts[train_users], kind=\"stable\")\n1221\t    ]\n1222\t    groups = [\n1223\t        sorted_users[start : start + config.user_batch_size]\n1224\t        for start in range(0, len(sorted_users), config.user_batch_size)\n1225\t    ]\n1226\t    group_order = torch.randperm(len(groups), generator=generator).numpy()\n1227\t    negative_count = config.uniform_negatives + config.inbatch_negatives\n1228\t    total_loss = 0.0\n1229\t    total_targets = 0\n1230\t    total_weight = 0.0\n1231\t    total_positive = 0.0\n1232\t    total_negative = 0.0\n1233\t    total_pair_correct = 0.0\n1234\t    batches = 0\n1235\t    started = time.monotonic()\n1236\t\n1237\t    for group_number in group_order:\n1238\t        users = groups[int(group_number)]\n1239\t        group_counts = target_counts[users]\n1240\t        hidden = torch.zeros(\n1241\t            1, len(users), config.embedding_dim, device=device\n1242\t        )\n1243\t        max_targets = int(group_counts.max())\n1244\t        for start in range(0, max_targets, config.bptt_steps):\n1245\t            steps = min(config.bptt_steps, max_targets - start)\n1246\t            block = build_dense_block(\n1247\t                prepared,\n1248\t                target_weights,\n1249\t                users,\n1250\t                window_starts[users],\n1251\t                group_counts,\n1252\t                np.zeros(len(users), dtype=np.int64),\n1253\t                start,\n1254\t                steps,\n1255\t                config,\n1256\t            )\n1257\t            sequence_outputs, _ = event_sequence(\n1258\t                model,\n1259\t                torch.from_numpy(block[0].astype(np.int64)).to(device),\n1260\t                torch.from_numpy(block[1].astype(np.float32)).to(device),\n1261\t                hidden,\n1262\t            )\n1263\t            hidden = torch.stack(\n1264\t                [\n1265\t                    sequence_outputs[row, count - 1]\n1266\t                    if count\n1267\t                    else hidden[0, row]\n1268\t                    for row, count in enumerate(block[7])\n1269\t                ]\n1270\t            ).unsqueeze(0).detach()\n1271\t            flat_scored = block[5].reshape(-1)\n1272\t            if not np.any(flat_scored):\n1273\t                continue\n1274\t            mask = torch.from_numpy(flat_scored).to(device)\n1275\t            sequence_vectors = sequence_outputs.reshape(\n1276\t                -1, config.embedding_dim\n1277\t            )[mask]\n1278\t            flat_states = block[3].reshape(-1)[flat_scored]\n1279\t            positive_items = torch.from_numpy(\n1280\t                block[4].reshape(-1)[flat_scored].astype(np.int64)\n1281\t            ).to(device)\n1282\t            known_history = torch.from_numpy(\n1283\t                block[6].reshape(-1, config.bptt_steps)[flat_scored].astype(\n1284\t                    np.int64\n1285\t                )\n1286\t            ).to(device)\n1287\t            liked_items = torch.from_numpy(\n1288\t                prepared.liked_states[flat_states].astype(np.int64)\n1289\t            ).to(device)\n1290\t            flat_user_rows = np.broadcast_to(\n1291\t                users[:, None], block[5].shape\n1292\t            ).reshape(-1)[flat_scored]\n1293\t            negatives, negative_weights = draw_training_negatives(\n1294\t                positive_items,\n1295\t                known_history,\n1296\t                liked_items,\n1297\t                flat_user_rows,\n1298\t                known_positive_packed,\n1299\t                prepared,\n1300\t                config,\n1301\t                item_correction,\n1302\t                generator,\n1303\t                device,\n1304\t            )\n1305\t            optimizer.zero_grad(set_to_none=True)\n1306\t            statistics, sequence_gradient = score_target_microbatches(\n1307\t                model,\n1308\t                prepared,\n1309\t                config,\n1310\t                sequence_vectors,\n1311\t                flat_states,\n1312\t                block[2].reshape(-1, 4)[flat_scored].astype(np.float32),\n1313\t                positive_items,\n1314\t                negatives,\n1315\t                negative_weights,\n1316\t                block[8].reshape(-1)[flat_scored],\n1317\t                device,\n1318\t                backward=True,\n1319\t            )\n1320\t            if sequence_gradient is None:\n1321\t                raise RuntimeError(\"training block omitted its sequence gradient\")\n1322\t            sequence_vectors.backward(sequence_gradient)\n1323\t            nn.utils.clip_grad_norm_(model.parameters(), config.gradient_clip)\n1324\t            optimizer.step()\n1325\t\n1326\t            count = len(positive_items)\n1327\t            total_loss += statistics[\"loss_sum\"]\n1328\t            total_targets += count\n1329\t            total_weight += statistics[\"weight_sum\"]\n1330\t            total_positive += statistics[\"positive_sum\"]\n1331\t            total_negative += statistics[\"negative_sum\"]\n1332\t            total_pair_correct += statistics[\"pair_correct\"]\n1333\t            batches += 1\n1334\t            if batches % 25 == 0:\n1335\t                release_accelerator_cache(device)\n1336\t            if batches % 250 == 0:\n1337\t                batch_bce = statistics[\"loss_sum\"] / max(\n1338\t                    statistics[\"weight_sum\"], 1.0e-12\n1339\t                )\n1340\t                running_bce = total_loss / max(total_weight, 1.0e-12)\n1341\t                log(\n1342\t                    f\"epoch={epoch}/{config.epochs} batches={batches:,} \"\n1343\t                    f\"targets={total_targets:,} \"\n1344\t                    f\"batch_bce={batch_bce:.6f} \"\n1345\t                    f\"running_bce={running_bce:.6f} \"\n1346\t                    f\"elapsed={time.monotonic() - started:.1f}s\"\n1347\t                )\n1348\t\n1349\t    return {\n1350\t        \"epoch\": float(epoch),\n1351\t        \"loss\": total_loss / max(total_weight, 1.0e-12),\n1352\t        \"positive_logit\": total_positive / max(total_targets, 1),\n1353\t        \"negative_logit\": total_negative / max(total_targets * negative_count, 1),\n1354\t        \"pair_accuracy\": total_pair_correct\n1355\t        / max(total_targets * negative_count, 1),\n1356\t        \"targets\": float(total_targets),\n1357\t        \"target_weight_sum\": total_weight,\n1358\t        \"batches\": float(batches),\n1359\t        \"seconds\": time.monotonic() - started,\n1360\t    }\n1361\t\n1362\t\n1363\t@torch.no_grad()\n1364\tdef evaluate_validation_bce(\n1365\t    model: base.SequentialTwoTower,\n1366\t    prepared: SequenceData,\n1367\t    config: Config,\n1368\t    target_weights: np.ndarray,\n1369\t    window_starts: np.ndarray,\n1370\t    training_counts: np.ndarray,\n1371\t    validation_counts: np.ndarray,\n1372\t    item_correction: torch.Tensor,\n1373\t    known_positive_packed: np.ndarray | None,\n1374\t    device: torch.device,\n1375\t) -> dict[str, float]:\n1376\t    \"\"\"Measure deterministic BCE on each user's chronological target suffix.\"\"\"\n1377\t    model.eval()\n1378\t    totals = training_counts + validation_counts\n1379\t    users_with_validation = np.flatnonzero(validation_counts > 0)\n1380\t    ordered = users_with_validation[\n1381\t        np.argsort(totals[users_with_validation], kind=\"stable\")\n1382\t    ]\n1383\t    groups = [\n1384\t        ordered[start : start + config.user_batch_size]\n1385\t        for start in range(0, len(ordered), config.user_batch_size)\n1386\t    ]\n1387\t    generator = torch.Generator(device=\"cpu\").manual_seed(config.seed + 20_000)\n1388\t    total_loss = 0.0\n1389\t    total_targets = 0\n1390\t    total_weight = 0.0\n1391\t    started = time.monotonic()\n1392\t\n1393\t    for group_number, users in enumerate(groups, start=1):\n1394\t        group_totals = totals[users]\n1395\t        group_starts = training_counts[users]\n1396\t        hidden = torch.zeros(\n1397\t            1, len(users), config.embedding_dim, device=device\n1398\t        )\n1399\t        max_targets = int(group_totals.max())\n1400\t        for start in range(0, max_targets, config.bptt_steps):\n1401\t            steps = min(config.bptt_steps, max_targets - start)\n1402\t            block = build_dense_block(\n1403\t                prepared,\n1404\t                target_weights,\n1405\t                users,\n1406\t                window_starts[users],\n1407\t                group_totals,\n1408\t                group_starts,\n1409\t                start,\n1410\t                steps,\n1411\t                config,\n1412\t            )\n1413\t            sequence_outputs, _ = event_sequence(\n1414\t                model,\n1415\t                torch.from_numpy(block[0].astype(np.int64)).to(device),\n1416\t                torch.from_numpy(block[1].astype(np.float32)).to(device),\n1417\t                hidden,\n1418\t            )\n1419\t            hidden = torch.stack(\n1420\t                [\n1421\t                    sequence_outputs[row, count - 1]\n1422\t                    if count\n1423\t                    else hidden[0, row]\n1424\t                    for row, count in enumerate(block[7])\n1425\t                ]\n1426\t            ).unsqueeze(0)\n1427\t            flat_scored = block[5].reshape(-1)\n1428\t            if not np.any(flat_scored):\n1429\t                continue\n1430\t            mask = torch.from_numpy(flat_scored).to(device)\n1431\t            sequence_vectors = sequence_outputs.reshape(\n1432\t                -1, config.embedding_dim\n1433\t            )[mask]\n1434\t            flat_states = block[3].reshape(-1)[flat_scored]\n1435\t            positive_items = torch.from_numpy(\n1436\t                block[4].reshape(-1)[flat_scored].astype(np.int64)\n1437\t            ).to(device)\n1438\t            known_history = torch.from_numpy(\n1439\t                block[6].reshape(-1, config.bptt_steps)[flat_scored].astype(\n1440\t                    np.int64\n1441\t                )\n1442\t            ).to(device)\n1443\t            liked_items = torch.from_numpy(\n1444\t                prepared.liked_states[flat_states].astype(np.int64)\n1445\t            ).to(device)\n1446\t            flat_user_rows = np.broadcast_to(\n1447\t                users[:, None], block[5].shape\n1448\t            ).reshape(-1)[flat_scored]\n1449\t            negatives, negative_weights = draw_training_negatives(\n1450\t                positive_items,\n1451\t                known_history,\n1452\t                liked_items,\n1453\t                flat_user_rows,\n1454\t                known_positive_packed,\n1455\t                prepared,\n1456\t                config,\n1457\t                item_correction,\n1458\t                generator,\n1459\t                device,\n1460\t            )\n1461\t            statistics, _ = score_target_microbatches(\n1462\t                model,\n1463\t                prepared,\n1464\t                config,\n1465\t                sequence_vectors,\n1466\t                flat_states,\n1467\t                block[2].reshape(-1, 4)[flat_scored].astype(np.float32),\n1468\t                positive_items,\n1469\t                negatives,\n1470\t                negative_weights,\n1471\t                block[8].reshape(-1)[flat_scored],\n1472\t                device,\n1473\t                backward=False,\n1474\t            )\n1475\t            total_loss += statistics[\"loss_sum\"]\n1476\t            total_targets += len(positive_items)\n1477\t            total_weight += statistics[\"weight_sum\"]\n1478\t        if group_number % 25 == 0:\n1479\t            release_accelerator_cache(device)\n1480\t    return {\n1481\t        \"validation_loss\": total_loss / max(total_weight, 1.0e-12),\n1482\t        \"validation_targets\": float(total_targets),\n1483\t        \"validation_target_weight_sum\": total_weight,\n1484\t        \"validation_seconds\": time.monotonic() - started,\n1485\t    }\n1486\t\n1487\t\n1488\tdef snapshot_model(model: nn.Module) -> dict[str, torch.Tensor]:\n1489\t    return {\n1490\t        name: value.detach().cpu().clone()\n1491\t        for name, value in model.state_dict().items()\n1492\t    }\n1493\t\n1494\t\n1495\tdef save_epoch_checkpoint(\n1496\t    checkpoint_dir: Path,\n1497\t    epoch: int,\n1498\t    model_state: dict[str, torch.Tensor],\n1499\t    config: Config,",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:03:08.928Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14953866 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:03:08.930Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 6,
      "role": "agent",
      "timestamp": "2026-10-03T09:03:13.108Z",
      "blocks": [
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:03:13.108Z",
          "callId": "toolu_01MPhipH3stNCWED78jeqScY",
          "name": "Read",
          "input": {
            "file_path": "/task/current_model/train_current_model.py",
            "offset": 1499
          },
          "result": {
            "timestamp": "2026-10-03T09:03:13.242Z",
            "content": "1499\t    config: Config,\n1500\t    diagnostics: dict[str, float],\n1501\t    optimizer: torch.optim.Optimizer,\n1502\t    generator: torch.Generator,\n1503\t) -> Path:\n1504\t    checkpoint_dir.mkdir(parents=True, exist_ok=True)\n1505\t    path = checkpoint_dir / f\"epoch-{epoch:02d}.pt\"\n1506\t    torch.save(\n1507\t        {\n1508\t            \"epoch\": epoch,\n1509\t            \"config\": asdict(config),\n1510\t            \"diagnostics\": diagnostics,\n1511\t            \"model_state\": model_state,\n1512\t            \"optimizer_state\": optimizer.state_dict(),\n1513\t            \"generator_state\": generator.get_state(),\n1514\t        },\n1515\t        path,\n1516\t    )\n1517\t    log(f\"saved epoch checkpoint: {path}\")\n1518\t    return path\n1519\t\n1520\t\n1521\tdef train_model(\n1522\t    public: Path,\n1523\t    stage: str,\n1524\t    prepared: SequenceData,\n1525\t    config: Config,\n1526\t    device: torch.device,\n1527\t    checkpoint_dir: Path | None,\n1528\t    resume_checkpoint: Path | None,\n1529\t) -> tuple[base.SequentialTwoTower, list[dict[str, float]]]:\n1530\t    partition = chronological_target_partition(\n1531\t        prepared,\n1532\t        config.validation_fraction,\n1533\t        config.max_train_targets_per_user,\n1534\t        config.max_validation_targets_per_user,\n1535\t    )\n1536\t    training_counts = partition.training_counts\n1537\t    validation_counts = partition.validation_counts\n1538\t    log(\n1539\t        f\"chronological BCE window: train={int(training_counts.sum()):,} \"\n1540\t        f\"validation={int(validation_counts.sum()):,} \"\n1541\t        f\"selected={partition.selected_count:,} \"\n1542\t        f\"discarded_old_targets={int(partition.window_starts.sum()):,} \"\n1543\t        f\"all={prepared.target_count:,}\"\n1544\t    )\n1545\t    model = base.SequentialTwoTower(prepared.item_features, model_config(config)).to(\n1546\t        device\n1547\t    )\n1548\t    optimizer = torch.optim.AdamW(\n1549\t        model.parameters(), lr=config.learning_rate, weight_decay=config.weight_decay\n1550\t    )\n1551\t    generator = torch.Generator(device=\"cpu\").manual_seed(config.seed + 10_000)\n1552\t    item_correction = build_item_correction(\n1553\t        prepared,\n1554\t        config,\n1555\t        partition.window_starts,\n1556\t        training_counts,\n1557\t    )\n1558\t    target_weights = build_target_weights(\n1559\t        public,\n1560\t        stage,\n1561\t        prepared,\n1562\t        partition.history_training_counts,\n1563\t        config,\n1564\t    )\n1565\t    known_positive_packed = (\n1566\t        build_known_positive_filter(prepared, partition.history_training_counts)\n1567\t        if config.negative_filter_scope == \"full-training-history\"\n1568\t        else None\n1569\t    )\n1570\t    history: list[dict[str, float]] = []\n1571\t    best_loss = float(\"inf\")\n1572\t    best_epoch = 0\n1573\t    best_state: dict[str, torch.Tensor] | None = None\n1574\t    epochs_without_improvement = 0\n1575\t    start_epoch = 0\n1576\t\n1577\t    if resume_checkpoint is not None:\n1578\t        payload = torch.load(\n1579\t            resume_checkpoint, map_location=device, weights_only=False\n1580\t        )\n1581\t        stored_config = payload.get(\"config\", {})\n1582\t        architecture_fields = (\n1583\t            \"bptt_steps\",\n1584\t            \"embedding_dim\",\n1585\t            \"hidden_dim\",\n1586\t            \"user_hidden_1\",\n1587\t            \"user_hidden_2\",\n1588\t            \"item_hidden_1\",\n1589\t            \"item_hidden_2\",\n1590\t        )\n1591\t        mismatches = {\n1592\t            name: (stored_config.get(name), getattr(config, name))\n1593\t            for name in architecture_fields\n1594\t            if stored_config.get(name) != getattr(config, name)\n1595\t        }\n1596\t        if mismatches:\n1597\t            raise RuntimeError(\n1598\t                f\"resume checkpoint architecture differs: {mismatches}\"\n1599\t            )\n1600\t        stored_filter_scope = stored_config.get(\n1601\t            \"negative_filter_scope\", \"last-100\"\n1602\t        )\n1603\t        stored_target_weighting = stored_config.get(\n1604\t            \"target_weighting\", \"uniform\"\n1605\t        )\n1606\t        stored_weight_values = (\n1607\t            stored_config.get(\"ordinary_target_weight\", 1.0),\n1608\t            stored_config.get(\"organic_strong_target_weight\", 1.0),\n1609\t            stored_config.get(\"organic_like_target_weight\", 3.0),\n1610\t            stored_config.get(\"discovery_horizon_days\", 7),\n1611\t        )\n1612\t        current_weight_values = (\n1613\t            config.ordinary_target_weight,\n1614\t            config.organic_strong_target_weight,\n1615\t            config.organic_like_target_weight,\n1616\t            config.discovery_horizon_days,\n1617\t        )\n1618\t        stored_window_values = (\n1619\t            stored_config.get(\"validation_fraction\", 0.10),\n1620\t            stored_config.get(\"max_train_targets_per_user\", 0),\n1621\t            stored_config.get(\"max_validation_targets_per_user\", 0),\n1622\t        )\n1623\t        current_window_values = (\n1624\t            config.validation_fraction,\n1625\t            config.max_train_targets_per_user,\n1626\t            config.max_validation_targets_per_user,\n1627\t        )\n1628\t        objective_changed = (\n1629\t            stored_filter_scope != config.negative_filter_scope\n1630\t            or stored_target_weighting != config.target_weighting\n1631\t            or stored_weight_values != current_weight_values\n1632\t            or stored_window_values != current_window_values\n1633\t        )\n1634\t        model.load_state_dict(payload[\"model_state\"])\n1635\t        if \"optimizer_state\" in payload and not objective_changed:\n1636\t            optimizer.load_state_dict(payload[\"optimizer_state\"])\n1637\t            for group in optimizer.param_groups:\n1638\t                group[\"lr\"] = config.learning_rate\n1639\t                group[\"weight_decay\"] = config.weight_decay\n1640\t            log(f\"restored optimizer state from {resume_checkpoint}\")\n1641\t        else:\n1642\t            log(\n1643\t                f\"using a fresh AdamW optimizer after loading {resume_checkpoint}\"\n1644\t            )\n1645\t        if \"generator_state\" in payload and not objective_changed:\n1646\t            generator.set_state(payload[\"generator_state\"])\n1647\t        start_epoch = int(payload[\"epoch\"])\n1648\t        if start_epoch >= config.epochs:\n1649\t            raise RuntimeError(\n1650\t                f\"resume epoch {start_epoch} must be below --epochs {config.epochs}\"\n1651\t            )\n1652\t        prior = {\n1653\t            str(name): float(value)\n1654\t            for name, value in payload.get(\"diagnostics\", {}).items()\n1655\t        }\n1656\t        if objective_changed:\n1657\t            prior.pop(\"validation_loss\", None)\n1658\t            log(\n1659\t                \"BCE objective changed: filter \"\n1660\t                f\"{stored_filter_scope}->{config.negative_filter_scope}, \"\n1661\t                \"target weighting \"\n1662\t                f\"{stored_target_weighting}->{config.target_weighting}, \"\n1663\t                f\"target window {stored_window_values}->{current_window_values}; \"\n1664\t                \"recomputing the resume checkpoint's validation BCE\"\n1665\t            )\n1666\t        if \"validation_loss\" not in prior:\n1667\t            prior.update(\n1668\t                evaluate_validation_bce(\n1669\t                    model,\n1670\t                    prepared,\n1671\t                    config,\n1672\t                    target_weights,\n1673\t                    partition.window_starts,\n1674\t                    training_counts,\n1675\t                    validation_counts,\n1676\t                    item_correction,\n1677\t                    known_positive_packed,\n1678\t                    device,\n1679\t                )\n1680\t            )\n1681\t        history.append(prior)\n1682\t        best_loss = float(prior[\"validation_loss\"])\n1683\t        best_epoch = start_epoch\n1684\t        best_state = snapshot_model(model)\n1685\t        log(\n1686\t            f\"resumed validation-BCE training: epoch={start_epoch} \"\n1687\t            f\"loss={best_loss:.6f}\"\n1688\t        )\n1689\t\n1690\t    for epoch in range(start_epoch + 1, config.epochs + 1):\n1691\t        diagnostics = run_training_epoch(\n1692\t            model,\n1693\t            optimizer,\n1694\t            prepared,\n1695\t            config,\n1696\t            target_weights,\n1697\t            partition.window_starts,\n1698\t            training_counts,\n1699\t            item_correction,\n1700\t            known_positive_packed,\n1701\t            generator,\n1702\t            device,\n1703\t            epoch,\n1704\t        )\n1705\t        validation = evaluate_validation_bce(\n1706\t            model,\n1707\t            prepared,\n1708\t            config,\n1709\t            target_weights,\n1710\t            partition.window_starts,\n1711\t            training_counts,\n1712\t            validation_counts,\n1713\t            item_correction,\n1714\t            known_positive_packed,\n1715\t            device,\n1716\t        )\n1717\t        diagnostics.update(validation)\n1718\t        history.append(diagnostics)\n1719\t        current_state = snapshot_model(model)\n1720\t        if checkpoint_dir is not None:\n1721\t            save_epoch_checkpoint(\n1722\t                checkpoint_dir,\n1723\t                epoch,\n1724\t                current_state,\n1725\t                config,\n1726\t                diagnostics,\n1727\t                optimizer,\n1728\t                generator,\n1729\t            )\n1730\t        improved = (\n1731\t            diagnostics[\"validation_loss\"]\n1732\t            < best_loss - config.early_stopping_min_delta\n1733\t        )\n1734\t        if improved:\n1735\t            best_loss = diagnostics[\"validation_loss\"]\n1736\t            best_epoch = epoch\n1737\t            best_state = current_state\n1738\t            epochs_without_improvement = 0\n1739\t            if checkpoint_dir is not None:\n1740\t                torch.save(\n1741\t                    {\n1742\t                        \"epoch\": epoch,\n1743\t                        \"config\": asdict(config),\n1744\t                        \"diagnostics\": diagnostics,\n1745\t                        \"model_state\": current_state,\n1746\t                        \"optimizer_state\": optimizer.state_dict(),\n1747\t                        \"generator_state\": generator.get_state(),\n1748\t                    },\n1749\t                    checkpoint_dir / \"best.pt\",\n1750\t                )\n1751\t        else:\n1752\t            epochs_without_improvement += 1\n1753\t        log(\n1754\t            f\"epoch={epoch}/{config.epochs} train_loss={diagnostics['loss']:.5f} \"\n1755\t            f\"validation_loss={diagnostics['validation_loss']:.5f} \"\n1756\t            f\"pair_accuracy={diagnostics['pair_accuracy']:.3f} \"\n1757\t            f\"train_targets={int(diagnostics['targets']):,} \"\n1758\t            f\"validation_targets={int(diagnostics['validation_targets']):,} \"\n1759\t            f\"train_seconds={diagnostics['seconds']:.1f} \"\n1760\t            f\"validation_seconds={diagnostics['validation_seconds']:.1f}\"\n1761\t        )\n1762\t        release_accelerator_cache(device)\n1763\t        if epochs_without_improvement >= config.early_stopping_patience:\n1764\t            log(\n1765\t                f\"early stopping after epoch={epoch}; \"\n1766\t                f\"best_epoch={best_epoch} best_validation_loss={best_loss:.6f}\"\n1767\t            )\n1768\t            break\n1769\t\n1770\t    if best_state is None:\n1771\t        raise RuntimeError(\"training did not produce a valid checkpoint\")\n1772\t    model.load_state_dict(best_state)\n1773\t    model.to(device).eval()\n1774\t    log(\n1775\t        f\"restored best validation-BCE checkpoint: epoch={best_epoch} \"\n1776\t        f\"loss={best_loss:.6f}\"\n1777\t    )\n1778\t    return model, history\n1779\t\n1780\t\n1781\t@torch.inference_mode()\n1782\tdef inference_queries(\n1783\t    model: base.SequentialTwoTower,\n1784\t    prepared: SequenceData,\n1785\t    config: Config,\n1786\t    device: torch.device,\n1787\t) -> torch.Tensor:\n1788\t    sequence_rows = prepared.inference_user_rows\n1789\t    lengths = np.where(\n1790\t        sequence_rows >= 0, prepared.lengths[np.maximum(sequence_rows, 0)], 0\n1791\t    )\n1792\t    ordered = np.argsort(lengths, kind=\"stable\")\n1793\t    result = torch.zeros(\n1794\t        len(sequence_rows), config.embedding_dim, dtype=torch.float32\n1795\t    )\n1796\t    for group_start in range(0, len(ordered), config.user_batch_size):\n1797\t        output_rows = ordered[group_start : group_start + config.user_batch_size]\n1798\t        rows = sequence_rows[output_rows]\n1799\t        group_lengths = lengths[output_rows]\n1800\t        hidden = torch.zeros(\n1801\t            1, len(output_rows), config.embedding_dim, device=device\n1802\t        )\n1803\t        for start in range(0, int(group_lengths.max(initial=0)), config.bptt_steps):\n1804\t            steps = min(\n1805\t                config.bptt_steps,\n1806\t                int(group_lengths.max(initial=0)) - start,\n1807\t            )\n1808\t            items = np.full(\n1809\t                (len(output_rows), steps),\n1810\t                len(prepared.item_ids),\n1811\t                dtype=np.uint16,\n1812\t            )\n1813\t            features = np.zeros((len(output_rows), steps, 3), dtype=np.float16)\n1814\t            counts = np.zeros(len(output_rows), dtype=np.int32)\n1815\t            for local_row, sequence_row in enumerate(rows):\n1816\t                if sequence_row < 0:\n1817\t                    continue\n1818\t                count = min(steps, max(int(group_lengths[local_row]) - start, 0))\n1819\t                if not count:\n1820\t                    continue\n1821\t                offset = int(prepared.offsets[sequence_row])\n1822\t                selected = slice(offset + start, offset + start + count)\n1823\t                items[local_row, :count] = prepared.sequence_items[selected]\n1824\t                features[local_row, :count] = prepared.event_features[selected]\n1825\t                counts[local_row] = count\n1826\t            outputs, _ = event_sequence(\n1827\t                model,\n1828\t                torch.from_numpy(items.astype(np.int64)).to(device),\n1829\t                torch.from_numpy(features.astype(np.float32)).to(device),\n1830\t                hidden,\n1831\t            )\n1832\t            next_rows: list[torch.Tensor] = []\n1833\t            for local_row, count in enumerate(counts):\n1834\t                next_rows.append(\n1835\t                    outputs[local_row, count - 1]\n1836\t                    if count\n1837\t                    else hidden[0, local_row]\n1838\t                )\n1839\t            hidden = torch.stack(next_rows).unsqueeze(0)\n1840\t\n1841\t        liked_items = torch.from_numpy(\n1842\t            prepared.inference_liked_items[output_rows].astype(np.int64)\n1843\t        ).to(device)\n1844\t        disliked_items = torch.from_numpy(\n1845\t            prepared.inference_disliked_items[output_rows].astype(np.int64)\n1846\t        ).to(device)\n1847\t        queries = user_queries(\n1848\t            model,\n1849\t            hidden.squeeze(0),\n1850\t            model._mean_context_channel(liked_items),\n1851\t            model._mean_context_channel(disliked_items),\n1852\t            torch.from_numpy(\n1853\t                prepared.inference_user_features[output_rows].astype(np.float32)\n1854\t            ).to(device),\n1855\t        )\n1856\t        result[torch.from_numpy(output_rows.astype(np.int64))] = queries.cpu()\n1857\t    return result\n1858\t\n1859\t\n1860\t@torch.inference_mode()\n1861\tdef rank_candidates(\n1862\t    model: base.SequentialTwoTower,\n1863\t    prepared: SequenceData,\n1864\t    eligibility: CandidateSet,\n1865\t    config: Config,\n1866\t    device: torch.device,\n1867\t    ranking_batch_size: int,\n1868\t) -> tuple[pd.DataFrame, dict[str, float]]:\n1869\t    model.eval()\n1870\t    queries = inference_queries(model, prepared, config, device)\n1871\t    item_parts: list[torch.Tensor] = []\n1872\t    for start in range(0, len(prepared.item_ids), 2_048):\n1873\t        rows = torch.arange(\n1874\t            start,\n1875\t            min(start + 2_048, len(prepared.item_ids)),\n1876\t            dtype=torch.long,\n1877\t            device=device,\n1878\t        )\n1879\t        item_parts.append(model.encode_items(rows).cpu())\n1880\t    items = torch.cat(item_parts)\n1881\t    rows: list[tuple[int, int, int]] = []\n1882\t    for start in range(0, len(eligibility.uids), ranking_batch_size):\n1883\t        end = min(start + ranking_batch_size, len(eligibility.uids))\n1884\t        scores = queries[start:end] @ items.T\n1885\t        eligible = np.unpackbits(\n1886\t            eligibility.packed[start:end],\n1887\t            axis=1,\n1888\t            count=len(prepared.item_ids),\n1889\t            bitorder=\"little\",\n1890\t        ).astype(bool, copy=False)\n1891\t        scores.masked_fill_(~torch.from_numpy(eligible), -torch.inf)\n1892\t        selected = torch.topk(scores, k=base.TOP_N, dim=1).indices.numpy()\n1893\t        for local_row, columns in enumerate(selected):\n1894\t            uid = int(eligibility.uids[start + local_row])\n1895\t            rows.extend(\n1896\t                (uid, int(prepared.item_ids[column]), rank)\n1897\t                for rank, column in enumerate(columns, start=1)\n1898\t            )\n1899\t        if end == len(eligibility.uids) or end % 1_024 == 0:\n1900\t            log(f\"ranked users={end:,}/{len(eligibility.uids):,}\")\n1901\t    query_norm = torch.linalg.vector_norm(queries, dim=1).numpy()\n1902\t    item_norm = torch.linalg.vector_norm(items, dim=1).numpy()\n1903\t    diagnostics = {\n1904\t        \"query_norm_mean\": float(query_norm.mean()),\n1905\t        \"query_norm_std\": float(query_norm.std()),\n1906\t        \"item_norm_mean\": float(item_norm.mean()),\n1907\t        \"item_norm_std\": float(item_norm.std()),\n1908\t    }\n1909\t    return pd.DataFrame(rows, columns=[\"uid\", \"item_id\", \"rank\"]), diagnostics\n1910\t\n1911\t\n1912\tdef write_ranking(frame: pd.DataFrame, output: Path) -> None:\n1913\t    output.parent.mkdir(parents=True, exist_ok=True)\n1914\t    if output.suffix == \".parquet\":\n1915\t        frame.to_parquet(output, index=False, compression=\"zstd\")\n1916\t    elif output.suffix == \".csv\":\n1917\t        frame.to_csv(output, index=False)\n1918\t    else:\n1919\t        raise ValueError(\"--output must end in .parquet or .csv\")\n1920\t\n1921\t\n1922\tdef main() -> int:\n1923\t    parser = argparse.ArgumentParser(description=__doc__)\n1924\t    parser.add_argument(\n1925\t        \"--stage\", choices=(\"validation\", \"submission\"), default=\"validation\"\n1926\t    )\n1927\t    parser.add_argument(\"--output\", type=Path, required=True)\n1928\t    parser.add_argument(\"--public-dir\", type=Path, required=True)\n1929\t    parser.add_argument(\"--prepared-cache\", type=Path)\n1930\t    parser.add_argument(\"--device\", choices=(\"cpu\", \"mps\"), default=\"cpu\")\n1931\t    parser.add_argument(\"--threads\", type=int, default=8)\n1932\t    parser.add_argument(\"--bptt-steps\", type=int, default=Config.bptt_steps)\n1933\t    parser.add_argument(\n1934\t        \"--user-batch-size\", type=int, default=Config.user_batch_size\n1935\t    )\n1936\t    parser.add_argument(\"--epochs\", type=int, default=Config.epochs)\n1937\t    parser.add_argument(\"--learning-rate\", type=float, default=Config.learning_rate)\n1938\t    parser.add_argument(\n1939\t        \"--loss-microbatch-size\",\n1940\t        type=int,\n1941\t        default=Config.loss_microbatch_size,\n1942\t    )\n1943\t    parser.add_argument(\n1944\t        \"--negative-filter-scope\",\n1945\t        choices=(\"full-training-history\", \"last-100\"),\n1946\t        default=Config.negative_filter_scope,\n1947\t    )\n1948\t    parser.add_argument(\n1949\t        \"--target-weighting\",\n1950\t        choices=(\"discovery-graded\", \"organic-strong\", \"uniform\"),\n1951\t        default=Config.target_weighting,\n1952\t    )\n1953\t    parser.add_argument(\n1954\t        \"--ordinary-target-weight\",\n1955\t        type=float,\n1956\t        default=Config.ordinary_target_weight,\n1957\t    )\n1958\t    parser.add_argument(\n1959\t        \"--organic-strong-target-weight\",\n1960\t        type=float,\n1961\t        default=Config.organic_strong_target_weight,\n1962\t    )\n1963\t    parser.add_argument(\n1964\t        \"--organic-like-target-weight\",\n1965\t        type=float,\n1966\t        default=Config.organic_like_target_weight,\n1967\t    )\n1968\t    parser.add_argument(\n1969\t        \"--discovery-horizon-days\",\n1970\t        type=int,\n1971\t        default=Config.discovery_horizon_days,\n1972\t    )\n1973\t    parser.add_argument(\n1974\t        \"--validation-fraction\",\n1975\t        type=float,\n1976\t        default=Config.validation_fraction,\n1977\t    )\n1978\t    parser.add_argument(\n1979\t        \"--max-train-targets-per-user\",\n1980\t        type=int,\n1981\t        default=Config.max_train_targets_per_user,\n1982\t        help=\"retain this many recent pre-validation targets per user; 0 is uncapped\",\n1983\t    )\n1984\t    parser.add_argument(\n1985\t        \"--max-validation-targets-per-user\",\n1986\t        type=int,\n1987\t        default=Config.max_validation_targets_per_user,\n1988\t        help=\"retain this many final validation targets per user; 0 is uncapped\",\n1989\t    )\n1990\t    parser.add_argument(\n1991\t        \"--early-stopping-patience\",\n1992\t        type=int,\n1993\t        default=Config.early_stopping_patience,\n1994\t    )\n1995\t    parser.add_argument(\n1996\t        \"--early-stopping-min-delta\",\n1997\t        type=float,\n1998\t        default=Config.early_stopping_min_delta,\n1999\t    )\n2000\t    parser.add_argument(\"--checkpoint-dir\", type=Path)\n2001\t    parser.add_argument(\"--resume-checkpoint\", type=Path)\n2002\t    parser.add_argument(\"--seed\", type=int, default=Config.seed)\n2003\t    parser.add_argument(\"--ranking-batch-size\", type=int, default=64)\n2004\t    parser.add_argument(\"--prepare-only\", action=\"store_true\")\n2005\t    args = parser.parse_args()\n2006\t\n2007\t    if args.threads < 1 or args.bptt_steps < 2 or args.user_batch_size < 1:\n2008\t        parser.error(\"threads, BPTT steps, and user batch size must be positive\")\n2009\t    if (\n2010\t        args.epochs < 1\n2011\t        or args.learning_rate <= 0\n2012\t        or args.loss_microbatch_size < 1\n2013\t        or args.early_stopping_patience < 1\n2014\t        or args.early_stopping_min_delta < 0\n2015\t        or args.ordinary_target_weight <= 0\n2016\t        or args.organic_strong_target_weight <= 0\n2017\t        or args.organic_like_target_weight <= 0\n2018\t        or args.discovery_horizon_days < 1\n2019\t        or args.max_train_targets_per_user < 0\n2020\t        or args.max_validation_targets_per_user < 0\n2021\t    ):\n2022\t        parser.error(\"training counts, learning rate, and patience are invalid\")\n2023\t    if not 0.0 < args.validation_fraction < 1.0:\n2024\t        parser.error(\"validation fraction must be strictly between zero and one\")\n2025\t    public = args.public_dir.resolve()\n2026\t    if not (public / \"data\" / \"candidate_catalog.parquet\").is_file():\n2027\t        parser.error(f\"public task data not found under {public}\")\n2028\t    config = Config(\n2029\t        bptt_steps=args.bptt_steps,\n2030\t        user_batch_size=args.user_batch_size,\n2031\t        epochs=args.epochs,\n2032\t        learning_rate=args.learning_rate,\n2033\t        loss_microbatch_size=args.loss_microbatch_size,\n2034\t        negative_filter_scope=args.negative_filter_scope,\n2035\t        target_weighting=args.target_weighting,\n2036\t        ordinary_target_weight=args.ordinary_target_weight,\n2037\t        organic_strong_target_weight=args.organic_strong_target_weight,\n2038\t        organic_like_target_weight=args.organic_like_target_weight,\n2039\t        discovery_horizon_days=args.discovery_horizon_days,\n2040\t        validation_fraction=args.validation_fraction,\n2041\t        max_train_targets_per_user=args.max_train_targets_per_user,\n2042\t        max_validation_targets_per_user=args.max_validation_targets_per_user,\n2043\t        early_stopping_patience=args.early_stopping_patience,\n2044\t        early_stopping_min_delta=args.early_stopping_min_delta,\n2045\t        seed=args.seed,\n2046\t    )\n2047\t    torch.set_num_threads(args.threads)\n2048\t    torch.set_num_interop_threads(1)\n2049\t    seed_everything(config.seed)\n2050\t    device = torch.device(args.device)\n2051\t    if device.type == \"mps\" and not torch.backends.mps.is_available():\n2052\t        parser.error(\"MPS was requested but is unavailable\")\n2053\t\n2054\t    started = time.monotonic()\n2055\t    prepared, eligibility = load_or_prepare(\n2056\t        public,\n2057\t        args.stage,\n2058\t        config,\n2059\t        args.prepared_cache.resolve() if args.prepared_cache else None,\n2060\t    )\n2061\t    target_partition = chronological_target_partition(\n2062\t        prepared,\n2063\t        config.validation_fraction,\n2064\t        config.max_train_targets_per_user,\n2065\t        config.max_validation_targets_per_user,\n2066\t    )\n2067\t    if args.prepare_only:\n2068\t        print(\n2069\t            json.dumps(\n2070\t                {\n2071\t                    \"stage\": args.stage,\n2072\t                    \"sequence_users\": len(prepared.user_ids),\n2073\t                    \"sequence_tokens\": len(prepared.sequence_items),\n2074\t                    \"next_item_targets\": prepared.target_count,\n2075\t                    \"selected_training_targets\": int(\n2076\t                        target_partition.training_counts.sum()\n2077\t                    ),\n2078\t                    \"selected_validation_targets\": int(\n2079\t                        target_partition.validation_counts.sum()\n2080\t                    ),\n2081\t                    \"discarded_old_targets\": int(\n2082\t                        target_partition.window_starts.sum()\n2083\t                    ),\n2084\t                    \"target_users\": len(eligibility.uids),\n2085\t                    \"runtime_seconds\": round(time.monotonic() - started, 3),\n2086\t                    \"config\": asdict(config),\n2087\t                },\n2088\t                indent=2,\n2089\t            )\n2090\t        )\n2091\t        return 0\n2092\t\n2093\t    model, training_history = train_model(\n2094\t        public,\n2095\t        args.stage,\n2096\t        prepared,\n2097\t        config,\n2098\t        device,\n2099\t        args.checkpoint_dir.resolve() if args.checkpoint_dir else None,\n2100\t        args.resume_checkpoint.resolve() if args.resume_checkpoint else None,\n2101\t    )\n2102\t    ranking, embedding_diagnostics = rank_candidates(\n2103\t        model,\n2104\t        prepared,\n2105\t        eligibility,\n2106\t        config,\n2107\t        device,\n2108\t        args.ranking_batch_size,\n2109\t    )\n2110\t    write_ranking(ranking, args.output.resolve())\n2111\t    print(\n2112\t        json.dumps(\n2113\t            {\n2114\t                \"baseline\": \"yambda-windowed-sequence-two-tower-base\",\n2115\t                \"stage\": args.stage,\n2116\t                \"output\": str(args.output.resolve()),\n2117\t                \"rows\": len(ranking),\n2118\t                \"users\": int(ranking.uid.nunique()),\n2119\t                \"runtime_seconds\": round(time.monotonic() - started, 3),\n2120\t                \"public_inputs_only\": True,\n2121\t                \"architecture\": {\n2122\t                    \"family\": \"pure-windowed-sequence-two-tower\",\n2123\t                    \"sequence_training\": (\n2124\t                        \"every-adjacent-target-within-recent-chronological-window\"\n2125\t                    ),\n2126\t                    \"sequence_encoder\": \"one-layer-GRU-dense-timestep-loss\",\n2127\t                    \"bptt_hidden_state\": \"carried-and-detached\",\n2128\t                    \"model_selection\": \"chronological-validation-BCE-early-stopping\",\n2129\t                    \"loss_execution\": \"gradient-accumulated-microbatches\",\n2130\t                    \"user_id_embedding\": False,\n2131\t                    \"user_mlp\": \"582-512-256-192\",\n2132\t                    \"item_mlp\": \"196-512-256-192\",\n2133\t                    \"normalization\": \"none\",\n2134\t                    \"score\": \"raw-dot-product\",\n2135\t                    \"objective\": \"sample-weighted-BCE-at-every-timestep\",\n2136\t                    \"negative_sampling\": (\n2137\t                        \"24-uniform-plus-8-propensity-corrected-inbatch\"\n2138\t                    ),\n2139\t                    \"false_negative_filter\": config.negative_filter_scope,\n2140\t                    \"target_weighting\": config.target_weighting,\n2141\t                },\n2142\t                \"config\": asdict(config),\n2143\t                \"sequence_tokens\": len(prepared.sequence_items),\n2144\t                \"all_next_item_targets\": prepared.target_count,\n2145\t                \"selected_training_targets\": int(\n2146\t                    target_partition.training_counts.sum()\n2147\t                ),\n2148\t                \"selected_validation_targets\": int(\n2149\t                    target_partition.validation_counts.sum()\n2150\t                ),\n2151\t                \"discarded_old_targets\": int(target_partition.window_starts.sum()),\n2152\t                \"training_history\": training_history,\n2153\t                \"embedding_diagnostics\": embedding_diagnostics,\n2154\t                \"torch_version\": torch.__version__,\n2155\t                \"device\": str(device),\n2156\t            },\n2157\t            indent=2,\n2158\t        )\n2159\t    )\n2160\t    return 0\n2161\t\n2162\t\n2163\tif __name__ == \"__main__\":\n2164\t    raise SystemExit(main())\n2165\t",
            "isError": false
          }
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:03:15.500Z",
          "callId": "toolu_01Gxww1g6s8ku64FvM9PpqCY",
          "name": "Bash",
          "input": {
            "command": "cd /app/solution && cp /task/current_model/*.py . && ls; python -c \"\nimport pandas as pd, numpy as np\nfor f in ['candidate_catalog','target_users','validation_preference_state']:\n    d=pd.read_parquet(f'/task/data/{f}.parquet'); print(f, d.shape); print(d.head(3))\nvl=pd.read_parquet('/task/data/val_listens.parquet'); print(vl.shape, vl.timestamp.min(), vl.timestamp.max()); print(vl.is_organic.mean(), (vl.played_ratio_pct>=80).mean())\n\"",
            "description": "Copy production source to solution dir and peek at data"
          },
          "result": {
            "timestamp": "2026-10-03T09:03:17.214Z",
            "content": "train_current_model.py\ntwo_tower_model.py\ncandidate_catalog (30000, 4)\n   item_id  positive_listens  organic_positive_listens  popularity_rank\n0  5862961             26615                     20620                1\n1  6901374             25536                     17347                2\n2  5635052             24691                     17194                3\ntarget_users (8456, 3)\n   uid  recent_positive_listens  history_positive_listens\n0  100                    844.0                      2604\n1  200                     50.0                       286\n2  300                    168.0                       359\nvalidation_preference_state (469124, 3)\n   uid  item_id  state\n0  100   410868  liked\n1  100   732449  liked\n2  100   982903  liked\n(1501697, 6) 24788600 25393395\n0.517072352145606 0.6023385543155511",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:03:17.219Z",
          "data": {
            "type": "environment",
            "snapshot": {
              "workingDirectory": "/app/solution",
              "isWorktree": false,
              "isGitRepo": false,
              "additionalWorkingDirectories": [],
              "platform": "linux",
              "shell": "unknown",
              "osVersion": "Linux 7.0.0-1013-aws"
            },
            "changes": [
              {
                "field": "workingDirectory",
                "from": "/app"
              }
            ]
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:03:17.219Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14940637 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:03:17.221Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 7,
      "role": "agent",
      "timestamp": "2026-10-03T09:03:24.515Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:03:24.515Z",
          "text": "With about 60 minutes total and roughly 5 used, I should kick off the baseline run now in the background with a prepared cache so I can reuse it, then think through the diagnosis while it runs.\n\n"
        },
        {
          "kind": "message",
          "timestamp": "2026-10-03T09:03:24.519Z",
          "text": "I have the full picture of the script. Now I'll launch the baseline backtest in the background (caching the prepared sequences for reuse), and meanwhile analyze the negative-sampling objective."
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:03:25.635Z",
          "callId": "toolu_01JHzMFSmLwihhZFfSZL3WBR",
          "name": "Bash",
          "input": {
            "command": "mkdir -p runs && (time python /task/current_model/train_current_model.py --stage validation --public-dir /task --prepared-cache /app/solution/runs/val_cache.npz --output /app/solution/production_validation.parquet > runs/baseline_val.json 2> runs/baseline_val.log; python /task/evaluate_public.py /app/solution/production_validation.parquet > runs/baseline_val.score 2>&1) > runs/baseline_time.txt 2>&1 &\necho started",
            "description": "Run baseline validation backtest in background with cache"
          },
          "result": {
            "timestamp": "2026-10-03T09:03:25.656Z",
            "content": "started",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:03:25.659Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14928860 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:03:25.661Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 8,
      "role": "agent",
      "timestamp": "2026-10-03T09:04:01.623Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:04:01.623Z",
          "text": "While that's running, let me diagnose the negative sampling issue: the 24 uniform negatives drawn from the 30k catalog mostly land on unpopular tail items, making them trivially easy and pushing the model toward learning a popularity bias since positives are themselves popularity-skewed. I should also look at how the 8 in-batch negatives are contributing to this dynamic.\n\nAveraging 32 negatives means each contributes only 1/32 the gradient of the positive, which is weak given uniform sampling makes the negatives too easy relative to the actual discovery ranking task. A stronger fix would be sampled softmax or InfoNCE with log-Q correction using popularity-proportional negative sampling, or expanding in-batch negatives to all unique batch targets with similar correction — both standard improvements over BCE with uniform negatives for two-tower retrieval.\n\nI need to check the cost of a full softmax over unique batch targets, which turns out cheap computationally (a few GFLOP, fine on CPU), but I still have to respect the fixed 60-minute CPU budget across baseline and final refit, so I should check how long the baseline run actually takes. There's also the false-negative issue: I need to mask out each user's known positive items from the in-batch negative set, which I can do efficiently with a packed-bit lookup matrix rather than a dense boolean mask.\n\nFor the actual training objective, I'm planning a sampled-softmax approach: for each batch, build a candidate set from the unique in-batch targets plus a pool of shared negatives drawn from a popularity-based (or uniform) distribution, compute logits as the dot product between queries and item vectors, then apply a log-Q correction to account for sampling bias and mask out any known positives before computing the weighted cross-entropy loss.\n\nThe real problem with the current setup is that uniform catalog negatives are mostly unpopular long-tail items that give almost no gradient once the model learns popularity, leaving only the in-batch negatives as informative signal -- and even those are hobbled by the clipped power correction. Switching to full in-batch softmax with logQ correction plus popularity-aware shared negatives would give far more informative negatives per target at similar compute cost. I'm also weighing whether raw, unnormalized dot products could make the softmax numerically unstable without some form of temperature scaling or normalization.\n\nSince the serving contract requires raw dot product scoring, I'll stick with raw dot products rather than adding L2 normalization, relying on gradient clipping to control large logits, and ranking behavior stays the same either way. I also need to make sure early stopping's validation BCE uses this same new objective for consistency, though with the default of one epoch early stopping barely matters since the best state is just epoch 1.\n\nNow let me check the training log to see how long the baseline run is taking.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:04:01.629Z",
          "callId": "toolu_01BCeuXXhZ3nNMYXQtesiL2m",
          "name": "Bash",
          "input": {
            "command": "sleep 60; tail -5 /app/solution/runs/baseline_val.log; cat /app/solution/runs/baseline_time.txt",
            "description": "Check baseline run progress"
          },
          "result": {
            "timestamp": "2026-10-03T09:05:01.681Z",
            "content": "saved public-derived full-sequence cache: /app/solution/runs/val_cache.npz\nchronological BCE window: train=1,052,953 validation=130,103 selected=1,183,056 discarded_old_targets=18,864,138 all=20,047,194\ninbatch correction: min=0.250 mean_on_targets=1.001 max=4.000\ntarget weighting=organic-strong min=0.250 mean=0.575 max=1.000\nfull-history false-negative filter: users=9,135 unique_user_items=5,524,275 bytes=34,256,250",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:05:01.684Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14926791 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:05:01.686Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 9,
      "role": "agent",
      "timestamp": "2026-10-03T09:05:41.846Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:05:41.846Z",
          "text": "Data prep finished in about 1.5 minutes and training on 1M targets is underway, so I'll check training speed while I draft the improved objective. I'm planning config changes for train_current_model.py, adding an objective option switching between bce and sampled-softmax, plus shared negative sampling parameters with popularity-based weighting.\n\nI'm designing a function to draw shared negatives and compute log-q corrections, then modifying the loss computation so candidates are shared across microbatches but encoded per microbatch for gradients, masking false negatives and tracking the positive's index among candidates. For log-q correction, I'm working out that the probability an item appears as an in-batch negative scales roughly with batch size times its sampling frequency, which needs to offset the sampled logits.\n\nRough compute estimate: logits matrix across block size and candidates comes to roughly 5-20ms per block on the forward pass, similar for false-negative masking via bit-packed known-positives, though the naive broadcast approach for liked items blows up memory, so I need a row-wise construction instead of full tensor comparison.\n\nFor liked items, I decide to build an item-to-candidate-position lookup array, map liked and target items into candidate-space indices, then scatter them into the mask with put_along_axis rather than materializing a huge boolean tensor. Since the microbatch size exceeds any block size, each block effectively runs as a single microbatch, simplifying the loss computation to a straightforward weighted cross-entropy over logits and positions.\n\nI'm keeping the diagnostic metrics approximate — tracking positive/negative sums and the fraction of correctly ranked pairs — while being careful to avoid division issues in the negative-count stat. I'll use raw dot-product logits without a learnable temperature, relying on gradient clipping and small initial weights to keep things stable, and I still need to sort out how validation loss should be computed for the softmax objective compared to the BCE evaluator's negative sampling.\n\nThinking about budget: with roughly 60 minutes and each run taking 8-10 minutes, I can likely fit in 2-3 validation runs plus a final refit, so I should decide whether to test popularity-weighted negative sampling power now or skip it given time constraints.\n\nNow let me start editing train_current_model.py to add the new functions.\n\n"
        },
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:05:41.861Z",
          "text": "Baseline training is running; meanwhile I'll update the solution's objective—swapping the uniform catalog negatives and clipped power correction for a full in-batch sampled softmax with popularity-sampled negatives, proper logQ correction, and the same false-negative filtering.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:06:18.177Z",
          "callId": "toolu_01KigizQuBPQdJ1jdxe7Ai5L",
          "name": "Bash",
          "input": {
            "command": "python - <<'EOF'\nimport re\np='train_current_model.py'\ns=open(p).read()\n\n# 1. Config additions\ns=s.replace('''    negative_filter_scope: str = \"full-training-history\"\n    target_weighting: str = \"organic-strong\"''','''    negative_filter_scope: str = \"full-training-history\"\n    objective: str = \"sampled-softmax\"\n    shared_negatives: int = 1024\n    shared_negative_power: float = 0.75\n    logq_correction: bool = True\n    target_weighting: str = \"organic-strong\"''')\n\n# 2. New sampled-softmax helpers inserted before corrected_negative_loss\nhelpers = '''\n@dataclass(frozen=True)\nclass SoftmaxCandidates:\n    \"\"\"Shared candidate set for one block's sampled-softmax loss.\"\"\"\n\n    items: torch.Tensor\n    log_q: torch.Tensor\n    positive_columns: torch.Tensor\n    invalid: torch.Tensor\n\n\ndef build_item_target_frequency(\n    prepared: SequenceData,\n    target_starts: np.ndarray,\n    target_counts: np.ndarray,\n) -> np.ndarray:\n    \"\"\"Smoothed frequency of every catalog item among selected training targets.\"\"\"\n    counts = np.zeros(len(prepared.item_ids), dtype=np.float64)\n    for user_row, count in enumerate(target_counts):\n        if not count:\n            continue\n        offset = int(prepared.offsets[user_row])\n        target_start = int(target_starts[user_row])\n        counts += np.bincount(\n            prepared.sequence_items[\n                offset + target_start + 1 : offset + target_start + int(count) + 1\n            ].astype(np.int64),\n            minlength=len(prepared.item_ids),\n        )\n    return (counts + 1.0) / (counts.sum() + len(counts))\n\n\ndef build_shared_negative_distribution(\n    target_frequency: np.ndarray, power: float\n) -> np.ndarray:\n    weights = np.power(target_frequency, power)\n    return weights / weights.sum()\n\n\ndef build_softmax_candidates(\n    targets: torch.Tensor,\n    user_rows: np.ndarray,\n    liked_items: torch.Tensor,\n    known_positive_packed: np.ndarray,\n    n_items: int,\n    config: Config,\n    target_frequency: np.ndarray,\n    shared_distribution: np.ndarray,\n    generator: torch.Generator,\n    device: torch.device,\n) -> SoftmaxCandidates:\n    \"\"\"Unique in-block targets plus popularity-sampled shared negatives.\n\n    Every target in the block is scored against the same candidate list, so a\n    block with B targets yields roughly B + shared_negatives informative\n    negatives per example instead of 32. Known public-training positives,\n    active likes, and the example's own target are masked, and a log-Q\n    correction removes the sampling bias of popular candidates.\n    \"\"\"\n    targets_cpu = targets.detach().cpu().numpy().astype(np.int64, copy=False)\n    liked_cpu = liked_items.detach().cpu().numpy().astype(np.int64, copy=False)\n    batch_size = len(targets_cpu)\n    unique_targets = np.unique(targets_cpu)\n    if config.shared_negatives:\n        sampled = torch.multinomial(\n            torch.from_numpy(shared_distribution.astype(np.float32)),\n            config.shared_negatives,\n            replacement=True,\n            generator=generator,\n        ).numpy()\n        candidates = np.union1d(unique_targets, sampled)\n    else:\n        candidates = unique_targets\n    n_candidates = len(candidates)\n\n    # Inclusion probability of each candidate in this block's candidate list.\n    if config.logq_correction:\n        p_target = target_frequency[candidates]\n        miss = np.power(np.maximum(1.0 - p_target, 1.0e-12), batch_size)\n        if config.shared_negatives:\n            miss *= np.power(\n                np.maximum(1.0 - shared_distribution[candidates], 1.0e-12),\n                config.shared_negatives,\n            )\n        q = np.clip(1.0 - miss, 1.0e-9, 1.0)\n        log_q = np.log(q).astype(np.float32)\n    else:\n        log_q = np.zeros(n_candidates, dtype=np.float32)\n\n    position = np.full(n_items + 1, -1, dtype=np.int64)\n    position[candidates] = np.arange(n_candidates, dtype=np.int64)\n    positive_columns = position[targets_cpu]\n    if np.any(positive_columns < 0):\n        raise RuntimeError(\"target missing from softmax candidate list\")\n\n    # False-negative mask from the complete public-training positive prefix.\n    byte_columns = candidates >> 3\n    bit_columns = (candidates & 7).astype(np.uint8)\n    known = known_positive_packed[user_rows[:, None], byte_columns[None, :]]\n    invalid = ((known >> bit_columns[None, :]) & 1).astype(bool)\n    liked_positions = position[np.minimum(liked_cpu, n_items)]\n    liked_positions[liked_cpu >= n_items] = -1\n    rows = np.broadcast_to(\n        np.arange(batch_size)[:, None], liked_positions.shape\n    )\n    keep = liked_positions >= 0\n    invalid[rows[keep], liked_positions[keep]] = True\n    invalid[np.arange(batch_size), positive_columns] = False\n    return SoftmaxCandidates(\n        items=torch.from_numpy(candidates).to(device),\n        log_q=torch.from_numpy(log_q).to(device),\n        positive_columns=torch.from_numpy(positive_columns).to(device),\n        invalid=torch.from_numpy(invalid).to(device),\n    )\n\n\ndef sampled_softmax_loss(\n    query_vectors: torch.Tensor,\n    candidate_vectors_: torch.Tensor,\n    candidates: SoftmaxCandidates,\n    row_slice: slice,\n) -> tuple[torch.Tensor, torch.Tensor, torch.Tensor]:\n    \"\"\"Per-example log-Q corrected cross entropy over the shared candidates.\"\"\"\n    logits = query_vectors @ candidate_vectors_.T\n    corrected = logits - candidates.log_q[None, :]\n    invalid = candidates.invalid[row_slice]\n    corrected = corrected.masked_fill(invalid, -1.0e4)\n    positive_columns = candidates.positive_columns[row_slice]\n    loss = F.cross_entropy(corrected, positive_columns, reduction=\"none\")\n    positive_logits = logits.gather(1, positive_columns[:, None]).squeeze(1)\n    with torch.no_grad():\n        valid_negatives = ~invalid\n        valid_negatives[\n            torch.arange(len(positive_columns), device=logits.device),\n            positive_columns,\n        ] = False\n        wins = (\n            (logits.detach() < positive_logits.detach()[:, None]) & valid_negatives\n        ).sum(dim=1).float() / valid_negatives.sum(dim=1).clamp_min(1).float()\n    return loss, positive_logits, wins\n\n'''\ns=s.replace('\\ndef corrected_negative_loss(', helpers+'\\ndef corrected_negative_loss(')\n\n# 3. score_target_microbatches: accept optional softmax candidates\ns=s.replace('''    sample_weights: np.ndarray,\n    device: torch.device,\n    backward: bool,\n) -> tuple[dict[str, float], torch.Tensor | None]:\n    \"\"\"Compute one logical block's exact BCE in bounded-memory slices.\"\"\"''','''    sample_weights: np.ndarray,\n    device: torch.device,\n    backward: bool,\n    softmax_candidates: SoftmaxCandidates | None = None,\n) -> tuple[dict[str, float], torch.Tensor | None]:\n    \"\"\"Compute one logical block's exact loss in bounded-memory slices.\"\"\"''')\n\ns=s.replace('''        positive_vectors, negative_vectors = candidate_vectors(\n            model,\n            positive_items[begin:end],\n            negatives[begin:end],\n        )\n        positive_logits = (query_vectors * positive_vectors).sum(dim=1)\n        negative_logits = torch.einsum(\n            \"bd,bkd->bk\", query_vectors, negative_vectors\n        )\n        positive_loss = F.softplus(-positive_logits)\n        negative_loss = corrected_negative_loss(\n            negative_logits, negative_weights[begin:end], config\n        )\n        selected_weights = torch.from_numpy(\n            sample_weights[begin:end].astype(np.float32, copy=False)\n        ).to(device)\n        loss_sum = (\n            selected_weights * (positive_loss + negative_loss) / 2.0\n        ).sum()''','''        selected_weights = torch.from_numpy(\n            sample_weights[begin:end].astype(np.float32, copy=False)\n        ).to(device)\n        if softmax_candidates is not None:\n            encoded_candidates = model.encode_items(softmax_candidates.items)\n            example_loss, positive_logits, wins = sampled_softmax_loss(\n                query_vectors,\n                encoded_candidates,\n                softmax_candidates,\n                slice(begin, end),\n            )\n            loss_sum = (selected_weights * example_loss).sum()\n            negative_logits = torch.zeros((end - begin, 1), device=device)\n            pair_correct = float(wins.sum().cpu())\n        else:\n            positive_vectors, negative_vectors = candidate_vectors(\n                model,\n                positive_items[begin:end],\n                negatives[begin:end],\n            )\n            positive_logits = (query_vectors * positive_vectors).sum(dim=1)\n            negative_logits = torch.einsum(\n                \"bd,bkd->bk\", query_vectors, negative_vectors\n            )\n            positive_loss = F.softplus(-positive_logits)\n            negative_loss = corrected_negative_loss(\n                negative_logits, negative_weights[begin:end], config\n            )\n            loss_sum = (\n                selected_weights * (positive_loss + negative_loss) / 2.0\n            ).sum()\n            pair_correct = float(\n                (positive_logits.detach()[:, None] > negative_logits.detach())\n                .float()\n                .mean(dim=1)\n                .sum()\n                .cpu()\n            )''')\ns=s.replace('''        statistics[\"pair_correct\"] += float(\n            (positive_logits.detach()[:, None] > negative_logits.detach()).sum().cpu()\n        )''','''        statistics[\"pair_correct\"] += pair_correct''')\n\nopen(p,'w').write(s)\nEOF\ngrep -n \"pair_accuracy\\|negative_count\" train_current_model.py | head",
            "description": "Patch config, add sampled-softmax helpers, and extend microbatch loss"
          },
          "result": {
            "timestamp": "2026-10-03T09:06:18.427Z",
            "content": "Traceback (most recent call last):\n  File \"<stdin>\", line 231, in <module>\nPermissionError: [Errno 13] Permission denied: 'train_current_model.py'\n1227:    negative_count = config.uniform_negatives + config.inbatch_negatives\n1353:        \"negative_logit\": total_negative / max(total_targets * negative_count, 1),\n1354:        \"pair_accuracy\": total_pair_correct\n1355:        / max(total_targets * negative_count, 1),\n1756:            f\"pair_accuracy={diagnostics['pair_accuracy']:.3f} \"",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:06:18.432Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14920628 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:06:18.436Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 10,
      "role": "agent",
      "timestamp": "2026-10-03T09:06:21.352Z",
      "blocks": [
        {
          "kind": "message",
          "timestamp": "2026-10-03T09:06:21.352Z",
          "text": "The copied files kept read-only permissions. I'll fix permissions and re-run the patch."
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:06:57.809Z",
          "callId": "toolu_017QqVRYnNYXd15rTxNwbM9T",
          "name": "Bash",
          "input": {
            "command": "chmod u+w *.py && python - <<'EOF'\np='train_current_model.py'\ns=open(p).read()\n\ns=s.replace('''    negative_filter_scope: str = \"full-training-history\"\n    target_weighting: str = \"organic-strong\"''','''    negative_filter_scope: str = \"full-training-history\"\n    objective: str = \"sampled-softmax\"\n    shared_negatives: int = 1024\n    shared_negative_power: float = 0.75\n    logq_correction: bool = True\n    target_weighting: str = \"organic-strong\"''')\n\nhelpers = '''\n@dataclass(frozen=True)\nclass SoftmaxCandidates:\n    \"\"\"Shared candidate set for one block's sampled-softmax loss.\"\"\"\n\n    items: torch.Tensor\n    log_q: torch.Tensor\n    positive_columns: torch.Tensor\n    invalid: torch.Tensor\n\n\ndef build_item_target_frequency(\n    prepared: SequenceData,\n    target_starts: np.ndarray,\n    target_counts: np.ndarray,\n) -> np.ndarray:\n    \"\"\"Smoothed frequency of every catalog item among selected training targets.\"\"\"\n    counts = np.zeros(len(prepared.item_ids), dtype=np.float64)\n    for user_row, count in enumerate(target_counts):\n        if not count:\n            continue\n        offset = int(prepared.offsets[user_row])\n        target_start = int(target_starts[user_row])\n        counts += np.bincount(\n            prepared.sequence_items[\n                offset + target_start + 1 : offset + target_start + int(count) + 1\n            ].astype(np.int64),\n            minlength=len(prepared.item_ids),\n        )\n    return (counts + 1.0) / (counts.sum() + len(counts))\n\n\ndef build_shared_negative_distribution(\n    target_frequency: np.ndarray, power: float\n) -> np.ndarray:\n    weights = np.power(target_frequency, power)\n    return weights / weights.sum()\n\n\ndef build_softmax_candidates(\n    targets: torch.Tensor,\n    user_rows: np.ndarray,\n    liked_items: torch.Tensor,\n    known_positive_packed: np.ndarray,\n    n_items: int,\n    config: Config,\n    target_frequency: np.ndarray,\n    shared_distribution: np.ndarray,\n    generator: torch.Generator,\n    device: torch.device,\n) -> SoftmaxCandidates:\n    \"\"\"Unique in-block targets plus popularity-sampled shared negatives.\n\n    Every target in the block is scored against the same candidate list, so a\n    block with B targets yields roughly B + shared_negatives informative\n    negatives per example instead of 32. Known public-training positives,\n    active likes, and the example's own target are masked, and a log-Q\n    correction removes the sampling bias of popular candidates.\n    \"\"\"\n    targets_cpu = targets.detach().cpu().numpy().astype(np.int64, copy=False)\n    liked_cpu = liked_items.detach().cpu().numpy().astype(np.int64, copy=False)\n    batch_size = len(targets_cpu)\n    unique_targets = np.unique(targets_cpu)\n    if config.shared_negatives:\n        sampled = torch.multinomial(\n            torch.from_numpy(shared_distribution.astype(np.float32)),\n            config.shared_negatives,\n            replacement=True,\n            generator=generator,\n        ).numpy()\n        candidates = np.union1d(unique_targets, sampled)\n    else:\n        candidates = unique_targets\n    n_candidates = len(candidates)\n\n    # Inclusion probability of each candidate in this block's candidate list.\n    if config.logq_correction:\n        p_target = target_frequency[candidates]\n        miss = np.power(np.maximum(1.0 - p_target, 1.0e-12), batch_size)\n        if config.shared_negatives:\n            miss *= np.power(\n                np.maximum(1.0 - shared_distribution[candidates], 1.0e-12),\n                config.shared_negatives,\n            )\n        q = np.clip(1.0 - miss, 1.0e-9, 1.0)\n        log_q = np.log(q).astype(np.float32)\n    else:\n        log_q = np.zeros(n_candidates, dtype=np.float32)\n\n    position = np.full(n_items + 1, -1, dtype=np.int64)\n    position[candidates] = np.arange(n_candidates, dtype=np.int64)\n    positive_columns = position[targets_cpu]\n    if np.any(positive_columns < 0):\n        raise RuntimeError(\"target missing from softmax candidate list\")\n\n    # False-negative mask from the complete public-training positive prefix.\n    byte_columns = candidates >> 3\n    bit_columns = (candidates & 7).astype(np.uint8)\n    known = known_positive_packed[user_rows[:, None], byte_columns[None, :]]\n    invalid = ((known >> bit_columns[None, :]) & 1).astype(bool)\n    liked_positions = position[np.minimum(liked_cpu, n_items)]\n    liked_positions[liked_cpu >= n_items] = -1\n    rows = np.broadcast_to(\n        np.arange(batch_size)[:, None], liked_positions.shape\n    )\n    keep = liked_positions >= 0\n    invalid[rows[keep], liked_positions[keep]] = True\n    invalid[np.arange(batch_size), positive_columns] = False\n    return SoftmaxCandidates(\n        items=torch.from_numpy(candidates).to(device),\n        log_q=torch.from_numpy(log_q).to(device),\n        positive_columns=torch.from_numpy(positive_columns).to(device),\n        invalid=torch.from_numpy(invalid).to(device),\n    )\n\n\ndef sampled_softmax_loss(\n    query_vectors: torch.Tensor,\n    candidate_vectors_: torch.Tensor,\n    candidates: SoftmaxCandidates,\n    row_slice: slice,\n) -> tuple[torch.Tensor, torch.Tensor, torch.Tensor]:\n    \"\"\"Per-example log-Q corrected cross entropy over the shared candidates.\"\"\"\n    logits = query_vectors @ candidate_vectors_.T\n    corrected = logits - candidates.log_q[None, :]\n    invalid = candidates.invalid[row_slice]\n    corrected = corrected.masked_fill(invalid, -1.0e4)\n    positive_columns = candidates.positive_columns[row_slice]\n    loss = F.cross_entropy(corrected, positive_columns, reduction=\"none\")\n    positive_logits = logits.gather(1, positive_columns[:, None]).squeeze(1)\n    with torch.no_grad():\n        valid_negatives = ~invalid\n        valid_negatives[\n            torch.arange(len(positive_columns), device=logits.device),\n            positive_columns,\n        ] = False\n        wins = (\n            (logits.detach() < positive_logits.detach()[:, None]) & valid_negatives\n        ).sum(dim=1).float() / valid_negatives.sum(dim=1).clamp_min(1).float()\n    return loss, positive_logits, wins\n\n'''\nassert '\\ndef corrected_negative_loss(' in s\ns=s.replace('\\ndef corrected_negative_loss(', helpers+'\\ndef corrected_negative_loss(')\n\nold='''    sample_weights: np.ndarray,\n    device: torch.device,\n    backward: bool,\n) -> tuple[dict[str, float], torch.Tensor | None]:\n    \"\"\"Compute one logical block's exact BCE in bounded-memory slices.\"\"\"'''\nassert old in s\ns=s.replace(old,'''    sample_weights: np.ndarray,\n    device: torch.device,\n    backward: bool,\n    softmax_candidates: SoftmaxCandidates | None = None,\n) -> tuple[dict[str, float], torch.Tensor | None]:\n    \"\"\"Compute one logical block's exact loss in bounded-memory slices.\"\"\"''')\n\nold='''        positive_vectors, negative_vectors = candidate_vectors(\n            model,\n            positive_items[begin:end],\n            negatives[begin:end],\n        )\n        positive_logits = (query_vectors * positive_vectors).sum(dim=1)\n        negative_logits = torch.einsum(\n            \"bd,bkd->bk\", query_vectors, negative_vectors\n        )\n        positive_loss = F.softplus(-positive_logits)\n        negative_loss = corrected_negative_loss(\n            negative_logits, negative_weights[begin:end], config\n        )\n        selected_weights = torch.from_numpy(\n            sample_weights[begin:end].astype(np.float32, copy=False)\n        ).to(device)\n        loss_sum = (\n            selected_weights * (positive_loss + negative_loss) / 2.0\n        ).sum()'''\nassert old in s\ns=s.replace(old,'''        selected_weights = torch.from_numpy(\n            sample_weights[begin:end].astype(np.float32, copy=False)\n        ).to(device)\n        if softmax_candidates is not None:\n            encoded_candidates = model.encode_items(softmax_candidates.items)\n            example_loss, positive_logits, wins = sampled_softmax_loss(\n                query_vectors,\n                encoded_candidates,\n                softmax_candidates,\n                slice(begin, end),\n            )\n            loss_sum = (selected_weights * example_loss).sum()\n            negative_logits = torch.zeros((end - begin, 1), device=device)\n            pair_correct = float(wins.sum().cpu())\n        else:\n            positive_vectors, negative_vectors = candidate_vectors(\n                model,\n                positive_items[begin:end],\n                negatives[begin:end],\n            )\n            positive_logits = (query_vectors * positive_vectors).sum(dim=1)\n            negative_logits = torch.einsum(\n                \"bd,bkd->bk\", query_vectors, negative_vectors\n            )\n            positive_loss = F.softplus(-positive_logits)\n            negative_loss = corrected_negative_loss(\n                negative_logits, negative_weights[begin:end], config\n            )\n            loss_sum = (\n                selected_weights * (positive_loss + negative_loss) / 2.0\n            ).sum()\n            pair_correct = float(\n                (positive_logits.detach()[:, None] > negative_logits.detach())\n                .float()\n                .mean(dim=1)\n                .sum()\n                .cpu()\n            )''')\nold='''        statistics[\"pair_correct\"] += float(\n            (positive_logits.detach()[:, None] > negative_logits.detach()).sum().cpu()\n        )'''\nassert old in s\ns=s.replace(old,'''        statistics[\"pair_correct\"] += pair_correct''')\n\n# pair accuracy now per-target fraction\nold='''        \"negative_logit\": total_negative / max(total_targets * negative_count, 1),\n        \"pair_accuracy\": total_pair_correct\n        / max(total_targets * negative_count, 1),'''\nassert old in s\ns=s.replace(old,'''        \"negative_logit\": total_negative / max(total_targets * negative_count, 1),\n        \"pair_accuracy\": total_pair_correct / max(total_targets, 1),''')\nopen(p,'w').write(s)\nprint(\"ok\")\nEOF\ntail -3 runs/baseline_val.log",
            "description": "Apply objective patch and check baseline progress"
          },
          "result": {
            "timestamp": "2026-10-03T09:06:57.921Z",
            "content": "ok\ninbatch correction: min=0.250 mean_on_targets=1.001 max=4.000\ntarget weighting=organic-strong min=0.250 mean=0.575 max=1.000\nfull-history false-negative filter: users=9,135 unique_user_items=5,524,275 bytes=34,256,250",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:06:57.924Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14916460 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:06:57.928Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 11,
      "role": "agent",
      "timestamp": "2026-10-03T09:07:10.509Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:07:10.509Z",
          "text": "I'm checking whether the \"batches=250\" log line should've appeared yet, given the batch size and target count, but it's probably just not reached that threshold yet. I'll keep wiring the training loop and check back on it.\n\nBoth run_training_epoch and evaluate_validation_bce call draw_training_negatives then score_target_microbatches, so I need train_model to compute target_frequency and shared_distribution for sampled-softmax and pass them through, with those functions building candidates instead of drawing negatives when in softmax mode. I think the cleanest approach is a NegativeSampler dataclass wrapping the config and correction/distribution state with a draw method, replacing the two call sites that currently invoke draw_training_negatives directly.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:07:43.375Z",
          "callId": "toolu_01TncYFwKhM1RjaP2WpkRVhm",
          "name": "Bash",
          "input": {
            "command": "python - <<'EOF'\np='train_current_model.py'\ns=open(p).read()\n\n# Sampler bundle inserted before event_sequence\nbundle='''\n@dataclass(frozen=True)\nclass NegativeSampler:\n    \"\"\"Bundle every per-run input that the block negative strategy needs.\"\"\"\n\n    config: Config\n    item_correction: torch.Tensor\n    known_positive_packed: np.ndarray | None\n    target_frequency: np.ndarray | None\n    shared_distribution: np.ndarray | None\n\n    @property\n    def softmax(self) -> bool:\n        return self.config.objective == \"sampled-softmax\"\n\n    def draw(\n        self,\n        positive_items: torch.Tensor,\n        known_history: torch.Tensor,\n        liked_items: torch.Tensor,\n        user_rows: np.ndarray,\n        prepared: SequenceData,\n        generator: torch.Generator,\n        device: torch.device,\n    ) -> tuple[torch.Tensor, torch.Tensor, SoftmaxCandidates | None]:\n        if self.softmax:\n            if (\n                self.known_positive_packed is None\n                or self.target_frequency is None\n                or self.shared_distribution is None\n            ):\n                raise RuntimeError(\"sampled-softmax inputs were not built\")\n            candidates = build_softmax_candidates(\n                positive_items,\n                user_rows,\n                liked_items,\n                self.known_positive_packed,\n                len(prepared.item_ids),\n                self.config,\n                self.target_frequency,\n                self.shared_distribution,\n                generator,\n                device,\n            )\n            empty = torch.zeros((len(positive_items), 0), dtype=torch.long, device=device)\n            return empty, empty.float(), candidates\n        negatives, weights = draw_training_negatives(\n            positive_items,\n            known_history,\n            liked_items,\n            user_rows,\n            self.known_positive_packed,\n            prepared,\n            self.config,\n            self.item_correction,\n            generator,\n            device,\n        )\n        return negatives, weights, None\n\n'''\nassert '\\ndef event_sequence(' in s\ns=s.replace('\\ndef event_sequence(', bundle+'\\ndef event_sequence(')\n\n# run_training_epoch signature\nold='''    target_counts: np.ndarray,\n    item_correction: torch.Tensor,\n    known_positive_packed: np.ndarray | None,\n    generator: torch.Generator,\n    device: torch.device,\n    epoch: int,\n) -> dict[str, float]:'''\nassert old in s\ns=s.replace(old,'''    target_counts: np.ndarray,\n    sampler: NegativeSampler,\n    generator: torch.Generator,\n    device: torch.device,\n    epoch: int,\n) -> dict[str, float]:''')\n\nold='''            negatives, negative_weights = draw_training_negatives(\n                positive_items,\n                known_history,\n                liked_items,\n                flat_user_rows,\n                known_positive_packed,\n                prepared,\n                config,\n                item_correction,\n                generator,\n                device,\n            )\n            optimizer.zero_grad(set_to_none=True)\n            statistics, sequence_gradient = score_target_microbatches(\n                model,\n                prepared,\n                config,\n                sequence_vectors,\n                flat_states,\n                block[2].reshape(-1, 4)[flat_scored].astype(np.float32),\n                positive_items,\n                negatives,\n                negative_weights,\n                block[8].reshape(-1)[flat_scored],\n                device,\n                backward=True,\n            )'''\nassert old in s\ns=s.replace(old,'''            negatives, negative_weights, softmax_candidates = sampler.draw(\n                positive_items,\n                known_history,\n                liked_items,\n                flat_user_rows,\n                prepared,\n                generator,\n                device,\n            )\n            optimizer.zero_grad(set_to_none=True)\n            statistics, sequence_gradient = score_target_microbatches(\n                model,\n                prepared,\n                config,\n                sequence_vectors,\n                flat_states,\n                block[2].reshape(-1, 4)[flat_scored].astype(np.float32),\n                positive_items,\n                negatives,\n                negative_weights,\n                block[8].reshape(-1)[flat_scored],\n                device,\n                backward=True,\n                softmax_candidates=softmax_candidates,\n            )''')\n\n# evaluate_validation_bce signature\nold='''    validation_counts: np.ndarray,\n    item_correction: torch.Tensor,\n    known_positive_packed: np.ndarray | None,\n    device: torch.device,\n) -> dict[str, float]:\n    \"\"\"Measure deterministic BCE on each user's chronological target suffix.\"\"\"'''\nassert old in s\ns=s.replace(old,'''    validation_counts: np.ndarray,\n    sampler: NegativeSampler,\n    device: torch.device,\n) -> dict[str, float]:\n    \"\"\"Measure deterministic loss on each user's chronological target suffix.\"\"\"''')\n\nold='''            negatives, negative_weights = draw_training_negatives(\n                positive_items,\n                known_history,\n                liked_items,\n                flat_user_rows,\n                known_positive_packed,\n                prepared,\n                config,\n                item_correction,\n                generator,\n                device,\n            )\n            statistics, _ = score_target_microbatches(\n                model,\n                prepared,\n                config,\n                sequence_vectors,\n                flat_states,\n                block[2].reshape(-1, 4)[flat_scored].astype(np.float32),\n                positive_items,\n                negatives,\n                negative_weights,\n                block[8].reshape(-1)[flat_scored],\n                device,\n                backward=False,\n            )'''\nassert old in s\ns=s.replace(old,'''            negatives, negative_weights, softmax_candidates = sampler.draw(\n                positive_items,\n                known_history,\n                liked_items,\n                flat_user_rows,\n                prepared,\n                generator,\n                device,\n            )\n            statistics, _ = score_target_microbatches(\n                model,\n                prepared,\n                config,\n                sequence_vectors,\n                flat_states,\n                block[2].reshape(-1, 4)[flat_scored].astype(np.float32),\n                positive_items,\n                negatives,\n                negative_weights,\n                block[8].reshape(-1)[flat_scored],\n                device,\n                backward=False,\n                softmax_candidates=softmax_candidates,\n            )''')\n\n# train_model: build sampler\nold='''    known_positive_packed = (\n        build_known_positive_filter(prepared, partition.history_training_counts)\n        if config.negative_filter_scope == \"full-training-history\"\n        else None\n    )'''\nassert old in s\ns=s.replace(old,'''    known_positive_packed = (\n        build_known_positive_filter(prepared, partition.history_training_counts)\n        if config.negative_filter_scope == \"full-training-history\"\n        or config.objective == \"sampled-softmax\"\n        else None\n    )\n    target_frequency = None\n    shared_distribution = None\n    if config.objective == \"sampled-softmax\":\n        target_frequency = build_item_target_frequency(\n            prepared, partition.window_starts, training_counts\n        )\n        shared_distribution = build_shared_negative_distribution(\n            target_frequency, config.shared_negative_power\n        )\n        log(\n            f\"sampled-softmax objective: shared_negatives={config.shared_negatives} \"\n            f\"power={config.shared_negative_power} logq={config.logq_correction}\"\n        )\n    sampler = NegativeSampler(\n        config=config,\n        item_correction=item_correction,\n        known_positive_packed=known_positive_packed,\n        target_frequency=target_frequency,\n        shared_distribution=shared_distribution,\n    )''')\n\n# replace the three call sites of item_correction/known_positive_packed args in train_model\nold='''                    training_counts,\n                    validation_counts,\n                    item_correction,\n                    known_positive_packed,\n                    device,\n                )'''\nassert s.count(old)==1\ns=s.replace(old,'''                    training_counts,\n                    validation_counts,\n                    sampler,\n                    device,\n                )''')\nold='''            training_counts,\n            item_correction,\n            known_positive_packed,\n            generator,\n            device,\n            epoch,\n        )'''\nassert s.count(old)==1\ns=s.replace(old,'''            training_counts,\n            sampler,\n            generator,\n            device,\n            epoch,\n        )''')\nold='''            training_counts,\n            validation_counts,\n            item_correction,\n            known_positive_packed,\n            device,\n        )'''\nassert s.count(old)==1\ns=s.replace(old,'''            training_counts,\n            validation_counts,\n            sampler,\n            device,\n        )''')\n\n# objective_changed on resume\nold='''        objective_changed = (\n            stored_filter_scope != config.negative_filter_scope'''\nassert old in s\ns=s.replace(old,'''        objective_changed = (\n            stored_config.get(\"objective\", \"bce\") != config.objective\n            or stored_filter_scope != config.negative_filter_scope''')\n\n# CLI args\nold='''    parser.add_argument(\n        \"--target-weighting\",'''\nassert old in s\ns=s.replace(old,'''    parser.add_argument(\n        \"--objective\",\n        choices=(\"sampled-softmax\", \"bce\"),\n        default=Config.objective,\n        help=\"sampled-softmax: log-Q corrected in-block softmax; bce: legacy 24+8 negatives\",\n    )\n    parser.add_argument(\n        \"--shared-negatives\", type=int, default=Config.shared_negatives\n    )\n    parser.add_argument(\n        \"--shared-negative-power\", type=float, default=Config.shared_negative_power\n    )\n    parser.add_argument(\n        \"--no-logq-correction\", action=\"store_true\"\n    )\n    parser.add_argument(\n        \"--target-weighting\",''')\nold='''        negative_filter_scope=args.negative_filter_scope,\n        target_weighting=args.target_weighting,'''\nassert old in s\ns=s.replace(old,'''        negative_filter_scope=args.negative_filter_scope,\n        objective=args.objective,\n        shared_negatives=args.shared_negatives,\n        shared_negative_power=args.shared_negative_power,\n        logq_correction=not args.no_logq_correction,\n        target_weighting=args.target_weighting,''')\nold='''                    \"negative_sampling\": (\n                        \"24-uniform-plus-8-propensity-corrected-inbatch\"\n                    ),'''\nassert old in s\ns=s.replace(old,'''                    \"objective_variant\": config.objective,\n                    \"negative_sampling\": (\n                        f\"in-block-unique-targets-plus-{config.shared_negatives}\"\n                        f\"-popularity^{config.shared_negative_power}-shared\"\n                        f\"-logq={config.logq_correction}\"\n                        if config.objective == \"sampled-softmax\"\n                        else \"24-uniform-plus-8-propensity-corrected-inbatch\"\n                    ),''')\nopen(p,'w').write(s)\nprint('ok')\nEOF\npython -c \"import ast,sys; ast.parse(open('train_current_model.py').read())\" && tail -2 runs/baseline_val.log",
            "description": "Wire the sampler into training, validation, and CLI"
          },
          "result": {
            "timestamp": "2026-10-03T09:07:43.597Z",
            "content": "ok\ntarget weighting=organic-strong min=0.250 mean=0.575 max=1.000\nfull-history false-negative filter: users=9,135 unique_user_items=5,524,275 bytes=34,256,250",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:07:43.604Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14912084 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:07:43.608Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 12,
      "role": "agent",
      "timestamp": "2026-10-03T09:07:54.305Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:07:54.305Z",
          "text": "The baseline is taking too long to hit 250 batches, so I'm estimating the total batch count: with about 9135 users grouped into batches of 64, that's roughly 143 groups, and with ~2 blocks of 100 steps per group, I'd expect around 280 batches total.\n\nWith a 60-minute budget and about 9 minutes already elapsed, I need to be efficient and test my new code quickly without fully competing for CPU with the baseline run. I'll run a smoke test using a reduced subset (few targets per user) and fewer threads, relying on the cache to make prep fast and verify the whole pipeline works.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:07:54.315Z",
          "callId": "toolu_012otFPG6xsTMT9piNLbVf4T",
          "name": "Bash",
          "input": {
            "command": "timeout 600 python train_current_model.py --stage validation --public-dir /task --prepared-cache runs/val_cache.npz --output runs/smoke.parquet --threads 2 --max-train-targets-per-user 3 --max-validation-targets-per-user 1 --shared-negatives 256 2>&1 | grep -v \"^ranked\" | tail -15; cat runs/baseline_time.txt; tail -2 runs/baseline_val.log",
            "description": "Smoke-test the new objective on a tiny target cap"
          },
          "result": {
            "timestamp": "2026-10-03T09:09:54.566Z",
            "content": "Command did not complete within its 120s timeout and was moved to the background (ID: b6dfq0kkc). Output is being written to: /tmp/claude-1000/-app/4e8789ae-79ff-49af-b921-d2d476bce141/tasks/b6dfq0kkc.output. You will be notified when it completes. If it is still running after 30m in the background, it will be stopped and you will be notified. To check interim output, use Read on that file path.",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:09:54.584Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14911378 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:09:54.586Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 13,
      "role": "agent",
      "timestamp": "2026-10-03T09:09:59.046Z",
      "blocks": [
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:09:59.046Z",
          "callId": "toolu_01WW78KrSP74G8GhRoeLHQFe",
          "name": "Bash",
          "input": {
            "command": "sleep 45; cat /tmp/claude-1000/-app/4e8789ae-79ff-49af-b921-d2d476bce141/tasks/b6dfq0kkc.output | grep -v \"^ranked\" | tail -12; echo ---; cat runs/baseline_time.txt; tail -3 runs/baseline_val.log",
            "description": "Check smoke test and baseline progress"
          },
          "result": {
            "timestamp": "2026-10-03T09:10:44.134Z",
            "content": "---\ntarget weighting=organic-strong min=0.250 mean=0.575 max=1.000\nfull-history false-negative filter: users=9,135 unique_user_items=5,524,275 bytes=34,256,250\nepoch=1/1 batches=250 targets=987,417 batch_bce=0.547529 running_bce=0.541614 elapsed=208.9s",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:10:44.149Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14911019 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:10:44.151Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 14,
      "role": "agent",
      "timestamp": "2026-10-03T09:10:53.041Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:10:53.041Z",
          "text": "The baseline trains at about 250 batches in 209 seconds, roughly a 4-minute epoch, with the full run taking around 8 minutes including prep and ranking — though the timing doesn't quite add up, so something upstream must be taking longer than expected.\n\nRight, the baseline was probably just competing for CPU with my smoke test. The smoke test hasn't produced output yet, likely because it's still loading the large 20M-token cache, so I'll wait on that.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:10:53.762Z",
          "callId": "toolu_01CYgS717bdGDwDQe4Viwmjx",
          "name": "Bash",
          "input": {
            "command": "sleep 60; grep -v \"^ranked\" /tmp/claude-1000/-app/4e8789ae-79ff-49af-b921-d2d476bce141/tasks/b6dfq0kkc.output | tail -12; echo ---; cat runs/baseline_time.txt; tail -2 runs/baseline_val.log; cat runs/baseline_val.score 2>/dev/null",
            "description": "Check smoke test and baseline results"
          },
          "result": {
            "timestamp": "2026-10-03T09:11:53.881Z",
            "content": "Exit code 1\n---\nfull-history false-negative filter: users=9,135 unique_user_items=5,524,275 bytes=34,256,250\nepoch=1/1 batches=250 targets=987,417 batch_bce=0.547529 running_bce=0.541614 elapsed=208.9s",
            "isError": true
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:11:53.887Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14910447 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:11:53.891Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 15,
      "role": "agent",
      "timestamp": "2026-10-03T09:11:59.730Z",
      "blocks": [
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:11:59.730Z",
          "callId": "toolu_011ydzssBL2WMfwZ7TLQ2NBi",
          "name": "Bash",
          "input": {
            "command": "ls -la /tmp/claude-1000/-app/4e8789ae-79ff-49af-b921-d2d476bce141/tasks/; cat /tmp/claude-1000/-app/4e8789ae-79ff-49af-b921-d2d476bce141/tasks/b6dfq0kkc.output | head -30; ps aux | grep train_current | grep -v grep | wc -l",
            "description": "Inspect smoke test output file and running processes"
          },
          "result": {
            "timestamp": "2026-10-03T09:11:59.825Z",
            "content": "total 8\ndrwxr-xr-x 2 agent agent 4096 Oct  3 09:11 .\ndrwxr-xr-x 3 agent agent 4096 Oct  3 09:02 ..\n-rw-r--r-- 1 agent agent    0 Oct  3 09:11 b5ls33pi6.output\n-rw-r--r-- 1 agent agent    0 Oct  3 09:07 b6dfq0kkc.output\n5",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:11:59.846Z",
          "data": {
            "type": "silent_turn_reminder",
            "text": "The user hasn't heard from you in a while. As you continue, keep them updated when there's something to tell — a finding, a change of plan."
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:11:59.847Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14910103 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:11:59.849Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 16,
      "role": "agent",
      "timestamp": "2026-10-03T09:12:07.606Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:12:07.606Z",
          "text": "The output file's empty since the pipe buffers until completion — makes sense, both processes are still running so I'll check back shortly. In the meantime, I'll write a quick unit test for the softmax candidate builder to verify the mask and logq correctness, since that's cheap and worthwhile.\n\n"
        },
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:12:07.612Z",
          "text": "While the baseline and smoke test keep running (full validation around 8 minutes), I'll add a small unit test for the new candidate builder.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:12:21.866Z",
          "callId": "toolu_01NgdMmMNgGQt2TRcF3ZGX37",
          "name": "Bash",
          "input": {
            "command": "cat > test_sampled_softmax.py <<'EOF'\n\"\"\"Unit checks for the sampled-softmax candidate builder and loss.\"\"\"\nimport numpy as np\nimport torch\n\nimport train_current_model as tcm\n\n\ndef pack(items: list[int], n_items: int) -> np.ndarray:\n    packed = np.zeros((n_items + 7) // 8, dtype=np.uint8)\n    for item in items:\n        packed[item >> 3] |= np.uint8(1 << (item & 7))\n    return packed\n\n\ndef test_candidates_mask_known_positives_and_likes_but_not_target():\n    n_items = 64\n    config = tcm.Config(shared_negatives=16, shared_negative_power=0.5)\n    known = np.stack([pack([1, 2, 3], n_items), pack([10, 11], n_items)])\n    targets = torch.tensor([3, 11])\n    liked = torch.tensor([[5, n_items, n_items], [n_items, 20, n_items]])\n    frequency = np.full(n_items, 1.0 / n_items)\n    shared = frequency.copy()\n    generator = torch.Generator().manual_seed(0)\n    result = tcm.build_softmax_candidates(\n        targets, np.array([0, 1]), liked, known, n_items, config,\n        frequency, shared, generator, torch.device(\"cpu\"),\n    )\n    items = result.items.numpy()\n    assert np.array_equal(items, np.unique(items)), \"candidates must be unique\"\n    assert {3, 11} <= set(items.tolist())\n    position = {int(item): column for column, item in enumerate(items)}\n    invalid = result.invalid.numpy()\n    assert not invalid[0, position[3]] and not invalid[1, position[11]]\n    for item in (1, 2):\n        if item in position:\n            assert invalid[0, position[item]]\n    if 10 in position:\n        assert invalid[1, position[10]]\n    if 5 in position:\n        assert invalid[0, position[5]]\n    if 20 in position:\n        assert invalid[1, position[20]]\n    # Target 3 is a known positive for user 0 but must stay valid as the label.\n    assert result.positive_columns.tolist() == [position[3], position[11]]\n    assert np.all(result.log_q.numpy() <= 0.0)\n\n\ndef test_logq_increases_with_popularity():\n    n_items = 100\n    config = tcm.Config(shared_negatives=0)\n    frequency = np.linspace(0.001, 0.05, n_items)\n    frequency /= frequency.sum()\n    targets = torch.tensor([0, 99])\n    known = np.zeros((2, (n_items + 7) // 8), dtype=np.uint8)\n    liked = torch.full((2, 1), n_items)\n    result = tcm.build_softmax_candidates(\n        targets, np.array([0, 1]), liked, known, n_items, config,\n        frequency, frequency, torch.Generator().manual_seed(0),\n        torch.device(\"cpu\"),\n    )\n    log_q = result.log_q.numpy()\n    assert log_q[0] < log_q[1], \"popular item should have a larger inclusion probability\"\n\n\ndef test_loss_ignores_masked_columns():\n    candidates = tcm.SoftmaxCandidates(\n        items=torch.tensor([0, 1, 2]),\n        log_q=torch.zeros(3),\n        positive_columns=torch.tensor([0]),\n        invalid=torch.tensor([[False, True, False]]),\n    )\n    query = torch.ones(1, 2)\n    vectors = torch.tensor([[1.0, 0.0], [50.0, 50.0], [0.0, 1.0]])\n    loss, positive, wins = tcm.sampled_softmax_loss(query, vectors, candidates, slice(0, 1))\n    assert abs(float(loss) - float(np.log(2.0))) < 1e-5\n    assert float(positive) == 1.0 and float(wins) == 0.0\n\n\nif __name__ == \"__main__\":\n    test_candidates_mask_known_positives_and_likes_but_not_target()\n    test_logq_increases_with_popularity()\n    test_loss_ignores_masked_columns()\n    print(\"all tests passed\")\nEOF\npython test_sampled_softmax.py; echo ---; cat runs/baseline_time.txt; tail -2 runs/baseline_val.log; cat runs/baseline_val.score 2>/dev/null",
            "description": "Write and run unit tests for the candidate builder"
          },
          "result": {
            "timestamp": "2026-10-03T09:12:27.532Z",
            "content": "Exit code 1\nall tests passed\n---\nepoch=1/1 train_loss=0.53984 validation_loss=0.49664 pair_accuracy=0.755 train_targets=1,052,953 validation_targets=130,103 train_seconds=246.0 validation_seconds=204.1\nrestored best validation-BCE checkpoint: epoch=1 loss=0.496636",
            "isError": true
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:12:01.294Z",
          "data": {
            "type": "queued_command",
            "prompt": "<task-notification>\n<task-id>b6dfq0kkc</task-id>\n<tool-use-id>toolu_012otFPG6xsTMT9piNLbVf4T</tool-use-id>\n<output-file>/tmp/claude-1000/-app/4e8789ae-79ff-49af-b921-d2d476bce141/tasks/b6dfq0kkc.output</output-file>\n<status>completed</status>\n<summary>Background command \"Smoke-test the new objective on a tiny target cap\" completed (exit code 0)</summary>\n</task-notification>",
            "source_uuid": "eeb3d327-5a9f-4900-8e65-05a4e46f895a",
            "delivery_id": "8910095d-c2c8-44ba-9989-05e1cc8502ab",
            "commandMode": "task-notification",
            "origin": {
              "kind": "task-notification",
              "producer": "session-task"
            },
            "timestamp": "2026-10-03T09:12:01.294Z"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:12:27.544Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14908141 tokens left</total_tokens>"
          }
        }
      ]
    },
    {
      "id": 17,
      "role": "agent",
      "timestamp": "2026-10-03T09:12:34.810Z",
      "blocks": [
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:12:34.810Z",
          "callId": "toolu_016wTvx5rwd9faHgyHN2Qv62",
          "name": "Bash",
          "input": {
            "command": "grep -v \"^ranked\" /tmp/claude-1000/-app/4e8789ae-79ff-49af-b921-d2d476bce141/tasks/b6dfq0kkc.output | grep -i \"epoch=\\|softmax\\|error\\|Trace\" | tail; python /task/evaluate_public.py runs/smoke.parquet 2>&1 | tail -4",
            "description": "Check smoke-test output and score"
          },
          "result": {
            "timestamp": "2026-10-03T09:12:39.866Z",
            "content": "epoch=1/1 train_loss=0.53984 validation_loss=0.49664 pair_accuracy=0.755 train_targets=1,052,953 validation_targets=130,103 train_seconds=246.0 validation_seconds=204.1\nrestored best validation-BCE checkpoint: epoch=1 loss=0.496636\n    \"quality_ndcg@10\": 0.019219,\n    \"quality_users\": 4263\n  }\n}",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:12:39.873Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14907466 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:12:39.878Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 18,
      "role": "agent",
      "timestamp": "2026-10-03T09:12:49.923Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:12:49.923Z",
          "text": "Something seems off here - the output file I'm checking seems to show the baseline's loss values rather than the smoke test's, even though the smoke test used a much smaller target count. That mismatch suggests the file might be stale or from a different run than I expect.\n\nI should verify directly by checking the raw file and confirming whether the smoke parquet evaluation score of 0.019 makes sense given only 3 targets per user, and also check whether the baseline validation score file has actually been written yet.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:12:51.334Z",
          "callId": "toolu_01V4vqXfGM6oMYS6RisPZKyK",
          "name": "Bash",
          "input": {
            "command": "head -c 3000 /tmp/claude-1000/-app/4e8789ae-79ff-49af-b921-d2d476bce141/tasks/b6dfq0kkc.output; echo; echo ---; cat runs/baseline_time.txt; cat runs/baseline_val.score 2>/dev/null; ls runs",
            "description": "Inspect raw smoke output and baseline score"
          },
          "result": {
            "timestamp": "2026-10-03T09:12:51.405Z",
            "content": "      \"validation_loss\": 5.49279216102079,\n      \"validation_targets\": 9053.0,\n      \"validation_target_weight_sum\": 5494.25,\n      \"validation_seconds\": 1.8541458769999508\n    }\n  ],\n  \"embedding_diagnostics\": {\n    \"query_norm_mean\": 0.8281947374343872,\n    \"query_norm_std\": 0.22615529596805573,\n    \"item_norm_mean\": 1.3652642965316772,\n    \"item_norm_std\": 0.6802813410758972\n  },\n  \"torch_version\": \"2.8.0+cpu\",\n  \"device\": \"cpu\"\n}\nepoch=1/1 train_loss=0.53984 validation_loss=0.49664 pair_accuracy=0.755 train_targets=1,052,953 validation_targets=130,103 train_seconds=246.0 validation_seconds=204.1\nrestored best validation-BCE checkpoint: epoch=1 loss=0.496636\n\n[exited with code 0]\n\n---\nbaseline_time.txt\nbaseline_val.json\nbaseline_val.log\nsmoke.parquet\nval_cache.npz",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:12:51.408Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14906757 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:12:51.411Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 19,
      "role": "agent",
      "timestamp": "2026-10-03T09:13:05.801Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:13:05.801Z",
          "text": "The smoke test passed with validation loss around 5.49 for the softmax target, confirming the pipeline runs end to end. Baseline ranking is now underway for roughly 8456 users and moving quickly, so I'll launch the full validation run for the new objective in parallel using 8 threads while the baseline finishes up.\n\nWith about 17 minutes gone, I'm estimating the new run needs 8-10 minutes total (cache load, training, validation, ranking), leaving just enough time for one validation experiment plus the final refit, which itself needs about 12 minutes. To hedge, I'll kick off the submission-stage cache preparation in the background now with a single thread, since that's mostly single-threaded data prep anyway and can run while the validation experiment finishes.\n\n"
        },
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:13:05.807Z",
          "text": "The smoke test and unit tests passed with the new objective. I'll now launch full validation of the sampled-softmax model while precomputing the submission-stage sequence cache to speed up the final refit.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:13:06.117Z",
          "callId": "toolu_017gkuuVzWutghMcqA6KgBcE",
          "name": "Bash",
          "input": {
            "command": "(time python train_current_model.py --stage validation --public-dir /task --prepared-cache runs/val_cache.npz --output runs/softmax_val.parquet --threads 7 > runs/softmax_val.json 2> runs/softmax_val.log; python /task/evaluate_public.py runs/softmax_val.parquet > runs/softmax_val.score 2>&1) > runs/softmax_time.txt 2>&1 &\n(python train_current_model.py --stage submission --public-dir /task --prepared-cache runs/sub_cache.npz --output runs/unused.parquet --threads 1 --prepare-only > runs/sub_prepare.json 2> runs/sub_prepare.log) &\nsleep 20; cat runs/baseline_time.txt; cat runs/baseline_val.score",
            "description": "Launch softmax validation run and submission cache prep"
          },
          "result": {
            "timestamp": "2026-10-03T09:13:26.181Z",
            "content": "Exit code 1\ncat: runs/baseline_val.score: No such file or directory",
            "isError": true
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:13:26.190Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14905497 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:13:26.195Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 20,
      "role": "agent",
      "timestamp": "2026-10-03T09:13:29.996Z",
      "blocks": [
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:13:29.996Z",
          "callId": "toolu_017e9ZEvhjiN45gjv9XSZnEx",
          "name": "Bash",
          "input": {
            "command": "sleep 90; cat runs/baseline_time.txt; cat runs/baseline_val.score; echo ---; tail -2 runs/softmax_val.log; tail -1 runs/sub_prepare.log",
            "description": "Wait for baseline score and check new runs"
          },
          "result": {
            "timestamp": "2026-10-03T09:15:00.257Z",
            "content": "/bin/bash: line 2:  8158 Killed                  python /task/current_model/train_current_model.py --stage validation --public-dir /task --prepared-cache /app/solution/runs/val_cache.npz --output /app/solution/production_validation.parquet > runs/baseline_val.json 2> runs/baseline_val.log\n\nreal\t11m15.352s\nuser\t58m53.411s\nsys\t1m40.171s\nTraceback (most recent call last):\n  File \"/task/evaluate_public.py\", line 157, in <module>\n    main()\n  File \"/task/evaluate_public.py\", line 152, in main\n    ranked = load_submission(path, eligibility, targets)\n             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/task/evaluate_public.py\", line 113, in load_submission\n    frame = validate_ranking(read_ranking(path), targets)\n                             ^^^^^^^^^^^^^^^^^^\n  File \"/task/ranking_evaluation.py\", line 98, in read_ranking\n    return pd.read_parquet(path) if path.suffix == \".parquet\" else pd.read_csv(path)\n           ^^^^^^^^^^^^^^^^^^^^^\n  File \"/opt/task-venv/lib/python3.12/site-packages/pandas/io/parquet.py\", line 669, in read_parquet\n    return impl.read(\n           ^^^^^^^^^^\n  File \"/opt/task-venv/lib/python3.12/site-packages/pandas/io/parquet.py\", line 258, in read\n    path_or_handle, handles, filesystem = _get_path_or_handle(\n                                          ^^^^^^^^^^^^^^^^^^^^\n  File \"/opt/task-venv/lib/python3.12/site-packages/pandas/io/parquet.py\", line 141, in _get_path_or_handle\n    handles = get_handle(\n              ^^^^^^^^^^^\n  File \"/opt/task-venv/lib/python3.12/site-packages/pandas/io/common.py\", line 882, in get_handle\n    handle = open(handle, ioargs.mode)\n             ^^^^^^^^^^^^^^^^^^^^^^^^^\nFileNotFoundError: [Errno 2] No such file or directory: '/app/solution/production_validation.parquet'\n---\nfull-history false-negative filter: users=9,135 unique_user_items=5,524,275 bytes=34,256,250\nsampled-softmax objective: shared_negatives=1024 power=0.75 logq=True\nsaved public-derived full-sequence cache: /app/solution/runs/sub_cache.npz",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:15:00.313Z",
          "data": {
            "type": "silent_turn_reminder",
            "text": "The user hasn't heard from you in a while. As you continue, keep them updated when there's something to tell — a finding, a change of plan."
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:15:00.314Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14905286 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:15:00.331Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 21,
      "role": "agent",
      "timestamp": "2026-10-03T09:15:13.009Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:15:13.009Z",
          "text": "The baseline run got killed by OOM since I ran three processes concurrently and each held the large token cache plus filter data in memory, exhausting RAM during ranking. I lost that run's score, but I still have the training log showing a validation BCE of 0.4966, so I need to rerun it more carefully.\n\nThe baseline's public score isn't an acceptance gate, so I should prioritize validating the improved model and producing the submission, then re-run the baseline later if time allows — maybe alongside the final refit if memory permits, since two processes together should be fine even though three was too many. Let me check current memory usage with `free -g` and process RSS to make sure the softmax run won't OOM too.\n\n"
        },
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:15:13.041Z",
          "text": "The baseline process got OOM-killed during ranking since three large processes ran simultaneously, but the improved-model run is still progressing with its submission cache built. I'll monitor memory usage and rerun the baseline separately afterward to get a clean record.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:15:13.043Z",
          "callId": "toolu_01RYdV13HFup758Ti4XWn67X",
          "name": "Bash",
          "input": {
            "command": "free -g | head -2; ps -o pid,rss,etime,args -C python | cut -c1-150; tail -1 runs/softmax_val.log",
            "description": "Check memory usage and softmax run progress"
          },
          "result": {
            "timestamp": "2026-10-03T09:15:13.116Z",
            "content": "               total        used        free      shared  buff/cache   available\nMem:              15           1           7           0           6          14\n    PID   RSS     ELAPSED COMMAND\nsampled-softmax objective: shared_negatives=1024 power=0.75 logq=True",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:15:13.120Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14903772 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:15:13.121Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 22,
      "role": "agent",
      "timestamp": "2026-10-03T09:15:20.474Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:15:20.474Z",
          "text": "No python processes running at all - looks like the softmax run also died. I should check the log and time file to see what happened.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:15:20.480Z",
          "callId": "toolu_01Haqjk6KXYxrxb5uutsEbcU",
          "name": "Bash",
          "input": {
            "command": "cat runs/softmax_time.txt; tail -5 runs/softmax_val.log; ls -la runs/",
            "description": "Check why the softmax run stopped"
          },
          "result": {
            "timestamp": "2026-10-03T09:15:20.512Z",
            "content": "/bin/bash: line 3:  8450 Killed                  python train_current_model.py --stage validation --public-dir /task --prepared-cache runs/val_cache.npz --output runs/softmax_val.parquet --threads 7 > runs/softmax_val.json 2> runs/softmax_val.log\n\nreal\t1m34.656s\nuser\t4m30.810s\nsys\t0m6.509s\nchronological BCE window: train=1,052,953 validation=130,103 selected=1,183,056 discarded_old_targets=18,864,138 all=20,047,194\ninbatch correction: min=0.250 mean_on_targets=1.001 max=4.000\ntarget weighting=organic-strong min=0.250 mean=0.575 max=1.000\nfull-history false-negative filter: users=9,135 unique_user_items=5,524,275 bytes=34,256,250\nsampled-softmax objective: shared_negatives=1024 power=0.75 logq=True\ntotal 1063532\ndrwxr-xr-x 2 agent agent      4096 Oct  3 09:14 .\ndrwxr-xr-x 1 agent agent      4096 Oct  3 09:12 ..\n-rw-r--r-- 1 agent agent       337 Oct  3 09:14 baseline_time.txt\n-rw-r--r-- 1 agent agent         0 Oct  3 09:03 baseline_val.json\n-rw-r--r-- 1 agent agent      1559 Oct  3 09:11 baseline_val.log\n-rw-r--r-- 1 agent agent      1423 Oct  3 09:14 baseline_val.score\n-rw-r--r-- 1 agent agent   1091576 Oct  3 09:12 smoke.parquet\n-rw-r--r-- 1 agent agent       291 Oct  3 09:14 softmax_time.txt\n-rw-r--r-- 1 agent agent         0 Oct  3 09:13 softmax_val.json\n-rw-r--r-- 1 agent agent       481 Oct  3 09:13 softmax_val.log\n-rw-r--r-- 1 agent agent      1404 Oct  3 09:14 softmax_val.score\n-rw-r--r-- 1 agent agent 552686232 Oct  3 09:14 sub_cache.npz\n-rw-r--r-- 1 agent agent      1409 Oct  3 09:14 sub_prepare.json\n-rw-r--r-- 1 agent agent       890 Oct  3 09:14 sub_prepare.log\n-rw-r--r-- 1 agent agent 535225808 Oct  3 09:04 val_cache.npz",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:15:20.516Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14903518 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:15:20.518Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 23,
      "role": "agent",
      "timestamp": "2026-10-03T09:15:39.393Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:15:39.393Z",
          "text": "Both processes got killed around the same time due to memory pressure from the cache save and concurrent training jobs. With memory freed and about 39 minutes left, I'm planning to run the softmax validation alone first, then the final refit, and squeeze in a baseline rerun if time allows.\n\nActually, I'm reconsidering running the baseline and softmax validation together at reduced thread counts, since two processes ran fine before but three caused the OOM. I'm trying to figure out what actually consumed the memory — the cache and arrays seem small, so maybe it's the token-building step or the parquet loading that's the real culprit — but it's hard to pin down exactly, so I'll just proceed cautiously with fewer simultaneous processes.\n\nGiven the submission is the priority, I'll run softmax validation alongside the baseline concurrently now at reduced thread counts, since I'll need the baseline score for the README anyway and can do the final refit afterward, watching memory closely as they run.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:15:41.225Z",
          "callId": "toolu_012r3JDVwSNi17afvgSxENsC",
          "name": "Bash",
          "input": {
            "command": "(time python train_current_model.py --stage validation --public-dir /task --prepared-cache runs/val_cache.npz --output runs/softmax_val.parquet --threads 5 > runs/softmax_val.json 2> runs/softmax_val.log; python /task/evaluate_public.py runs/softmax_val.parquet > runs/softmax_val.score 2>&1) > runs/softmax_time.txt 2>&1 &\nsleep 5\n(time python /task/current_model/train_current_model.py --stage validation --public-dir /task --prepared-cache /app/solution/runs/val_cache.npz --output /app/solution/production_validation.parquet --threads 3 > runs/baseline_val.json 2> runs/baseline_val.log; python /task/evaluate_public.py /app/solution/production_validation.parquet > runs/baseline_val.score 2>&1) > runs/baseline_time.txt 2>&1 &\nsleep 100; free -g | head -2; ps -o pid,rss,etime,args -C python | cut -c1-120; tail -1 runs/softmax_val.log",
            "description": "Rerun softmax and baseline validation concurrently with watched memory"
          },
          "result": {
            "timestamp": "2026-10-03T09:17:26.291Z",
            "content": "               total        used        free      shared  buff/cache   available\nMem:              15           7           1           0           7           8\n    PID   RSS     ELAPSED COMMAND\n   8590 2991288     01:45 python train_current_model.py --stage validation --public-dir /task --prepared-cache runs/val_\n   8605 3169068     01:40 python /task/current_model/train_current_model.py --stage validation --public-dir /task --prep\nsampled-softmax objective: shared_negatives=1024 power=0.75 logq=True",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:17:26.295Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14901414 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:17:26.298Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 24,
      "role": "agent",
      "timestamp": "2026-10-03T09:17:35.751Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:17:35.751Z",
          "text": "Memory usage looks fine with each process around 3GB, roughly 24 minutes in. While waiting I'll sketch out the README skeleton and plan the final refit command, keeping in mind I need a fallback baseline submission in case the softmax model underperforms, so I can refit whichever approach turns out better once validation results come in.\n\nLet me check the training progress logs again in about 2.5 minutes.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:17:35.753Z",
          "callId": "toolu_01Y1M2L5ZNrREZsS2LsFYnmN",
          "name": "Bash",
          "input": {
            "command": "sleep 150; free -g | head -2; tail -1 runs/softmax_val.log; tail -1 runs/baseline_val.log",
            "description": "Check training progress of both runs"
          },
          "result": {
            "timestamp": "2026-10-03T09:19:35.817Z",
            "content": "Exit code 143\nCommand timed out after 2m 0s",
            "isError": true
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:19:35.833Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14900921 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:19:35.839Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 25,
      "role": "agent",
      "timestamp": "2026-10-03T09:19:39.582Z",
      "blocks": [
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:19:39.582Z",
          "callId": "toolu_01HFHSRvs7ccbpttnhz6Y8Df",
          "name": "Bash",
          "input": {
            "command": "free -g | head -2; tail -1 runs/softmax_val.log; tail -1 runs/baseline_val.log; ps -o pid,etime -C python",
            "description": "Check training progress of both runs"
          },
          "result": {
            "timestamp": "2026-10-03T09:19:39.668Z",
            "content": "               total        used        free      shared  buff/cache   available\nMem:              15           7           1           0           6           7\nrestored best validation-BCE checkpoint: epoch=1 loss=6.921512\nfull-history false-negative filter: users=9,135 unique_user_items=5,524,275 bytes=34,256,250\n    PID     ELAPSED\n   8590       03:58\n   8605       03:53",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:19:39.673Z",
          "data": {
            "type": "silent_turn_reminder",
            "text": "The user hasn't heard from you in a while. As you continue, keep them updated when there's something to tell — a finding, a change of plan."
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:19:39.673Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14900740 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:19:39.676Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 26,
      "role": "agent",
      "timestamp": "2026-10-03T09:19:47.099Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:19:47.099Z",
          "text": "Surprisingly, the softmax run finished training and validation in under four minutes with five threads, restoring the best checkpoint at epoch 1. That's faster than the baseline because sampled softmax replaces the per-target negative gather with a single matmul, skipping the 32-round rejection loop entirely—it's ranking now.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:19:47.107Z",
          "callId": "toolu_01PfyzC44V6diPuBxKLANVfM",
          "name": "Bash",
          "input": {
            "command": "grep \"epoch=1/1\" runs/softmax_val.log; sleep 45; cat runs/softmax_val.score; cat runs/softmax_time.txt",
            "description": "Read softmax epoch diagnostics and score"
          },
          "result": {
            "timestamp": "2026-10-03T09:20:32.182Z",
            "content": "epoch=1/1 batches=250 targets=987,417 batch_bce=7.377289 running_bce=7.962077 elapsed=154.1s\nepoch=1/1 train_loss=7.95329 validation_loss=6.92151 pair_accuracy=0.637 train_targets=1,052,953 validation_targets=130,103 train_seconds=164.4 validation_seconds=11.2\nTraceback (most recent call last):\n  File \"/task/evaluate_public.py\", line 157, in <module>\n    main()\n  File \"/task/evaluate_public.py\", line 152, in main\n    ranked = load_submission(path, eligibility, targets)\n             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/task/evaluate_public.py\", line 113, in load_submission\n    frame = validate_ranking(read_ranking(path), targets)\n                             ^^^^^^^^^^^^^^^^^^\n  File \"/task/ranking_evaluation.py\", line 98, in read_ranking\n    return pd.read_parquet(path) if path.suffix == \".parquet\" else pd.read_csv(path)\n           ^^^^^^^^^^^^^^^^^^^^^\n  File \"/opt/task-venv/lib/python3.12/site-packages/pandas/io/parquet.py\", line 669, in read_parquet\n    return impl.read(\n           ^^^^^^^^^^\n  File \"/opt/task-venv/lib/python3.12/site-packages/pandas/io/parquet.py\", line 258, in read\n    path_or_handle, handles, filesystem = _get_path_or_handle(\n                                          ^^^^^^^^^^^^^^^^^^^^\n  File \"/opt/task-venv/lib/python3.12/site-packages/pandas/io/parquet.py\", line 141, in _get_path_or_handle\n    handles = get_handle(\n              ^^^^^^^^^^^\n  File \"/opt/task-venv/lib/python3.12/site-packages/pandas/io/common.py\", line 882, in get_handle\n    handle = open(handle, ioargs.mode)\n             ^^^^^^^^^^^^^^^^^^^^^^^^^\nFileNotFoundError: [Errno 2] No such file or directory: 'runs/softmax_val.parquet'",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:20:32.186Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14900274 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:20:32.189Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 27,
      "role": "agent",
      "timestamp": "2026-10-03T09:20:39.664Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:20:39.664Z",
          "text": "That score file is stale from the earlier killed run—the current run is still ranking and will overwrite it. Since training is fast (164s), I have headroom to add shared negatives or run 2 epochs for the final version, but I'm around 29 minutes in so time is limited.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:20:39.667Z",
          "callId": "toolu_016euBaeyR1RKTDoCeXwjvyr",
          "name": "Bash",
          "input": {
            "command": "sleep 60; cat runs/softmax_time.txt; cat runs/softmax_val.score; tail -1 runs/baseline_val.log",
            "description": "Wait for softmax ranking and score"
          },
          "result": {
            "timestamp": "2026-10-03T09:21:39.699Z",
            "content": "real\t4m59.914s\nuser\t19m32.985s\nsys\t1m45.380s\n{\n  \"model\": \"runs/softmax_val.parquet\",\n  \"scores\": {\n    \"quality_ndcg@10\": 0.015948,\n    \"quality_users\": 4263\n  }\n}\nepoch=1/1 batches=250 targets=987,417 batch_bce=0.547529 running_bce=0.541614 elapsed=327.9s",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:21:39.705Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14899226 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:21:39.707Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 28,
      "role": "agent",
      "timestamp": "2026-10-03T09:22:46.628Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:22:46.628Z",
          "text": "The softmax run scores 0.01595 NDCG@10, oddly lower than the quick smoke test with only 3 training targets per user which got 0.019. That's strange—more training data lowering the score suggests the fuller run might be overfitting toward popularity signals or the loss is optimizing against the discovery objective somehow.\n\nWith logQ correction, learned raw logits should approximate the true unbiased conditional probability, so ranking by raw scores at serving time naturally favors popular items as expected—this is standard behavior, not a bug. The smoke test's better score is likely just an artifact of being undertrained (near random/popularity init with only 27k targets), so I'm waiting on the baseline comparison to clarify things, while also considering whether the training targets (full of repeat listens) are mismatched with the validation objective, which is focused on genuinely novel, eligible items the user hasn't encountered yet.\n\nWhat's odd is that for discovery NDCG, the near-random untrained model actually scored higher (0.019) than the fully trained one (0.0159), which suggests the softmax training is actively hurting ranking rather than helping — I need to check against the baseline number to see if this is a genuine bug or just an expected tradeoff. One suspect is the log-Q correction in sampled softmax: I'm checking whether subtracting log(q(y)) from the logits is actually biasing scores correctly for popular versus rare positives.\n\nRight, the known-positive filter spans the full training prefix, so items the user listens to later also get masked — same future-leakage the baseline has. Working through the inclusion-probability math: with batch size 6400, the miss rate (1-p)^B gives q around 0.19 for average items, near 1 for popular ones, and down to about 0.06 for rare items, so log_q ranges roughly −2.8 to 0 — not an extreme spread.\n\nOn training dynamics, the softmax loss over ~4500 candidates starts near log(4500)=8.4 and only drops to about 7.38 by batch 250 with validation at 6.92, so there's only modest learning happening. With just ~280 optimizer steps total in one epoch, both the softmax model and the BCE baseline are heavily undertrained, which likely explains why the baseline ends up leaning mostly on popularity signal.\n\nWith only 280 Adam steps and embeddings initialized at std 0.02, the parameters can shift meaningfully but the fit is still crude given so few updates. Given roughly 30 minutes left and a 7-minute refit cost with caching, I'm considering shrinking the user batch size (e.g., to 16 users) to get 4x more optimizer steps per epoch, trading off some extra Python overhead for better-trained embeddings.\n\nBut undertraining alone may not explain why the trained model performs worse than the untrained baseline—I suspect the real issue is that the GRU learns to score recently-encountered items highly since users mostly re-listen to history, but since eligible candidates exclude all seen items at serving time, that learned signal becomes useless and the ranking among genuinely unseen items ends up driven by whatever spurious correlations remain.\n\nChecking the smoke test numbers more carefully, I'm realizing random initialization would give near-zero NDCG given the candidate pool size, so the smoke model with its ~143 training steps actually did learn something real, likely picking up on popularity signals from the item tower features.\n\nThis suggests the fully trained model's lower score may mean it's drifting away from popularity signal toward re-listen prediction, which hurts discovery metrics since those favor novel organic engagement. The discovery-graded weighting scheme (downweighting repeats, upweighting novel strong signals) might be the fix, though I need to check how it compares to the current default weighting.\n\nI'm also wondering whether masking known positives from candidates could itself be anti-popularity in a subtle way, since it disproportionately strips popular items for heavy users who've already encountered them.\n\nActually, the bigger issue is probably that the GRU just learns to copy — if 70%+ of targets are repeats of the user's listening prefix, softmax CE is dominated by trivial repeat prediction, and the baseline BCE likely suffers the same fate given its similarly low score. That suggests target weighting might be the real quick win rather than negative sampling alone, though the task explicitly asks me to focus on diagnosing and improving the negative-sampling strategy.\n\nSince the real test is hidden NDCG, I'll pursue both: softmax negatives plus discovery-focused target weighting that downweights repeats. First I need to check the baseline score to have something to compare against.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:22:48.918Z",
          "callId": "toolu_01SSpDLh3Gs4Y9Gm3MgvRMwR",
          "name": "Bash",
          "input": {
            "command": "sleep 30; cat runs/baseline_val.score; cat runs/baseline_time.txt | tail -3; python - <<'EOF'\nimport numpy as np\na=np.load('runs/val_cache.npz')\nitems=a['sequence_items']; off=a['offsets']; ef=a['event_features']\n# fraction of recent-128 targets that are repeats of user's earlier prefix\nrep=0; tot=0; org_strong_novel=0\nrng=np.random.default_rng(0)\nfor u in rng.choice(len(off)-1, 1500, replace=False):\n    s,e=off[u],off[u+1]\n    if e-s<2: continue\n    seq=items[s:e].astype(np.int64)\n    seen=set(seq[:max(0,len(seq)-129)].tolist())\n    start=max(1,len(seq)-128)\n    for p in range(start,len(seq)):\n        seen.add(int(seq[p-1]))\n        tot+=1\n        if int(seq[p]) in seen: rep+=1\n        elif ef[s+p,0]>0.5 and ef[s+p,1]>=0.8: org_strong_novel+=1\nprint('repeat fraction among recent targets', rep/tot, 'novel organic-strong', org_strong_novel/tot, tot)\nEOF",
            "description": "Get baseline score and measure repeat-target fraction"
          },
          "result": {
            "timestamp": "2026-10-03T09:23:19.781Z",
            "content": "Traceback (most recent call last):\n  File \"/task/evaluate_public.py\", line 157, in <module>\n    main()\n  File \"/task/evaluate_public.py\", line 152, in main\n    ranked = load_submission(path, eligibility, targets)\n             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n  File \"/task/evaluate_public.py\", line 113, in load_submission\n    frame = validate_ranking(read_ranking(path), targets)\n                             ^^^^^^^^^^^^^^^^^^\n  File \"/task/ranking_evaluation.py\", line 98, in read_ranking\n    return pd.read_parquet(path) if path.suffix == \".parquet\" else pd.read_csv(path)\n           ^^^^^^^^^^^^^^^^^^^^^\n  File \"/opt/task-venv/lib/python3.12/site-packages/pandas/io/parquet.py\", line 669, in read_parquet\n    return impl.read(\n           ^^^^^^^^^^\n  File \"/opt/task-venv/lib/python3.12/site-packages/pandas/io/parquet.py\", line 258, in read\n    path_or_handle, handles, filesystem = _get_path_or_handle(\n                                          ^^^^^^^^^^^^^^^^^^^^\n  File \"/opt/task-venv/lib/python3.12/site-packages/pandas/io/parquet.py\", line 141, in _get_path_or_handle\n    handles = get_handle(\n              ^^^^^^^^^^^\n  File \"/opt/task-venv/lib/python3.12/site-packages/pandas/io/common.py\", line 882, in get_handle\n    handle = open(handle, ioargs.mode)\n             ^^^^^^^^^^^^^^^^^^^^^^^^^\nFileNotFoundError: [Errno 2] No such file or directory: '/app/solution/production_validation.parquet'\nrepeat fraction among recent targets 0.6634795152914021 novel organic-strong 0.10003462204270051 173300",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:23:19.784Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14895073 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:23:19.786Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 29,
      "role": "agent",
      "timestamp": "2026-10-03T09:23:31.137Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:23:31.137Z",
          "text": "With two-thirds of training targets being repeats and only a tenth genuinely novel, and the stale baseline score file still skewing rankings, I need to move fast with limited time left. I'm deciding to add a repeat_target_weight config, downweighting targets that already appeared earlier in a user's sequence, and implementing it with a per-user loop inside the weight-building function.\n\nMy plan: implement the repeat weighting in a couple minutes, then launch a validation run combining softmax with repeat downweighting and a larger batch size across 5 threads while the baseline score finishes computing. Once I see which config wins, I'll kick off the final refit using the cached data at 8 threads, aiming to finish with just enough buffer to write the README while it runs.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:23:44.981Z",
          "callId": "toolu_019iqaLSjCa1rMCnETju7rgb",
          "name": "Bash",
          "input": {
            "command": "python - <<'EOF'\np='train_current_model.py'\ns=open(p).read()\nold='''    target_weighting: str = \"organic-strong\"\n    ordinary_target_weight: float = 0.25'''\nassert old in s\ns=s.replace(old,'''    target_weighting: str = \"organic-strong\"\n    repeat_target_weight: float = 0.05\n    ordinary_target_weight: float = 0.25''')\n# apply repeat weighting at the end of build_target_weights (before final log)\nold='''    log(\n        f\"target weighting={config.target_weighting} \"\n        f\"min={weights.min():.3f} mean={weights.mean():.3f} \"\n        f\"max={weights.max():.3f}\"\n    )\n    return weights'''\nassert old in s\ns=s.replace(old,'''    if config.repeat_target_weight > 0 and config.repeat_target_weight < 1.0:\n        # Re-listens of items already in the user's prefix cannot be discovery\n        # outcomes: eligibility excludes every encountered item, so those\n        # targets are scaled down to keep the objective on first encounters.\n        repeats = 0\n        for user_row in range(len(prepared.user_ids)):\n            start = int(prepared.offsets[user_row])\n            end = int(prepared.offsets[user_row + 1])\n            if end - start < 2:\n                continue\n            sequence = prepared.sequence_items[start:end].astype(np.int64)\n            _, first_positions = np.unique(sequence, return_index=True)\n            is_first = np.zeros(len(sequence), dtype=bool)\n            is_first[first_positions] = True\n            repeat_positions = np.flatnonzero(~is_first)\n            weights[start + repeat_positions] *= np.float32(config.repeat_target_weight)\n            repeats += len(repeat_positions)\n        log(f\"repeat targets down-weighted by {config.repeat_target_weight}: {repeats:,}\")\n    log(\n        f\"target weighting={config.target_weighting} \"\n        f\"min={weights.min():.3f} mean={weights.mean():.3f} \"\n        f\"max={weights.max():.3f}\"\n    )\n    return weights''')\nold='''    parser.add_argument(\n        \"--ordinary-target-weight\",'''\nassert old in s\ns=s.replace(old,'''    parser.add_argument(\n        \"--repeat-target-weight\",\n        type=float,\n        default=Config.repeat_target_weight,\n        help=\"multiplier for re-listen targets already in the user's prefix; 1 disables\",\n    )\n    parser.add_argument(\n        \"--ordinary-target-weight\",''')\nold='''        ordinary_target_weight=args.ordinary_target_weight,'''\nassert old in s\ns=s.replace(old,'''        repeat_target_weight=args.repeat_target_weight,\n        ordinary_target_weight=args.ordinary_target_weight,''')\nold='''        or args.ordinary_target_weight <= 0'''\ns=s.replace(old,'''        or args.ordinary_target_weight <= 0\n        or not 0.0 < args.repeat_target_weight <= 1.0''')\n# resume objective_changed should include repeat weight\nold='''            stored_config.get(\"ordinary_target_weight\", 1.0),'''\ns=s.replace(old,'''            stored_config.get(\"repeat_target_weight\", 1.0),\n            stored_config.get(\"ordinary_target_weight\", 1.0),''')\nold='''            config.ordinary_target_weight,\n            config.organic_strong_target_weight,'''\ns=s.replace(old,'''            config.repeat_target_weight,\n            config.ordinary_target_weight,\n            config.organic_strong_target_weight,''')\nopen(p,'w').write(s)\nEOF\npython -c \"import ast; ast.parse(open('train_current_model.py').read())\" && python test_sampled_softmax.py && \\\n(time python train_current_model.py --stage validation --public-dir /task --prepared-cache runs/val_cache.npz --output runs/sm_rep_val.parquet --threads 5 --user-batch-size 32 > runs/sm_rep_val.json 2> runs/sm_rep_val.log; python /task/evaluate_public.py runs/sm_rep_val.parquet > runs/sm_rep_val.score 2>&1) > runs/sm_rep_time.txt 2>&1 &\nsleep 2; cat runs/baseline_time.txt | tail -3; cat runs/baseline_val.score | tail -5",
            "description": "Add repeat-target down-weighting and launch second validation run"
          },
          "result": {
            "timestamp": "2026-10-03T09:23:47.030Z",
            "content": "real\t7m50.535s\nuser\t16m23.515s\nsys\t1m40.001s\n  \"scores\": {\n    \"quality_ndcg@10\": 0.02128,\n    \"quality_users\": 4263\n  }\n}",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:23:47.034Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14892360 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:23:47.035Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 30,
      "role": "agent",
      "timestamp": "2026-10-03T09:24:04.810Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:24:04.810Z",
          "text": "My softmax objective actually performs worse than baseline (0.01595 vs 0.02128), and even the barely-trained smoke run beats it. With about 36 minutes gone and 24 left, I need to secure a valid submission as a safety net right away, likely by running the baseline in the submission stage since the cache exists and it's relatively fast.\n\nRunning the experiment at 5 threads and the baseline refit at 3 threads in parallel should both finish by roughly T+46. If the experiment ends up winning, I'd then do a final refit of that configuration, pushing to about T+52 -- tight but doable. I'll kick off the baseline-config submission now using the production script to keep things equivalent and safe.\n\n"
        },
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:24:04.814Z",
          "text": "My first softmax variant scored 0.01595, worse than the 0.02128 baseline. I'm refitting a fallback submission using the production config to ensure a valid artifact exists, while the second variant (softmax plus repeat down-weighting with smaller user batches) runs.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:24:05.046Z",
          "callId": "toolu_01Rhv2XS8yjjY3Jao6JGc1YY",
          "name": "Bash",
          "input": {
            "command": "(time python /task/current_model/train_current_model.py --stage submission --public-dir /task --prepared-cache /app/solution/runs/sub_cache.npz --output /app/solution/runs/baseline_submission.parquet --threads 3 > runs/baseline_sub.json 2> runs/baseline_sub.log) > runs/baseline_sub_time.txt 2>&1 &\nsleep 90; tail -2 runs/sm_rep_val.log; free -g | head -2",
            "description": "Launch fallback production refit and monitor the experiment"
          },
          "result": {
            "timestamp": "2026-10-03T09:25:35.083Z",
            "content": "sampled-softmax objective: shared_negatives=1024 power=0.75 logq=True\nepoch=1/1 batches=250 targets=502,922 batch_bce=7.103409 running_bce=7.679726 elapsed=69.7s\n               total        used        free      shared  buff/cache   available\nMem:              15           6           2           0           7           9",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:25:35.087Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14891587 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:25:35.089Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 31,
      "role": "agent",
      "timestamp": "2026-10-03T09:25:58.432Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:25:58.432Z",
          "text": "I'm trying to figure out why softmax underperformed relative to BCE here, thinking through how BCE's uniform plus in-batch negatives push scores toward popularity-aware log-odds, whereas sampled softmax with logQ correction might handle the negative distribution differently in a way that hurts performance.\n\nThe key difference seems to be gradient weighting: softmax concentrates gradient on the hardest negatives, which tend to be popular items, so the model actively suppresses popular items for users who didn't choose them — more so than BCE does. Since the discovery metric rewards popularity, this could explain the gap, though the logQ correction using inclusion probability should theoretically account for this by saturating near 1 for popular items in the unique in-batch candidate set.\n\nMaybe the real issue is undertraining — only 280 steps versus the second run's double step count at batch 32 — rather than an inherent flaw in the objective. With limited time left, I'm weighing options: wait on the sm_rep result to see if it beats the baseline, fall back to the safe baseline submission, or launch a cheap variant testing repeat-target-weighting directly in BCE mode to see if that alone helps. Running a third process concurrently is a memory risk given the earlier OOM from the data-prep step, so I need to be careful about resource usage before committing to that path.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:25:58.446Z",
          "callId": "toolu_01WX7hWfy6fyPwY2eD9YqtUi",
          "name": "Bash",
          "input": {
            "command": "(time python train_current_model.py --stage validation --public-dir /task --prepared-cache runs/val_cache.npz --output runs/bce_rep_val.parquet --threads 2 --objective bce > runs/bce_rep_val.json 2> runs/bce_rep_val.log; python /task/evaluate_public.py runs/bce_rep_val.parquet > runs/bce_rep_val.score 2>&1) > runs/bce_rep_time.txt 2>&1 &\nsleep 75; free -g | head -2; tail -1 runs/sm_rep_val.log; tail -1 runs/baseline_sub.log; tail -1 runs/bce_rep_val.log",
            "description": "Launch BCE plus repeat-weighting variant and monitor all runs"
          },
          "result": {
            "timestamp": "2026-10-03T09:27:13.570Z",
            "content": "               total        used        free      shared  buff/cache   available\nMem:              15           6           3           0           6           9\nrestored best validation-BCE checkpoint: epoch=1 loss=6.728610\nfull-history false-negative filter: users=9,153 unique_user_items=5,682,910 bytes=34,323,750\nfull-history false-negative filter: users=9,135 unique_user_items=5,524,275 bytes=34,256,250",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:27:13.599Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14890200 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:27:13.611Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 32,
      "role": "agent",
      "timestamp": "2026-10-03T09:27:18.007Z",
      "blocks": [
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:27:18.007Z",
          "callId": "toolu_01BmLst4SoSgJTjuiz7BSPyr",
          "name": "Bash",
          "input": {
            "command": "sleep 100; cat runs/sm_rep_val.score 2>/dev/null | grep ndcg; tail -1 runs/baseline_sub.log; tail -1 runs/bce_rep_val.log; free -g | head -2",
            "description": "Wait for second variant score and monitor runs"
          },
          "result": {
            "timestamp": "2026-10-03T09:28:58.095Z",
            "content": "    \"quality_ndcg@10\": 0.022804,\nfull-history false-negative filter: users=9,153 unique_user_items=5,682,910 bytes=34,323,750\nfull-history false-negative filter: users=9,135 unique_user_items=5,524,275 bytes=34,256,250\n               total        used        free      shared  buff/cache   available\nMem:              15           4           4           0           6          10",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:28:58.100Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14889872 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:28:58.102Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 33,
      "role": "agent",
      "timestamp": "2026-10-03T09:29:07.649Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:29:07.649Z",
          "text": "The sm_rep config beats baseline by 7%, and with only 17 minutes left, I'll launch the final refit now using that configuration, freeing up CPU threads by killing bce_rep since it's not needed.\n\n"
        },
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:29:07.653Z",
          "text": "The sampled softmax plus repeat down-weighting variant with 32-user batches hit 0.022804 versus the 0.02128 baseline, a 7% improvement. I'll stop the ablation run to free CPU and launch the final hidden-test refit using this configuration.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:29:09.477Z",
          "callId": "toolu_01R2wHRYABeRBYrVgKZA9T28",
          "name": "Bash",
          "input": {
            "command": "pkill -f \"bce_rep_val\" ; sleep 1\n(time python train_current_model.py --stage submission --public-dir /task --prepared-cache runs/sub_cache.npz --output /app/solution/runs/softmax_submission.parquet --threads 5 --user-batch-size 32 > runs/softmax_sub.json 2> runs/softmax_sub.log) > runs/softmax_sub_time.txt 2>&1 &\nsleep 3; ps -o pid,etime,args -C python | cut -c1-110; grep -E \"epoch=1/1 train|repeat targets\" runs/sm_rep_val.log",
            "description": "Stop ablation and launch final refit with winning config"
          },
          "result": {
            "timestamp": "2026-10-03T09:29:09.516Z",
            "content": "Exit code 144",
            "isError": true
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:29:09.519Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14889090 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:29:09.520Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 34,
      "role": "agent",
      "timestamp": "2026-10-03T09:29:15.408Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:29:15.408Z",
          "text": "That pkill likely killed my own shell too since the command line matched \"bce_rep_val\" - I'm checking whether the refit actually launched despite that.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:29:15.411Z",
          "callId": "toolu_01PmpsdKq9MWX6XryjoY77fj",
          "name": "Bash",
          "input": {
            "command": "ps -o pid,etime,args -C python | cut -c1-120; ls runs/ | grep softmax_sub",
            "description": "Check which training processes are running"
          },
          "result": {
            "timestamp": "2026-10-03T09:29:15.437Z",
            "content": "    PID     ELAPSED COMMAND",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:29:15.439Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14888889 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:29:15.442Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 35,
      "role": "agent",
      "timestamp": "2026-10-03T09:29:30.569Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:29:30.569Z",
          "text": "That pkill command was a disaster — it killed everything, including the baseline submission refit. The pattern shouldn't have matched that command directly, but it likely caught the parent bash shell, wiping out the whole process group including backgrounded jobs. About 44 minutes have elapsed now.\n\nWith 16 minutes left, I only have time for the final softmax refit, roughly 5-6 minutes at 8 threads including cache load, training, and ranking — no room for a parallel fallback since that would just compete for CPU and risk both failing. The primary config already validated successfully end-to-end, so I'll run it alone at full threads while drafting the README in parallel, making sure the submission uses test-eligible candidates rather than the validation ranking.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:29:30.574Z",
          "callId": "toolu_01LyoJEgXfZg9x4ydkNgT9hv",
          "name": "Bash",
          "input": {
            "command": "nohup bash -c '(time python train_current_model.py --stage submission --public-dir /task --prepared-cache runs/sub_cache.npz --output /app/solution/runs/softmax_submission.parquet --threads 8 --user-batch-size 32 > runs/softmax_sub.json 2> runs/softmax_sub.log) > runs/softmax_sub_time.txt 2>&1' > /dev/null 2>&1 &\nsleep 2; ps -o pid,etime,args -C python | cut -c1-120",
            "description": "Relaunch final refit detached with full CPU"
          },
          "result": {
            "timestamp": "2026-10-03T09:29:32.607Z",
            "content": "    PID     ELAPSED COMMAND\n   9042       00:02 python train_current_model.py --stage submission --public-dir /task --prepared-cache runs/sub_cache.",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:29:32.610Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14888117 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:29:32.611Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 36,
      "role": "agent",
      "timestamp": "2026-10-03T09:29:36.228Z",
      "blocks": [
        {
          "kind": "message",
          "timestamp": "2026-10-03T09:29:36.228Z",
          "text": "The final refit is running with all 8 threads. While it trains, I'll write the README and gather the validation numbers for the record."
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:29:38.807Z",
          "callId": "toolu_01UnwkZJbQxY9xk6HuKYiZrD",
          "name": "Bash",
          "input": {
            "command": "grep -E \"epoch=1/1 train|repeat targets|sampled-softmax objective\" runs/sm_rep_val.log runs/softmax_val.log runs/baseline_val.log; cat runs/sm_rep_time.txt | grep real; cat runs/softmax_time.txt | grep real; cat runs/baseline_time.txt | grep real",
            "description": "Collect training diagnostics and timings for README"
          },
          "result": {
            "timestamp": "2026-10-03T09:29:38.847Z",
            "content": "runs/sm_rep_val.log:repeat targets down-weighted by 0.05: 14,491,403\nruns/sm_rep_val.log:sampled-softmax objective: shared_negatives=1024 power=0.75 logq=True\nruns/sm_rep_val.log:epoch=1/1 train_loss=7.53172 validation_loss=6.72861 pair_accuracy=0.643 train_targets=1,052,953 validation_targets=130,103 train_seconds=159.4 validation_seconds=13.2\nruns/softmax_val.log:sampled-softmax objective: shared_negatives=1024 power=0.75 logq=True\nruns/softmax_val.log:epoch=1/1 train_loss=7.95329 validation_loss=6.92151 pair_accuracy=0.637 train_targets=1,052,953 validation_targets=130,103 train_seconds=164.4 validation_seconds=11.2\nruns/baseline_val.log:epoch=1/1 train_loss=0.53984 validation_loss=0.49664 pair_accuracy=0.755 train_targets=1,052,953 validation_targets=130,103 train_seconds=343.8 validation_seconds=20.0\nreal\t5m3.701s\nreal\t4m59.914s\nreal\t7m50.535s",
            "isError": false
          }
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:29:58.632Z",
          "callId": "toolu_015PtDCLxQVojLHbjGfe8Dpm",
          "name": "Write",
          "input": {
            "file_path": "/app/solution/README.md",
            "content": "# Made for You two-tower: negative-sampling fix\n\n## Diagnosis\n\nThe production trainer scores every next-item target with sample-weighted BCE\nagainst 24 uniform catalog negatives and 8 unique in-batch negatives. Three\nproblems with that objective, confirmed on the public backtest:\n\n1. **Uniform negatives are uninformative.** Drawing uniformly from the 30k\n   catalog returns long-tail tracks that the item tower already scores low\n   from its catalog popularity features. After a few hundred steps these\n   negatives contribute almost no gradient, so three quarters of the negative\n   budget is wasted.\n2. **Only 8 informative negatives per target.** The in-batch draws are the\n   only hard negatives, and their popularity bias is handled by a clipped\n   power-law reweighting of the loss rather than a proper log-Q correction of\n   the logits.\n3. **Two thirds of the targets are re-listens.** In the retained window 66% of\n   adjacent targets are items already in the user's prefix. Those targets\n   teach the user tower to copy its context, which is useless at the cutoff\n   because every encountered item is removed from the eligible candidates.\n   Only about 10% of targets are novel organic strong listens, the pattern the\n   discovery objective rewards.\n\n## Change\n\n`train_current_model.py` keeps the data protocol, chronological split,\ntwo-tower model, false-negative filter, and raw dot-product serving path, and\nreplaces the objective:\n\n- **Sampled softmax over a shared candidate list.** Every target in a block is\n  scored against all unique targets of the block plus 1024 shared negatives\n  sampled proportionally to training-target popularity^0.75. One matmul gives\n  thousands of informative negatives per example instead of 32, and training\n  is faster than the baseline because the per-row rejection loop disappears.\n- **Log-Q correction.** Each candidate's logit is shifted by its block\n  inclusion probability so popular items are not over-penalised.\n- **Same false-negative masking.** Known public-training positives, active\n  likes, and the row's own target are masked in every row.\n- **Repeat targets down-weighted** by 0.05 so the loss concentrates on\n  first-encounter targets, matching eligibility at the cutoff.\n- **32-user batches** to double the number of optimizer steps within the one\n  epoch budget.\n\nThe legacy objective remains available with `--objective bce\n--repeat-target-weight 1.0`.\n\n## Public validation results (NDCG@10, 4263 scored users)\n\n| Model | NDCG@10 | Train time |\n| --- | --- | --- |\n| Production baseline (BCE, 24 uniform + 8 in-batch) | 0.021280 | 246 s |\n| Sampled softmax + log-Q, 64-user batches, no repeat weighting | 0.015948 | 164 s |\n| Sampled softmax + log-Q + repeat weight 0.05, 32-user batches (shipped) | 0.022804 | see log |\n\nThe negative-sampling change alone was not enough: with the re-listen targets\nstill dominating, the sharper softmax objective learned to copy context even\nmore aggressively and lost to the baseline. Combining it with the repeat\ndown-weighting gave a 7% relative improvement over production.\n\n## Commands\n\n```sh\n# public backtest of the shipped configuration\npython /app/solution/train_current_model.py --stage validation --public-dir /task \\\n  --user-batch-size 32 --output /app/solution/runs/sm_rep_val.parquet\npython /task/evaluate_public.py /app/solution/runs/sm_rep_val.parquet\n\n# final hidden-test submission (refit on train + val)\npython /app/solution/train_current_model.py --stage submission --public-dir /task \\\n  --user-batch-size 32 --output /app/solution/submission.parquet\n\n# unit tests for the candidate builder and loss\npython /app/solution/test_sampled_softmax.py\n```\n\nLogs and intermediate rankings are under `/app/solution/runs/`.\n"
          },
          "result": {
            "timestamp": "2026-10-03T09:29:58.697Z",
            "content": "File created successfully at: /app/solution/README.md (file state is current in your context — no need to Read it back)",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:29:58.713Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14886390 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:29:58.716Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 37,
      "role": "agent",
      "timestamp": "2026-10-03T09:30:04.354Z",
      "blocks": [
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:30:04.354Z",
          "callId": "toolu_01CtjjvCJgdo8APVohsiyYkT",
          "name": "Bash",
          "input": {
            "command": "sed -i 's/| Sampled softmax + log-Q + repeat weight 0.05, 32-user batches (shipped) | 0.022804 | see log |/| Sampled softmax + log-Q + repeat weight 0.05, 32-user batches (shipped) | 0.022804 | 159 s |/' README.md; sleep 60; tail -2 runs/softmax_sub.log; ps -o pid,etime -C python",
            "description": "Fix README timing and check refit progress"
          },
          "result": {
            "timestamp": "2026-10-03T09:31:04.441Z",
            "content": "sampled-softmax objective: shared_negatives=1024 power=0.75 logq=True\nepoch=1/1 batches=250 targets=503,141 batch_bce=7.628614 running_bce=7.714888 elapsed=61.7s\n    PID     ELAPSED\n   9042       01:33",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:31:04.454Z",
          "data": {
            "type": "edited_text_file",
            "filename": "/app/solution/README.md",
            "snippet": "46\t--repeat-target-weight 1.0`.\n47\t\n48\t## Public validation results (NDCG@10, 4263 scored users)\n49\t\n50\t| Model | NDCG@10 | Train time |\n51\t| --- | --- | --- |\n52\t| Production baseline (BCE, 24 uniform + 8 in-batch) | 0.021280 | 246 s |\n53\t| Sampled softmax + log-Q, 64-user batches, no repeat weighting | 0.015948 | 164 s |\n54\t| Sampled softmax + log-Q + repeat weight 0.05, 32-user batches (shipped) | 0.022804 | 159 s |\n55\t\n56\tThe negative-sampling change alone was not enough: with the re-listen targets\n57\tstill dominating, the sharper softmax objective learned to copy context even\n58\tmore aggressively and lost to the baseline. Combining it with the repeat\n59\tdown-weighting gave a 7% relative improvement over production.\n60\t\n61\t## Commands\n62\t"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:31:04.455Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14885625 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:31:04.457Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 38,
      "role": "agent",
      "timestamp": "2026-10-03T09:31:11.708Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:31:11.708Z",
          "text": "Training is moving fast with 8 threads, should wrap around T+50, so I'll get the submission validation script ready now to check column format, user coverage, 100 rows per user, ranks, and eligibility constraints.\n\n"
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:31:17.554Z",
          "callId": "toolu_019Jhs1tA3XQzCV4ZhCZF1cN",
          "name": "Bash",
          "input": {
            "command": "cat > check_submission.py <<'EOF'\n\"\"\"Validate a hidden-test submission against the deliverable contract.\"\"\"\nimport sys\nimport numpy as np\nimport pandas as pd\n\npath = sys.argv[1]\nframe = pd.read_parquet(path)\ntargets = set(pd.read_parquet(\"/task/data/target_users.parquet\").uid.astype(int))\nwith np.load(\"/task/data/test_eligible_candidates.npz\") as z:\n    uids = z[\"uids\"]; item_ids = z[\"item_ids\"]; packed = z[\"packed_eligible\"]\nrow_of = {int(u): r for r, u in enumerate(uids)}\ncol_of = pd.Index(item_ids)\nassert {\"uid\", \"item_id\", \"rank\"} <= set(frame.columns)\nfor c in (\"uid\", \"item_id\", \"rank\"):\n    v = frame[c].to_numpy()\n    assert np.isfinite(v).all() and np.array_equal(v, v.astype(np.int64)), c\nassert set(frame.uid.astype(int)) == targets, \"user set mismatch\"\ng = frame.groupby(\"uid\")\nassert (g.size() == 100).all(), \"row count\"\nassert (g.item_id.nunique() == 100).all(), \"distinct items\"\nassert (g[\"rank\"].apply(lambda r: sorted(r.tolist()) == list(range(1, 101)))).all(), \"ranks\"\ncols = col_of.get_indexer(frame.item_id.to_numpy())\nassert (cols >= 0).all(), \"unknown items\"\nrows = np.array([row_of[int(u)] for u in frame.uid.to_numpy()])\nbits = (packed[rows, cols >> 3] >> (cols & 7)) & 1\nassert bits.all(), \"ineligible items\"\nprint(\"submission valid:\", len(frame), \"rows,\", frame.uid.nunique(), \"users\")\nEOF\nsleep 75; tail -2 runs/softmax_sub.log; ls -la runs/softmax_submission.parquet 2>/dev/null",
            "description": "Write submission checker and wait for refit"
          },
          "result": {
            "timestamp": "2026-10-03T09:32:32.624Z",
            "content": "Exit code 2\nepoch=1/1 train_loss=7.55699 validation_loss=6.75101 pair_accuracy=0.639 train_targets=1,067,606 validation_targets=131,997 train_seconds=132.9 validation_seconds=10.3\nrestored best validation-BCE checkpoint: epoch=1 loss=6.751012",
            "isError": true
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:32:32.631Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14884230 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:32:32.633Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 39,
      "role": "agent",
      "timestamp": "2026-10-03T09:32:36.663Z",
      "blocks": [
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:32:36.663Z",
          "callId": "toolu_01PRDS2cZaZYzrBtHSykaNT2",
          "name": "Bash",
          "input": {
            "command": "sleep 50; tail -1 runs/softmax_sub.log; cat runs/softmax_sub_time.txt | grep real; ls -la runs/softmax_submission.parquet 2>/dev/null",
            "description": "Wait for ranking phase to finish"
          },
          "result": {
            "timestamp": "2026-10-03T09:33:26.733Z",
            "content": "Exit code 2\nrestored best validation-BCE checkpoint: epoch=1 loss=6.751012",
            "isError": true
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:33:26.738Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14883930 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:33:26.741Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 40,
      "role": "agent",
      "timestamp": "2026-10-03T09:33:30.712Z",
      "blocks": [
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:33:30.712Z",
          "callId": "toolu_01JQq4MMVEvkvYnhRYk5nvPS",
          "name": "Bash",
          "input": {
            "command": "sleep 45; tail -1 runs/softmax_sub.log; cat runs/softmax_sub_time.txt | grep real; ls -la runs/softmax_submission.parquet 2>/dev/null; ps -o pid,etime -C python",
            "description": "Check whether final ranking has been written"
          },
          "result": {
            "timestamp": "2026-10-03T09:34:15.776Z",
            "content": "Exit code 1\nranked users=8,456/8,456\nreal\t4m15.929s\n-rw-r--r-- 1 agent agent 1217145 Oct  3 09:33 runs/softmax_submission.parquet\n    PID     ELAPSED",
            "isError": true
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:34:15.780Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14883701 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:34:15.782Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 41,
      "role": "agent",
      "timestamp": "2026-10-03T09:34:19.594Z",
      "blocks": [
        {
          "kind": "message",
          "timestamp": "2026-10-03T09:34:19.594Z",
          "text": "The refit finished in just over four minutes. Now I'll copy it to the deliverable path and validate it against the contract."
        },
        {
          "kind": "tool",
          "timestamp": "2026-10-03T09:34:21.112Z",
          "callId": "toolu_01AwXkCUCiPjXEiBbw5729dD",
          "name": "Bash",
          "input": {
            "command": "cp runs/softmax_submission.parquet /app/solution/submission.parquet && python check_submission.py /app/solution/submission.parquet && ls -la /app/solution/ && head -c 600 runs/softmax_sub.json",
            "description": "Install and validate final submission"
          },
          "result": {
            "timestamp": "2026-10-03T09:34:23.292Z",
            "content": "submission valid: 845600 rows, 8456 users\ntotal 2544\ndrwxr-xr-x 1 agent agent    4096 Oct  3 09:34 .\ndrwxr-xr-x 1 agent agent    4096 Oct  3 08:58 ..\n-rw-r--r-- 1 agent agent    3739 Oct  3 09:30 README.md\n-rw-r--r-- 1 agent agent    1284 Oct  3 09:31 check_submission.py\n-rw-r--r-- 1 agent agent 1244231 Oct  3 09:23 production_validation.parquet\ndrwxr-xr-x 2 agent agent    4096 Oct  3 09:33 runs\n-rw-r--r-- 1 agent agent 1217145 Oct  3 09:34 submission.parquet\n-rw-r--r-- 1 agent agent    3242 Oct  3 09:12 test_sampled_softmax.py\n-rw-r--r-- 1 agent agent   91712 Oct  3 09:23 train_current_model.py\n-rw-r--r-- 1 agent agent   15985 Oct  3 09:03 two_tower_model.py\n{\n  \"baseline\": \"yambda-windowed-sequence-two-tower-base\",\n  \"stage\": \"submission\",\n  \"output\": \"/app/solution/runs/softmax_submission.parquet\",\n  \"rows\": 845600,\n  \"users\": 8456,\n  \"runtime_seconds\": 251.555,\n  \"public_inputs_only\": true,\n  \"architecture\": {\n    \"family\": \"pure-windowed-sequence-two-tower\",\n    \"sequence_training\": \"every-adjacent-target-within-recent-chronological-window\",\n    \"sequence_encoder\": \"one-layer-GRU-dense-timestep-loss\",\n    \"bptt_hidden_state\": \"carried-and-detached\",\n    \"model_selection\": \"chronological-validation-BCE-early-stopping\",\n    \"loss_execution\": \"gr",
            "isError": false
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:34:23.296Z",
          "data": {
            "type": "total_tokens_reminder",
            "text": "<total_tokens>14883393 tokens left</total_tokens>"
          }
        },
        {
          "kind": "context",
          "timestamp": "2026-10-03T09:34:23.305Z",
          "data": {
            "type": "batching_reminder_sent",
            "text": "First privately list what you need next; then request every item that doesn't depend on another's result in this one response.",
            "model": "claude-fable-5-1",
            "clearAt": "next_user_message"
          }
        }
      ]
    },
    {
      "id": 42,
      "role": "agent",
      "timestamp": "2026-10-03T09:34:38.487Z",
      "blocks": [
        {
          "kind": "reasoning",
          "timestamp": "2026-10-03T09:34:38.487Z",
          "text": "About 55 minutes have elapsed. I could clean up the large intermediate caches under /app/solution for tidiness, but that's not strictly necessary since they're allowed artifacts, so I'll leave them and wrap up with the final recap, noting the production_validation.parquet baseline file is present.\n\n"
        },
        {
          "kind": "message",
          "timestamp": "2026-10-03T09:34:40.943Z",
          "text": "The submission is in place and validated. Final recap:\n\n**Diagnosis.** The production objective spends 24 of its 32 negatives on uniform catalog draws, which are long-tail tracks the item tower already scores low from its popularity features, so they carry almost no gradient. Only the 8 in-batch negatives are informative, and their popularity bias is handled by a clipped reweighting rather than a log-Q correction. On top of that, 66% of training targets are re-listens of items already in the user's prefix, which teaches the user tower to copy context even though every encountered item is excluded from the eligible candidates at the cutoff.\n\n**Change** in `/app/solution/train_current_model.py`, with the data protocol, two-tower model, false-negative filter, and raw dot-product serving path unchanged:\n- Sampled softmax over a shared candidate list per block: all unique block targets plus 1024 shared negatives sampled by popularity^0.75, with log-Q correction on the logits and the same masking of known positives, active likes, and the row's own target.\n- Repeat targets down-weighted by 0.05 so the loss concentrates on first encounters.\n- 32-user batches to double optimizer steps. Training is faster than the baseline because the per-row rejection loop is gone.\n- The legacy objective stays available via `--objective bce --repeat-target-weight 1.0`.\n\n**Public validation NDCG@10** (4263 scored users):\n\n| Model | NDCG@10 |\n| --- | --- |\n| Production baseline | 0.021280 |\n| Sampled softmax alone, 64-user batches | 0.015948 |\n| Sampled softmax + repeat weight 0.05, 32-user batches (shipped) | 0.022804 |\n\nThe negative-sampling change alone lost to the baseline. The sharper objective copied context even harder while re-listen targets dominated. Combined with repeat down-weighting it gives a 7% relative improvement.\n\n**Deliverables.** `/app/solution/submission.parquet` was refit on train plus val with the shipped configuration and passes all contract checks: 845,600 rows, exactly the 8456 target users, 100 distinct eligible items and ranks 1 to 100 per user. The README records the diagnosis, scores, and commands. Unit tests for the candidate builder and loss are in `test_sampled_softmax.py`, and `check_submission.py` reproduces the contract validation.\n\n**Caveats.** Two early runs were OOM-killed when three trainers ran at once, and I killed a BCE-plus-repeat-weighting ablation to free CPU for the final refit, so that ablation has no result. The validation improvement is from a single seed and one epoch."
        }
      ]
    }
  ]
}
