yambda-discovery-ranking-two-tower-base / gemini-3-8-flash-high-base-r04-b9049e57 Recorded model: gemini-3.8-flash ## Step 1 · user · 2026-09-29T01:34:04.574Z This is the Gemini CLI. We are setting up the context for our chat. Today's date is Tuesday, September 29, 2026 (formatted according to the user's locale). My operating system is: linux The project's temporary directory is: /home/agent/.gemini/tmp/app - **Workspace Directories:** - /app - **Directory Structure:** Showing up to 200 items (files + folders). /app/ └───solution/ ## Step 2 · user · 2026-09-29T01:34:04.615Z # Build a latency-efficient PyTorch two-tower neural-network ranker Build a two-tower neural network in CPU PyTorch for the "Made for You" shelf of a music streaming service. Although the supplied benchmark is small, it represents a production system with millions of users and millions of items; the training approach must scale to that setting and therefore must not construct or decompose a global user-item interaction matrix. The production shelf has a strict request-time latency budget. Candidate item embeddings are computed offline and stored in a nearest-neighbor index. At request time, the system computes one user embedding and retrieves items by maximum inner-product search. The model must therefore decompose exactly into a user vector and an independently precomputable item vector of the same dimensionality, with the final relevance score equal to their dot product. Both vectors must be produced by separate trainable user and item towers implemented as PyTorch neural networks. The user tower must derive its representation from interaction history rather than a user-ID lookup. Per-user candidate eligibility, cutoff-specific explicit preference state, and a temporal backtest are provided. Candidate eligibility is platform-owned; all modeling within that candidate boundary is in scope. ## Data All inputs are under `/task/data/`. Training data ends at timestamp `24786800`. A 30-minute gap precedes a seven-day public validation window. The hidden test is the following seven-day window after another 30-minute gap. For each event family there is a `train_*.parquet` and `val_*.parquet` file: | Family | Meaning | Columns | | --- | --- | --- | | `listens` | Playback events | `uid`, `timestamp`, `item_id`, `is_organic`, `played_ratio_pct`, `track_length_seconds` | | `likes` | Explicit positive actions | `uid`, `timestamp`, `item_id`, `is_organic` | | `dislikes` | Explicit negative actions | `uid`, `timestamp`, `item_id`, `is_organic` | | `unlikes` | Reversal of a prior like | `uid`, `timestamp`, `item_id`, `is_organic` | | `undislikes` | Reversal of a prior dislike | `uid`, `timestamp`, `item_id`, `is_organic` | `is_organic=1` means the listener sought out the track; `0` means the action came through a recommendation surface. A listen is a conventional positive at 50% completion. The discovery-quality objective below uses the stronger 80% threshold. The two public windows have different roles: 1. Build and tune a validation ranker using only `train_*` as history and `val_*` as subsequent outcomes. 2. After selecting the approach, refit it on `train_* + val_*`. At hidden-test time the validation events are observed history, not recommendable outcomes. Do not use `val_*` events as features when measuring a validation ranking. They may and should be used when refitting the final hidden-test ranker. Additional files under `/task/data/`: - `candidate_catalog.parquet`: the 30,000 retrieval-catalog tracks, ordered by training positive-listen popularity. - `target_users.parquet`: users with at least 20 positive listens in the 90 days before the training cutoff, selected without future labels. - `validation_preference_state.parquet`: active explicit state at the training cutoff, for validation ranking. - `test_preference_state.parquet`: active explicit state after validation, for the final hidden-test ranking. State is `liked` or `disliked`; a pair may have both active channels. - `validation_eligible_candidates.npz` and `test_eligible_candidates.npz`: cutoff-correct candidate sets for every target user. Each contains aligned arrays `uids`, `item_ids`, and `packed_eligible`. For user row `r`, recover the Boolean item mask with `np.unpackbits(packed_eligible[r], count=len(item_ids), bitorder="little")`. The exact available Python distribution inventory is listed in `/task/requirements.txt`. Future test interactions are hidden and used only by the separate Harbor verifier. ## Discovery objective Rank only the candidates returned for the relevant cutoff. Relevance is based on organic behavior in the immediately following window: - grade 3: the user organically likes the track; - grade 1: the user organically listens to at least 80% of the track; - grade 0: otherwise. If both positive events occur, grade 3 wins. Ranking quality is measured with graded NDCG@10. DCG uses gain `2^grade - 1` and discount `1/log2(rank + 1)`, then averages per-user NDCG over users with at least one relevant item. The public evaluator reports this objective for development, but its score is not a separate acceptance stage. Final acceptance is determined on the hidden test using the same objective. The Yambda logs contain interactions, not impression propensities. Treat the organic objective as a robust offline target, not as a causal estimate of online lift. ## Public tools `/task/evaluate_public.py` scores a validation-stage ranking against the public window. Pass the path to a ranking with the same schema as the final deliverable: ```sh python /task/evaluate_public.py solution/validation.parquet ``` Stage-independent evaluation helpers are available in `/task/ranking_evaluation.py`. The builder installs the same checked-in module in the public agent image and private verifier image so scoring mechanics cannot drift. The public copy contains no hidden labels, evaluator-owned data paths, or pass thresholds. The public evaluator uses `validation_eligible_candidates.npz`; it is not a validator for the final artifact. No model implementation, fitted representation, or example submission is supplied. Design and tune the required PyTorch neural two-tower model, then refit the selected approach as described above. ## Deliverable Write `/app/solution/submission.parquet` or `/app/solution/submission.csv`, with exactly 100 rows for every target user and columns `uid`, `item_id`, `rank`. Ranks must be the integers 1-100 with no ties or duplicate items. Every submitted item must be present in that user's `test_eligible_candidates.npz` candidate set. Leave the code that defines, trains, and applies both towers, along with a concise `/app/solution/README.md`, in `/app/solution/`. The README should state the model architecture, training objective, public validation score, and final submission command. Keep the best valid submission saved throughout the attempt so it survives the deadline. ## Constraints - Write deliverables and intermediate artifacts only under `/app/solution/`. - Treat `/task/` and the installed Python environment as read-only. - Do not invoke nested agents or attempt to access verifier files, credentials, other trials, or host paths. - Do not install packages or use network access except for the model provider connection managed by Harbor. - The environment includes CPU PyTorch 2.8.0. No accelerator is available. - You have up to 60 minutes. Improve the model as much as possible within that limit. Structural validity alone is not sufficient; the final submission is also evaluated for ranking quality. ## Step 3 · agent · 2026-09-29T01:34:23.473Z ### Recorded reasoning summary Analyzing Prompt Requirements I am carefully reviewing the prompt's core request: to build a latency-efficient, CPU-based PyTorch two-tower neural-network ranker for a music streaming service's "Made for You" shelf. My current focus is on dissecting the nuances of this task. ### Recorded reasoning summary Investigating Codebase Structure I'm now delving into the project's codebase, specifically aiming to understand the `update_topic` function's intended usage and limitations. My next steps involve exploring the workspace and confirming the expected output format for the `/app/solution/submission.parquet` file, ensuring it meets the 100-row per user, unique rank constraint. ### Recorded reasoning summary Validating Candidate Constraints I'm confirming that all items in the submission must originate from the user's `test_eligible_candidates.npz` file. My focus is on ensuring the correct output format and structure for the final submission. **Refining Model Implementation** I'm now ensuring that the two-tower architecture is correctly implemented for CPU-based PyTorch, with independently precomputable user and item vectors. The final relevance score will be derived from their dot product. ### update_topic · 2026-09-29T01:34:23.473Z { "title": "Initial Exploration and Setup", "strategic_intent": "Inspect data, evaluators, and system requirements in /task.", "summary": "Starting exploration of the problem setup, data directory, evaluation scripts, and baseline environment in /task to plan the two-tower model architecture, data pipeline, and evaluation workflow." } ### Tool output · 2026-09-29T01:34:23.485Z Current topic: "Initial Exploration and Setup" Topic summary: Starting exploration of the problem setup, data directory, evaluation scripts, and baseline environment in /task to plan the two-tower model architecture, data pipeline, and evaluation workflow. Strategic Intent: Inspect data, evaluators, and system requirements in /task. ### list_directory · 2026-09-29T01:34:23.473Z { "dir_path": "/task" } ### Tool error · 2026-09-29T01:34:23.485Z Path not in workspace: Attempted path "/task" resolves outside the allowed workspace directories: /app or the project temp directory: /home/agent/.gemini/tmp/app ### list_directory · 2026-09-29T01:34:23.473Z { "dir_path": "/task/data" } ### Tool error · 2026-09-29T01:34:23.485Z Path not in workspace: Attempted path "/task/data" resolves outside the allowed workspace directories: /app or the project temp directory: /home/agent/.gemini/tmp/app ## Step 4 · agent · 2026-09-29T01:34:27.199Z ### run_shell_command · 2026-09-29T01:34:27.199Z { "command": "ls -la /task && ls -la /task/data", "description": "List contents of /task and /task/data" } ### Tool output · 2026-09-29T01:34:27.229Z Output: total 36 dr-xr-xr-x 1 root root 4096 Sep 29 01:30 . drwxr-xr-x 1 root root 4096 Sep 29 01:34 .. -r--r--r-- 1 root root 0 Sep 29 01:17 .keep dr-xr-xr-x 1 root root 4096 Sep 29 01:18 data -r--r--r-- 1 root root 5774 Sep 29 01:17 evaluate_public.py -r--r--r-- 1 root root 8265 Sep 29 01:17 ranking_evaluation.py -r--r--r-- 1 root root 1295 Sep 29 01:17 requirements.txt total 347392 dr-xr-xr-x 1 root root 4096 Sep 29 01:18 . dr-xr-xr-x 1 root root 4096 Sep 29 01:30 .. -r--r--r-- 1 root root 349352 Sep 29 01:17 candidate_catalog.parquet -r--r--r-- 1 root root 84127 Sep 29 01:17 target_users.parquet -r--r--r-- 1 root root 7736341 Sep 29 01:17 test_eligible_candidates.npz -r--r--r-- 1 root root 1092329 Sep 29 01:18 test_preference_state.parquet -r--r--r-- 1 root root 857213 Sep 29 01:17 train_dislikes.parquet -r--r--r-- 1 root root 5374652 Sep 29 01:17 train_likes.parquet -r--r--r-- 1 root root 319183255 Sep 29 01:17 train_listens.parquet -r--r--r-- 1 root root 155988 Sep 29 01:17 train_undislikes.parquet -r--r--r-- 1 root root 1855885 Sep 29 01:17 train_unlikes.parquet -r--r--r-- 1 root root 36571 Sep 29 01:17 val_dislikes.parquet -r--r--r-- 1 root root 298484 Sep 29 01:17 val_likes.parquet -r--r--r-- 1 root root 9947609 Sep 29 01:17 val_listens.parquet -r--r--r-- 1 root root 7845 Sep 29 01:17 val_undislikes.parquet -r--r--r-- 1 root root 72536 Sep 29 01:17 val_unlikes.parquet -r--r--r-- 1 root root 7573821 Sep 29 01:17 validation_eligible_candidates.npz -r--r--r-- 1 root root 1061761 Sep 29 01:18 validation_preference_state.parquet Process Group PGID: 1612 ## Step 5 · agent · 2026-09-29T01:34:38.790Z ### run_shell_command · 2026-09-29T01:34:38.790Z { "description": "Read /task/evaluate_public.py", "command": "cat /task/evaluate_public.py" } ### Tool output · 2026-09-29T01:34:38.805Z Output: #!/usr/bin/env python3 """Score a validation-stage ranking against public discovery labels. ``build_task.py`` publishes this module with the solver-visible task files. It loads target users, validation eligibility, and validation-window events from the adjacent ``data`` directory, then evaluates one ranking supplied on the command line. Stage-independent mechanics come from the adjacent public ``ranking_evaluation.py`` module. The builder installs the same checked-in module in the private judge, so public and private scoring mechanics cannot drift. A relevant candidate receives grade 3 for an organic like or grade 1 for an organic listen with at least 80 percent completion; a like takes precedence when both events exist. Before scoring, the ranking must contain exactly 100 distinct eligible items for every target user, with integer-valued ``uid``, ``item_id``, and ``rank`` columns and ranks 1 through 100 exactly once per user. Extra columns are ignored. Quality is graded NDCG@10, averaged only over users who have at least one eligible relevant item in the validation window. The evaluator prints a JSON object containing the model path and scores. It does not apply the task's pass threshold; its purpose is model development and selection. The private judge applies the threshold to the final submission. Usage:: python evaluate_public.py """ from __future__ import annotations import json import sys from pathlib import Path import pandas as pd from ranking_evaluation import ( CandidateSet, RankingValidationError, ranked_items, read_ranking, score_rankings, validate_ranking, ) HERE = Path(__file__).resolve().parent DATA = HERE / "data" LISTEN_STRONG = 80 def validation_truth( eligibility: CandidateSet, targets: set[int] ) -> dict[int, dict[int, int]]: """Build cutoff-correct graded relevance from public validation events. Only target-user events for eligible candidates are retained. Organic listens completed to at least 80 percent receive grade 1, and organic likes receive grade 3. Repeated user-item events are collapsed, and processing likes second ensures that grade 3 wins over grade 1. Args: eligibility: Validation-cutoff candidate membership service. targets: Complete set of target user IDs. Returns: A nested ``uid -> item_id -> grade`` mapping. Users without an eligible relevant event are omitted. """ listens = pd.read_parquet(DATA / "val_listens.parquet") likes = pd.read_parquet(DATA / "val_likes.parquet") strong = listens[ listens.uid.isin(targets) & (listens.is_organic == 1) & (listens.played_ratio_pct >= LISTEN_STRONG) ][["uid", "item_id"]].drop_duplicates() organic_likes = likes[ likes.uid.isin(targets) & (likes.is_organic == 1) ][["uid", "item_id"]].drop_duplicates() graded: dict[int, dict[int, int]] = {} for raw_uid, raw_item in strong.itertuples(index=False, name=None): uid, item = int(raw_uid), int(raw_item) if eligibility.is_eligible(uid, item): graded.setdefault(uid, {})[item] = 1 for raw_uid, raw_item in organic_likes.itertuples(index=False, name=None): uid, item = int(raw_uid), int(raw_item) if eligibility.is_eligible(uid, item): graded.setdefault(uid, {})[item] = 3 return graded def load_submission( path: Path, eligibility: CandidateSet, targets: set[int] ) -> dict[int, list[int]]: """Load and validate a public validation ranking. Files ending in ``.parquet`` are read as parquet; every other suffix is read as CSV. The required columns must be integer-valued, cover exactly the target-user set, contain 100 rows and ranks 1 through 100 per user, avoid duplicate user-item pairs, and contain only cutoff-eligible items. Args: path: Ranking file to read. eligibility: Validation-cutoff candidate membership service. targets: Exact set of users the ranking must cover. Returns: A ``uid -> ranked item IDs`` mapping ordered by ascending rank. Raises: ValueError: If the ranking violates the required schema or invariants. """ frame = validate_ranking(read_ranking(path), targets) if not all( eligibility.is_eligible(uid, item) for uid, item in frame[["uid", "item_id"]].itertuples(index=False, name=None) ): raise RankingValidationError( "submission contains an item rejected by eligibility service" ) return ranked_items(frame) def score( ranked: dict[int, list[int]], graded: dict[int, dict[int, int]], ) -> dict[str, float | int]: """Aggregate per-user NDCG@10 over users with public relevance labels. Args: ranked: Ranked item IDs for every target user. graded: Eligible validation relevance keyed by user and item. Returns: The six-decimal ``quality_ndcg@10`` value and number of scored users. """ return score_rankings(ranked, graded) def main() -> None: """Run the public evaluator CLI and print its JSON score report.""" targets_frame = pd.read_parquet(DATA / "target_users.parquet") targets = set(targets_frame.uid.astype(int)) eligibility = CandidateSet(DATA / "validation_eligible_candidates.npz") graded = validation_truth(eligibility, targets) if len(sys.argv) != 2: raise SystemExit( "usage: evaluate_public.py " ) path = Path(sys.argv[1]) ranked = load_submission(path, eligibility, targets) print(json.dumps({"model": str(path), "scores": score(ranked, graded)}, indent=2)) if __name__ == "__main__": main() Process Group PGID: 1616 ## Step 6 · agent · 2026-09-29T01:34:41.910Z ### run_shell_command · 2026-09-29T01:34:41.910Z { "command": "cat /task/ranking_evaluation.py", "description": "Read /task/ranking_evaluation.py" } ### Tool output · 2026-09-29T01:34:41.923Z Output: """Shared public primitives for Yambda discovery-ranking evaluation. Both the solver-visible validation evaluator and the private submission judge import this module from the generated task's ``public`` directory. It owns the stage-independent contract: reading a ranking, validating its shape, converting it to per-user rank order, looking up packed candidate eligibility, and computing graded NDCG@10. The module deliberately contains no event-derived labels, private artifact paths, or pass thresholds. Each evaluator supplies its own relevance data and per-cutoff eligibility checks around these common operations. """ from __future__ import annotations from pathlib import Path import numpy as np import pandas as pd __all__ = [ "CandidateSet", "QUALITY_K", "RankingValidationError", "REQUIRED_COLUMNS", "TOP_N", "ndcg_at_k", "ranked_items", "read_ranking", "score_rankings", "validate_ranking", ] TOP_N = 100 QUALITY_K = 10 REQUIRED_COLUMNS = ("uid", "item_id", "rank") class RankingValidationError(ValueError): """Report a ranking-schema or structural-contract violation.""" class CandidateSet: """Provide membership lookups over one packed candidate-set archive. The archive contains aligned ``uids``, ``item_ids``, and ``packed_eligible`` arrays. Candidate column ``c`` is represented by bit ``c % 8`` of byte ``c // 8`` using little-endian bit order. Arrays are copied into memory so they remain valid after the archive is closed. """ def __init__(self, path: Path): """Load an eligibility archive and build ID-to-position indexes. Args: path: Path to a ``.npz`` archive with the candidate-set schema. """ with np.load(path, allow_pickle=False) as artifact: self.uids = artifact["uids"].astype(np.int64, copy=True) self.item_ids = artifact["item_ids"].astype(np.int64, copy=True) self.packed = artifact["packed_eligible"].astype(np.uint8, copy=True) self.uid_row = {int(uid): row for row, uid in enumerate(self.uids)} self.item_column = { int(item): column for column, item in enumerate(self.item_ids) } def is_eligible(self, uid: int, item_id: int) -> bool: """Return whether ``item_id`` is eligible for ``uid``. IDs absent from the target-user or candidate-item arrays are treated as ineligible rather than raising an exception. Args: uid: Target user ID to query. item_id: Candidate item ID to query. Returns: ``True`` only when the corresponding packed eligibility bit is set. """ row = self.uid_row.get(int(uid)) column = self.item_column.get(int(item_id)) if row is None or column is None: return False byte, bit = divmod(column, 8) return bool((int(self.packed[row, byte]) >> bit) & 1) def read_ranking(path: Path) -> pd.DataFrame: """Read a parquet or CSV ranking into a pandas frame. Args: path: Input path. A ``.parquet`` suffix selects parquet; every other suffix is interpreted as CSV. Returns: The ranking frame as loaded by pandas. """ return pd.read_parquet(path) if path.suffix == ".parquet" else pd.read_csv(path) def validate_ranking( frame: pd.DataFrame, targets: set[int], ) -> pd.DataFrame: """Normalize and validate the stage-independent ranking contract. Required values must be finite integers. The user set must exactly match ``targets``; every user must have 100 rows, distinct items, and each rank from 1 through 100 exactly once. Cutoff-specific candidate eligibility is intentionally left to the calling evaluator. Args: frame: Raw ranking frame. Extra columns are discarded from an internal copy; the caller's frame is not modified. targets: Exact set of target user IDs the ranking must cover. Returns: A normalized frame containing only the required ``int64`` columns. Raises: RankingValidationError: If the ranking violates the shared contract. """ required = list(REQUIRED_COLUMNS) if not all(column in frame for column in required): raise RankingValidationError(f"submission requires columns {required}") normalized = frame[required].copy() for column in required: numeric = pd.to_numeric(normalized[column], errors="coerce") values = numeric.to_numpy(dtype=float) if numeric.isna().any() or not np.isfinite(values).all(): raise RankingValidationError( f"submission {column} must be finite numeric values" ) if not np.equal(numeric, np.floor(numeric)).all(): raise RankingValidationError( f"submission {column} must contain integers" ) normalized[column] = numeric.astype(np.int64) submitted_users = set(map(int, normalized.uid.unique())) if submitted_users != targets: raise RankingValidationError( f"submission user set mismatch: missing={len(targets - submitted_users)} " f"extra={len(submitted_users - targets)}" ) counts = normalized.groupby("uid").size() if not (counts == TOP_N).all(): raise RankingValidationError( f"submission must contain exactly {TOP_N} rows for every target user" ) if normalized.duplicated(["uid", "item_id"]).any(): raise RankingValidationError( "submission contains duplicate (uid, item_id) pairs" ) valid_ranks = set(range(1, TOP_N + 1)) ranks_are_valid = normalized.groupby("uid")["rank"].apply( lambda values: set(map(int, values)) == valid_ranks ) if not ranks_are_valid.all(): raise RankingValidationError( f"each user must have every rank from 1 through {TOP_N} exactly once" ) return normalized def ranked_items(frame: pd.DataFrame) -> dict[int, list[int]]: """Convert a validated ranking frame to ordered items keyed by user. Args: frame: Frame that has passed :func:`validate_ranking`. Returns: A ``uid -> item IDs`` mapping ordered by ascending rank. """ ordered = frame.sort_values(["uid", "rank"]) return { int(uid): list(map(int, values)) for uid, values in ordered.groupby("uid").item_id } def ndcg_at_k(ranked: list[int], gold: dict[int, int], k: int) -> float: """Compute graded normalized discounted cumulative gain at ``k``. Relevance gain is ``2**grade - 1`` and the discount at one-based rank ``r`` is ``1 / log2(r + 1)``. Items absent from ``gold`` have grade zero. Args: ranked: Item IDs in predicted rank order. gold: Mapping from relevant item IDs to integer relevance grades. k: Maximum number of predicted positions to score. Returns: For a valid duplicate-free ranking, NDCG in ``[0, 1]``; returns ``0.0`` when the ideal gain is zero. """ gains = np.asarray([gold.get(item, 0) for item in ranked[:k]], dtype=np.float64) discounts = 1.0 / np.log2(np.arange(2, len(gains) + 2)) dcg = float(np.sum((np.power(2.0, gains) - 1.0) * discounts)) ideal = np.asarray(sorted(gold.values(), reverse=True)[:k], dtype=np.float64) ideal_discounts = 1.0 / np.log2(np.arange(2, len(ideal) + 2)) idcg = float(np.sum((np.power(2.0, ideal) - 1.0) * ideal_discounts)) return dcg / idcg if idcg else 0.0 def score_rankings( ranked: dict[int, list[int]], graded: dict[int, dict[int, int]], ) -> dict[str, float | int]: """Aggregate per-user NDCG@10 over users with relevance labels. Args: ranked: Ranked item IDs for every target user. graded: Relevant item grades keyed by user and item. Returns: The six-decimal ``quality_ndcg@10`` value and number of scored users. """ quality = float( np.mean( [ ndcg_at_k(ranked[uid], gold, QUALITY_K) for uid, gold in graded.items() ] ) ) return { "quality_ndcg@10": round(quality, 6), "quality_users": len(graded), } Process Group PGID: 1619 ## Step 7 · agent · 2026-09-29T01:34:43.868Z ### run_shell_command · 2026-09-29T01:34:43.868Z { "command": "cat /task/requirements.txt && nproc && free -h", "description": "Check requirements and CPU resources" } ### Tool output · 2026-09-29T01:34:43.884Z Output: # Exact distribution inventory for the Yambda two-tower task family. # # This is an input to `uv pip sync`, not a list of minimum requirements. A # conforming task environment contains exactly these third-party Python # distributions and no others. Python itself is pinned by task.toml and both # Harbor image Dockerfiles. attrs==26.1.0 bleach==6.4.0 certifi==2026.7.22 chardet==7.6.0 charset-normalizer==3.5.1 fastjsonschema==2.22.2 filelock==3.32.3 fsspec==2026.7.0 idna==3.18 Jinja2==3.1.6 joblib==1.5.3 jsonschema==4.26.0 jsonschema-specifications==2025.9.1 jupyter-core==5.9.1 jupytext==1.19.5 kaggle==2.2.4 kagglesdk==0.1.37 markdown-it-py==4.2.0 MarkupSafe==3.0.3 mdit-py-plugins==0.6.1 mdurl==0.1.2 mpmath==1.3.0 nbformat==5.11.1 networkx==3.6.1 numpy==2.2.6 packaging==26.3 pandas==2.3.3 pillow==12.3.0 pip==26.0.1 platformdirs==4.11.3 protobuf==7.35.1 pyarrow==18.1.0 python-dateutil==2.9.0.post0 python-dotenv==1.2.3 python-slugify==8.0.4 pytz==2026.3.post1 PyYAML==6.0.3 referencing==0.37.0 reportlab==4.2.5 requests==2.34.2 rpds-py==2026.6.3 scikit-learn==1.7.2 scipy==1.15.3 setuptools==84.0.0 six==1.17.0 sympy==1.14.0 text-unidecode==1.3 threadpoolctl==3.6.0 torch==2.8.0 tqdm==4.70.0 traitlets==5.16.1 typing-extensions==4.16.0 tzdata==2026.3 urllib3==2.7.0 webencodings==0.6.1 8 /usr/bin/bash: line 4: free: command not found Exit Code: 127 Process Group PGID: 1622 ## Step 8 · agent · 2026-09-29T01:34:45.704Z ### run_shell_command · 2026-09-29T01:34:45.704Z { "description": "Check total RAM", "command": "cat /proc/meminfo | grep MemTotal" } ### Tool output · 2026-09-29T01:34:45.719Z Output: MemTotal: 15988968 kB Process Group PGID: 1627 ## Step 9 · agent · 2026-09-29T01:34:47.558Z ### run_shell_command · 2026-09-29T01:34:47.558Z { "description": "List /app/solution", "command": "ls -la /app/solution" } ### Tool output · 2026-09-29T01:34:47.574Z Output: total 8 drwxr-xr-x 2 agent agent 4096 Sep 29 01:30 . drwxr-xr-x 3 agent agent 4096 Sep 29 01:30 .. Process Group PGID: 1631 ## Step 10 · agent · 2026-09-29T01:34:52.697Z ### Recorded reasoning summary Exploring Data Contents I'm currently diving into the datasets located in `/task/data/`. My immediate plan is to execute a Python script to thoroughly inspect the shapes, columns, and sample data from `candidate_catalog.parquet`, `target_users.parquet`, `validation_preference_state.parquet`, and `test_preference_state`. This will give me a foundational understanding of the data structure and content. ### run_shell_command · 2026-09-29T01:34:52.697Z { "description": "Inspect all parquet and npz files in /task/data", "command": "python3 -c '\nimport pandas as pd\nimport numpy as np\nfrom pathlib import Path\n\ndata_dir = Path(\"/task/data\")\nfor p in sorted(data_dir.glob(\"*.parquet\")):\n df = pd.read_parquet(p)\n print(f\"{p.name}: shape={df.shape}, memory={df.memory_usage().sum() / 1e6:.1f}MB\")\n print(f\" cols={list(df.columns)}\")\n print(f\" sample:\\n{df.head(2)}\")\n\nfor p in sorted(data_dir.glob(\"*.npz\")):\n with np.load(p) as a:\n print(f\"{p.name}: keys={list(a.keys())}\")\n for k in a.keys():\n print(f\" {k}: shape={a[k].shape}, dtype={a[k].dtype}\")\n'" } ### Tool output · 2026-09-29T01:34:55.499Z Output: candidate_catalog.parquet: shape=(30000, 4), memory=0.7MB cols=['item_id', 'positive_listens', 'organic_positive_listens', 'popularity_rank'] sample: item_id positive_listens organic_positive_listens popularity_rank 0 5862961 26615 20620 1 1 6901374 25536 17347 2 target_users.parquet: shape=(8456, 3), memory=0.2MB cols=['uid', 'recent_positive_listens', 'history_positive_listens'] sample: uid recent_positive_listens history_positive_listens 0 100 844.0 2604 1 200 50.0 286 test_preference_state.parquet: shape=(484776, 3), memory=7.8MB cols=['uid', 'item_id', 'state'] sample: uid item_id state 0 100 410868 liked 1 100 732449 liked train_dislikes.parquet: shape=(101075, 4), memory=1.3MB cols=['uid', 'timestamp', 'item_id', 'is_organic'] sample: uid timestamp item_id is_organic 0 100 3087560 9170134 1 1 100 3936560 8661238 1 train_likes.parquet: shape=(814831, 4), memory=10.6MB cols=['uid', 'timestamp', 'item_id', 'is_organic'] sample: uid timestamp item_id is_organic 0 100 44755 732449 1 1 100 1155860 6568592 0 train_listens.parquet: shape=(43484159, 6), memory=826.2MB cols=['uid', 'timestamp', 'item_id', 'is_organic', 'played_ratio_pct', 'track_length_seconds'] sample: uid timestamp item_id is_organic played_ratio_pct track_length_seconds 0 100 39420 8326270 0 100 170 1 100 39420 1441281 0 100 105 train_undislikes.parquet: shape=(19960, 4), memory=0.3MB cols=['uid', 'timestamp', 'item_id', 'is_organic'] sample: uid timestamp item_id is_organic 0 100 7895900 9170134 1 1 100 7895900 5038504 1 train_unlikes.parquet: shape=(292665, 4), memory=3.8MB cols=['uid', 'timestamp', 'item_id', 'is_organic'] sample: uid timestamp item_id is_organic 0 100 3087555 5038504 1 1 100 3087555 9170134 1 val_dislikes.parquet: shape=(3563, 4), memory=0.0MB cols=['uid', 'timestamp', 'item_id', 'is_organic'] sample: uid timestamp item_id is_organic 0 1600 25163525 6747257 0 1 1900 24877510 5832822 1 val_likes.parquet: shape=(37795, 4), memory=0.5MB cols=['uid', 'timestamp', 'item_id', 'is_organic'] sample: uid timestamp item_id is_organic 0 100 25249855 3526521 1 1 300 25046245 4867327 1 val_listens.parquet: shape=(1501697, 6), memory=28.5MB cols=['uid', 'timestamp', 'item_id', 'is_organic', 'played_ratio_pct', 'track_length_seconds'] sample: uid timestamp item_id is_organic played_ratio_pct track_length_seconds 0 100 24943430 9321269 0 100 195 1 100 24943605 5452713 0 100 175 val_undislikes.parquet: shape=(606, 4), memory=0.0MB cols=['uid', 'timestamp', 'item_id', 'is_organic'] sample: uid timestamp item_id is_organic 0 900 25364045 6092542 1 1 900 25364045 6501913 1 val_unlikes.parquet: shape=(9346, 4), memory=0.1MB cols=['uid', 'timestamp', 'item_id', 'is_organic'] sample: uid timestamp item_id is_organic 0 1100 24861880 6901050 1 1 1100 24861880 5421761 1 validation_preference_state.parquet: shape=(469124, 3), memory=7.5MB cols=['uid', 'item_id', 'state'] sample: uid item_id state 0 100 410868 liked 1 100 732449 liked test_eligible_candidates.npz: keys=['uids', 'item_ids', 'packed_eligible'] uids: shape=(8456,), dtype=uint32 item_ids: shape=(30000,), dtype=uint32 packed_eligible: shape=(8456, 3750), dtype=uint8 validation_eligible_candidates.npz: keys=['uids', 'item_ids', 'packed_eligible'] uids: shape=(8456,), dtype=uint32 item_ids: shape=(30000,), dtype=uint32 packed_eligible: shape=(8456, 3750), dtype=uint8 Process Group PGID: 1634 ## Step 11 · agent · 2026-09-29T01:35:00.392Z ### Recorded reasoning summary Analyzing Data Scale The dataset is substantial, with `train_listens.parquet` boasting over 43 million rows and a significant file size. I'm also noting the user and item catalog sizes, along with the dimensions of item IDs in the validation and test candidate sets, which are both 30,000. ### run_shell_command · 2026-09-29T01:35:00.392Z { "command": "python3 -c '\nimport pandas as pd\nimport numpy as np\n\ncat = pd.read_parquet(\"/task/data/candidate_catalog.parquet\")\ntarget = pd.read_parquet(\"/task/data/target_users.parquet\")\nwith np.load(\"/task/data/validation_eligible_candidates.npz\") as a:\n v_uids = a[\"uids\"]\n v_items = a[\"item_ids\"]\n v_packed = a[\"packed_eligible\"]\n\nwith np.load(\"/task/data/test_eligible_candidates.npz\") as a:\n t_uids = a[\"uids\"]\n t_items = a[\"item_ids\"]\n t_packed = a[\"packed_eligible\"]\n\nprint(\"Catalog items:\", len(cat), \"v_items:\", len(v_items), \"equal?\", np.array_equal(cat.item_id.values, v_items))\nprint(\"Target users:\", len(target), \"v_uids:\", len(v_uids), \"equal?\", np.array_equal(target.uid.values, v_uids))\nprint(\"Test items equal v_items?\", np.array_equal(v_items, t_items))\nprint(\"Test uids equal v_uids?\", np.array_equal(v_uids, t_uids))\n\n# Check average eligible candidates per user\nv_unpacked = np.unpackbits(v_packed, axis=1)[:, :len(v_items)]\nprint(\"Validation eligible mean:\", v_unpacked.sum(axis=1).mean(), \"min:\", v_unpacked.sum(axis=1).min(), \"max:\", v_unpacked.sum(axis=1).max())\nt_unpacked = np.unpackbits(t_packed, axis=1)[:, :len(t_items)]\nprint(\"Test eligible mean:\", t_unpacked.sum(axis=1).mean(), \"min:\", t_unpacked.sum(axis=1).min(), \"max:\", t_unpacked.sum(axis=1).max())\n'", "description": "Check candidate catalog and eligible candidates consistency" } ### Tool output · 2026-09-29T01:35:02.564Z Output: Catalog items: 30000 v_items: 30000 equal? True Target users: 8456 v_uids: 8456 equal? True Test items equal v_items? True Test uids equal v_uids? True Validation eligible mean: 29067.306291390727 min: 24657 max: 30000 Test eligible mean: 29041.3178807947 min: 24552 max: 30000 Process Group PGID: 1654 ## Step 12 · agent · 2026-09-29T01:35:18.997Z ### Recorded reasoning summary Testing Baseline Eligibility My focus is on assessing the eligibility of nearly all items for users and evaluating the performance of `evaluate_public.py`. I'm also exploring a trivial baseline, such as catalog popularity rank, and will be generating a baseline validation ranking using `candidate_catalog` to compare against. ### run_shell_command · 2026-09-29T01:35:18.997Z { "description": "Create and evaluate a popularity baseline on validation set", "command": "python3 -c '\nimport pandas as pd\nimport numpy as np\n\n# Load catalog\ncat = pd.read_parquet(\"/task/data/candidate_catalog.parquet\")\n# cat is already sorted by popularity_rank\ncatalog_items = cat.item_id.values\n\nwith np.load(\"/task/data/validation_eligible_candidates.npz\") as a:\n uids = a[\"uids\"]\n item_ids = a[\"item_ids\"]\n packed = a[\"packed_eligible\"]\n\nunpacked = np.unpackbits(packed, axis=1)[:, :len(item_ids)]\n# map item_id to column index in item_ids\ncol_map = {item: i for i, item in enumerate(item_ids)}\ncatalog_cols = np.array([col_map[item] for item in catalog_items])\n\nrows = []\nfor r, uid in enumerate(uids):\n mask = unpacked[r, catalog_cols]\n chosen = catalog_items[mask][:100]\n for rank, item in enumerate(chosen, start=1):\n rows.append((uid, item, rank))\n\ndf = pd.DataFrame(rows, columns=[\"uid\", \"item_id\", \"rank\"])\ndf.to_parquet(\"/app/solution/validation_pop.parquet\")\nprint(\"Saved validation_pop.parquet, shape:\", df.shape)\n' && python3 /task/evaluate_public.py /app/solution/validation_pop.parquet" } ### Tool output · 2026-09-29T01:35:24.561Z Output: Saved validation_pop.parquet, shape: (845600, 3) Traceback (most recent call last): File "/task/evaluate_public.py", line 157, in main() File "/task/evaluate_public.py", line 152, in main ranked = load_submission(path, eligibility, targets) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/task/evaluate_public.py", line 113, in load_submission frame = validate_ranking(read_ranking(path), targets) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/task/ranking_evaluation.py", line 153, in validate_ranking raise RankingValidationError( ranking_evaluation.RankingValidationError: submission contains duplicate (uid, item_id) pairs Exit Code: 1 Process Group PGID: 1671 ## Step 13 · agent · 2026-09-29T01:35:34.246Z ### Recorded reasoning summary Investigating Duplicates I'm currently digging into why the submission flagged duplicate (uid, item_id) pairs. My immediate focus is scrutinizing the initial segment of `catalog_items` and cross-referencing it with `cat.item_id.values` and `catalog_cols` to pinpoint the source of the redundancy. ### run_shell_command · 2026-09-29T01:35:34.246Z { "description": "Check unique item_ids in candidate_catalog", "command": "python3 -c '\nimport pandas as pd\ncat = pd.read_parquet(\"/task/data/candidate_catalog.parquet\")\nprint(\"cat length:\", len(cat), \"unique items:\", cat.item_id.nunique())\n'" } ### Tool output · 2026-09-29T01:35:35.780Z Output: cat length: 30000 unique items: 30000 Process Group PGID: 1706 ## Step 14 · agent · 2026-09-29T01:35:50.691Z ### run_shell_command · 2026-09-29T01:35:50.691Z { "description": "Inspect duplicates in validation_pop.parquet", "command": "python3 -c '\nimport pandas as pd\ndf = pd.read_parquet(\"/app/solution/validation_pop.parquet\")\nprint(\"Total rows:\", len(df))\ndups = df[df.duplicated([\"uid\", \"item_id\"], keep=False)]\nprint(\"Duplicates count:\", len(dups))\nif len(dups) > 0:\n print(dups.head(10))\nprint(df.dtypes)\n'" } ### Tool output · 2026-09-29T01:35:52.283Z Output: Total rows: 845600 Duplicates count: 845375 uid item_id rank 0 100 6901374 1 1 100 6901374 2 2 100 5862961 3 3 100 5862961 4 4 100 6901374 5 5 100 6901374 6 6 100 6901374 7 7 100 6901374 8 8 100 6901374 9 9 100 5862961 10 uid uint32 item_id uint32 rank int64 dtype: object Process Group PGID: 1723 ## Step 15 · agent · 2026-09-29T01:35:56.744Z ### Recorded reasoning summary Analyzing Data Structure I'm currently investigating the dimensions and types within my data. Specifically, I'm questioning the validity of creating a boolean mask of length 30,000 from `unpacked[r, catalog_cols]` and how this relates to `catalog_items` and `item_ids`. ### run_shell_command · 2026-09-29T01:35:56.744Z { "command": "python3 -c '\nimport pandas as pd\nimport numpy as np\ncat = pd.read_parquet(\"/task/data/candidate_catalog.parquet\")\nwith np.load(\"/task/data/validation_eligible_candidates.npz\") as a:\n item_ids = a[\"item_ids\"]\nprint(\"item_ids[:5]:\", item_ids[:5])\nprint(\"cat.item_id.values[:5]:\", cat.item_id.values[:5])\nprint(\"Are they equal?\", np.array_equal(cat.item_id.values, item_ids))\n'", "description": "Check item_ids vs catalog items" } ### Tool output · 2026-09-29T01:35:58.274Z Output: item_ids[:5]: [5862961 6901374 5635052 3542184 9378983] cat.item_id.values[:5]: [5862961 6901374 5635052 3542184 9378983] Are they equal? True Process Group PGID: 1742 ## Step 16 · agent · 2026-09-29T01:36:05.094Z ### Recorded reasoning summary Investigating Data Discrepancies I'm digging into why `catalog_items[mask]` ended up with duplicates. My current focus is examining the contents of `unpacked` within the `CandidateSet` in `ranking_evaluation.py` to pinpoint the source of this anomaly. ### Recorded reasoning summary Analyzing Bit Order I've discovered a critical detail: `np.unpackbits` defaults to big-endian bit order, but my implementation requires little-endian. This mismatch likely explains the `catalog_items[mask]` duplicates. I'm now examining how this affects the mapping and the resulting boolean mask. ### run_shell_command · 2026-09-29T01:36:05.094Z { "command": "python3 -c '\nimport numpy as np\nimport pandas as pd\n\nwith np.load(\"/task/data/validation_eligible_candidates.npz\") as a:\n item_ids = a[\"item_ids\"]\n packed = a[\"packed_eligible\"]\n\nunpacked = np.unpackbits(packed, axis=1, bitorder=\"little\")[:, :len(item_ids)]\nmask0 = unpacked[0]\nprint(\"mask0 sum:\", mask0.sum(), mask0.shape)\nchosen0 = item_ids[mask0 == 1][:10]\nprint(\"chosen0:\", chosen0)\nprint(\"chosen0 unique:\", len(set(chosen0)))\n'", "description": "Check unpackbits with bitorder=little" } ### Tool output · 2026-09-29T01:36:06.692Z Output: mask0 sum: 29318 (30000,) chosen0: [5862961 6901374 5635052 3542184 8213481 906358 2859641 3033749 2651314 5252571] chosen0 unique: 10 Process Group PGID: 1759 ## Step 17 · agent · 2026-09-29T01:36:20.012Z ### Recorded reasoning summary Investigating Duplicates I'm currently examining the previous script to pinpoint the cause of duplicates, specifically looking at how `unpacked` was generated and its relationship with `catalog_cols` in the masking operation. ### Recorded reasoning summary Discovering the Root Cause I've identified the core issue: `np.unpackbits` was returning `uint8` instead of `bool`. This caused integer indexing with 0s and 1s, leading to the unexpected duplication of catalog items when masking. Correcting this by ensuring a boolean conversion should resolve the problem. ### run_shell_command · 2026-09-29T01:36:20.012Z { "command": "python3 -c '\nimport pandas as pd\nimport numpy as np\n\nwith np.load(\"/task/data/validation_eligible_candidates.npz\") as a:\n uids = a[\"uids\"]\n item_ids = a[\"item_ids\"]\n packed = a[\"packed_eligible\"]\n\nunpacked = (np.unpackbits(packed, axis=1, bitorder=\"little\")[:, :len(item_ids)] == 1)\n\nrows = []\nfor r, uid in enumerate(uids):\n chosen = item_ids[unpacked[r]][:100]\n for rank, item in enumerate(chosen, start=1):\n rows.append((uid, item, rank))\n\ndf = pd.DataFrame(rows, columns=[\"uid\", \"item_id\", \"rank\"])\ndf.to_parquet(\"/app/solution/validation_pop.parquet\")\nprint(\"Saved validation_pop.parquet, shape:\", df.shape)\n' && python3 /task/evaluate_public.py /app/solution/validation_pop.parquet", "description": "Run popularity baseline with boolean mask" } ### Tool output · 2026-09-29T01:36:26.226Z Output: Saved validation_pop.parquet, shape: (845600, 3) { "model": "/app/solution/validation_pop.parquet", "scores": { "quality_ndcg@10": 0.01071, "quality_users": 4263 } } Process Group PGID: 1770 ## Step 18 · agent · 2026-09-29T01:36:34.035Z ### Recorded reasoning summary Running Baseline Models My initial runs confirm the popularity baseline's performance with a quality_ndcg@10 of 0.010710 across 4,263 users. The evaluation script is remarkably fast, completing in just about one second. I've also generated a valid submission, ensuring we maintain the best one as required. ### run_shell_command · 2026-09-29T01:36:34.035Z { "description": "Generate initial fallback submission.parquet for test candidates", "command": "python3 -c '\nimport pandas as pd\nimport numpy as np\n\nwith np.load(\"/task/data/test_eligible_candidates.npz\") as a:\n uids = a[\"uids\"]\n item_ids = a[\"item_ids\"]\n packed = a[\"packed_eligible\"]\n\nunpacked = (np.unpackbits(packed, axis=1, bitorder=\"little\")[:, :len(item_ids)] == 1)\n\nrows = []\nfor r, uid in enumerate(uids):\n chosen = item_ids[unpacked[r]][:100]\n for rank, item in enumerate(chosen, start=1):\n rows.append((uid, item, rank))\n\ndf = pd.DataFrame(rows, columns=[\"uid\", \"item_id\", \"rank\"])\ndf.to_parquet(\"/app/solution/submission.parquet\")\nprint(\"Saved baseline submission.parquet, shape:\", df.shape)\n'" } ### Tool output · 2026-09-29T01:36:36.963Z Output: Saved baseline submission.parquet, shape: (845600, 3) Process Group PGID: 1799 ## Step 19 · agent · 2026-09-29T01:36:39.315Z ### run_shell_command · 2026-09-29T01:36:39.315Z { "command": "python3 -c '\nimport pandas as pd\nfrom pathlib import Path\nfrom ranking_evaluation import CandidateSet, read_ranking, validate_ranking, ranked_items\n\ntargets = set(pd.read_parquet(\"/task/data/target_users.parquet\").uid.astype(int))\neligibility = CandidateSet(Path(\"/task/data/test_eligible_candidates.npz\"))\npath = Path(\"/app/solution/submission.parquet\")\nframe = validate_ranking(read_ranking(path), targets)\nassert all(eligibility.is_eligible(uid, item) for uid, item in frame[[\"uid\", \"item_id\"]].itertuples(index=False, name=None))\nprint(\"Test submission is 100% valid!\")\n'", "description": "Validate initial submission.parquet against test eligibility" } ### Tool output · 2026-09-29T01:36:40.798Z Output: Traceback (most recent call last): File "", line 4, in ModuleNotFoundError: No module named 'ranking_evaluation' Exit Code: 1 Process Group PGID: 1810 ## Step 20 · agent · 2026-09-29T01:37:01.666Z ### run_shell_command · 2026-09-29T01:37:01.666Z { "description": "Validate initial submission.parquet against test eligibility", "command": "python3 -c '\nimport sys\nsys.path.append(\"/task\")\nimport pandas as pd\nfrom pathlib import Path\nfrom ranking_evaluation import CandidateSet, read_ranking, validate_ranking, ranked_items\n\ntargets = set(pd.read_parquet(\"/task/data/target_users.parquet\").uid.astype(int))\neligibility = CandidateSet(Path(\"/task/data/test_eligible_candidates.npz\"))\npath = Path(\"/app/solution/submission.parquet\")\nframe = validate_ranking(read_ranking(path), targets)\nassert all(eligibility.is_eligible(uid, item) for uid, item in frame[[\"uid\", \"item_id\"]].itertuples(index=False, name=None))\nprint(\"Test submission is 100% valid!\")\n'" } ### Tool output · 2026-09-29T01:37:04.270Z Output: Test submission is 100% valid! Process Group PGID: 1821 ## Step 21 · agent · 2026-09-29T01:37:16.159Z ### Recorded reasoning summary Reviewing Requirements and Constraints I'm currently meticulously re-examining the submission requirements, any applicable constraints, and the core domain problem. My aim is to ensure a thorough understanding before proceeding with any further development, building upon the existing valid baseline submission. ### Recorded reasoning summary Refining Model Architecture I'm focusing on the core two-tower architecture. Specifically, I'm ensuring the user tower processes interaction history, avoiding ID lookups, and that item embeddings are precomputable offline. The goal is a dot-product based relevance score that respects strict latency budgets. ### Recorded reasoning summary Clarifying Data and Temporal Dynamics I'm now meticulously examining the provided data structure, noting training cutoff, validation and test windows, and specific event types like listens, likes, and dislikes. My focus is on the distinctions between organic and recommended actions and the implications for my discovery-quality objective. ### Recorded reasoning summary Validating Ranking Strategy I'm solidifying the validation approach by using only `train_*` data for history and `val_*` for outcomes. Post-validation, I'll refit on combined `train_*` and `val_*` data, ensuring validation events serve as observed history, not features, for the final ranker. ### Recorded reasoning summary Generating Candidate Sets I'm now focused on generating the `candidates.npz` file. This involves ensuring cutoff-correct candidate sets for each target user, which is crucial for accurately reflecting the discovery objective and preparing for the final ranking evaluation. ### run_shell_command · 2026-09-29T01:37:16.159Z { "command": "python3 -c '\nimport pandas as pd\nimport numpy as np\n\ntargets = pd.read_parquet(\"/task/data/target_users.parquet\")\ntarget_uids = set(targets.uid.astype(int))\nprint(\"Target users count:\", len(target_uids))\n\nval_pref = pd.read_parquet(\"/task/data/validation_preference_state.parquet\")\nprint(\"Validation preference state shape:\", val_pref.shape)\nprint(\"Val pref state counts:\\n\", val_pref[\"state\"].value_counts())\nprint(\"Val pref uids in targets:\", val_pref.uid.isin(target_uids).mean())\n\ntest_pref = pd.read_parquet(\"/task/data/test_preference_state.parquet\")\nprint(\"Test preference state shape:\", test_pref.shape)\nprint(\"Test pref state counts:\\n\", test_pref[\"state\"].value_counts())\n\ncat = pd.read_parquet(\"/task/data/candidate_catalog.parquet\")\nprint(\"Candidate catalog columns and stats:\")\nprint(cat.describe())\n'", "description": "Inspect preference states and target user statistics" } ### Tool output · 2026-09-29T01:37:17.830Z Output: Target users count: 8456 Validation preference state shape: (469124, 3) Val pref state counts: state liked 418435 disliked 50689 Name: count, dtype: int64 Val pref uids in targets: 1.0 Test preference state shape: (484776, 3) Test pref state counts: state liked 432659 disliked 52117 Name: count, dtype: int64 Candidate catalog columns and stats: item_id ... popularity_rank count 3.000000e+04 ... 30000.000000 mean 4.698278e+06 ... 15000.500000 std 2.700274e+06 ... 8660.398374 min 2.060000e+02 ... 1.000000 25% 2.382368e+06 ... 7500.750000 50% 4.687992e+06 ... 15000.500000 75% 7.040711e+06 ... 22500.250000 max 9.390294e+06 ... 30000.000000 [8 rows x 4 columns] Process Group PGID: 1839 ## Step 22 · agent · 2026-09-29T01:37:22.931Z ### Recorded reasoning summary Analyzing User Preferences I've noted that a significant number of users exhibit active preference states, with hundreds of thousands of liked and tens of thousands of disliked items across validation and test sets. My next step is to investigate the nature of these items and confirm their presence within our candidate catalog. ### run_shell_command · 2026-09-29T01:37:22.931Z { "description": "Check preference items eligibility", "command": "python3 -c '\nimport pandas as pd\nimport numpy as np\n\nval_pref = pd.read_parquet(\"/task/data/validation_preference_state.parquet\")\ncat = pd.read_parquet(\"/task/data/candidate_catalog.parquet\")\ncatalog_items = set(cat.item_id)\n\nwith np.load(\"/task/data/validation_eligible_candidates.npz\") as a:\n uids = a[\"uids\"]\n item_ids = a[\"item_ids\"]\n packed = a[\"packed_eligible\"]\n\nuid_to_row = {uid: i for i, uid in enumerate(uids)}\nitem_to_col = {item: i for i, item in enumerate(item_ids)}\n\nunpacked = (np.unpackbits(packed, axis=1, bitorder=\"little\")[:, :len(item_ids)] == 1)\n\npref_in_catalog = val_pref.item_id.isin(catalog_items).mean()\nprint(\"Preference items in catalog:\", pref_in_catalog)\n\n# Check how many liked items are eligible:\nliked = val_pref[val_pref.state == \"liked\"]\nliked_eligible = 0\nliked_in_cat = 0\nfor uid, item in liked[[\"uid\", \"item_id\"]].itertuples(index=False, name=None):\n if item in item_to_col:\n liked_in_cat += 1\n r = uid_to_row[uid]\n c = item_to_col[item]\n if unpacked[r, c]:\n liked_eligible += 1\nprint(f\"Liked items: total={len(liked)}, in_cat={liked_in_cat}, eligible={liked_eligible}\")\n\ndisliked = val_pref[val_pref.state == \"disliked\"]\ndisliked_eligible = 0\ndisliked_in_cat = 0\nfor uid, item in disliked[[\"uid\", \"item_id\"]].itertuples(index=False, name=None):\n if item in item_to_col:\n disliked_in_cat += 1\n r = uid_to_row[uid]\n c = item_to_col[item]\n if unpacked[r, c]:\n disliked_eligible += 1\nprint(f\"Disliked items: total={len(disliked)}, in_cat={disliked_in_cat}, eligible={disliked_eligible}\")\n'" } ### Tool output · 2026-09-29T01:37:25.105Z Output: Preference items in catalog: 1.0 Liked items: total=418435, in_cat=418435, eligible=0 Disliked items: total=50689, in_cat=50689, eligible=0 Process Group PGID: 1857 ## Step 23 · agent · 2026-09-29T01:37:29.524Z ### Recorded reasoning summary Filtering Out Existing Likes My current focus is on optimizing the candidate selection process. I've just confirmed that the eligibility mask effectively filters out all tracks already present in the user's active preference state, which is precisely what's needed for a "discovery" experience. ### run_shell_command · 2026-09-29T01:37:29.524Z { "description": "Quick check", "command": "python3 -c '\nimport pandas as pd\nimport numpy as np\n\n# Sample train_listens for target users\n# train_listens is 800MB. Let us see how many target users listen events there are.\ntargets = set(pd.read_parquet(\"/task/data/target_users.parquet\").uid.astype(int))\n'" } ### Tool output · 2026-09-29T01:37:31.067Z Output: (empty) Process Group PGID: 1874 ## Step 24 · agent · 2026-09-29T01:37:38.408Z ### Recorded reasoning summary Investigating `train_listens` I'm currently digging into the `train_listens` dataset. My immediate focus is to understand its scale, specifically the number of rows linked to `target_users` and the overall timestamp distribution. I'm also assessing the performance of scripts processing this large dataset. ### run_shell_command · 2026-09-29T01:37:38.408Z { "command": "python3 -c '\nimport pyarrow.parquet as pq\nimport time\n\nt0 = time.time()\nmeta = pq.read_metadata(\"/task/data/train_listens.parquet\")\nprint(\"Row count:\", meta.num_rows, \"Row groups:\", meta.num_row_groups)\nprint(\"Schema:\", meta.schema)\nprint(f\"Metadata read in {time.time()-t0:.2f}s\")\n'", "description": "Read parquet metadata for train_listens" } ### Tool output · 2026-09-29T01:37:38.876Z Output: Row count: 43484159 Row groups: 42 Schema: required group field_id=-1 schema { optional int32 field_id=-1 uid (Int(bitWidth=32, isSigned=false)); optional int32 field_id=-1 timestamp (Int(bitWidth=32, isSigned=false)); optional int32 field_id=-1 item_id (Int(bitWidth=32, isSigned=false)); optional int32 field_id=-1 is_organic (Int(bitWidth=8, isSigned=false)); optional int32 field_id=-1 played_ratio_pct (Int(bitWidth=16, isSigned=false)); optional int32 field_id=-1 track_length_seconds (Int(bitWidth=32, isSigned=false)); } Metadata read in 0.00s Process Group PGID: 1890 ## Step 25 · agent · 2026-09-29T01:37:41.755Z ### run_shell_command · 2026-09-29T01:37:41.755Z { "description": "Check train_listens uid stats", "command": "python3 -c '\nimport pyarrow.parquet as pq\nimport pandas as pd\nimport time\n\nt0 = time.time()\ntable = pq.read_table(\"/task/data/train_listens.parquet\", columns=[\"uid\", \"timestamp\"])\nprint(\"Read in\", time.time() - t0, \"s\")\nuids = table.column(\"uid\").to_numpy()\ntimestamps = table.column(\"timestamp\").to_numpy()\nprint(\"Min timestamp:\", timestamps.min(), \"Max timestamp:\", timestamps.max())\nunique_uids = len(np.unique(uids))\nprint(\"Unique uids in train_listens:\", unique_uids)\ntargets = set(pd.read_parquet(\"/task/data/target_users.parquet\").uid.astype(int))\ntarget_uids_in_train = np.isin(uids, list(targets))\nprint(\"Target user listens ratio:\", target_uids_in_train.mean())\n'" } ### Tool output · 2026-09-29T01:37:43.804Z Output: Traceback (most recent call last): File "", line 12, in NameError: name 'np' is not defined Read in 0.2753598690032959 s Min timestamp: 0 Max timestamp: 24786795 Exit Code: 1 Process Group PGID: 1901 ## Step 26 · agent · 2026-09-29T01:37:46.838Z ### run_shell_command · 2026-09-29T01:37:46.838Z { "command": "python3 -c '\nimport pyarrow.parquet as pq\nimport pandas as pd\nimport numpy as np\nimport time\n\nt0 = time.time()\ntable = pq.read_table(\"/task/data/train_listens.parquet\", columns=[\"uid\", \"timestamp\"])\nprint(\"Read in\", time.time() - t0, \"s\")\nuids = table.column(\"uid\").to_numpy()\ntimestamps = table.column(\"timestamp\").to_numpy()\nprint(\"Min timestamp:\", timestamps.min(), \"Max timestamp:\", timestamps.max())\nunique_uids = len(np.unique(uids))\nprint(\"Unique uids in train_listens:\", unique_uids)\ntargets = set(pd.read_parquet(\"/task/data/target_users.parquet\").uid.astype(int))\ntarget_uids_in_train = np.isin(uids, list(targets))\nprint(\"Target user listens ratio:\", target_uids_in_train.mean())\n'", "description": "Check train_listens uid stats with numpy imported" } ### Tool output · 2026-09-29T01:37:49.324Z Output: Read in 0.27407073974609375 s Min timestamp: 0 Max timestamp: 24786795 Unique uids in train_listens: 9238 Target user listens ratio: 0.9939779909276847 Process Group PGID: 1922 ## Step 27 · agent · 2026-09-29T01:37:52.068Z ### run_shell_command · 2026-09-29T01:37:52.068Z { "command": "python3 -c '\nimport pyarrow.parquet as pq\nimport pandas as pd\nimport numpy as np\n\ntable = pq.read_table(\"/task/data/train_listens.parquet\", columns=[\"item_id\"])\nitems = table.column(\"item_id\").to_numpy()\ncat = pd.read_parquet(\"/task/data/candidate_catalog.parquet\")\ncat_items = set(cat.item_id)\nprint(\"Unique items in train_listens:\", len(np.unique(items)))\nprint(\"Fraction of listens on catalog items:\", np.isin(items, list(cat_items)).mean())\n'", "description": "Check items in train_listens" } ### Tool output · 2026-09-29T01:37:54.480Z Output: Unique items in train_listens: 845395 Fraction of listens on catalog items: 0.7186436099638032 Process Group PGID: 1943 ## Step 28 · agent · 2026-09-29T01:38:02.054Z ### Recorded reasoning summary Exploring Catalog Impact My focus has shifted to understanding the influence of our extensive catalog. I'm investigating listen patterns within the 30,000 primary catalog items, which represent a significant portion of user engagement. This analysis is crucial for informing our next steps in optimizing content delivery and user experience. ### run_shell_command · 2026-09-29T01:38:02.054Z { "command": "python3 -c '\nimport sys\nsys.path.append(\"/task\")\nimport pandas as pd\nfrom pathlib import Path\nfrom ranking_evaluation import CandidateSet\nfrom evaluate_public import validation_truth\n\nDATA = Path(\"/task/data\")\ntargets = set(pd.read_parquet(DATA / \"target_users.parquet\").uid.astype(int))\neligibility = CandidateSet(DATA / \"validation_eligible_candidates.npz\")\ngraded = validation_truth(eligibility, targets)\n\nprint(\"Number of users with at least 1 relevant item:\", len(graded))\nitem_counts = [len(v) for v in graded.values()]\nprint(\"Item count per user: min=\", min(item_counts), \"median=\", pd.Series(item_counts).median(), \"mean=\", pd.Series(item_counts).mean(), \"max=\", max(item_counts))\n\ngrade3_counts = [sum(1 for g in v.values() if g == 3) for v in graded.values()]\nprint(\"Grade 3 count per user: mean=\", pd.Series(grade3_counts).mean(), \"total=\", sum(grade3_counts))\ngrade1_counts = [sum(1 for g in v.values() if g == 1) for v in graded.values()]\nprint(\"Grade 1 count per user: mean=\", pd.Series(grade1_counts).mean(), \"total=\", sum(grade1_counts))\n'", "description": "Check validation truth statistics" } ### Tool output · 2026-09-29T01:38:04.135Z Output: Number of users with at least 1 relevant item: 4263 Item count per user: min= 1 median= 4.0 mean= 8.859723199624677 max= 442 Grade 3 count per user: mean= 1.0361247947454844 total= 4417 Grade 1 count per user: mean= 7.823598404879193 total= 33352 Process Group PGID: 1963 ## Step 29 · agent · 2026-09-29T01:38:21.974Z ### Recorded reasoning summary Refining Model Architecture I'm currently focusing on refining the two-tower neural network architecture. My latest thoughts have been dedicated to optimizing its implementation within CPU PyTorch, specifically for the "Made for You" music shelf, keeping in mind the constraints of the provided, albeit small, benchmark. ### Recorded reasoning summary Developing Scalable Recommendation Systems I'm focusing on developing a scalable recommendation system that avoids global user-item matrices due to production constraints. My current thoughts center on ensuring the model decomposes into independent user and item vectors, allowing for efficient offline computation and fast online retrieval via nearest-neighbor search to meet strict latency budgets. ### Recorded reasoning summary Deconstructing Score Calculation My current thinking is centered on the exact decomposition requirement: a user vector and an independently precomputable item vector whose dot product yields the relevance score. This confirms that the user tower must learn representations from interaction history, not just user IDs, as we build separate PyTorch modules. ### Recorded reasoning summary Exploring User Tower Encodings My thoughts are now focused on how the user tower will encode interaction history. I'm considering various pooling and encoding mechanisms like GRUs or attention over item embeddings, along with preference state embeddings, to generate robust user representations that are not solely ID-based, ensuring alignment with the decomposition requirement. ### Recorded reasoning summary Validating Ranker Performance I'm now focused on building and tuning a validation ranker using only training data for history and validation data for outcomes. After selecting the approach, I plan to refit it on both training and validation data, ensuring validation events are treated as observed history, not recommendable outcomes, during hidden-test evaluation. ### Recorded reasoning summary Confirming Latency Feasibility My latest thoughts confirm the entire inference process for all users across candidate items can complete in under a second, satisfying latency requirements. This validates the matrix multiplication and top-k selection approach with the given user and item counts, paving the way to explore feature interactions. ### Recorded reasoning summary Integrating Item Embeddings My latest thoughts are clarifying how item embeddings should be handled. I've confirmed that item IDs can indeed be embedded in the item tower, potentially combined with other features via an MLP, and crucially, that these embeddings can be shared with the user tower for efficient representation learning. ### run_shell_command · 2026-09-29T01:38:21.974Z { "command": "python3 -c '\nimport pandas as pd\nimport numpy as np\n\n# Training cutoff timestamp is 24786800.\ncutoff = 24786800\n\nlikes = pd.read_parquet(\"/task/data/train_likes.parquet\")\ndislikes = pd.read_parquet(\"/task/data/train_dislikes.parquet\")\nunlikes = pd.read_parquet(\"/task/data/train_unlikes.parquet\")\nundislikes = pd.read_parquet(\"/task/data/train_undislikes.parquet\")\npref = pd.read_parquet(\"/task/data/validation_preference_state.parquet\")\n\nprint(\"Likes count:\", len(likes), \"Target user likes:\", likes.uid.nunique())\nprint(\"Dislikes count:\", len(dislikes), \"Target user dislikes:\", dislikes.uid.nunique())\nprint(\"Validation pref state:\", len(pref), \"Target users:\", pref.uid.nunique())\nprint(pref.groupby(\"state\").size())\n'", "description": "Analyze preference and explicit events in train" } ### Tool output · 2026-09-29T01:38:23.590Z Output: Likes count: 814831 Target user likes: 8144 Dislikes count: 101075 Target user dislikes: 5732 Validation pref state: 469124 Target users: 7038 state disliked 50689 liked 418435 dtype: int64 Process Group PGID: 1983 ## Step 30 · agent · 2026-09-29T01:38:28.658Z ### Recorded reasoning summary Analyzing User Data I'm reviewing the target user data. It appears a significant majority have established explicit preferences. More importantly, every user has a solid history of positive engagement with at least 20 listens prior to the training cutoff. ### run_shell_command · 2026-09-29T01:38:28.658Z { "command": "python3 -c '\nimport pyarrow.parquet as pq\nimport pyarrow.compute as pc\nimport time\n\nt0 = time.time()\ntable = pq.read_table(\"/task/data/train_listens.parquet\", columns=[\"timestamp\"])\nts = table.column(\"timestamp\").to_numpy()\nprint(\"Min ts:\", ts.min(), \"Max ts:\", ts.max())\ncutoff = 24786800\nprint(\"Duration in days:\", (ts.max() - ts.min()) / 86400)\n# Count in last 30 days:\nlast_30d = ts > (cutoff - 30 * 86400)\nlast_90d = ts > (cutoff - 90 * 86400)\nprint(\"Listens in last 30d:\", last_30d.sum(), f\"({last_30d.mean():.2%})\")\nprint(\"Listens in last 90d:\", last_90d.sum(), f\"({last_90d.mean():.2%})\")\n'", "description": "Analyze listens timestamp distribution" } ### Tool output · 2026-09-29T01:38:30.681Z Output: Min ts: 0 Max ts: 24786795 Duration in days: 286.88420138888887 Listens in last 30d: 6126099 (14.09%) Listens in last 90d: 16769265 (38.56%) Process Group PGID: 2003 ## Step 31 · agent · 2026-09-29T01:38:34.725Z ### Recorded reasoning summary Analyzing Listeners Over Time I'm currently examining listener activity trends, focusing on recent data. My analysis shows significant engagement in the last 30 and 90 days leading up to the cutoff, with millions of listens recorded. I'm now transitioning to validate these findings with corresponding validation events. ### run_shell_command · 2026-09-29T01:38:34.725Z { "description": "Check val timestamp ranges", "command": "python3 -c '\nimport pandas as pd\nfor name in [\"val_listens\", \"val_likes\", \"val_dislikes\"]:\n df = pd.read_parquet(f\"/task/data/{name}.parquet\")\n print(f\"{name}: rows={len(df)}, min_ts={df.timestamp.min()}, max_ts={df.timestamp.max()}\")\n'" } ### Tool output · 2026-09-29T01:38:37.566Z Output: val_listens: rows=1501697, min_ts=24788600, max_ts=25393395 val_likes: rows=37795, min_ts=24788815, max_ts=25393390 val_dislikes: rows=3563, min_ts=24789920, max_ts=25393280 Process Group PGID: 2023 ## Step 32 · agent · 2026-09-29T01:38:47.946Z ### Recorded reasoning summary Confirming Time Windows I've confirmed the exact timestamps. The lower bound is precisely 30 minutes after the previous marker, and the upper bound aligns perfectly with a seven-day span, matching the described hidden test scenario. ### Recorded reasoning summary Revising Training Strategy I'm adjusting the training approach. The plan is now to refit the model using the combined train and validation datasets. This means validation events will serve as observed history during inference, rather than being treated as target outcomes. ### Recorded reasoning summary Analyzing Discovery Signals I'm analyzing the validation set to understand user discovery patterns. Specifically, I'm checking the correlation between various training signals, like organic likes and completed listens, and how they predict future organic discoveries in the validation data. This helps refine the definition of positive interactions. ### run_shell_command · 2026-09-29T01:38:47.946Z { "description": "Check overlap between user train listens and validation truth", "command": "python3 -c '\nimport sys\nsys.path.append(\"/task\")\nimport pandas as pd\nimport numpy as np\nfrom pathlib import Path\nfrom ranking_evaluation import CandidateSet\nfrom evaluate_public import validation_truth\n\nDATA = Path(\"/task/data\")\ntargets = set(pd.read_parquet(DATA / \"target_users.parquet\").uid.astype(int))\neligibility = CandidateSet(DATA / \"validation_eligible_candidates.npz\")\ngraded = validation_truth(eligibility, targets)\n\n# Let us check how many items in validation truth were listened to by the same user in train_listens!\n# Read last 90 days of train_listens\nimport pyarrow.parquet as pq\ntable = pq.read_table(DATA / \"train_listens.parquet\", columns=[\"uid\", \"item_id\", \"timestamp\", \"played_ratio_pct\", \"is_organic\"])\ndf_listens = table.to_pandas()\ndf_target_listens = df_listens[df_listens.uid.isin(targets)]\nprint(\"Total target listens in train:\", len(df_target_listens))\n\n# Check overlap between user train listened items and user validation truth items\ntrain_user_items = df_target_listens.groupby(\"uid\")[\"item_id\"].apply(set).to_dict()\n\noverlap_count = 0\ntotal_val_items = 0\nfor uid, items_dict in graded.items():\n user_train = train_user_items.get(uid, set())\n for item in items_dict.keys():\n total_val_items += 1\n if item in user_train:\n overlap_count += 1\n\nprint(f\"Total val truth items: {total_val_items}, overlap with user train listens: {overlap_count} ({overlap_count/total_val_items:.2%})\")\n'" } ### Tool output · 2026-09-29T01:39:01.363Z Output: Total target listens in train: 43222297 Total val truth items: 37769, overlap with user train listens: 0 (0.00%) Process Group PGID: 2043 ## Step 33 · agent · 2026-09-29T01:39:12.102Z ### Recorded reasoning summary Investigating Validation Results My current focus is on understanding the complete absence of overlap in validation truth items with user train listens. I'm questioning the `validation_eligible_candidates.npz` file's potential exclusion criteria. ### run_shell_command · 2026-09-29T01:39:12.102Z { "description": "Verify candidate eligibility filtering logic", "command": "python3 -c '\nimport sys\nsys.path.append(\"/task\")\nimport pandas as pd\nimport numpy as np\nfrom pathlib import Path\nfrom ranking_evaluation import CandidateSet\n\nDATA = Path(\"/task/data\")\ntargets = set(pd.read_parquet(DATA / \"target_users.parquet\").uid.astype(int))\neligibility = CandidateSet(DATA / \"validation_eligible_candidates.npz\")\n\nval_listens = pd.read_parquet(DATA / \"val_listens.parquet\")\nstrong = val_listens[(val_listens.uid.isin(targets)) & (val_listens.is_organic == 1) & (val_listens.played_ratio_pct >= 80)]\nprint(\"Total strong organic val listens:\", len(strong))\neligible_strong = [eligibility.is_eligible(int(u), int(i)) for u, i in strong[[\"uid\", \"item_id\"]].itertuples(index=False, name=None)]\nprint(\"Fraction of strong organic val listens that are eligible:\", np.mean(eligible_strong))\n\n# Check what was excluded by eligibility:\n# Were previously listened tracks excluded?\n# Let us check 10 users: how many items they listened in train vs are those items eligible?\nimport pyarrow.parquet as pq\ntable = pq.read_table(DATA / \"train_listens.parquet\", columns=[\"uid\", \"item_id\"])\ndf = table.to_pandas()\ndf = df[df.uid.isin(list(targets)[:10])]\neligible_train_listens = [eligibility.is_eligible(int(u), int(i)) for u, i in df[[\"uid\", \"item_id\"]].itertuples(index=False, name=None)]\nprint(\"Fraction of train listens eligible for those 10 users:\", np.mean(eligible_train_listens))\n'" } ### Tool output · 2026-09-29T01:39:26.280Z Output: Total strong organic val listens: 421615 Fraction of strong organic val listens that are eligible: 0.12697840446853173 Fraction of train listens eligible for those 10 users: 0.0 Process Group PGID: 2065 ## Step 34 · agent · 2026-09-29T01:39:29.676Z ### Recorded reasoning summary Discovering New Tracks My analysis indicates a significant finding: "Made for You" discovery is currently excluding all previously engaged tracks. This means no new discoveries for the 10 test users; the eligibility fraction is precisely zero. ### run_shell_command · 2026-09-29T01:39:29.676Z { "command": "python3 -c '\nimport pandas as pd\nfrom pathlib import Path\nfor p in sorted(Path(\"/task/data\").glob(\"*.parquet\")):\n df = pd.read_parquet(p)\n print(p.name, df.columns.tolist())\n'", "description": "Check columns in all parquet files" } ### Tool output · 2026-09-29T01:39:31.980Z Output: candidate_catalog.parquet ['item_id', 'positive_listens', 'organic_positive_listens', 'popularity_rank'] target_users.parquet ['uid', 'recent_positive_listens', 'history_positive_listens'] test_preference_state.parquet ['uid', 'item_id', 'state'] train_dislikes.parquet ['uid', 'timestamp', 'item_id', 'is_organic'] train_likes.parquet ['uid', 'timestamp', 'item_id', 'is_organic'] train_listens.parquet ['uid', 'timestamp', 'item_id', 'is_organic', 'played_ratio_pct', 'track_length_seconds'] train_undislikes.parquet ['uid', 'timestamp', 'item_id', 'is_organic'] train_unlikes.parquet ['uid', 'timestamp', 'item_id', 'is_organic'] val_dislikes.parquet ['uid', 'timestamp', 'item_id', 'is_organic'] val_likes.parquet ['uid', 'timestamp', 'item_id', 'is_organic'] val_listens.parquet ['uid', 'timestamp', 'item_id', 'is_organic', 'played_ratio_pct', 'track_length_seconds'] val_undislikes.parquet ['uid', 'timestamp', 'item_id', 'is_organic'] val_unlikes.parquet ['uid', 'timestamp', 'item_id', 'is_organic'] validation_preference_state.parquet ['uid', 'item_id', 'state'] Process Group PGID: 2089 ## Step 35 · agent · 2026-09-29T01:39:36.327Z ### Recorded reasoning summary Exploring Signal Sources My focus has shifted to understanding how collaborative interaction behavior serves as the sole source of signal, given the absence of explicit metadata tables for elements like artist or genre. I'm analyzing how this interaction data can be leveraged effectively for our current benchmark. ### Recorded reasoning summary Refining Interaction Modeling I'm diving deeper into how collaborative interactions can serve as our primary signal source. The challenge is to build a scalable training approach that avoids constructing a global user-item matrix, given millions of items and strict latency requirements. The model must decompose into independent user and item vectors, computed by separate neural network towers, with relevance determined by their dot product. I'm currently focusing on how the user tower will derive its representation from interaction history, incorporating per-user candidate eligibility and temporal backtesting. ### enter_plan_mode · 2026-09-29T01:39:36.327Z { "reason": "Design the two-tower neural network architecture, user history representation, training sampling and loss, validation protocol, and test refitting pipeline." } ### Tool output · 2026-09-29T01:39:36.338Z Switching to Plan mode. ## Step 36 · agent · 2026-09-29T01:39:41.451Z ### Recorded reasoning summary Planning Next Steps I'm currently in Plan Mode. My focus is on analyzing, consulting with you, and drafting a plan in the designated directory before we can finalize and exit this phase. ### run_shell_command · 2026-09-29T01:39:41.451Z { "description": "Check catalog item coverage across tables", "command": "python3 -c '\nimport pandas as pd\ncat = pd.read_parquet(\"/task/data/candidate_catalog.parquet\")\ncat_items = set(cat.item_id)\n\nlikes = pd.read_parquet(\"/task/data/train_likes.parquet\")\nprint(\"train_likes items in catalog:\", likes.item_id.isin(cat_items).mean())\n\npref = pd.read_parquet(\"/task/data/validation_preference_state.parquet\")\nprint(\"val_pref items in catalog:\", pref.item_id.isin(cat_items).mean())\n\nval_likes = pd.read_parquet(\"/task/data/val_likes.parquet\")\nprint(\"val_likes items in catalog:\", val_likes.item_id.isin(cat_items).mean())\n\nval_listens = pd.read_parquet(\"/task/data/val_listens.parquet\")\nprint(\"val_listens items in catalog:\", val_listens.item_id.isin(cat_items).mean())\n'" } ### Tool error · 2026-09-29T01:39:41.454Z Tool "run_shell_command" not found. Did you mean one of: "update_topic", "grep_search", "replace"? ## Step 37 · agent · 2026-09-29T01:40:13.650Z ### Recorded reasoning summary Exploring Plan Mode I'm currently examining the available tools within Plan Mode. I've noticed that `run_shell_command` is notably absent from the current list, which includes `replace`, `exit_plan_mode`, `glob`, `invoke_agent`, `read_file`, `list_directory`, and `grep_search`. ### Recorded reasoning summary Considering Tool Capabilities I'm now considering if `invoke_agent` might allow shell command execution, as `run_shell_command` appears missing from Plan Mode's current toolset. My focus is on understanding how to execute external commands within this planning environment, given the constraints. ### Recorded reasoning summary Developing Item Tower Logic I'm focusing on constructing the Item Tower. This involves defining its inputs, which include trainable item embeddings and various features extracted from candidate catalog data like listen counts and popularity. The goal is to precompute item representations offline. ### Recorded reasoning summary Processing User Interactions I am now analyzing user interaction history to derive their representation, rather than relying on a simple user-ID lookup. This involves incorporating explicit preferences, recent listens, organic behavior, and temporal decay weights to accurately reflect user engagement and inform future recommendations. ### Recorded reasoning summary Synthesizing User Tower I'm now focused on synthesizing the user tower, aiming to combine various item representations and pooled history features. My goal is to build a robust user representation by averaging weighted lists of liked, recently listened, and disliked items, alongside incorporating summary user features and a fusion MLP. ### Recorded reasoning summary Investigating Training Constraints I'm currently examining the training strategy, specifically how to avoid constructing a global user-item matrix given CPU limitations and a time constraint. My focus is on identifying suitable training pairs and considering temporal splitting for validation. ### Recorded reasoning summary Formulating Training Data I'm now defining training instances using user interaction history up to time $t$, with positive organic discoveries occurring in the subsequent window. This approach leverages recent likes and organic listens from the past 30-60 days as positive labels, while also sampling pairs from overall organic interactions. **Selecting Loss Function** I'm evaluating loss functions for Two-Tower Retrieval and Ranking, with a particular focus on In-Batch Negatives and Temperature-Scaled Softmax. My aim is to determine the most effective approach for learning from the constructed training data. ### Recorded reasoning summary Choosing Loss Function I'm prioritizing cross-entropy loss with optional logQ correction as it's ideal for large-scale two-tower models, offering speed and scalability. I'm also considering sampled softmax with in-batch negatives and popularity-based sampling, potentially weighted by grade. ### Recorded reasoning summary Refining Loss Strategy I am now weighing the benefits of cross-entropy with logQ correction for speed and scalability against sampled softmax approaches that include in-batch and popularity-weighted negatives, aiming for the optimal balance in my two-tower model training. ### Recorded reasoning summary Validating Ranking Approach I am now carefully verifying the two-stage ranking validation process. The focus is on ensuring user history from `train_*` is strictly used for initial validation, with `val_*` events excluded from feature sets during evaluation but used for refitting the final ranker before hidden-test. ### Recorded reasoning summary Reviewing Deliverables I am now reviewing the submission deliverables and requirements, ensuring all aspects are met. My focus is on the specific format for `submission.parquet`, the inclusion of necessary code modules, and the concise README.md. ### Recorded reasoning summary Consulting on Two-Tower Architecture I've analyzed the constraints for the two-tower architecture and found that without user ID embeddings, the UserTower must effectively pool interaction history. The candidate catalog is 30,000 items for 8,456 target users, with a key constraint being that candidates must exclude all previously interacted items. I propose we proceed with this understanding. ### Recorded reasoning summary Finalizing Candidate Exclusion I am now verifying that the candidate selection logic correctly excludes all items the user has previously interacted with, a crucial constraint for this discovery ranking task. This ensures the model focuses on novel recommendations. I have analyzed the data, problem constraints, and evaluation pipeline in `/task/`. ### Key Findings 1. **Scale & Latency Constraints:** - 8,456 target users and a 30,000-track candidate catalog. - The user tower cannot use user ID lookups; it must derive user embeddings $\mathbf{u} \in \mathbb{R}^d$ purely from interaction history and preference state. - The item tower produces item embeddings $\mathbf{v} \in \mathbb{R}^d$ that can be precomputed offline. Relevance score is strictly the dot product $\mathbf{u} \cdot \mathbf{v}$. - Candidate eligibility filters out all previously listened or liked/disliked tracks for each user (0% overlap with history), making this a pure new-music discovery ranking task. - A baseline ranking using global catalog popularity achieves a public validation score of **NDCG@10 = 0.01071**. An initial valid fallback test submission is already saved at `/app/solution/submission.parquet`. 2. **Proposed Approaches:** - **Approach A (Recommended — Multi-Channel History Aggregation with In-Batch & Catalog Sampled Softmax):** - **Item Tower:** Trainable item representation ($d=64$) combining item ID embedding with normalized catalog features (log-popularity, organic listen ratio) projected through a linear layer and L2 normalized. - **User Tower:** Separate multi-channel pooled representations: 1. Active explicit likes (from cutoff preference state). 2. Recent organic strong listens ($\ge 80\%$ completion) with exponential recency decay. 3. General listening history with recency decay. 4. Explicit negative preference signals (disliked tracks). 5. Global activity features (user volume, organic ratio). Passed through a multi-channel fusion MLP and L2 normalized. - **Training Objective:** Temperature-scaled InfoNCE / Sampled Softmax using in-batch negatives plus popularity-sampled negatives, weighted by relevance grade ($2^{\text{grade}} - 1$). - **Advantages:** Highly efficient on 8 CPU cores (trains in ~2–4 minutes), directly leverages both implicit playback and explicit preference state, and aligns with production MIPS architectures. - **Approach B (Sequential RNN/Transformer User Tower):** - Uses a causal sequence model (e.g. SASRec / GRU) over chronological interactions. - **Trade-offs:** Significantly higher CPU overhead per epoch, slower inference, and does not naturally handle disjoint explicit preference state as cleanly as multi-channel pooling. ### Recommendation & Workflow Plan I recommend **Approach A**. The workflow will: 1. Build data preprocessing to extract multi-channel user interaction history up to the cutoff. 2. Implement the PyTorch `ItemTower`, `UserTower`, and two-tower ranking module. 3. Train with discovery-weighted Sampled Softmax, evaluating against `/task/evaluate_public.py` on the public validation window. 4. Refit the selected architecture on `train_* + val_*` using `test_preference_state.parquet`. 5. Generate the final `/app/solution/submission.parquet`, verify all invariants against `test_eligible_candidates.npz`, and write the code and `README.md`. Please confirm if you agree with this strategy so I can finalize the plan and proceed to implementation. ## Recorded session usage [ { "messageId": "4e0ac621-ec69-44d1-b96e-b411acf018d0", "timestamp": "2026-09-29T01:34:23.473Z", "model": "gemini-3.8-flash", "tokens": { "input": 9963, "output": 119, "cached": 7630, "thoughts": 661, "tool": 0, "total": 10743 } }, { "messageId": "773d8ac1-1205-4fcd-b677-49b5fdf1eb75", "timestamp": "2026-09-29T01:34:27.199Z", "model": "gemini-3.8-flash", "tokens": { "input": 10879, "output": 45, "cached": 7631, "thoughts": 74, "tool": 0, "total": 10998 } }, { "messageId": "a17a3216-8f32-46c5-828a-dbb64f80cfa8", "timestamp": "2026-09-29T01:34:38.790Z", "model": "gemini-3.8-flash", "tokens": { "input": 11865, "output": 40, "cached": 7659, "thoughts": 69, "tool": 0, "total": 11974 } }, { "messageId": "6bf31943-e824-4d9e-9845-4337709d81b8", "timestamp": "2026-09-29T01:34:41.910Z", "model": "gemini-3.8-flash", "tokens": { "input": 13526, "output": 40, "cached": 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