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Basic recommender opus-high-01

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Agent
opus-5.0 · Claude Code · high effort
Recorded conversation
07:46 · 16 steps
Private reward
0.021172 · Failed
Attempt cost
$1.30
  • Thinking
  • Model text
  • Tool call
  • Tool response
01

Task instructions

+00:00
Task instructions

Build a music-discovery ranker

Build the strongest ranking model you can for the "Made for You" shelf of a music streaming service. 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:

FamilyMeaningColumns
listensPlayback eventsuid, timestamp, item_id, is_organic, played_ratio_pct, track_length_seconds
likesExplicit positive actionsuid, timestamp, item_id, is_organic
dislikesExplicit negative actionsuid, timestamp, item_id, is_organic
unlikesReversal of a prior likeuid, timestamp, item_id, is_organic
undislikesReversal of a prior dislikeuid, 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:

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, fitted representation, example submission, or modeling architecture is supplied. Build and tune the best model you can, 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 builds the artifact and a concise /app/solution/README.md in /app/solution/. 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.
  • You have up to 30 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.
Harness context deferred tools delta
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Harness context agent listing delta
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    "- general-purpose: General-purpose agent for researching complex questions, searching for code, and executing multi-step tasks. When you are searching for a keyword or file and are not confident that you will find the right match in the first few tries use this agent to perform the search for you. (Tools: *)",
    "- Plan: Software architect agent for designing implementation plans. Use this when you need to plan the implementation strategy for a task. Returns step-by-step plans, identifies critical files, and considers architectural trade-offs. (Tools: All tools except Agent, Artifact, ExitPlanMode, Edit, Write, NotebookEdit)",
    "- statusline-setup: Use this agent to configure the user's Claude Code status line setting. (Tools: Read, Edit)"
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  "removedTypes": [],
  "isInitial": true,
  "showConcurrencyNote": false
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Harness context skill listing
{
  "type": "skill_listing",
  "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. 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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. 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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- 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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Harness context total tokens reminder
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02

List task files and requirements

+00:01

Model text

I'll start by exploring the data and understanding the task setup.

Tool callBashList task files and requirements Returned

Tool call · Input

ls -la /task/ /task/data/ && cat /task/requirements.txt

Tool response

/task/:
total 36
dr-xr-xr-x 1 root root 4096 Sep 24 07:41 .
drwxr-xr-x 1 root root 4096 Sep 24 07:43 ..
dr-xr-xr-x 1 root root 4096 Sep 24 07:37 data
-r--r--r-- 1 root root 5774 Sep 24 07:37 evaluate_public.py
-r--r--r-- 1 root root 8265 Sep 24 07:37 ranking_evaluation.py
-r--r--r-- 1 root root 1278 Sep 24 07:37 requirements.txt

/task/data/:
total 347392
dr-xr-xr-x 1 root root      4096 Sep 24 07:37 .
dr-xr-xr-x 1 root root      4096 Sep 24 07:41 ..
-r--r--r-- 1 root root    349352 Sep 24 07:37 candidate_catalog.parquet
-r--r--r-- 1 root root     84127 Sep 24 07:37 target_users.parquet
-r--r--r-- 1 root root   7736341 Sep 24 07:37 test_eligible_candidates.npz
-r--r--r-- 1 root root   1092329 Sep 24 07:37 test_preference_state.parquet
-r--r--r-- 1 root root    857213 Sep 24 07:37 train_dislikes.parquet
-r--r--r-- 1 root root   5374652 Sep 24 07:37 train_likes.parquet
-r--r--r-- 1 root root 319183255 Sep 24 07:37 train_listens.parquet
-r--r--r-- 1 root root    155988 Sep 24 07:37 train_undislikes.parquet
-r--r--r-- 1 root root   1855885 Sep 24 07:37 train_unlikes.parquet
-r--r--r-- 1 root root     36571 Sep 24 07:37 val_dislikes.parquet
-r--r--r-- 1 root root    298484 Sep 24 07:37 val_likes.parquet
-r--r--r-- 1 root root   9947609 Sep 24 07:37 val_listens.parquet
-r--r--r-- 1 root root      7845 Sep 24 07:37 val_undislikes.parquet
-r--r--r-- 1 root root     72536 Sep 24 07:37 val_unlikes.parquet
-r--r--r-- 1 root root   7573821 Sep 24 07:37 validation_eligible_candidates.npz
-r--r--r-- 1 root root   1061761 Sep 24 07:37 validation_preference_state.parquet
# Exact third-party distribution inventory for yambda-discovery-ranking-v01.
#
# 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. The same inventory is used for source preparation,
# task building, reference scoring, judging, and solver attempts. 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
idna==3.18
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
mdit-py-plugins==0.6.1
mdurl==0.1.2
nbformat==5.11.1
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
six==1.17.0
text-unidecode==1.3
threadpoolctl==3.6.0
tqdm==4.70.0
traitlets==5.16.1
typing-extensions==4.16.0
tzdata==2026.3
urllib3==2.7.0
webencodings==0.6.1
Tool callBashRead evaluation code Returned

Tool call · Input

cat /task/ranking_evaluation.py; echo "=== EVAL ==="; cat /task/evaluate_public.py

Tool response

"""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),
    }
=== EVAL ===
#!/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 <validation-ranking.parquet|csv>
"""
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 <validation-ranking.parquet|csv>"
        )
    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()
Harness context total tokens reminder
{
  "type": "total_tokens_reminder",
  "text": "<total_tokens>14982081 tokens left</total_tokens>"
}
03

Bash command

+00:09
Thinking unavailable No text recorded

The archive records a thinking event with empty text. No readable thinking is available for this event.

Tool callBashpython -c " Returned

Tool call · Input

python -c "
import pandas as pd, numpy as np, pyarrow.parquet as pq
for f in ['candidate_catalog','target_users','validation_preference_state','test_preference_state']:
    d=pd.read_parquet('/task/data/%s.parquet'%f); print(f, d.shape, list(d.columns)); print(d.head(3))
p=pq.ParquetFile('/task/data/train_listens.parquet'); print('train_listens rows', p.metadata.num_rows, p.schema_arrow)
d=pd.read_parquet('/task/data/val_listens.parquet'); print('val listens', d.shape, d.timestamp.min(), d.timestamp.max())
z=np.load('/task/data/validation_eligible_candidates.npz'); print({k:(v.shape,v.dtype) for k,v in z.items()})
"

Tool response

candidate_catalog (30000, 4) ['item_id', 'positive_listens', 'organic_positive_listens', 'popularity_rank']
   item_id  positive_listens  organic_positive_listens  popularity_rank
0  5862961             26615                     20620                1
1  6901374             25536                     17347                2
2  5635052             24691                     17194                3
target_users (8456, 3) ['uid', 'recent_positive_listens', 'history_positive_listens']
   uid  recent_positive_listens  history_positive_listens
0  100                    844.0                      2604
1  200                     50.0                       286
2  300                    168.0                       359
validation_preference_state (469124, 3) ['uid', 'item_id', 'state']
   uid  item_id  state
0  100   410868  liked
1  100   732449  liked
2  100   982903  liked
test_preference_state (484776, 3) ['uid', 'item_id', 'state']
   uid  item_id  state
0  100   410868  liked
1  100   732449  liked
2  100   982903  liked
train_listens rows 43484159 uid: uint32
timestamp: uint32
item_id: uint32
is_organic: uint8
played_ratio_pct: uint16
track_length_seconds: uint32
-- schema metadata --
pandas: '{"index_columns": [], "column_indexes": [], "columns": [{"name":' + 797
val listens (1501697, 6) 24788600 25393395
{'uids': ((8456,), dtype('uint32')), 'item_ids': ((30000,), dtype('uint32')), 'packed_eligible': ((8456, 3750), dtype('uint8'))}
Harness context total tokens reminder
{
  "type": "total_tokens_reminder",
  "text": "<total_tokens>14974366 tokens left</total_tokens>"
}
04

Bash command

+00:28
Thinking unavailable No text recorded

The archive records a thinking event with empty text. No readable thinking is available for this event.

Tool callBashfree -g; nproc; mkdir -p /app/solution Returned

Tool call · Input

free -g; nproc; mkdir -p /app/solution

Tool response

               total        used        free      shared  buff/cache   available
Mem:              15           1           4           0           9          14
Swap:              0           0           0
8
Tool callBashcd /app/solution && python -c " Returned

Tool call · Input

cd /app/solution && python -c "
import numpy as np, pandas as pd, time
t=time.time()
z=np.load('/task/data/validation_eligible_candidates.npz')
uids=z['uids']; items=z['item_ids']; pk=z['packed_eligible']
E=np.unpackbits(pk,axis=1,count=len(items),bitorder='little').astype(bool)
print('elig per user', E.sum(1).mean(), E.sum(1).min(), E.sum(1).max(), time.time()-t)
tu=pd.read_parquet('/task/data/target_users.parquet')
print((uids==tu.uid.values).all() if len(uids)==len(tu) else 'diff')
# check whether eligible items overlap user's train history
import pyarrow.parquet as pq
"

Tool response

elig per user 29067.306291390727 24657 30000 0.3459436893463135
True
Harness context total tokens reminder
{
  "type": "total_tokens_reminder",
  "text": "<total_tokens>14972372 tokens left</total_tokens>"
}
05

Bash command

+01:07
Thinking unavailable No text recorded

The archive records a thinking event with empty text. No readable thinking is available for this event.

Model text

Eligibility is near-full-catalog, so this is essentially full ranking. Let me write a safety submission first, then build the real model.

Tool callBashcat > /app/solution/fallback.py <<'EOF' Returned

Tool call · Input

cat > /app/solution/fallback.py <<'EOF'
import numpy as np, pandas as pd
z=np.load('/task/data/test_eligible_candidates.npz')
uids=z['uids'].astype(np.int64); items=z['item_ids'].astype(np.int64)
E=np.unpackbits(z['packed_eligible'],axis=1,count=len(items),bitorder='little').astype(bool)
cat=pd.read_parquet('/task/data/candidate_catalog.parquet')
pop=cat.set_index('item_id').loc[items,'organic_positive_listens'].to_numpy(float)
order=np.argsort(-pop)
rows=[]
for r,u in enumerate(uids):
    sel=[c for c in order if E[r,c]][:100]
    rows.append(pd.DataFrame({'uid':u,'item_id':items[sel],'rank':np.arange(1,101)}))
pd.concat(rows).to_parquet('/app/solution/submission.parquet',index=False)
print('ok')
EOF
timeout 600 python fallback.py

Tool response

ok
Harness context total tokens reminder
{
  "type": "total_tokens_reminder",
  "text": "<total_tokens>14969302 tokens left</total_tokens>"
}
06

Bash command

+02:35
Thinking unavailable No text recorded

The archive records a thinking event with empty text. No readable thinking is available for this event.

Tool callBashcat > /app/solution/build.py <<'PYEOF' Returned

Tool call · Input

cat > /app/solution/build.py <<'PYEOF'
"""Discovery ranker: implicit-MF (randomized SVD) + repeat-affinity + popularity blend."""
import sys, time, json
import numpy as np, pandas as pd
import scipy.sparse as sp
from sklearn.utils.extmath import randomized_svd

T0 = time.time()
def log(*a): print(f"[{time.time()-T0:7.1f}s]", *a, flush=True)

DATA = "/task/data/"
CAT = pd.read_parquet(DATA + "candidate_catalog.parquet")
CAT_ITEMS = np.sort(CAT.item_id.to_numpy(np.int64))
NI = len(CAT_ITEMS)
POPV = CAT.set_index("item_id").loc[CAT_ITEMS, "organic_positive_listens"].to_numpy(np.float64)
TARGETS = pd.read_parquet(DATA + "target_users.parquet").uid.to_numpy(np.int64)

def cat_idx(x):
    x = np.asarray(x, np.int64)
    pos = np.searchsorted(CAT_ITEMS, x)
    pos[pos >= NI] = 0
    return np.where(CAT_ITEMS[pos] == x, pos, -1)

def load_events(name, stage):
    fs = [DATA + f"train_{name}.parquet"] + ([DATA + f"val_{name}.parquet"] if stage == "test" else [])
    return pd.concat([pd.read_parquet(f) for f in fs], ignore_index=True)

def build_stage(stage):
    """stage in {'val','test'}: history = train (+val for test)."""
    cols = ["uid", "timestamp", "item_id", "is_organic", "played_ratio_pct"]
    parts = [pd.read_parquet(DATA + "train_listens.parquet", columns=cols)]
    if stage == "test":
        parts.append(pd.read_parquet(DATA + "val_listens.parquet", columns=cols))
    L = pd.concat(parts, ignore_index=True) if len(parts) > 1 else parts[0]
    log("listens loaded", L.shape)
    ii = cat_idx(L.item_id.to_numpy())
    keep = (ii >= 0) & (L.played_ratio_pct.to_numpy() >= 50)
    uid = L.uid.to_numpy(np.int64)[keep]
    ts = L.timestamp.to_numpy(np.int64)[keep]
    org = L.is_organic.to_numpy(np.uint8)[keep]
    pr = L.played_ratio_pct.to_numpy(np.int32)[keep]
    item = ii[keep]
    del L, ii, keep
    T_END = int(ts.max())
    log("positive listens in catalog", len(uid), "t_end", T_END)

    # ---- global item-user matrix (all users) for implicit MF
    urow, uuniq = pd.factorize(uid, sort=False)
    NU = len(uuniq)
    w = np.ones(len(uid), np.float32)
    R = sp.csr_matrix((w, (urow, item)), shape=(NU, NI), dtype=np.float32)
    R.sum_duplicates()
    R.data = np.log1p(R.data).astype(np.float32)          # count damping
    # bm25-ish: idf on items, l2 on users
    df = np.asarray((R > 0).sum(0)).ravel().astype(np.float64)
    idf = np.log1p(NU / np.maximum(df, 1)).astype(np.float32)
    R = R.multiply(idf[None, :]).tocsr().astype(np.float32)
    nr = np.sqrt(np.asarray(R.multiply(R).sum(1)).ravel()); nr[nr == 0] = 1
    R = sp.diags((1.0 / nr).astype(np.float32)) @ R
    R = R.astype(np.float32).tocsr()
    log("R built", R.shape, R.nnz)

    K = 160
    U_, S_, Vt = randomized_svd(R, n_components=K, n_iter=4, random_state=0)
    V = (Vt.T * S_).astype(np.float32)                     # item factors 30000 x K
    Vn = V / np.maximum(np.linalg.norm(V, axis=1, keepdims=True), 1e-8)
    log("svd done")
    del R, U_, Vt

    # ---- target-user histories
    tset = pd.Series(np.arange(len(TARGETS)), index=TARGETS)
    m = np.isin(uid, TARGETS)
    tu = tset.reindex(uid[m]).to_numpy()
    t_item, t_ts, t_org, t_pr = item[m], ts[m], org[m], pr[m]
    del uid, item, ts, org, pr

    HL = 14 * 86400.0
    age = (T_END - t_ts) / HL
    dec_long = np.exp2(-age).astype(np.float32)
    dec_short = np.exp2(-(T_END - t_ts) / (3 * 86400.0)).astype(np.float32)
    strong = ((t_pr >= 80) & (t_org == 1)).astype(np.float32)
    wgt = (0.4 + 0.6 * (t_pr >= 80)) * (0.5 + 0.5 * (t_org == 1))

    def spmat(vals):
        M = sp.csr_matrix((vals.astype(np.float32), (tu, t_item)),
                          shape=(len(TARGETS), NI), dtype=np.float32)
        M.sum_duplicates()
        return M

    P_long = spmat(dec_long * wgt)
    P_short = spmat(dec_short * wgt)
    CNT = spmat(np.ones(len(tu), np.float32))
    STR = spmat(strong * dec_long)
    log("profiles built")

    # explicit signals
    pref = pd.read_parquet(DATA + ("validation_preference_state.parquet" if stage == "val"
                                   else "test_preference_state.parquet"))
    pi = cat_idx(pref.item_id.to_numpy()); pu = tset.reindex(pref.uid.to_numpy()).to_numpy()
    okp = (pi >= 0) & ~np.isnan(pu)
    pu = pu[okp].astype(np.int64); pi = pi[okp]; pst = pref.state.to_numpy()[okp]
    LIKED = sp.csr_matrix((np.ones((pst == "liked").sum(), np.float32),
                           (pu[pst == "liked"], pi[pst == "liked"])), shape=(len(TARGETS), NI))
    DISL = sp.csr_matrix((np.ones((pst == "disliked").sum(), np.float32),
                          (pu[pst == "disliked"], pi[pst == "disliked"])), shape=(len(TARGETS), NI))
    LIKED.sum_duplicates(); DISL.sum_duplicates()

    likes = load_events("likes", stage)
    li = cat_idx(likes.item_id.to_numpy()); lu = tset.reindex(likes.uid.to_numpy()).to_numpy()
    okl = (li >= 0) & ~np.isnan(lu)
    LIKE_T = sp.csr_matrix((np.exp2(-(T_END - likes.timestamp.to_numpy(np.int64)[okl]) / HL).astype(np.float32),
                            (lu[okl].astype(np.int64), li[okl])), shape=(len(TARGETS), NI))
    LIKE_T.sum_duplicates()

    # profile embeddings (cosine-style user vectors)
    def emb(P):
        X = (P @ Vn).astype(np.float32)
        X /= np.maximum(np.linalg.norm(X, axis=1, keepdims=True), 1e-8)
        return X
    E_long, E_short = emb(P_long), emb(P_short)
    E_like = emb(LIKE_T + P_long * 0.0 + LIKE_T * 0.0) if LIKE_T.nnz else E_long
    log("embeddings built")

    # popularity: global + recent trend
    pop_all = np.log1p(POPV).astype(np.float32)
    pop_all = (pop_all - pop_all.mean()) / pop_all.std()
    return dict(Vn=Vn, E_long=E_long, E_short=E_short, E_like=E_like,
                CNT=CNT, STR=STR, P_long=P_long, LIKED=LIKED, DISL=DISL,
                LIKE_T=LIKE_T, pop=pop_all, T_END=T_END)

def elig_mask(stage):
    z = np.load(DATA + ("validation_eligible_candidates.npz" if stage == "val"
                        else "test_eligible_candidates.npz"))
    uids = z["uids"].astype(np.int64); items = z["item_ids"].astype(np.int64)
    E = np.unpackbits(z["packed_eligible"], axis=1, count=len(items), bitorder="little").astype(bool)
    assert (uids == TARGETS).all()
    col = cat_idx(items)                       # npz item order -> catalog order
    Ec = np.zeros((len(TARGETS), NI), bool)
    Ec[:, col] = E
    return Ec

FEATS = ["cf_long", "cf_short", "cf_like", "cnt", "str", "pop", "liked", "disl"]

def feature_block(F, rows, cols):
    """features for given (row, col) arrays -> dict of 1d arrays"""
    out = {}
    out["cf_long"] = np.einsum("ij,ij->i", F["E_long"][rows], F["Vn"][cols])
    out["cf_short"] = np.einsum("ij,ij->i", F["E_short"][rows], F["Vn"][cols])
    out["cf_like"] = np.einsum("ij,ij->i", F["E_like"][rows], F["Vn"][cols])
    for name, M in (("cnt", F["CNT"]), ("str", F["STR"]), ("liked", F["LIKED"]), ("disl", F["DISL"])):
        v = np.asarray(M[rows, cols]).ravel()
        out[name] = np.log1p(v) if name in ("cnt", "str") else v
    out["pop"] = F["pop"][cols]
    return out

def full_score(F, w, E):
    """dense score matrix (nusers x NI)"""
    S = (F["E_long"] @ F["Vn"].T) * np.float32(w["cf_long"])
    S += (F["E_short"] @ F["Vn"].T) * np.float32(w["cf_short"])
    S += (F["E_like"] @ F["Vn"].T) * np.float32(w["cf_like"])
    S += F["pop"][None, :] * np.float32(w["pop"])
    for name, M in (("cnt", F["CNT"]), ("str", F["STR"])):
        C = M.tocoo()
        S[C.row, C.col] += np.log1p(C.data) * np.float32(w[name])
    for name, M in (("liked", F["LIKED"]), ("disl", F["DISL"])):
        C = M.tocoo()
        S[C.row, C.col] += C.data * np.float32(w[name])
    S[~E] = -1e9
    return S
PYEOF
echo written

Tool response

written
Harness context total tokens reminder
{
  "type": "total_tokens_reminder",
  "text": "<total_tokens>14962599 tokens left</total_tokens>"
}
07

Bash command

+03:26
Thinking unavailable No text recorded

The archive records a thinking event with empty text. No readable thinking is available for this event.

Tool callBashcat >> /app/solution/build.py <<'PYEOF' Returned

Tool call · Input

cat >> /app/solution/build.py <<'PYEOF'

# ---------------- validation truth + fast NDCG ----------------
def val_gold(E):
    ln = pd.read_parquet(DATA + "val_listens.parquet")
    lk = pd.read_parquet(DATA + "val_likes.parquet")
    tset = pd.Series(np.arange(len(TARGETS)), index=TARGETS)
    G = np.zeros((len(TARGETS), NI), np.int8)
    def add(df, grade, cond):
        d = df[cond]
        r = tset.reindex(d.uid.to_numpy()).to_numpy()
        c = cat_idx(d.item_id.to_numpy())
        ok = (c >= 0) & ~np.isnan(r)
        r = r[ok].astype(np.int64); c = c[ok]
        ok2 = E[r, c]
        G[r[ok2], c[ok2]] = grade
    add(ln, 1, (ln.is_organic == 1) & (ln.played_ratio_pct >= 80))
    add(lk, 3, lk.is_organic == 1)
    return G

def ndcg_from_top(top, G, idcg, scored):
    g = G[np.arange(G.shape[0])[:, None], top].astype(np.float64)
    disc = 1.0 / np.log2(np.arange(2, g.shape[1] + 2))
    dcg = ((2.0 ** g - 1.0) * disc).sum(1)
    return float((dcg[scored] / idcg[scored]).mean())

def idcg_of(G):
    disc = 1.0 / np.log2(np.arange(2, 11))
    out = np.zeros(G.shape[0])
    for r in range(G.shape[0]):
        row = G[r]
        nz = row[row > 0]
        if nz.size:
            nz = np.sort(nz)[::-1][:10].astype(np.float64)
            out[r] = ((2.0 ** nz - 1.0) * disc[:len(nz)]).sum()
    return out
PYEOF
echo ok

Tool response

ok
Harness context total tokens reminder
{
  "type": "total_tokens_reminder",
  "text": "<total_tokens>14960833 tokens left</total_tokens>"
}
08

Bash command

+03:46
Tool callBashcat > /app/solution/run_val.py <<'PYEOF' Returned

Tool call · Input

cat > /app/solution/run_val.py <<'PYEOF'
import numpy as np, pandas as pd, itertools, json, pickle, time
import sys; sys.path.insert(0,'/app/solution')
from build import *

E = elig_mask("val")
F = build_stage("val")
log("stage built")
G = val_gold(E)
idcg = idcg_of(G); scored = idcg > 0
log("gold users", scored.sum())

nu = len(TARGETS)
# ---- candidate pool: union of tops from each component
def topk_cols(M, k):
    M = np.where(E, M, -1e9)
    return np.argpartition(-M, k, axis=1)[:, :k]
cf_l = F["E_long"] @ F["Vn"].T
pools = [topk_cols(cf_l, 250)]
del cf_l
cf_s = F["E_short"] @ F["Vn"].T; pools.append(topk_cols(cf_s, 120)); del cf_s
cf_k = F["E_like"] @ F["Vn"].T; pools.append(topk_cols(cf_k, 120)); del cf_k
cnt = np.zeros((nu, NI), np.float32); C = F["CNT"].tocoo(); cnt[C.row, C.col] = np.log1p(C.data)
cnt += F["pop"][None,:]*1e-3
pools.append(topk_cols(cnt, 120)); del cnt
pop_top = np.argsort(-F["pop"])[:400]
pools.append(np.where(E[:, pop_top], pop_top[None,:], pop_top[0])[:, :120])
POOL = np.concatenate(pools, axis=1)
log("pool", POOL.shape)
np.save('/app/solution/pool_val.npy', POOL)

rows = np.repeat(np.arange(nu), POOL.shape[1])
cols = POOL.ravel()
FB = feature_block(F, rows, cols)
FB = {k: v.reshape(POOL.shape).astype(np.float32) for k, v in FB.items()}
log("features extracted")

# duplicate mask within pool
srt = np.argsort(POOL, axis=1)
ps = np.take_along_axis(POOL, srt, 1)
dup = np.zeros(POOL.shape, bool)
d = ps[:, 1:] == ps[:, :-1]
np.put_along_axis(dup, srt[:, 1:], d, 1)
elig_pool = E[np.arange(nu)[:,None], POOL] & ~dup
log("dup masked")

def evalw(w):
    S = np.zeros(POOL.shape, np.float32)
    for k, v in w.items(): S += FB[k] * np.float32(v)
    S[~elig_pool] = -1e9
    top = np.argpartition(-S, 10, axis=1)[:, :10]
    tv = np.take_along_axis(S, top, 1)
    order = np.argsort(-tv, axis=1)
    top = np.take_along_axis(top, order, 1)
    return ndcg_from_top(np.take_along_axis(POOL, top, 1), G, idcg, scored), S

W0 = dict(cf_long=1.0, cf_short=0.3, cf_like=0.3, cnt=0.3, str=0.3, pop=0.05, liked=0.0, disl=-1.0)
base, _ = evalw(W0); log("base ndcg", base)
pickle.dump(dict(FB=FB, elig_pool=elig_pool, POOL=POOL, G=G, idcg=idcg, scored=scored),
            open('/app/solution/valtune.pkl','wb'), protocol=4)
log("saved tune data")
PYEOF
timeout 900 python run_val.py 2>&1 | tail -30

Tool response

[    2.1s] listens loaded (43484159, 5)
[    6.6s] positive listens in catalog 20056329 t_end 24786795
[    7.8s] R built (9135, 30000) 5564926
[   11.2s] svd done
[   15.7s] profiles built
[   16.3s] embeddings built
[   16.4s] stage built
Traceback (most recent call last):
  File "/app/solution/run_val.py", line 9, in <module>
    idcg = idcg_of(G); scored = idcg > 0
           ^^^^^^^^^^
  File "/app/solution/build.py", line 202, in idcg_of
    out[r] = ((2.0 ** nz - 1.0) * disc[:len(nz)]).sum()
              ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~
ValueError: operands could not be broadcast together with shapes (10,) (9,)
Harness context total tokens reminder
{
  "type": "total_tokens_reminder",
  "text": "<total_tokens>14959462 tokens left</total_tokens>"
}
09

Bash command

+04:14
Thinking unavailable No text recorded

The archive records a thinking event with empty text. No readable thinking is available for this event.

Tool callBashpython - <<'EOF' Returned

Tool call · Input

python - <<'EOF'
import re
s=open('build.py').read()
s=s.replace("    disc = 1.0 / np.log2(np.arange(2, 11))\n    out","    disc = 1.0 / np.log2(np.arange(2, 12))\n    out")
open('build.py','w').write(s)
EOF
timeout 900 python run_val.py 2>&1 | tail -20

Tool response

[    2.1s] listens loaded (43484159, 5)
[    6.6s] positive listens in catalog 20056329 t_end 24786795
[    7.8s] R built (9135, 30000) 5564926
[   12.1s] svd done
[   16.7s] profiles built
[   17.3s] embeddings built
[   17.3s] stage built
[   17.5s] gold users 4263
Harness context total tokens reminder
{
  "type": "total_tokens_reminder",
  "text": "<total_tokens>14958243 tokens left</total_tokens>"
}
10

Bash command

+04:46
Thinking unavailable No text recorded

The archive records a thinking event with empty text. No readable thinking is available for this event.

Tool callBashcat > /app/solution/run_val.py <<'PYEOF' Returned

Tool call · Input

cat > /app/solution/run_val.py <<'PYEOF'
import numpy as np, pandas as pd, pickle, sys
sys.path.insert(0,'/app/solution')
from build import *

E = elig_mask("val")
F = build_stage("val")
G = val_gold(E); idcg = idcg_of(G); scored = idcg > 0
log("gold users", scored.sum())
nu = len(TARGETS)
CNTd = F["CNT"].tocsr(); STRd = F["STR"].tocsr()
pop_top = np.argsort(-F["pop"])[:200]
POOLS = []
CH = 1000
for s in range(0, nu, CH):
    e = min(s + CH, nu)
    sl = slice(s, e)
    Eb = E[sl]
    def tk(M, k):
        M = np.where(Eb, M, -1e9)
        return np.argpartition(-M, k, axis=1)[:, :k]
    parts = []
    for emb_, k in (("E_long", 250), ("E_short", 120), ("E_like", 120)):
        parts.append(tk(F[emb_][sl] @ F["Vn"].T, k))
    c = np.zeros((e - s, NI), np.float32)
    C = CNTd[sl].tocoo(); c[C.row, C.col] = np.log1p(C.data)
    C = STRd[sl].tocoo(); c[C.row, C.col] += np.log1p(C.data)
    c += F["pop"][None, :] * 1e-3
    parts.append(tk(c, 120)); del c
    parts.append(np.broadcast_to(pop_top[None, :120], (e - s, 120)))
    POOLS.append(np.concatenate(parts, 1))
POOL = np.concatenate(POOLS, 0).astype(np.int32)
log("pool", POOL.shape)

rows = np.repeat(np.arange(nu), POOL.shape[1]); cols = POOL.ravel()
FB = {k: v.reshape(POOL.shape).astype(np.float32) for k, v in feature_block(F, rows, cols).items()}
log("features")
srt = np.argsort(POOL, 1); ps = np.take_along_axis(POOL, srt, 1)
dup = np.zeros(POOL.shape, bool)
np.put_along_axis(dup, srt[:, 1:], ps[:, 1:] == ps[:, :-1], 1)
elig_pool = E[np.arange(nu)[:, None], POOL] & ~dup
pickle.dump(dict(FB=FB, elig_pool=elig_pool, POOL=POOL, G=G, idcg=idcg, scored=scored),
            open('/app/solution/valtune.pkl','wb'), protocol=4)
log("saved")

def evalw(w):
    S = np.zeros(POOL.shape, np.float32)
    for k, v in w.items(): S += FB[k] * np.float32(v)
    S[~elig_pool] = -1e9
    top = np.argpartition(-S, 10, 1)[:, :10]
    tv = np.take_along_axis(S, top, 1)
    top = np.take_along_axis(top, np.argsort(-tv, 1), 1)
    return ndcg_from_top(np.take_along_axis(POOL, top, 1), G, idcg, scored)

W = dict(cf_long=1.0, cf_short=0.3, cf_like=0.3, cnt=0.3, str=0.3, pop=0.05, liked=0.0, disl=-1.0)
best = evalw(W); log("base", round(best, 5), W)
grid = {"cf_long":[0,.5,1,2], "cf_short":[0,.1,.3,.6,1.2], "cf_like":[0,.1,.3,.6,1.2],
        "cnt":[0,.05,.15,.3,.6,1.2], "str":[0,.05,.15,.3,.6,1.2], "pop":[0,.02,.05,.1,.2],
        "liked":[-1,0,.5], "disl":[-2,0]}
for it in range(3):
    for k, vals in grid.items():
        cur = W[k]; bv = cur
        for v in vals:
            if v == cur: continue
            W[k] = v; s = evalw(W)
            if s > best: best, bv = s, v
        W[k] = bv
    log("iter", it, round(best, 5), W)
json.dump({"w": W, "ndcg": best}, open('/app/solution/best_weights.json','w'))
log("DONE", best, W)
PYEOF
timeout 900 python run_val.py 2>&1 | tail -20; echo "EXIT=$?"

Tool response

[    2.1s] listens loaded (43484159, 5)
[    6.6s] positive listens in catalog 20056329 t_end 24786795
[    7.8s] R built (9135, 30000) 5564926
[   11.2s] svd done
[   15.7s] profiles built
[   16.3s] embeddings built
[   16.6s] gold users 4263
[   26.0s] pool (8456, 730)
EXIT=0
Harness context total tokens reminder
{
  "type": "total_tokens_reminder",
  "text": "<total_tokens>14956073 tokens left</total_tokens>"
}
11

Bash command

+05:38
Thinking unavailable No text recorded

The archive records a thinking event with empty text. No readable thinking is available for this event.

Tool callBashcat > /app/solution/pipeline.py <<'PYEOF' Returned

Tool call · Input

cat > /app/solution/pipeline.py <<'PYEOF'
import numpy as np, pandas as pd, pickle, sys, json
sys.path.insert(0,'/app/solution')
from build import *

def feats_for_pool(F, POOL, E):
    nu, P = POOL.shape
    out = {k: np.zeros((nu, P), np.float32) for k in FEATS}
    CH = 400
    for s in range(0, nu, CH):
        e = min(s + CH, nu); pl = POOL[s:e]
        for name, key in (("cf_long","E_long"), ("cf_short","E_short"), ("cf_like","E_like")):
            out[name][s:e] = np.einsum("ij,ikj->ik", F[key][s:e], F["Vn"][pl])
        for name, M in (("cnt", F["CNT"]), ("str", F["STR"]), ("liked", F["LIKED"]), ("disl", F["DISL"])):
            d = np.asarray(M[s:e].todense())
            v = np.take_along_axis(d, pl, 1)
            out[name][s:e] = np.log1p(v) if name in ("cnt", "str") else v
        out["pop"][s:e] = F["pop"][pl]
    return out

def make_pool(F, E, sizes=(250,120,120,120,120)):
    nu = len(TARGETS); pop_top = np.argsort(-F["pop"])[:200]
    CNTd, STRd = F["CNT"].tocsr(), F["STR"].tocsr()
    POOLS = []
    for s in range(0, nu, 1000):
        e = min(s + 1000, nu); sl = slice(s, e); Eb = E[sl]
        def tk(M, k):
            M = np.where(Eb, M, -1e9)
            return np.argpartition(-M, k, 1)[:, :k]
        parts = [tk(F[k_][sl] @ F["Vn"].T, n) for k_, n in
                 (("E_long", sizes[0]), ("E_short", sizes[1]), ("E_like", sizes[2]))]
        c = np.zeros((e - s, NI), np.float32)
        C = CNTd[sl].tocoo(); c[C.row, C.col] = np.log1p(C.data)
        C = STRd[sl].tocoo(); c[C.row, C.col] += np.log1p(C.data)
        c += F["pop"][None, :] * 1e-3
        parts.append(tk(c, sizes[3])); del c
        parts.append(np.broadcast_to(pop_top[None, :sizes[4]], (e - s, sizes[4])))
        POOLS.append(np.concatenate(parts, 1))
    return np.concatenate(POOLS, 0).astype(np.int32)

def dedup_mask(POOL, E):
    nu = POOL.shape[0]
    srt = np.argsort(POOL, 1); ps = np.take_along_axis(POOL, srt, 1)
    dup = np.zeros(POOL.shape, bool)
    np.put_along_axis(dup, srt[:, 1:], ps[:, 1:] == ps[:, :-1], 1)
    return E[np.arange(nu)[:, None], POOL] & ~dup

# ---------- validation: tune ----------
Ev = elig_mask("val"); Fv = build_stage("val")
G = val_gold(Ev); idcg = idcg_of(G); scored = idcg > 0
POOL = make_pool(Fv, Ev); log("pool", POOL.shape)
FB = feats_for_pool(Fv, POOL, Ev); log("feats")
ep = dedup_mask(POOL, Ev)

def evalw(w, K=10):
    S = np.zeros(POOL.shape, np.float32)
    for k, v in w.items(): S += FB[k] * np.float32(v)
    S[~ep] = -1e9
    top = np.argpartition(-S, K, 1)[:, :K]
    top = np.take_along_axis(top, np.argsort(-np.take_along_axis(S, top, 1), 1), 1)
    return ndcg_from_top(np.take_along_axis(POOL, top, 1), G, idcg, scored)

W = dict(cf_long=1.0, cf_short=0.3, cf_like=0.3, cnt=0.3, str=0.3, pop=0.05, liked=0.0, disl=-1.0)
best = evalw(W); log("base", round(best, 5))
grid = {"cf_long":[0,.5,1,2,4], "cf_short":[0,.1,.3,.6,1.2], "cf_like":[0,.1,.3,.6,1.2],
        "cnt":[0,.05,.15,.3,.6,1.2,2.5], "str":[0,.05,.15,.3,.6,1.2,2.5],
        "pop":[0,.02,.05,.1,.25,.5], "liked":[-1,0,.5,1.5], "disl":[-2,0,.5]}
for it in range(3):
    改 = False
    for k, vals in grid.items():
        cur = W[k]; bv = cur
        for v in vals:
            if v == cur: continue
            W[k] = v; s = evalw(W)
            if s > best + 1e-6: best, bv, 改 = s, v, True
        W[k] = bv
    log("iter", it, round(best, 5), W)
    if not 改: break
json.dump({"w": W, "val_ndcg": best}, open('/app/solution/best_weights.json','w'), indent=1)
log("TUNED", best, W)

# validation artifact for the public evaluator
def write_ranking(F, E, W, path):
    nu = len(TARGETS); rows = []
    CNTc, STRc, LKc, DSc = F["CNT"].tocsr(), F["STR"].tocsr(), F["LIKED"].tocsr(), F["DISL"].tocsr()
    for s in range(0, nu, 1000):
        e = min(s + 1000, nu); sl = slice(s, e)
        S = (F["E_long"][sl] @ F["Vn"].T) * np.float32(W["cf_long"])
        S += (F["E_short"][sl] @ F["Vn"].T) * np.float32(W["cf_short"])
        S += (F["E_like"][sl] @ F["Vn"].T) * np.float32(W["cf_like"])
        S += F["pop"][None, :] * np.float32(W["pop"])
        for name, M in (("cnt", CNTc), ("str", STRc)):
            C = M[sl].tocoo(); S[C.row, C.col] += np.log1p(C.data) * np.float32(W[name])
        for name, M in (("liked", LKc), ("disl", DSc)):
            C = M[sl].tocoo(); S[C.row, C.col] += C.data.astype(np.float32) * np.float32(W[name])
        S[~E[sl]] = -1e9
        top = np.argpartition(-S, 100, 1)[:, :100]
        top = np.take_along_axis(top, np.argsort(-np.take_along_axis(S, top, 1), 1), 1)
        rows.append(pd.DataFrame({
            "uid": np.repeat(TARGETS[sl], 100),
            "item_id": CAT_ITEMS[top.ravel()],
            "rank": np.tile(np.arange(1, 101), e - s)}))
    pd.concat(rows, ignore_index=True).to_parquet(path, index=False)
    log("wrote", path)

write_ranking(Fv, Ev, W, '/app/solution/validation.parquet')
del Fv, FB, POOL, ep, G, Ev

# ---------- test: refit on train+val ----------
Et = elig_mask("test"); Ft = build_stage("test")
write_ranking(Ft, Et, W, '/app/solution/submission_new.parquet')
PYEOF
nohup timeout 1500 python /app/solution/pipeline.py > /app/solution/pipeline.log 2>&1 &
sleep 60; tail -5 /app/solution/pipeline.log

Tool response

[   43.8s] wrote /app/solution/validation.parquet
[   46.0s] listens loaded (44985856, 5)
[   50.7s] positive listens in catalog 20712971 t_end 25393395
[   51.9s] R built (9153, 30000) 5724357
[   55.0s] svd done
Harness context total tokens reminder
{
  "type": "total_tokens_reminder",
  "text": "<total_tokens>14952487 tokens left</total_tokens>"
}
12

Bash command

+07:02
Thinking unavailable No text recorded

The archive records a thinking event with empty text. No readable thinking is available for this event.

Tool callBashcat /app/solution/pipeline.log; ls -la /app/solution/ Returned

Tool call · Input

cat /app/solution/pipeline.log; ls -la /app/solution/

Tool response

[    2.2s] listens loaded (43484159, 5)
[    6.6s] positive listens in catalog 20056329 t_end 24786795
[    7.8s] R built (9135, 30000) 5564926
[   11.2s] svd done
[   15.8s] profiles built
[   16.4s] embeddings built
[   26.0s] pool (8456, 730)
[   29.1s] feats
[   29.4s] base 0.0203
[   32.8s] iter 0 0.02263 {'cf_long': 0.5, 'cf_short': 1.2, 'cf_like': 0, 'cnt': 0.3, 'str': 0.3, 'pop': 0.05, 'liked': 0.0, 'disl': -1.0}
[   36.1s] iter 1 0.02305 {'cf_long': 0, 'cf_short': 1.2, 'cf_like': 0.1, 'cnt': 0.3, 'str': 0.3, 'pop': 0.05, 'liked': 0.0, 'disl': -1.0}
[   39.3s] iter 2 0.02305 {'cf_long': 0, 'cf_short': 1.2, 'cf_like': 0.1, 'cnt': 0.3, 'str': 0.3, 'pop': 0.05, 'liked': 0.0, 'disl': -1.0}
[   39.3s] TUNED 0.023054987356453685 {'cf_long': 0, 'cf_short': 1.2, 'cf_like': 0.1, 'cnt': 0.3, 'str': 0.3, 'pop': 0.05, 'liked': 0.0, 'disl': -1.0}
[   43.8s] wrote /app/solution/validation.parquet
[   46.0s] listens loaded (44985856, 5)
[   50.7s] positive listens in catalog 20712971 t_end 25393395
[   51.9s] R built (9153, 30000) 5724357
[   55.0s] svd done
[   59.7s] profiles built
[   60.3s] embeddings built
total 2540
drwxr-xr-x 1 agent agent    4096 Sep 24 07:51 .
drwxr-xr-x 1 agent agent    4096 Sep 24 07:41 ..
-rw-r--r-- 1 agent agent     176 Sep 24 07:51 best_weights.json
-rw-r--r-- 1 agent agent    8925 Sep 24 07:48 build.py
-rw-r--r-- 1 agent agent     667 Sep 24 07:45 fallback.py
-rw-r--r-- 1 agent agent    1122 Sep 24 07:51 pipeline.log
-rw-r--r-- 1 agent agent    5045 Sep 24 07:50 pipeline.py
-rw-r--r-- 1 agent agent    2765 Sep 24 07:49 run_val.py
-rw-r--r-- 1 agent agent  704183 Sep 24 07:46 submission.parquet
-rw-r--r-- 1 agent agent 1845788 Sep 24 07:51 validation.parquet
Harness context total tokens reminder
{
  "type": "total_tokens_reminder",
  "text": "<total_tokens>14952241 tokens left</total_tokens>"
}
13

Bash command

+07:07
Thinking unavailable No text recorded

The archive records a thinking event with empty text. No readable thinking is available for this event.

Tool callBashtimeout 400 python /task/evaluate_public.py validation.parquet; tail -3 pipeline.log Returned

Tool call · Input

timeout 400 python /task/evaluate_public.py validation.parquet; tail -3 pipeline.log

Tool response

{
  "model": "validation.parquet",
  "scores": {
    "quality_ndcg@10": 0.023055,
    "quality_users": 4263
  }
}
[   59.7s] profiles built
[   60.3s] embeddings built
[   64.7s] wrote /app/solution/submission_new.parquet
Harness context total tokens reminder
{
  "type": "total_tokens_reminder",
  "text": "<total_tokens>14950833 tokens left</total_tokens>"
}
14

Bash command

+07:15
Thinking unavailable No text recorded

The archive records a thinking event with empty text. No readable thinking is available for this event.

Tool callBashtimeout 300 python -c " Returned

Tool call · Input

timeout 300 python -c "
import numpy as np, pandas as pd, sys
sys.path.insert(0,'/task')
from ranking_evaluation import validate_ranking
d=pd.read_parquet('submission_new.parquet')
t=set(pd.read_parquet('/task/data/target_users.parquet').uid.astype(int))
n=validate_ranking(d,t); print('schema ok',n.shape)
z=np.load('/task/data/test_eligible_candidates.npz')
uids=z['uids'].astype(np.int64); items=z['item_ids'].astype(np.int64)
E=np.unpackbits(z['packed_eligible'],axis=1,count=len(items),bitorder='little').astype(bool)
ur={int(u):i for i,u in enumerate(uids)}; ic={int(i):c for c,i in enumerate(items)}
r=n.uid.map(ur).to_numpy(); c=n.item_id.map(ic).to_numpy()
assert not pd.isna(c).any(); print('all eligible:', E[r,c.astype(int)].all())
" && cp submission_new.parquet submission.parquet && echo SWAPPED

Tool response

schema ok (845600, 3)
all eligible: True
SWAPPED
Harness context total tokens reminder
{
  "type": "total_tokens_reminder",
  "text": "<total_tokens>14949988 tokens left</total_tokens>"
}
15

Bash command

+07:23
Thinking unavailable No text recorded

The archive records a thinking event with empty text. No readable thinking is available for this event.

Tool callBashcat > /app/solution/README.md <<'EOF' Returned

Tool call · Input

cat > /app/solution/README.md <<'EOF'
# Made-for-You discovery ranker

Final artifact: `submission.parquet` (8,456 users x 100 ranked eligible items).
Validation-stage ranking: `validation.parquet` — public evaluator score
**quality_ndcg@10 = 0.023055** over 4,263 scored users.

## Approach

A linear blend of collaborative-filtering and behavioural features, with blend
weights tuned directly on the public validation window.

1. **History construction** (`build.py:build_stage`). Positive listens
   (`played_ratio_pct >= 50`) restricted to the 30k candidate catalog. For the
   validation stage history = `train_*` only; for the hidden-test stage the
   whole pipeline is refit with history = `train_* + val_*` (the same code path,
   `stage="test"`), so validation events are used as observed history only.
2. **Implicit MF item factors.** User x item matrix with `log1p` count damping,
   item IDF weighting and L2 user normalisation, factorised by randomized SVD
   (k=160). Item factors are L2-normalised so CF scores are cosine-like and do
   not simply re-rank by popularity.
3. **User profiles / features** scored per (user, candidate):
   - `cf_long`, `cf_short`: fold-in profile embeddings over the user's positive
     listens with 14-day and 3-day half-life decay, weighted by completion
     (>=80%) and organic flag, dotted with item factors.
   - `cf_like`: same fold-in over the user's decayed explicit likes.
   - `cnt`, `str`: log repeat-affinity — the user's own past listen count and
     recency-decayed strong-organic-listen count for that exact track.
   - `pop`: standardised `log1p(organic_positive_listens)` catalog prior.
   - `liked`, `disl`: active explicit preference state at the correct cutoff
     (`validation_preference_state` / `test_preference_state`).
4. **Weight tuning.** A generous per-user candidate pool (730 = union of top-N
   by each individual signal) is materialised; coordinate-ascent over a weight
   grid maximises graded NDCG@10 directly on the validation window. The internal
   scorer reproduces `evaluate_public.py` exactly (0.023055 both ways).
   Selected weights are in `best_weights.json`; the short-horizon CF term plus
   repeat-affinity dominate, dislikes are strongly penalised.
5. **Final ranking.** Scores are recomputed densely in user chunks, ineligible
   candidates masked to `-inf`, top-100 emitted per user. Every submitted item
   was verified present in `test_eligible_candidates.npz`.

## Files
- `build.py` — data loading, feature/profile construction, eligibility, NDCG.
- `pipeline.py` — end-to-end: tune on validation, refit on train+val, write both
  rankings. Run: `python pipeline.py`.
- `fallback.py` — popularity-only safety submission (superseded).

## Notes / limits
Only the checked-in environment (numpy/scipy/sklearn/pandas) was available, so
no GBDT ranker; with more time the natural next steps are a full item-item
cosine KNN term (feasible here — only ~9.1k distinct users) and a learned
pointwise ranker trained on an in-train temporal split instead of a hand-tuned
linear blend.
EOF
rm -f /app/solution/run_val.py /app/solution/pool_val.npy; ls /app/solution

Tool response

README.md
best_weights.json
build.py
fallback.py
pipeline.log
pipeline.py
submission.parquet
submission_new.parquet
validation.parquet
Harness context total tokens reminder
{
  "type": "total_tokens_reminder",
  "text": "<total_tokens>14948560 tokens left</total_tokens>"
}
16

Final response

+07:46

Model text

Done. Final state in /app/solution/:

Deliverable: submission.parquet — 845,600 rows (8,456 users × 100 ranks), schema-validated with ranking_evaluation.validate_ranking, and every item confirmed present in that user's test_eligible_candidates.npz mask.

Model: linear blend of

  • randomized-SVD implicit-MF item factors (k=160, IDF-weighted, L2-normalised) scored against two recency-decayed user fold-in profiles (14-day and 3-day half-life) and a likes-based profile,
  • log repeat-affinity (past listen count, recency-weighted strong-organic listens on the same track),
  • catalog popularity prior,
  • cutoff-correct explicit like/dislike state.

Weights were fit by coordinate ascent on graded NDCG@10 over the validation window using a 730-candidate per-user pool; the final ranker was then refit end-to-end with train_* + val_* as history for the test cutoff.

Measured quality: python /task/evaluate_public.py validation.parquet → quality_ndcg@10 = 0.023055 over 4,263 scored users (up from 0.0203 at the untuned starting weights). My internal scorer reproduces the public evaluator exactly. The hidden-test ranking uses the identical code path with the later cutoff, so it is unscored here.

Two things worth flagging: the tuned weights zeroed the long-horizon CF term in favour of the 3-day one, which is a fairly aggressive recency preference fit on a single 7-day window — some overfitting risk to the public window. And the environment has no GBDT library, so the ranker is a hand-tuned linear blend rather than a learned one; a full item-item KNN term is cheap here (only ~9.1k distinct users in the logs) and is the first thing I'd add with more time. Both are noted in the README.

About this recording

The full recorded conversation: task prompt, agent messages, thinking text when available, tool inputs and outputs, and harness context. Empty thinking entries are labeled unavailable, not reconstructed from tool calls. Disclosures change the view; they do not shorten the content. Any truncation already present in tool output is preserved.

Steps follow the recorded model messages and reasoning events. Tool results appear with their originating call. Elapsed time starts with the first recorded event and excludes verification.

Attempt
yambda-opus-high-2026-09-24-00-34-15-04330cf-1
Recorded model
claude-opus-5
Harness version
2.1.251
Session
4a518b1f-cdfb-4d01-832c-90f11d172c16
Source SHA-256
ffe0d3d7c8c97703a5df7b44821d7eb933a41180dad85c7999e7e6fa5837724f

Session bookkeeping and encrypted reasoning or signatures are excluded from the reading export. The harness’s system prompt is not present in this session archive.