README.md

metadata

license: cc-by-4.0
pretty_name: AtlasOpenCoder

AtlasOpenCoder — v1.0

Calibrated concept profiles for OpenCoder-1.5B-Base, read on 169 Python constructs across 61 pretraining and annealing checkpoints. This dataset is the battery, the licence tables and the artefacts every figure and table of two papers reads:

• "Calibrated Concept Profiles: Making the Reading of a Model's Neurons a Measurement" (Wilam, 2026) — the method. Its code: piotrwilam/AtlasCalibratedConceptProfiles.
• "Representational Drift in a Code Model: Behaviour Settles, Which Neurons Carry It Does Not" (Wilam, 2026) — the finding, read with that instrument on this dataset. Its code: piotrwilam/AtlasRepresentationalDrift.

MANIFEST_PAPER1.md and MANIFEST_PAPER2.md below are named for the first and the second of those, in that order.

What is here

phase_battery/	the battery: 557,990 prompts in sets A, B and C, two twins and the nu arm
battery/	the earlier pilot battery
validation/	every artefact a figure or table in either paper reads
inventory/, calibration/	the 206 constructs and the corpus rate tables
probe/companions.json	the logged companion shares
MANIFEST_PAPER1.md, MANIFEST_PAPER2.md	every number in each paper, to its file, field and script

The battery cannot be regenerated. Its per-prompt seeds came from abs(hash(...)), salted per process, so the seeds recorded in CONTENT_HASHES.json do not reproduce the prompts they name. That is why it is published.

What is not here

The raw record (2,022 GB over 61 references) — per-core accumulators and per-prompt activations. It is regenerable from OpenCoder's released checkpoints, this battery and the code. One reference of it is planned for the next version.

The pilot recording. Two artefacts were once computed from a pilot tree and later found to differ from the phase recording at every reference; everything derived from it is excluded and named in the papers.

Two batteries, two hashes

The recorded battery — the one the model was run on, and the one the papers' numbers come from — carries prompt-content hash 570b42db…, and its per-set hashes are the figures the papers cite.

The released battery differs from it in 1,927 of 557,990 prompts (0.35%): those prompts drew padding containing one of six third-party email addresses, which are replaced here with user@example.com. The token offsets each prompt stores are recomputed to match, and the recomputation is verified per prompt. See phase_battery/REDACTION.json and phase_battery/RELEASED_HASHES.json.

Only a reader who re-runs the model on those 1,927 prompts sees a difference. Every artefact in validation/ was computed on the recorded battery.

Licence

The dataset's own content (generator text, profiles, tables, artefacts) is CC BY 4.0 (LICENSE); the padding snippets in the battery remain under their original licences, listed in ATTRIBUTION.md.

The padding is not ours. Padding blocks were drawn from codeparrot/codeparrot-clean and carry the licences of the repositories they came from: MIT, Apache-2.0, BSD, GPL, AGPL, LGPL and others. Roughly 29% of prompts contain at least one such fragment, each one to three lines and a median of 45 characters. Every block, its source repositories and their licences are listed in ATTRIBUTION.md.

Citing

Cite the paper that owns this dataset, and the DOI together with the tag — the method paper, named above. The dataset is its instrument and its realisation on OpenCoder; the second paper reads it.

Wilam, P. (2026). Calibrated Concept Profiles: Making the Reading of a Model's Neurons a Measurement. Dataset: AtlasOpenCoder, tag v1.

The DOI is shown on this page, above the file list, and belongs in the citation beside the tag. It is not repeated here: a DOI names the revision it was minted on, so a card cannot carry its own without pointing at a later revision than the one the DOI names. The paper's arXiv identifier is in the paper's own listing.

A Hugging Face DOI is assigned to the revision it is generated on, so a later version takes a new DOI and the earlier one is marked outdated. Name the tag as well as the DOI: the tag says which content a number came from in words a reader can check against this repository's history. Version 1 is the 20-cell yardstick (4 token classes x 5 fifths of the prompt). A later version computed under a different yardstick names different neurons for the same constructs, so a figure from one version cannot be compared with a figure from another.

What the directory names mean

validation/paper1/ and validation/paper2/ record which paper's script wrote a file, not which paper reads it. Both papers read across them: the first paper's numbers come from 31 files under validation/paper2/ and validation/r2/, and the second paper's from 14 under validation/paper1/. MANIFEST_PAPER1.md and MANIFEST_PAPER2.md in this repository give, for every number printed in each paper, the file and the field it is read from and the script that rebuilds that file -- 407 numbers and 495, including the few that no released file holds, which are marked and collected in a section of their own.

Provenance

The model is OpenCoder-LLM/OpenCoder-1.5B-Base-Checkpoints (MIT). The reference corpus is codeparrot/codeparrot-clean. The yardstick is the 20-cell split (4 token classes × 5 fifths of the prompt), version 1.