AGENTS.md@specs/023-agent-native-repo-borrowing/evidence git:20260816.64bcfd3A

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# evidence Agent Contract

Frozen measurement artifacts for round 023: the differential probe runners and their raw outputs, committed so the `RED-baseline` claims in `skill-extraction-workflow/references/source-register.md` can be independently checked instead of taken on the author's word.

Rules:

- **Frozen after the round lands.** Do not edit, re-grade, prune, or regenerate these files to make a later claim look better. A superseding measurement is a new file in a new round's evidence directory, and the register row that cites it says so.
- **These runners are evidence tools, not repository gates.** They call a live model, so they are non-deterministic and are never wired into `make test` or any blocking check. A green run here proves nothing about the repository; it records what two pinned skill revisions produced on one task set.
- **Read the runner before citing its numbers.** Each one resolves both arms to immutable commit SHAs before any model call, aborts when a required `SKILL.md`/revision read fails or the skills tree is dirty, and records the sha256 of every prompt input beside the score, so a cited base/head pair is verifiable. Four historical runners represent a reference absent at one arm with an explicit named placeholder instead of aborting; that can cue the model to the missing topic, so affected no-delta observations are advisory only and do not prove absence of an effect. Grading is a keyword contract: a compliant paraphrase can read as a miss, which is why every raw answer is kept in the JSON except machine-only host paths or credentials, which are replaced by neutral placeholders with an explicit `redactions` field; redaction must not intersect the grading patterns, and `len` records the retained text.
- **Tightening a grading contract does not rewrite history.** Keep the original runner and raw output intact; add a deterministic re-grade that binds its source and each stored answer by sha256. `red-baseline-023-strict-regrade.rb` is the round-023 example.
- **Numbers are reported as measured.** Weak or absent deltas stay in the record with the rule they failed to move; a candidate that measured 4/4 on both arms was withdrawn rather than relabelled.
- **No credentials, no host paths, no third-party content.** The runners take a worktree path as an argument and read only committed blobs from it.