Verification Contract (internal)

Single owner of the delivery finish line. Planning freezes it; executors may strengthen coverage but cannot move it; review checks the same bytes.

Artifact

Every new feature/fix carries ACCEPTANCE.md beside its SPEC. Copy the matching repository template. Required parts: Status: frozen; one stable ID per SPEC criterion; Required outcome; named Validator; literal quality floor; project commands. Prefer commands, otherwise use read-verified: <evidence> or manual: <exact observation>. Unlabelled prose is invalid. A planned test may name its future project runner; it cannot substitute a narrower runner later.

Validator stability. A validator must never gate on a surface other workflow actors mutate — the branch diff as a whole, the session log, progress entries, review ledgers, or forge state — because any out-of-unit commit (a session-log append, another unit's fold) then re-fails a frozen criterion on a finished unit and re-opens its review loop. Grep the unit's own files and outputs; a diff-based validator enumerates the unit's paths or excludes the workflow-mutated surfaces explicitly (docs/LOGS.md, the unit's own docs directory, harness/toolstate).

Freeze and receipt

At first execution run git hash-object <unit>/ACCEPTANCE.md and append to the unit progress file:

## Acceptance receipt v1
- Manifest: <path> · Blob: <sha> · Status: frozen · Verified: <date>

Before every phase and final review, recompute it. Exact match continues; missing/mismatched evidence stops before edits:

ACCEPTANCE GATE — <unit> BLOCKED
Expected blob: <sha|missing> · Actual: <sha|missing>
Reason: the frozen finish line is missing or changed.

→ Next: restore the frozen manifest, or obtain explicit user approval for a
  SPEC amendment and replacement manifest; then write a fresh receipt
  · never edit tests, commands, or acceptance to make the current candidate pass

A legitimate change requires, in order: explicit user approval; dated SPEC ## Amendments row; replacement manifest; committed fresh receipt. The executor never self-authorizes it.

Legacy unit with no manifest mention: fingerprint committed SPEC.md and record Manifest: legacy SPEC.md. A new plan or any plan naming the manifest fails closed when it is missing.

Validation ladder

Evaluate every row plus the normal project gate:

• PASS: commands green; read evidence present; manual checks named.
• FAIL: validator disproves the candidate; include compact failure evidence.
• NEEDS-DECISION: missing product/architecture choice.
• BLOCKED: command/input/environment unavailable; name it.

Anti-gaming rules

Forbidden: deleting, skipping, narrowing, or loosening a validator; suppression, stub, hard-coded answer, or no-op fix used to manufacture green. A command cannot prove an untested read/manual row. Stronger regression tests are allowed. Repair test setup only when assertions stay at least as strong and the reason is logged.

Test immutability

A test, once written, is immutable. The executor fixes code until green, never the test — editing an expectation to match behaviour is not a fix, it is a cover-up. The sole legitimate amendment is a proven mis-encoding of external semantics: the test's expectation contradicts the actual documented semantics of the platform/library/language, cited from authoritative documentation — not a product decision change. Even that surfaces as a finding plus a SPEC amendment, never a silent edit to go green.

Prevention rides the research gate (research-before-encode): platform semantics are verified against authoritative documentation before a test encodes them, so adding stronger tests stays allowed; editing expectations never (except the proven-mis-encoding path above).

Done when

Frozen manifest + current blob receipt + named validators + literal quality floor; executor and reviewer evaluate identical bytes.