Reproduce Bug

When to Use

Use for the reproduction step of patching-bugs with one finding.json and a local baseline checkout. Read the record contract. Before target commands, follow its project guidance.

When NOT to Use

Do not use for bug discovery, patching, or a claim that cannot be exercised locally. Report a blocker when the build or environment cannot exercise the claim.

Procedure

1. Select failure_type from the record contract. Build the current baseline with the project's own command. Exercise the planned scoped inputs before any edit and retain their observations, including valid controls. Save raw stdout, stderr, exit status, and timing. If the behavior is absent with trustworthy evidence, report not_reproduced; if setup or observations are unreliable, report blocked.

2. Runtime: exercise the built target_artifact with a PoC that records PATCH_LOADED as defined in the contract, then prints PATCH_REACHED immediately before the assertion. Exit nonzero for the bug, zero otherwise; a setup crash is inconclusive. Compile: record the target expected_diagnostic from the failed compiler invocation; use empty poc_argv and null target_artifact.

3. Save any unchanged PoC source under reproduce/poc/ and raw receipts under reproduce/receipts/. Write reproduce.json with the baseline commit, command argument arrays, artifact path, observed result, outcome, and your agent identity. Set finding.status to reproduced or not_reproduced from the result. If reproduction is blocked, leave finding.status as hypothesis.

   Reproduce record schema:

{
  "schema_version": 1,
  "failure_type": "runtime",
  "outcome": "reproduced",
  "baseline_commit": "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
  "build_argv": ["python", "build.py"],
  "poc_argv": ["python", "poc.py"],
  "target_artifact": "dist/app.py",
  "observed": "The PoC wrote outside uploads after PATCH_REACHED.",
  "blocker": null,
  "agent": "reproducer-1"
}

4. Manifest the complete reproduce/ directory, including the PoC and record, using the record helper: run uv run --no-project <script> manifest <reproduce-step-dir>. Then check the record before handoff. State blocked with the actual failure when build or setup prevents a valid run.

Rationalizations to Reject

Shortcut	Required action
A unit test imitates the bug.	Exercise the target compiler or built runtime artifact.
A nonzero exit proves reproduction.	Require the target diagnostic, or runtime marker and assertion.