[EdbertChan]

Summary

A checker can stop a reply that uses a test as proof the real program works.

The written rule already said to rerun the check that failed. A later test could still stand in for the program a person runs.

The checker now reads the commands from the session. After that program has run and files have changed, the same program and action must run again.

Review Claim

A test cannot stand in for the real program that already showed the behavior.

Review Lane

behavior

Review Unit

engine-runtime

Safety Invariant

The gate blocks only when a product command already ran, a file was edited after it, and a test runner then ran without that same program and subcommand. An unreadable transcript does not block. A session that never ran a product command does not block.

Confirmed by the user on 2026-10-10.

Slice Rationale

This slice is the checker only. The written skill page that points at it stays out, so the review stays on one unit.

Non-goals

Does not install the checker into a running editor. Does not change the written skill page. Does not change the app people run.

Architecture

Before

graph TD
    A["reply ends"] --> B["ship claim check"]
    B --> C["allow or block that claim"]

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After

graph TD
    A["reply ends"] --> B["ship claim check"]
    B --> C["same command check"]
    C --> D["allow or block"]

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Measured

Command: CATSTACK_HOOK_TEST_MODEL=gpt-5.6-sol python3 -m unittest discover -s engine/hooks/prove-it-ship-gate/tests -k TestSameRepro -q

• base: git grep -c TestSameRepro origin/main -- engine/hooks/prove-it-ship-gate/tests/test_hooks.py exited 1 and printed nothing
• head: Ran 7 tests in 0.006s then OK, exit 0

Command: replay the session up to the test-runner turn, then same_repro_gap

• base: the check is absent on main
• head: ['invoker-cli --help', 'invoker-cli --version', 'invoker-cli doctor', 'invoker-cli query']

Test Plan

Test Plan

• python3 scripts/ci/check_hook_test_coverage.py engine/hooks/prove-it-ship-gate — check_hook_test_coverage: OK (1 hook(s) checked)
• ruff check --select E9,F engine/hooks/prove-it-ship-gate/cursor_stop_check.py engine/hooks/prove-it-ship-gate/detect.py engine/hooks/prove-it-ship-gate/tests/test_hooks.py — All checks passed!
• CATSTACK_HOOK_TEST_MODEL=gpt-5.6-sol python3 -m unittest discover -s engine/hooks/prove-it-ship-gate/tests -q — Ran 38 tests in 0.504s then OK
• Not run: installing the checker into the live editor. Blocker: that changes every later Cursor stop until this pull request is merged and the installer is run

Revert Plan

Revert Plan

• Safe to revert? Yes
• Revert command: git revert 3199d8af
• Post-revert steps: None
• Data migration? No

[cursor]

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(requestId: 7cde26fb-cce2-4071-a41a-92544739bcad)

[EdbertChan]

This pull request is part of a Mergify stack:

#	Pull Request	Link
1	Stop a test from standing in for the real program	#1322	👈
2	Stop the same proof miss in Claude, Cursor, and Codex.	#1323

[EdbertChan]

@Mergifyio queue

[mergify]

Merge Queue Status

• ✅ Entered queue — 2026-10-11 17:51 UTC · Rule: admin-bypass · triggered by @EdbertChan with the @mergifyio queue command
• ✅ Checks passed · on draft merge queue: checking #1322 on main (0adc86f) #1337
• ✅ Merged — 2026-10-11 18:52 UTC · at 0d8f2e02985d9359ca92df6b001426b2d7e836b1 · squash

This pull request spent 1 hour 50 seconds in the queue, including 1 hour 31 seconds running CI.

Required conditions to merge

• check-success = lint
• check-success = test
• check-success = validate