chain-verifier

Do not attempt to reconstruct the pipeline's history. Treat this as an independent audit — evaluate only what is present in the provided files and git diff. Requesting chain history defeats the purpose of this skill.

Input: Original requirements (verbatim) + final affected file paths + optional TEST_COMMAND.

Step 0 — Verify git repo and read chain start commit.

First, confirm this is a git repository:

Bash("git rev-parse --is-inside-work-tree 2>/dev/null || echo NOT_GIT")

If the result is NOT_GIT: output CHAIN_VERIFICATION_BLOCKED: not a git repository — chain-verifier requires git to compute diffs. Run chain-verifier only in git-managed projects. and stop.

Resolve working dir and read the chain start commit:

Bash("git rev-parse --show-toplevel 2>/dev/null || echo '.'")   # → WORKING_DIR
Bash("cat \"[WORKING_DIR]/.claude/checkpoints/chain-start-commit\" 2>/dev/null || echo NO_CHECKPOINT")   # → start-commit

This file is written by checkpoint-writer at the start of Phase 1. If the result is NO_CHECKPOINT, set start-commit to HEAD~1 and report: "chain-start-commit not found — checkpoint-writer may not have run. Falling back to HEAD~1 as approximate start commit — run git log --oneline -10 to verify the correct range, then diff with git diff HEAD~1."

Verify independently in this order:

1. Read the affected files. Use Read to examine every file in the affected file paths list. Do not skim — read enough to assess whether the requirements are met.

2. Verify requirements are satisfied. Compare the current code state against the original requirements text. Do not compare against any intermediate agent output.

3. Review all changes made by the chain. Resolve working dir first: Bash("git rev-parse --show-toplevel 2>/dev/null || echo '.'") → WORKING_DIR. Then run Bash("git -C [WORKING_DIR] diff [start-commit]") to see every change the pipeline made. Check for unexpected modifications outside the stated scope.

4. Check for unexpected changes. List any files modified that were not in the affected file paths list. Flag any behavior changes that the original requirements did not call for.

5. Run tests if a TEST_COMMAND was provided. Execute it with Bash and record the result.

Output format:

CHAIN_VERIFICATION:
Original requirement: "[verbatim quote]"
Actual code state: [summary of what the code currently does]
Changes made: [summary of git diff — files changed, lines added/removed]
Requirement met: YES | PARTIAL | NO
  Detail: [what is or is not satisfied]
Unexpected changes: [list of files or behaviors outside stated scope, or NONE]
Tests: PASS | FAIL | N/A
  Detail: [test output summary or "no TEST_COMMAND provided"]

VERDICT: APPROVED | NEEDS_REVERT | NEEDS_FIX
  Reason: [one sentence]

• APPROVED — requirements met, no unexpected changes, tests pass
• NEEDS_REVERT — cascaded errors make the changes unsafe; include the git log for revert target selection
• NEEDS_FIX — requirements partially met or tests fail, but revert is not necessary