fix(#990): add critical commit-before-exit rule to skill

[fullsend-ai-coder]

Summary

Adds two instruction-level guardrails to skills/code-implementation/SKILL.md to prevent the recurring "completed work, no commit" failure where the agent finishes implementation and verification but stops before executing git add / git commit, discarding all work when the sandbox exits.

Changes:

• Top-level critical rule (new ## Critical rule — commit before exit section before the Process flow): States that git add and git commit must be the agent's final tool calls before any text response, and that a disclosed partial commit is always better than no commit.
• Step transition guard (between step 9d and step 10): Instructs the agent to proceed IMMEDIATELY to commit after verification passes, without producing text summaries or status updates first.

Context

This addresses the specific failure variant observed in agents#318 (run 32757440821) where the agent completed all work with 31 minutes remaining and simply ended the session before committing. It complements existing defense-in-depth proposals:

• Post-code guard: detect uncommitted working-tree changes after agent exit #976 — harness-level detection of uncommitted changes
• Code-implementation skill should add a time checkpoint during implementation to commit partial work before timeout #773 — time-budget checkpoint during implementation
• Code-implementation skill should verify git working tree is clean after commit #584 — post-commit staging verification
• Code-implementation skill: add commit-existence gate before declaring success #821 — commit-existence gate before declaring success

The step-transition language (change #2) is scoped to avoid duplicating #821's proposed change #3 per the triage agent's coordination note.

Testing

• Secret scan passed on changed files and staged content
• Pre-commit hooks run directly (sandbox network blocked pre-commit run): trailing-whitespace, end-of-file-fixer, detect-private-key, check-merge-conflict, mixed-line-ending all passed
• make test — all tests pass except pre-existing failures in post-retro-test.sh (unrelated to this change)
• gitlint validation passed

---

Closes #990

Post-script verification

• Branch is not main/master (agent/990-commit-before-exit-rule)
• Secret scan passed (gitleaks — dc7c805632ebb6b79a4b0890ef6da17fe8fc539d..HEAD)
• PR body secret scan passed (gitleaks — no-git)

[fullsend-ai-review]

🤖 Finished Review · ✅ Success · Started 6:53 PM UTC · Completed 7:03 PM UTC

Commit: 7e50e32 · View workflow run →

Runtime: claude · Model: opus → claude-opus-4-6 · Effort: high · Cost: $2.20

[fullsend-ai-review]

Review

Findings

Medium

• [protected-path] skills/code-implementation/SKILL.md — This file is under the skills/ protected path. The PR links to issue Code-implementation skill should add a critical commit-before-exit rule #990 and the description explains the rationale (addressing the recurring "completed work, no commit" failure), providing sufficient context. Human approval is always required for protected-path changes, regardless of context.

Low

• [scope-overlap-coordination] skills/code-implementation/SKILL.md:854 — The triage note on issue Code-implementation skill should add a critical commit-before-exit rule #990 warned that the step-transition guard (change chore: update fullsend shim workflow #2) overlaps with Code-implementation skill: add commit-existence gate before declaring success #821's proposed change fix(#1): update harness dest paths and restructure for forge #3. The PR author acknowledged this in the body and states the change was scoped to avoid duplication. The two changes address different failure triggers (Code-implementation skill: add commit-existence gate before declaring success #821: pre-commit failure causing step-skipping; this PR: model voluntarily stopping after verification), making them complementary. A future merge conflict is possible when Code-implementation skill: add commit-existence gate before declaring success #821 lands — the Code-implementation skill: add commit-existence gate before declaring success #821 implementer should check this section for potential duplication or consolidation.

[fullsend-ai-review]

See the review comment for full details.

[fullsend-ai-review]

[low] scope-overlap-coordination

The triage note on issue #990 warned that the step-transition guard (change #2) overlaps with #821 proposed change #3. The PR author acknowledged this in the body and states the change was scoped to avoid duplication. The two changes address different failure triggers (#821: pre-commit failure causing step-skipping; this PR: model voluntarily stopping after verification), making them complementary. A future merge conflict is possible when #821 lands.

Suggested fix: When #821 is implemented, the implementer should check this section for potential duplication or consolidation. No blocking action needed before merging this PR.