Bug Fix Skill

Trigger

• Keywords: bug, issue, fix, error, broken, failing

When NOT to Use

• New feature development (use feature-dev)
• Just want to understand code (use code-explore)
• Pure test-only tasks without feature changes (use /codex-test-review directly)

Prohibited Actions

❌ git add | git commit | git push — per @rules/git-workflow.md

This skill fixes bugs but does not commit. /precommit is a quality gate only. To commit, the user must invoke /smart-commit --execute separately.

Workflow

Investigate → Locate → Fix → Test + Review → Precommit Gate
  │             │       │         │                │
  ▼             ▼       ▼         ▼                ▼
gh issue      Grep    Edit     /verify          /precommit
/git-investigate  Read  tests  /codex-test-review
                               /codex-review-fast

Phase 1: Investigation

Before fixing: if the bug maps to a feature under docs/features/, read docs/features/<key>/intent-<key>.md when it exists — a fix that contradicts one of its INV-* invariants or Non-goals stops and asks the user (cite the line). No identifiable feature → nothing to load; proceed.

Source	Action
GitHub Issue	gh issue view <number>
Error message	Grep("error message")
Code history	/git-investigate

Output root cause analysis:

• Problem location: src/<module>/<file>:<line>
• Root cause:
• Impact scope:

Phase 2: Fix

Principle	Description
Minimal changes	Only modify what is necessary
No new issues	Confirm changes don't affect other features
Design preserved	Choose the smallest root-cause fix that keeps current responsibilities. If the fix moves a boundary or adds an abstraction, say which shape you chose and why — "direct fix; existing design retained" is the expected common answer

Phase 3: Add Regression Test ⚠️

Follow @rules/testing.md for conventions (AAA, naming, evidence model). Follow @rules/testing-project.md for project-specific overrides.

Bug fixes must have tests at the corresponding level:

Bug Type	Required	Recommended
Logic error	Unit	-
Service issue	Unit	Integration
API issue	Integration	E2E
Cross-service/data flow	Integration	E2E
User flow	E2E	-

Phase 4: Verify + Review

Step 1: Run tests

/verify → all tests pass?
  Yes → Step 2
  No → fix failures → re-run /verify

Step 2: Test adequacy review (mandatory for code changes)

/codex-test-review → ✅ Tests sufficient?
  Yes → Step 3
  No → close gaps (Step 2a) → /codex-test-review --continue <threadId>

Step 2a: Gap closure

Gap Type	Remediation
Unit test missing	/codex-test-gen → write tests → /verify
Integration/E2E missing	/post-dev-test → write tests → /verify

Step 3: Code review (auto-loop)

/codex-review-fast → ✅ Ready?
  Yes → Precommit Gate
  No → fix issues → re-run /codex-review-fast (auto-loop)

Freshness rule

If code changes after the latest ✅ Tests sufficient gate (e.g., fixes from code review), rerun /verify then /codex-test-review --continue <threadId> before proceeding to precommit gate.

Review Loop

MUST re-review after fix until PASS (per @rules/auto-loop.md)

Fix → Review → Issues found → Fix again → ... → ✅ Pass → Next step

Doc Sync

Doc Sync is governed by @rules/auto-loop.md (behavior-layer rule). After precommit pass, triggers conditionally when changes map to docs/features/.

Output

## Bug Fix Report
- **Root cause**: <analysis>
- **Fix**: <description of changes>
- **Regression test**: <test result>
- **Gate**: ✅ Fixed / ⛔ Needs further investigation

Verification Checklist

• Root cause identified and documented
• Regression test written at appropriate level
• All tests pass (/verify)
• Test adequacy reviewed (/codex-test-review)
• Code review passed (/codex-review-fast ✅ Ready)
• Precommit passed (/precommit ✅ All Pass)
• No git add/commit/push executed

Examples

Input: Fix issue #123 - calculation error
Action: gh issue view → locate → fix → write Unit Test → /verify → /codex-test-review → /codex-review-fast → /precommit

Input: API returning 500 error
Action: Grep error → read code → fix → write Integration Test → /verify → /codex-test-review → /codex-review-fast → /precommit