fix

name	fix
description	Applies targeted fix to known bug/lint error, verifies with same command that surfaced it. Triggers: fix, apply fix, fix bug, fix lint, targeted fix.
effort	low
disable-model-invocation	true
argument-hint	[test or lint target]
allowed-tools	Bash, Read, Edit, Grep

Fix Command

$ARGUMENTS

Attempts to fix code errors autonomously.

Usage

/fix <file_or_scope>
# Example: /fix src/utils.ts

Automated Error Classification

Before entering the fix loop, classify errors to prioritize auto-fixable ones:

# Pipe lint or test output
ruff check . 2>&1 | python3 ${CLAUDE_SKILL_DIR}/scripts/error-classifier.py
mypy src/ 2>&1 | python3 ${CLAUDE_SKILL_DIR}/scripts/error-classifier.py
npx eslint . 2>&1 | python3 ${CLAUDE_SKILL_DIR}/scripts/error-classifier.py

The script outputs JSON with:

• total_errors: count of all parsed errors
• auto_fixable_count: errors that tools can fix automatically (e.g., F401 unused imports, formatting)
• manual_count: errors requiring human/agent intervention
• tools_detected: which linters produced the output (ruff, mypy, eslint, tsc, phpstan)
• errors[]: each error with file, line, code, message, and auto_fixable flag
• suggested_order: files to fix, auto-fixable first
• fix_strategy: recommended approach (auto-fix first, then manual)

Use this to run auto-fixers (e.g., ruff check --fix .) before spending time on manual fixes.

---

Protocol (The "Fix Loop")

1. Analyze: Run validation to get the exact error message.

   # Get error
   npm test src/utils.ts 2>&1 | tee error.log
   

2. Diagnose: Analyze error.log.

   • Use debugging-tactics skill.
   • Trace the error to the source line.

3. Patch: Apply a fix.

   • Use sed or write_file.

4. Verify: Run validation again.

   • If PASS: Stop.
   • If FAIL: Repeat (Max 3 retries).

Safety Limits

• Max Retries: 3
• Scope: Only modify the specified files.
• Stop Condition: If new errors appear that are totally different, STOP and ask user.

Example Flow

User: /fix app.py
Agent: Running tests... FAIL (NameError)
Agent: Fixing app.py (Import missing module)
Agent: Running tests... PASS
Agent: Fixed NameError in app.py

Rules

• MUST know the exact symptom (error message, failing test, lint code) before editing — guessing is not fixing
• MUST verify the fix by rerunning the same command that exposed the problem, not a different validator
• NEVER modify tests to make them pass — fixing the test is not fixing the bug
• NEVER touch files outside the declared scope — scope creep hides regressions
• CRITICAL: hard-stop after 3 iterations. If the fix loop has not converged, the problem is deeper than /fix handles — escalate to /debug.
• MANDATORY: if new, unrelated errors appear during a fix attempt, stop and ask the user — do not chase them

Gotchas

• ruff check --fix reorders imports and rewrites them. On files with circular imports or conditional-imports-under-TYPE_CHECKING, the "fix" can break things silently. Run --check first, inspect the diff, then apply.
• eslint --fix --cache skips already-cached files even if their content changed (cache invalidation by mtime). On first-run misses, clear the cache with --no-cache to force a complete pass.
• mypy --install-types auto-installs stub packages, adding dependencies to the environment the user did not request. Reserve it for explicit opt-in; in CI, pass --non-interactive to prevent surprise installs.
• npm test -- path/to/test in a workspace repo runs the root workspace's test runner, not the leaf package's. Use npm test --workspace=<name> or the per-package cd packages/foo && npm test form.
• Fix loops occasionally produce cycle diffs — iteration 1 fixes A which triggers B, iteration 2 fixes B which re-breaks A. After every iteration compare the diff to the previous; identical or inverse diffs mean a cycle — stop.

When NOT to Use

• When the root cause is unknown — use /debug first, then /fix with a clear target
• For systemic refactoring across modules — use /refactor or /refactor-plan
• For writing new features test-first — use /tdd
• For CI failures spanning many files — use /workflow debugging (coordinated)
• When the failing validation is itself broken — repair the validator separately, do not patch code to satisfy it