Vibe Fix Bug Skill

Spec-driven bug diagnosis and surgical fixing. Diagnosis before fix. Regression test before fix code. Smallest possible change.

Use Plan Mode (Shift+Tab) for Steps 1–5. Exit before Step 6.

The O'Reilly principles this enforces

Spec before code — root cause confirmed and fix plan approved before any code changes. Context preservation — CODEBASE.md read first, ARCHITECTURE.md patterns followed. Incremental verifiable progress — regression test first, fix second, verify third. Drift prevention — DECISIONS.md updated, ARCHITECTURE.md updated if fix reveals new pattern.

Two audiences. Two file types.

Human-facing:

• vibe/TASKS.md — plain English, updated after every task

Agent-facing (human never opens these):

• vibe/bugs/[date-slug]/BUG_SPEC.md · BUG_PLAN.md · BUG_TASKS.md
• vibe/CODEBASE.md · vibe/ARCHITECTURE.md · vibe/DECISIONS.md

Step 1 — Gather the bug report and triage severity

Extract or ask for:

• What's happening — the symptom
• What should happen — expected behaviour
• Steps to reproduce — how to trigger it
• Frequency — always / sometimes / only under X
• Errors or logs — any messages or stack traces

Triage — three paths:

Environment bug — route to vibe-doctor, NOT the bug workflow:

Check for these signals first:

• App won't start / server fails to launch
• WebSocket/HMR connection errors
• Cannot find module, MODULE_NOT_FOUND
• Tailwind classes not applying / CSS not loading
• husky: command not found or git hook failures
• Environment variable undefined at startup
• .git operation failures or submodule errors
• Build tool errors (Vite, Webpack, tsc) that aren't TypeScript type errors

If 2+ environment signals → this is an environment bug:

"This looks like an environment issue, not a code bug. Running doctor: to diagnose..."

Invoke vibe-doctor. After doctor: completes:

• If doctor fixed it and app starts → close, no bug folder created
• If doctor fixed env but code bug remains → continue to Trivial or Significant path
• If doctor can't fix → surface doctor's "NEEDS ATTENTION" items to user

Trivial bug — ALL of these must be true:

• Root cause obvious from description (typo, missing CSS class, obvious off-by-one)
• Fix touches 1-2 lines in 1 file
• No regression risk in other features
• No architectural implication
• NOT an environment issue (handled above)

→ "This is a quick fix. Regression test, fix, verify — 3 tasks, no spec folder needed." → Jump to Trivial path below.

Significant bug — root cause unclear, multiple files, regression risk, or architectural implication. → "This needs full diagnosis. Let me read the codebase." → Continue to Step 2.

Trivial path

Insert into TASKS.md directly — no bug folder created:

🐛 [Bug summary — plain English] (0/3)
   [ ] BUG-001 · Regression test — write test that fails on current code
   [ ] BUG-002 · Apply fix — [one line: exactly what changes]
   [ ] BUG-003 · Verify — regression test passes, full suite green, linter clean
   → Trivial fix — no spec folder

Update "What just happened" and "What's next":

## What just happened
🐛 Bug found: [plain English description]
Quick fix path — regression test first.

## What's next
⬜ BUG-001 · Write a test that reproduces the bug
Say "next" to begin.

After BUG-003, collapse to: ✅ [Bug summary] — fixed [date] (3/3 ✅)

CLAUDE.md: No active bug section needed for trivial fixes — complexity doesn't warrant it.

DECISIONS.md: Append a brief entry:

---
### D-[ID] — Trivial fix: [bug summary]
- **Date**: [date] · **Type**: drift (trivial bug)
- **Root cause**: [one sentence]
- **Fix**: [one sentence — what changed and in which file]
- **Regression test**: [test name]
- **Approved by**: human
---

Step 2 — Read vibe/CODEBASE.md (significant bugs only)

If vibe/CODEBASE.md exists: Read fully. Use section 9 (key file paths) and section 5 (API routes) to pinpoint where to look. If significantly out of date, note this to the user.

If vibe/CODEBASE.md does not exist: Read references/CODEBASE_MD.md for the generation template. Explore codebase focused on the bug area first — don't let CODEBASE.md generation delay diagnosis. Generate after the bug is understood.

Also read vibe/ARCHITECTURE.md — the fix must follow existing patterns. Also read vibe/DESIGN_SYSTEM.md if the bug is in a styled component.

Step 3 — Explore and diagnose (time-boxed)

Check for dependency graph first:

ls vibe/graph/DEPENDENCY_GRAPH.json 2>/dev/null && echo "GRAPH EXISTS" || echo "NO GRAPH"

If graph exists — query it for the suspected file:

vibe-graph: query [suspected file from Step 2]

The graph returns the blast radius immediately — imports, imported_by, test file, verifier, API routes, concept. Load only those files. Do NOT load the full CODEBASE.md — the graph replaces that read.

Also query the concept:

vibe-graph: query [concept name from graph result]

This shows upstream/downstream concepts where the bug may originate or propagate.

If no graph exists — fall back to CODEBASE.md: Using CODEBASE.md section 9 as your map, read relevant files.

In both cases:

• Read the blast radius files fully — do not skim
• Trace execution path from entry to failure
• Check recent git changes: git log --oneline -20 -- <file>
• Read relevant test files to understand expected behaviour

Time-box: If after reading 5 files the root cause is still unclear, stop. Present findings and top 2 hypotheses to the user. Ask for additional context. Don't explore indefinitely — surface uncertainty early.

Form a hypothesis. Point to the exact file, function, and line.

Step 4 — Generate BUG_SPEC.md

Draft BUG_SPEC.md:

1. Bug summary — one sentence
2. Files involved — exact paths from CODEBASE.md section 9
3. Root cause hypothesis — specific theory with line-level detail
4. Confidence level — how confident? what would change your mind?
5. Blast radius — what else could be affected by this bug or the fix?
6. Fix approach — what should change and why
7. What NOT to change — leave alone to avoid regressions
8. Verification plan — exact steps to confirm fix worked
9. Regression test — what test would catch this if it reappeared

Present. Ask: "Does this diagnosis look right?" Wait for confirmation. Save as vibe/bugs/[date-slug]/BUG_SPEC.md.

Step 5 — Generate BUG_PLAN.md

Read BUG_SPEC.md, files involved, existing tests. Check ARCHITECTURE.md — fix must follow patterns.

Draft BUG_PLAN.md:

1. Exact files to modify — nothing outside this list
2. Exact files NOT to touch — explicit list
3. Change description — for each file: what changes, which line, why
4. Conventions to follow — from CODEBASE.md section 6 and ARCHITECTURE.md
5. Side effects check — what could break?
6. Test plan — regression test spec + existing tests that must still pass
7. Rollback plan — how to revert
8. CODEBASE.md update needed? — Yes (which sections) or No (state explicitly)
9. ARCHITECTURE.md update needed? — Yes if fix reveals a pattern to document / No

Principle: Smallest possible change. Never fix other bugs noticed — log them separately.

Present. Ask: "Does this fix plan look right?" Wait for approval. Save as vibe/bugs/[date-slug]/BUG_PLAN.md.

Step 6 — Update CLAUDE.md (project root)

Append bug fix section — do NOT overwrite:

---
### Active Bug Fix: [Bug summary]
> Folder: vibe/bugs/[date-slug]/ | Added: [date]

**Files in scope**: [only files from BUG_PLAN.md]
**Files out of scope**: [everything else]
**Design system**: [check vibe/DESIGN_SYSTEM.md if bug is in styled component]
**Scope changes**: If user says "change:" — stop and run vibe-change-spec.

**Boundaries:**
Always: write regression test BEFORE fix · run full suite after fix ·
        smallest change only · follow ARCHITECTURE.md patterns ·
        update CODEBASE.md if fix changes routes/schema/files/patterns ·
        update TASKS.md after every task in plain English
Ask first: touching any file not in BUG_PLAN.md · refactoring beyond minimal fix
Never: fix other bugs noticed · modify existing passing tests ·
       introduce new patterns · change unrelated code "while here"

**Done condition:**
- [ ] Regression test written and passing
- [ ] Full test suite green · Linter clean
- [ ] No files outside BUG_PLAN.md scope modified
- [ ] CODEBASE.md updated if fix changed structure
- [ ] ARCHITECTURE.md updated if fix revealed a pattern

**Session startup:** Read CLAUDE.md · CODEBASE.md · ARCHITECTURE.md · TASKS.md · BUG_SPEC.md · BUG_TASKS.md
**Between tasks:** "next" → re-read TASKS.md silently → state next task in plain English → confirm.
---

Save updated CLAUDE.md.

Step 7 — Generate BUG_TASKS.md

Read BUG_SPEC.md, BUG_PLAN.md, CODEBASE.md.

---
### BUG-001 · Write the regression test
- **Status**: `[ ]` | **Depends on**: None | **Touches**: [test file path]

**What to do**: Write a test that reproduces the bug exactly.
Must FAIL on current code before the fix. Name it clearly.

**Acceptance criteria**:
- [ ] Test exists and clearly named
- [ ] Test FAILS on current unfixed code — verified
- [ ] Test isolates the exact failing behaviour

**⚠️ Boundaries**: Do not touch any non-test files in this task.
**Decisions**: > Filled in by agent. None yet.
---

### BUG-002 · Implement the fix
- **Status**: `[ ]` | **Depends on**: BUG-001 | **Touches**: [exact paths from BUG_PLAN.md]
- **CODEBASE.md update**: [Yes — which sections / No — logic only]

**What to do**: [Fix from BUG_PLAN.md — specific and precise]
Modify only files in BUG_PLAN.md. Follow ARCHITECTURE.md patterns.
If CODEBASE.md update required, do it before marking done.

**Acceptance criteria**:
- [ ] Only BUG_PLAN.md files modified
- [ ] Matches BUG_PLAN.md approach
- [ ] Follows existing patterns — no new patterns introduced without ARCHITECTURE.md update
- [ ] No other behaviour changed
- [ ] CODEBASE.md updated if structural change

**⚠️ Boundaries**: Ask first before files not in BUG_PLAN.md · never refactor unrelated code
**Decisions**: > Filled in by agent. None yet.
---

### BUG-003 · Verify fix and run full suite
- **Status**: `[ ]` | **Depends on**: BUG-002 | **Touches**: none

**What to do**:
1. Run regression test from BUG-001 — must now pass
2. Run full test suite — all pre-existing tests must still pass
3. Run linter — no new errors

**Acceptance criteria**:
- [ ] Regression test passes
- [ ] All pre-existing tests pass — no regressions
- [ ] Linter clean

**Decisions**: > Filled in by agent. None yet.
---

### BUG-004 · Update docs
- **Status**: `[ ]` | **Depends on**: BUG-003
- **Touches**: [files with comments about buggy behaviour, if any]

**What to do**:
1. Update inline comments or JSDoc describing now-fixed behaviour
2. If BUG_PLAN.md section 8 says CODEBASE.md needs updating: update and add changelog line
3. If BUG_PLAN.md section 9 says ARCHITECTURE.md needs updating: add the pattern now

**Acceptance criteria**:
- [ ] Comments reflect corrected behaviour
- [ ] CODEBASE.md updated if fix changed structure
- [ ] ARCHITECTURE.md updated if fix revealed a pattern to document

**Decisions**: > Filled in by agent. None yet.
---

End with sign-off checklist:

---
#### Bug Fix Sign-off: [Bug summary]
- [ ] Regression test written, named clearly, passes after fix
- [ ] Full test suite green — no regressions
- [ ] Linter clean
- [ ] No files outside BUG_PLAN.md scope modified
- [ ] CODEBASE.md updated if fix changed structure
- [ ] ARCHITECTURE.md updated if fix revealed a pattern to document
- [ ] DECISIONS.md updated if any deviation from BUG_PLAN.md
- [ ] Doc commits separate from code commits
---

Save as vibe/bugs/[date-slug]/BUG_TASKS.md.

Step 8 — Update vibe/TASKS.md

1. Note previously active feature or "none".

2. Insert inline bug block above active feature:

🐛 [Bug summary in plain English] (0/4)
   [ ] BUG-001 · Regression test — reproduce the bug in a test
   [ ] BUG-002 · Implement fix — smallest change that resolves root cause
   [ ] BUG-003 · Verify and run full suite — regression passes, nothing else broke
   [ ] BUG-004 · Update docs
   → Full specs: vibe/bugs/[date-slug]/BUG_TASKS.md (agent use)

3. Update "What just happened" and "What's next":

## What just happened
🐛 Bug found: [plain English description of what was broken]
Starting fix — regression test first, then fix.

## What's next
⬜ BUG-001 · Write a test that reproduces the bug
   Must fail before fix and pass after — proves the fix works.
Say "next" to begin.

After each task: mark [x], update count, update What just happened + What's next in plain English.

When fix completes: collapse to single line, restore interrupted feature:

✅ [Bug summary] — fixed [date] (4/4 ✅)

Step 9 — Update vibe/DECISIONS.md

---
### D-[ID] — Bug fix: [Bug summary]
- **Date**: [date] · **Type**: drift
- **Folder**: vibe/bugs/[date-slug]/
- **Root cause**: [one line from BUG_SPEC.md]
- **Files in scope**: [from BUG_PLAN.md]
- **Fix approach**: [one line]
- **CODEBASE.md update**: [Yes — what / No]
- **ARCHITECTURE.md update**: [Yes — what pattern documented / No]
- **Deviations from BUG_PLAN.md**: [logged below / none]
---

Tell the user:

✅ Bug fix kit ready.

>

Created: vibe/bugs/[date-slug]/ BUG_SPEC.md · BUG_PLAN.md · BUG_TASKS.md Updated: vibe/TASKS.md · CLAUDE.md · vibe/DECISIONS.md

Read execution mode:

grep "VIBE_MODE" CLAUDE.md 2>/dev/null | cut -d= -f2 | tr -d ' '

If autonomous → read ~/.claude/skills/vibe-mode/references/AUTONOMOUS_EXECUTION_BLOCK.md and follow the autonomous execution protocol. Begin immediately. Note: regression test task always runs first — it has no dependencies.

If manual or not set → tell the user:

Tell your coding agent: `` Read CLAUDE.md, vibe/CODEBASE.md, vibe/ARCHITECTURE.md, vibe/TASKS.md. Confirm first task before writing any code. `` Regression test first. Always. Fix second. Say "next" after each task.

Step 10 — Update dependency graph

After the fix is complete and verified, invoke vibe-graph: update.

The graph reads git diff --name-only HEAD to detect exactly which files the fix touched. Only those nodes are re-indexed. Any new files created during the fix get added as new nodes. Edges are updated to reflect any import changes made during the fix.

This step runs automatically — no user input needed. Keeps blast radius data accurate for the next bug that touches these files.