Bug Fix Brief (BFB)

Overview

This skill generates a Bug Fix Brief (BFB): a structured document in docs/bfb/ that uniformly captures every bug fix with root cause, repro steps, fix options, and checklist.

When to Use

• User asks to create a BFB
• User wants to document a bug fix in a structured way
• After identifying the root cause of a bug and before implementing the fix

Trigger: "create BFB", "document bug", "bug fix brief", "document fix"

Instructions

Phase 1: Gather Information

Check existing numbering:

ls docs/bfb/ 2>/dev/null || echo "Directory does not exist"

Ask the user for:

• BFB number (or propose next sequential)
• Concise title (3-5 words, kebab-case)
• Issue link (e.g. #1287)
• Environment (Prod/Stg/Dev) + version
• Observed vs expected behavior
• File/function/line of the cause

Phase 2: Generate Template

Complete the full BFB template:

## BFB-XXX: [Title]

**Reference:** [Issue link]
**Environment:** [Env] `vX.Y.Z`
**Date:** YYYY-MM-DD

---

### 1. Bug
- **Observed:** [wrong behavior]
- **Expected:** [correct behavior]

### 2. Repro

1. ...
2. ...

→ [error/output]

### 3. Cause
`path/file.ext` — `function()` @ line N
[Why it happens, max 3 lines]

### 4. Decision
| Option | Fix | Choice |
|--------|-----|--------|
| A | [desc] | ✅/❌ |
| B | [desc] | ✅/❌ |

**Rationale:** [why]

### 5. Fix
- [ ] [change 1]
- [ ] [test]
- [ ] [verify repro]

### 6. Notes
[recurring patterns, links, warnings]

Phase 3: Ask Confirmation

Show the generated BFB and ask with AskUserQuestion:

• "Create the BFB"
• "Edit before creating"
• "Cancel"

Phase 4: Write to Disk

Only after approval:

mkdir -p docs/bfb

Write to docs/bfb/BFB-XXX-title.md

Examples

Input: "create BFB for login email null crash"

Final output:

## BFB-042: Login crash with null email

**Reference:** #1287
**Environment:** Prod `v2.4.1`
**Date:** 2026-05-02

---

### 1. Bug
- **Observed:** App crashes if email field is empty
- **Expected:** Error message "Email required"

### 2. Repro

1. Open login screen
2. Tap "Login" without entering email

→ NullPointerException @ AuthManager.kt:34

### 3. Cause
`AuthManager.kt` — `validateEmail()` @ line 34
Missing null check on email.trim()

### 4. Decision
| Option | Fix | Choice |
|--------|-----|--------|
| A | Add safe call `?.` | ✅ |
| B | Refactor with Result type | ❌ |

**Rationale:** Option A is minimal, zero impact.

### 5. Fix
- [ ] Add `email?.trim()?.isNotEmpty() == true`
- [ ] Test `validateEmail_null_returnsFalse()`
- [ ] Verify repro

### 6. Notes
- Check other forms for missing null checks

Best Practices

1. Sequential numbering: BFB-001, BFB-002, no gaps
2. Concise title: 3-5 words, kebab-case in filename
3. Root cause: exact file, function, line
4. 2+ fix options: with pros/cons and rationale
5. Verifiable checklist: each item must be testable

Constraints and Warnings

• Confirmation required: Always ask before writing
• Max 3 lines for cause: Stay concise
• Directory `docs/bfb/`: Create if it does not exist