git-bisect-debugging

# Git Bisect Debugging

## Overview

Systematically identify which commit introduced a bug or regression using git bisect. This skill provides a structured workflow for automated, manual, and hybrid bisect approaches.

**Core principle:** Binary search through commit history to find the exact commit that introduced the issue. Main agent orchestrates, subagents execute verification at each step.

**Announce at start:** "I'm using git-bisect-debugging to find which commit introduced this issue."

## Quick Reference

| Phase | Key Activities | Output |
|-------|---------------|--------|
| **1. Setup & Verification** | Identify good/bad commits, verify clean state | Confirmed commit range |
| **2. Strategy Selection** | Choose automated/manual/hybrid approach | Test script or verification steps |
| **3. Execution** | Run bisect with subagents | First bad commit hash |
| **4. Analysis & Handoff** | Show commit details, analyze root cause | Root cause understanding |

## MANDATORY Requirements

These are **non-negotiable**. No exceptions for time pressure, production incidents, or "simple" cases:

1. **✅ ANNOUNCE skill usage** at start:
   ```
   "I'm using git-bisect-debugging to find which commit introduced this issue."
   ```

2. **✅ CREATE TodoWrite checklist** immediately (before Phase 1):
   - Copy the exact checklist from "The Process" section below
   - Update status as you progress through phases
   - Mark phases complete ONLY when finished

3. **✅ VERIFY safety checks** (Phase 1 - no skipping):
   - Working directory MUST be clean (`git status`)
   - Good commit MUST be verified (actually good)
   - Bad commit MUST be verified (actually bad)
   - If ANY check fails → abort and fix before proceeding

4. **✅ USE AskUserQuestion** for strategy selection (Phase 2):
   - Present all 3 approaches (automated, manual, hybrid)
   - Don't default to automated without asking
   - User must explicitly choose

5. **✅ LAUNCH subagents** for verification (Phase 3):
   - Main a