/git-investigate

name: git-investigate
description: "Git history investigation. Use when: tracking code changes, finding where bugs were introduced, root cause analysis. Not for: code exploration (use code-explore), issue analysis (use issue-analyze). Output: history trace + root cause report."
allowed-tools: Bash(git:*), Read, Grep, Glob, Agent

Git Investigate Skill

Trigger

• Keywords: code history, git blame, track changes, who wrote this, when was it changed, root cause, code archaeology

When NOT to Use

• Code review (use codex-review)
• Feature development (use feature-dev)
• Just want to read code (use Read directly)

Command

/git-investigate src/service/xxx.ts:123      # Specific line
/git-investigate processToken                 # Function name
/git-investigate "error message"              # Keyword

Workflow

Locate code -> git blame -> find commit -> trace history -> analyze changes -> report

Investigation Framework

| Question | Method | | ------------------ | ----------------------------- | | Who wrote it? | `git blame` | | When was it changed?| `git log --follow` | | Why was it changed?| commit message + PR | | What was missed? | `git diff` compare original vs problematic version |

Common Patterns

| Pattern | Symptom | Root Cause | | ------------------ | -------------------- | ----------------------------- | | Type removed | Enum value deleted | Assumed no longer needed | | Condition simplified| If conditions reduced| Missed during refactoring | | Rename | Partially unchanged | Incomplete search-and-replace | | Boundary ignored | Only handles main flow| Edge cases not considered |

Output

## Git Investigation Report
- **Target**: <file/feature>
- **Timeline**: <commit range>
- **Root cause**: <analysis>
- **Introduced by**: <commit hash + author>

Verification

• Report includes: investigation target, author info, timeline, original vs problematic code
• Root cause has clear analysis
• Fix recommendation is specific and actionable

References

• `references/commands.md` - Git command reference + report template

Examples

Input: Who changed this line of code?
Action: git blame -> find commit -> trace PR -> output report

Input: When was this bug introduced?
Action: git log -p -S -> locate introduction point -> analyze cause -> output report