git:20260305.3ae8b92 to git:20260321.4a2afd0

---

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."

---

# 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

```bash

/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

```markdown

## 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

```