git-intelligence Skill

Zero-install git analysis skill. The agent runs read-only git commands directly and uses its own reasoning to produce structured reports — no CLI tools, no API keys, no compilation.

When to Use

Activate when the user asks to:

"Summarize commits from the last N days / this week"
"Generate release notes between two tags"
"Analyze this PR / branch"
"Is this branch / PR risky?"
"What does this branch affect?"
"Who should review this PR?"

Step 1 — Verify Git Repository

Before any analysis, run:

git rev-parse --git-dir

If it returns a path → proceed
If it fails → stop and tell the user: "This directory is not a git repository. Please navigate to your project root first."

Step 2 — Intent Mapping

User says	Capability	Go to
"Summarize commits" / "What changed this week?"	summarize-commits	Step 3A
"Release notes" / "What's in v1.3?"	release-notes	Step 3B
"Analyze this PR" / "Full PR review"	analyze-pr	Step 3C
"Is this risky?" / "Risk check"	detect-risk	Step 3D
"What does this branch affect?" / "Impact?"	change-impact	Step 3E

Step 3A — Summarize Commits

Collect data:

# Convert duration: 7d=7 days ago, 2w=14 days, 1mo=1 month
git log --since="<ISO date>" --oneline --no-merges

Analyze: Classify each commit message by keyword:

feat / add / new / implement / support → Features
fix / bug / patch / resolve / hotfix → Fixes
refactor / clean / move / rename → Refactor
perf / optim / speed / cache → Performance
BREAKING CHANGE or !: notation → Breaking Changes
Unmatched → Features (default)

Use your own understanding to improve on keyword matching when the meaning is clear.

Output format:

## Commit Summary (since <duration>)

### Features
- <commit message>

### Fixes
- <commit message>

### Performance
- <commit message>

Omit empty sections. If no commits found: "No commits found since ."

Step 3B — Release Notes

Collect data:

# Verify tags exist first
git rev-parse --verify refs/tags/<from>
git rev-parse --verify refs/tags/<to>

# Get commits between tags
git log <from>..<to> --oneline --no-merges

If a tag doesn't exist, stop and report: "Tag <tag> not found. Run git tag -l to list available tags."

Analyze: Same classification as Step 3A, but rewrite commit messages into user-facing language where appropriate.

Output format:

## Release Notes: <from> → <to>

### Breaking Changes
- <change>

### Features
- <feature description>

### Fixes
- <fix description>

### Performance
- <improvement>

Omit empty sections (especially Breaking Changes).

Step 3C — Analyze PR

Combines risk detection + impact analysis + reviewer suggestion.

Collect data:

# Auto-detect base branch
git symbolic-ref refs/remotes/origin/HEAD   # e.g. refs/remotes/origin/main → "main"
# If fails → use "master"

# Get diff statistics
git diff <base>...<branch> --numstat

# For reviewer suggestion: blame top changed files (up to 5)
git blame --porcelain -- <file>

Analyze:

Compute risk score (same rules as Step 3D)
Map changed files → logical modules (group by top 2 path segments)
Parse blame output → count lines per author email → take top 3 authors by blame-line count
If fewer than 2 blame authors found, add role fallbacks: auth/ → "security team", payment/ → "payments team", infra/ → "infra team"
Suggest test cases based on affected modules and sensitive areas

Output format:

## PR Analysis: <branch>

### Summary
<1–2 sentence description of what the branch changes>

### Impacted Modules
- <module>

### Risk Score
<🔴/🟡/🟢> <score>/10

### Suggested Reviewers
- <name or role>

### Suggested Tests
- <test scenario>

Step 3D — Detect Risk

Collect data:

git symbolic-ref refs/remotes/origin/HEAD   # base branch, fallback to master
git diff <base>...<branch> --numstat

Risk scoring (heuristic):

Condition	Points
Files changed > 50	+3
Total lines changed > 1000	+3
Sensitive folder touched: `auth/`, `payment/`, `infra/`, `middleware/`, `cache/`	+2 per folder (max +4)
Test files < 10% of changed files	+1

Start at 1. Clamp final score to [1, 10]. Add your own reasoning on top of the heuristic if the code context warrants it.

Risk label: 🔴 score ≥ 8 · 🟡 score 5–7 · 🟢 score ≤ 4

Output format:

## Risk Assessment: <branch>

**Risk Score**: 🔴 8/10

**Reasons**:
- Large diff (1200 lines)
- Middleware module modified
- Low test coverage for changed files

Step 3E — Change Impact

Collect data:

git symbolic-ref refs/remotes/origin/HEAD   # base branch, fallback to master
git diff <base>...<branch> --numstat

Analyze:

Group files by top 2 path segments → logical module names
Identify sensitive modules (auth, payment, infra, middleware, cache) and flag them
Use your understanding of the codebase to infer downstream effects

Output format:

## Change Impact: <branch>

### Modules Affected
- <module path> — <brief impact note>

### Potential Risks
- <risk description>

Handling Edge Cases

Situation	Action
No commits in range	"No commits found for this period."
Tag not found	Report tag name, suggest `git tag -l`
Branch doesn't exist	Report error from git diff, suggest `git branch -a`
Large diff (> 100 files)	Analyze first 100 files, note truncation
Empty repository	"No commits yet in this repository."
Detached HEAD	Use `git rev-parse HEAD` as current ref

Read-Only Guarantee

This skill ONLY runs read-only git commands: git log, git diff, git blame, git rev-parse, git symbolic-ref, git tag, git show.

It NEVER runs: git commit, git checkout, git merge, git push, git stash, git reset, git add.

No files are created or modified in the repository.