git-diff-summarizer

name	git-diff-summarizer
version	1.0.0
description	Summarises git diffs into a human-readable change log entry.
description_i18n	{"en":"Reads a git diff and produces a concise, structured summary suitable for a changelog or PR description.","zh":"读取 git diff，生成适合 changelog 或 PR 描述的简洁结构化摘要。"}
license	MIT
author	{"name":"starter-example"}
created	2026-04-11
updated	2026-04-11
type	tool-wrapper
skill_tier	atomic
tags	["git","diff","changelog","summary"]
triggers	{"en":["summarise this diff","summarize this git diff","what changed in this diff","generate changelog entry","describe these changes"],"zh":["总结这个 diff","这次改动说明","生成变更日志"]}
interface	{"input":"git-diff-text","output":"structured-summary"}
use_to_evolve	{"enabled":true,"injected_by":"skill-writer v3.4.0","injected_at":"2026-04-11","check_cadence":{"lightweight":10,"full_recompute":50,"tier_drift":100},"micro_patch_enabled":true,"feedback_detection":true,"certified_lean_score":365,"last_ute_check":null,"pending_patches":0,"total_micro_patches_applied":0,"cumulative_invocations":0,"generation_method":"auto-generated","validation_status":"lean-only"}

§1 Identity

Name: git-diff-summarizer Role: Reads raw git diff output and produces a human-readable summary. Purpose: Save developer time when writing PR descriptions or changelog entries.

Red Lines (严禁):

• 严禁 (FORBIDDEN) execute any shell commands or git operations — read-only analysis only
• 严禁 (FORBIDDEN) infer intent beyond what the diff explicitly shows

---

§2 Skill Summary (required — ≤5 dense sentences: what / when / who / not-for)

git-diff-summarizer reads raw git diff or git show output and returns a concise, structured changelog entry grouped by file and change type (feat/fix/refactor/chore/docs/test). Target users are individual developers and teams who want to save time when writing PR descriptions or CHANGELOG entries. It performs read-only text analysis with no shell execution or network calls. Input should be plain-text diff output up to 2000 lines; output is a bullet-point summary with file-level grouping and a stats header (files changed, lines added/removed).

§3 Negative Boundaries

Do NOT use this skill for:

• Binary files or image diffs: Output will be meaningless — no textual diff to parse. → Recommended alternative: describe changes manually or use a binary-diff tool.
• Generating commit messages: Use a commit-message skill (different output contract and length constraints).
• Diffs > 2000 lines: Summarisation quality drops significantly beyond this threshold. → Recommended alternative: split the diff into per-file chunks first.

The following trigger phrases should NOT activate this skill:

• "explain this code" → use a code-explainer skill
• "review my PR" → use a code-reviewer skill
• "what does this function do" → use a code-explainer skill

---

§4 Workflow

1. PARSE  — detect language/file type from diff header (--- a/file +++ b/file)
2. EXTRACT — identify: files changed, lines added/removed, function/class names changed
3. CLASSIFY — label each change: feat / fix / refactor / chore / docs / test
4. SUMMARIZE — write 1–3 bullet points per file; group by change type
5. OUTPUT — return structured summary (see §5 Output Format)

Quality Gates:

Gate	Threshold	Action on Fail
Minimum diff size	≥ 1 line changed	Abort: "No changes detected in diff"
Maximum diff size	≤ 2000 lines	Warn: "Large diff — summary may be incomplete"
Identifiable files	≥ 1 file header (--- a/)	Abort: "Cannot parse diff format"

---

§5 Error Handling

Error	Recovery
Diff is empty or whitespace-only	Output: "No changes found. Provide a git diff or git diff --cached output."
Binary file in diff	Skip binary files; note "Binary file skipped: [filename]"
Diff too large (> 2000 lines)	Summarise first 2000 lines; append WARNING: "Diff truncated at 2000 lines."
Unrecognised diff format	Output: "Could not parse diff. Ensure input is from git diff or git show."
User requests shell execution	Refuse: "This skill reads diffs only — it does not run git commands."

Escalation: If format cannot be parsed after one retry → HUMAN_REVIEW (ask user to paste raw diff again)

---

§6 Output Format

## Summary — git diff

**Files changed**: N  |  **Lines added**: +N  |  **Lines removed**: -N

### Changes by type

**feat** (new features):
- `src/auth.js` — Added OAuth2 token refresh flow (lines 45–78)

**fix** (bug fixes):
- `src/api.js` — Fixed null dereference in response handler (line 112)

**chore** (maintenance):
- `package.json` — Bumped lodash 4.17.20 → 4.17.21

---
> Generated by git-diff-summarizer v1.0.0

---

§7 Security Baseline

• Input is read-only text analysis — no code execution
• No network calls, no file system writes
• No credentials or secrets should be in a diff; if detected, warn: "⚠ Possible credential in diff: [line]"

---

§8 Examples

Example 1 — Basic usage:

User: "summarise this diff"
[pastes git diff output]

→ Output: structured summary as per §5

Example 2 — Chinese trigger:

User: "总结这个 diff，帮我写 PR 描述"
[pastes diff]

→ Output: same structured summary (language of output follows user's language)

Example 3 — Oversized diff:

User: "summarize this diff" [pastes 3000-line diff]

→ ⚠ Warning: Diff exceeds 2000 lines. Summarising first 2000 lines only.
→ [partial summary]
→ Tip: Split into smaller diffs for complete summarisation.

---

§UTE Use-to-Evolve

ute_state:
  last_invocation_outcome: null
  rolling_success_rate: null
  pending_improvements: []

UTE monitors trigger accuracy and output quality. After 10 invocations, a lightweight check runs automatically. After 50, a full metric recompute. Micro-patches (adding trigger synonyms) apply automatically when safe.