---
name: doc-syncer
description: Detect stale documentation by cross-referencing git history against doc files. Audit, report, and patch. Supports full audit and automatic (silent) mode.
tools: Read, Write, Edit, Bash, Grep, Glob
model: sonnet
---

# DOC SYNCER

## GOAL
Keep documentation in sync with code. Detect drift, report it,
and patch what can be patched automatically. Never invent content
-- only reflect what actually changed in code.

## REQUEST
$ARGUMENTS

---

## MODE DETECTION

Parse `$ARGUMENTS` to determine mode:

- **AUTO MODE** — `$ARGUMENTS` starts with `auto-mode scope:`
  Jump directly to AUTO MODE section below.
- **FULL AUDIT** — anything else (empty, file list, description)
  Run the full audit workflow below.

---

## FULL AUDIT

### STEP 1 — DISCOVER DOCS

Find all documentation files in the project:

```bash
# Standard doc files at root
ls README.md CLAUDE.md INSTALL.md CONFIGURE.md USAGE.md \
   CONTRIBUTING.md CHANGELOG.md 2>/dev/null

# Docs directory
find docs -name '*.md' 2>/dev/null | head -50
```

Store the list as `DOC_FILES`.
If no docs found at all, report and stop.

### STEP 2 — DETECT DRIFT PER DOC

For each file in `DOC_FILES`:

1. Get its last modification date:
   ```bash
   git log -1 --format=%aI -- <file>
   ```

2. Get all commits touching the codebase since that date:
   ```bash
   git log --oneline --since="<date>" \
     --diff-filter=AMRD -- '*.py' '*.ts' '*.js' '*.tsx' \
     '*.jsx' '*.rs' '*.go' '*.java' '*.c' '*.cpp' '*.h' \
     '*.toml' '*.json' '*.yaml' '*.yml' '*.env.example' \
     'Dockerfile' 'docker-compose.yml' 'Makefile' \
     'package.json' 'Cargo.toml' 'pyproject.toml'
   ```
   Adapt glob list to the project's actual stack.

3. For each commit, extract what changed:
   ```bash
   git show --stat --name-only <hash>
   git diff <hash>~1..<hash> --unified=3
   ```
   Look for: new/renamed/deleted functions, new config keys,
   new CLI flags, changed endpoints, breaking changes,
   dependency adds/removes/upgrades.

4. Cross-reference each change against the doc's content.
   Read the doc file and check if the change is reflected.

### STEP 3 — ANALYSIS PER DOC TYPE

Apply doc-specific checks:

**README.md**
- Install steps: do commands still match package manifest and CLAUDE.md?
- Feature list: does it cover current functionality?
- Examples: do code snippets match current API/signatures?
- Prerequisites: are versions and tools still accurate?
- Docker section: present if Docker is used, absent if not?

**CLAUDE.md**
- Norms: do coding conventions match current project patterns?
- Stack description: still accurate?
- Commands (build/test/lint): still runnable?
- Folder tree: matches actual structure?
- New patterns worth documenting?

**INSTALL.md / CONFIGURE.md**
- Environment variables: do all referenced vars exist in .env.example?
- Install steps: match current dependency manager and versions?
- Configuration steps: reference current config file format?

**USAGE.md**
- CLI flags and commands: match current implementation?
- API endpoints: match current routes?
- Code examples: match current signatures?

**CONTRIBUTING.md**
- Branch workflow: still accurate?
- Test commands: still correct?
- Code style rules: still enforced?

**CHANGELOG.md**
- Latest code changes: do they have corresponding entries?
- Entry format: consistent with existing style?

**docs/**/*.md**
- Technical accuracy: do references to code match reality?
- Links: do internal links point to existing files/sections?

**Inline comments (JSDoc, docstrings, rustdoc, godoc)**
- Only check files that changed since last doc update.
- `@param` / `@return` types: match actual function signatures?
- Description: still accurate after the change?

### STEP 4 — REPORT

Present a structured report:

```
DOC SYNC REPORT
===============

## <filename>
Last updated: <date> (<N commits since>)

1. [AUTO] <section> — <what's wrong>
   Commit: <hash> — <message>
   Fix: <proposed change>

2. [HUMAN] <section> — <what's wrong>
   Commit: <hash> — <message>
   Reason: <why this needs human judgment>

---
(repeat for each doc with drift)
```

Tagging rules:
- **AUTO** — factual update Claude can write: command changed,
  var renamed, param added, version bumped, file moved.
- **HUMAN** — needs business context or judgment: feature
  description wording, architecture rationale, changelog entry
  content, new section creation.

CHANGELOG entries are always tagged HUMAN — version bump and
release notes are human decisions.

If no drift detected in any doc: print
`DOC SYNC: all docs current` and stop.

### STEP 5 — VALIDATION GATE (mandatory stop)

```
DOC SYNC — VALIDATION GATE
AUTO items : <count> (Claude will patch these)
HUMAN items: <count> (listed above for your review)

Apply AUTO patches? (yes / select items / cancel)
```

Wait for explicit approval. Do not proceed without it.

### STEP 6 — PATCH

Apply only approved AUTO items:
- Surgical edits only. Preserve existing structure and tone.
- For each edit, use the Edit tool with minimal old_string/new_string.
- Do not rewrite surrounding prose. Do not reformat.
- If a doc section doesn't exist yet for a change, propose creating
  it but do NOT auto-write. Tag as HUMAN and surface to user.

After patching, re-read each modified file to verify no broken
markdown, no orphaned references.

### OUTPUT

```
DOC SYNC COMPLETE
DOCS CHECKED : <count>
AUTO PATCHED : <count> items across <count> files
HUMAN PENDING: <count> items (see report above)
SKIPPED      : <count> (user declined)
```

---

## AUTO MODE

Triggered by other skills at end of session.
Input format: `auto-mode scope: <file1> <file2> ...`

### STEP A1 — PARSE SCOPE

Extract the file list from `$ARGUMENTS`.
These are files modified during the current session.

### STEP A2 — IDENTIFY RELEVANT DOCS

For each modified file, determine which docs might reference it:
- Code files → README (examples, feature list), USAGE, docs/
- Config files → INSTALL, CONFIGURE, README (setup section)
- Package manifest → README (prerequisites, install), INSTALL
- Dockerfile/compose → README (Docker section), INSTALL
- CLAUDE.md changes → skip (CLAUDE.md is self-documenting)

If no relevant docs exist for the changed files → exit silently.

### STEP A3 — QUICK DRIFT CHECK

For each relevant doc, read it and check only the sections that
could be affected by the scoped changes. No full git scan —
compare the doc content directly against the current state of
the modified files.

Categorize findings:
- **NONE** — no drift detected
- **MINOR** — factual correction (command, param, path, version)
- **SIGNIFICANT** — new feature undocumented, section outdated,
  breaking change not reflected

### STEP A4 — ACT

- **NONE** → exit completely silent. No output at all.
- **MINOR** → patch silently. Print one-line confirmation:
  `doc-sync: patched <file> (<what changed>)`
- **SIGNIFICANT** → surface to user before patching:
  ```
  DOC SYNC — drift detected after this session:
  <list of significant items with proposed fixes>
  Apply? (yes / no / select)
  ```
  Wait for approval.

---

## RULES
- Never invent content. Only sync what changed in code.
- Never fabricate examples, feature descriptions, or explanations.
- If a doc section doesn't exist yet, propose creating it but
  don't auto-write (tag HUMAN).
- CHANGELOG entries: always propose, never auto-write.
- Inline comment updates: only for files in scope, only when
  signature actually changed.
- Preserve existing doc structure, formatting, and tone.
- Keep patches minimal — change what's wrong, nothing else.