ln-614-docs-fact-checker

What this skill does

> **Paths:** File paths (`references/`, `../ln-*`) are relative to this skill directory.

# Documentation Fact-Checker (L3 Worker)

**Type:** L3 Worker

Specialized worker that extracts verifiable claims from documentation and validates each against the actual codebase.

## Purpose & Scope

- Prioritize canonical and high-claim docs, then extract verifiable claims from markdown documentation
- Verify each claim against codebase (Grep/Glob/Read/Bash)
- Detect **cross-document contradictions** (same fact stated differently)
- Includes `docs/reference/`, `docs/tasks/`, `tests/` in scope
- Single invocation (not per-document) -> cross-doc checks require global view
- Does NOT check scope alignment or structural quality

## Inputs

**MANDATORY READ:** Load `references/audit_worker_core_contract.md`, `references/docs_quality_contract.md`, and `references/markdown_read_protocol.md`.
Optional rule catalog: load `references/docs_quality_rules.json` only when exact rule IDs, path matrices, or allowlisted placeholder exceptions are needed.
Tool policy: follow host AGENTS.md MCP preferences; load `references/mcp_tool_preferences.md` and `references/mcp_integration_patterns.md` only when host policy is absent or MCP behavior is unclear.

Receives `contextStore` with: `tech_stack`, `project_root`, `output_dir`.

## Workflow

### Phase 1: Parse Context

Extract tech stack, project root, output_dir from contextStore.

### Phase 2: Discover Documents

Glob markdown docs in project. Exclude:
- `node_modules/`, `.git/`, `dist/`, `build/`
- `docs/project/.audit/` (audit output, not project docs)
- `CHANGELOG.md` (historical by design)

If `docs/project/.context/doc_registry.json` exists:
- load it first
- prioritize `doc_role=canonical`
- prioritize files with dense claim types (paths, endpoints, versions, commands)
- de-prioritize navigation hubs unless contradictions point back to them

### Phase 3: Extract Claims (Layer 1)

Detection policy: use two-layer detection (candidate scan, then context verification); load `references/two_layer_detection.md` only when the verification method is ambiguous.

For each prioritized document, use section-first reads to extract verifiable claims using Grep/regex patterns.

For code files referenced by docs, use `outline()` and discovery-first `read_file()` before built-in reads. Only request `edit_ready=true, verbosity="full"` if verification turns into a follow-up edit. Use `hex-graph` only when entity identity or reference resolution remains ambiguous after direct manifest/file checks.

**MANDATORY READ:** Load [references/claim_extraction_rules.md](references/claim_extraction_rules.md) for detailed extraction patterns per claim type.

9 claim types:

| # | Claim Type | What to Extract | Extraction Pattern |
|---|-----------|-----------------|-------------------|
| 1 | **File paths** | Paths to source files, dirs, configs | Backtick paths, link targets matching `src/`, `lib/`, `app/`, `docs/`, `config/`, `tests/` |
| 2 | **Versions** | Package/tool/image versions | Semver patterns near dependency/package/image names |
| 3 | **Counts/Statistics** | Numeric claims about codebase | `\d+ (modules|formats|endpoints|services|tables|parsers|files|workers)` |
| 4 | **API endpoints** | HTTP method + path | `(GET|POST|PUT|DELETE|PATCH) /[\w/{}:]+` |
| 5 | **Config keys/env vars** | Environment variables, config keys | `[A-Z][A-Z_]{2,}` in config context, `process.env.`, `os.environ` |
| 6 | **CLI commands** | Shell commands | `npm run`, `python`, `docker`, `make` in backtick blocks |
| 7 | **Function/class names** | Code entity references | CamelCase/snake_case in backticks or code context |
| 8 | **Line number refs** | file:line patterns | `[\w/.]+:\d+` patterns |
| 9 | **Docker/infra claims** | Image tags, ports, service names | Image names with tags, port mappings in docker context |

Output per claim: `{doc_path, line, claim_type, claim_value, raw_context}`.

### Phase 4: Verify Claims (Layer 2)

For each extracted claim, verify against codebase:

| Claim Type | Verification Method | Finding Type |
|------------|-------------------|--------------|
| File paths | Glob or `ls` for existence | PATH_NOT_FOUND |
| Versions | Grep package files (package.json, requirements.txt, docker-compose.yml), compare | VERSION_MISMATCH |
| Counts | Glob/Grep to count actual entities, compare with claimed number | COUNT_MISMATCH |
| API endpoints | Grep route/controller definitions | ENDPOINT_NOT_FOUND |
| Config keys | Grep in source for actual usage | CONFIG_NOT_FOUND |
| CLI commands | Check package.json scripts, Makefile targets, binary existence | COMMAND_NOT_FOUND |
| Function/class | Grep in source for definition | ENTITY_NOT_FOUND |
| Line numbers | Read file at line, check content matches claimed context | LINE_MISMATCH |
| Docker/infra | Grep docker-compose.yml for image tags, ports | INFRA_MISMATCH |

**False positive filtering (Layer 2 reasoning):**
- Template placeholders (`{placeholder}`, `YOUR_*`, `<project>`, `xxx`) -> skip
- Example/hypothetical paths (preceded by "e.g.", "for example", "such as") -> skip
- Future-tense claims ("will add", "planned", "TODO") -> skip or LOW
- Conditional claims ("if using X, configure Y") -> verify only if X detected in tech_stack
- External service paths (URLs, external repos) -> skip
- Paths in SCOPE/comment HTML blocks describing other projects -> skip
- `.env.example` values -> skip (expected to differ from actual)

### Phase 5: Cross-Document Consistency

Compare extracted claims across documents to find contradictions:

| Check | Method | Finding Type |
|-------|--------|--------------|
| Same path, different locations | Group file path claims, check if all point to same real path | CROSS_DOC_PATH_CONFLICT |
| Same entity, different version | Group version claims by entity name, compare values | CROSS_DOC_VERSION_CONFLICT |
| Same metric, different count | Group count claims by subject, compare values | CROSS_DOC_COUNT_CONFLICT |
| Endpoint in spec but not in guide | Compare endpoint claims across api_spec.md vs guides/runbook | CROSS_DOC_ENDPOINT_GAP |

Algorithm:
```
claim_index = {}  # key: normalized(claim_type + entity), value: [{doc, line, value}]
FOR claim IN all_verified_claims WHERE claim.verified == true:
  key = normalize(claim.claim_type, claim.entity_name)
  claim_index[key].append({doc: claim.doc_path, line: claim.line, value: claim.claim_value})

FOR key, entries IN claim_index:
  unique_values = set(entry.value for entry in entries)
  IF len(unique_values) > 1:
    CREATE finding(type=CROSS_DOC_*_CONFLICT, severity=HIGH,
      location=entries[0].doc + ":" + entries[0].line,
      issue="'" + key + "' stated as '" + val1 + "' in " + doc1 + " but '" + val2 + "' in " + doc2)
```

### Phase 6: Score & Report

**MANDATORY READ:** Load `references/audit_scoring.md`.

Calculate score using penalty formula. Write report.

## Audit Categories (for Checks table)

| ID | Check | What It Covers |
|----|-------|---------------|
| `path_claims` | File/Directory Paths | All path references verified against filesystem |
| `version_claims` | Version Numbers | Package, tool, image versions against manifests |
| `count_claims` | Counts & Statistics | Numeric assertions against actual counts |
| `endpoint_claims` | API Endpoints | Route definitions against controllers/routers |
| `config_claims` | Config & Env Vars | Environment variables, config keys against source |
| `command_claims` | CLI Commands | Scripts, commands against package.json/Makefile |
| `entity_claims` | Code Entity Names | Functions, classes against source definitions |
| `line_ref_claims` | Line Number References | file:line against actual file content |
| `cross_doc` | Cross-Document Consistency | Same facts across documents agree |

## Severity Mapping

| Issue Type | Severity | Rationale |
|------------|----------|-----------|
| PATH_NOT_FOUND (critical file: AGENTS.md, CLAUDE.md, runbook, api_spec) | CRITICAL | Setup/onboardin