Doc Gap Check

Doc-gap check (DOC-164 slice 7+)

Build or refresh the cross-sidecar doc-gap report at lineage/{repo}/doc-gaps.md. The doc-gap-finder reducer walks every per-node sidecar's docs_link_semantic block, re-WebFetches each claimed URL to verify status + anchor + content alignment, joins the concept catalog (concepts.yaml) against the live documentation/docs/SUMMARY.md to surface concept-without-page gaps, runs the Type-5 bidirectional drift probe per adrs/drafts/research/agentic-code-ontology/PROBES.md, and writes a ranked candidate list the maintainer triages.

This skill is the third reducer in the agentic-code-ontology layer (per adrs/drafts/agentic-code-ontology.md rev 2). The first per-node enrichment slice was /enrich (slice 5). The first reducer was /concepts (slice 6 — concept catalog). /doc-gap-check (slice 7) consumes both.

Argument forms

Incremental input resolution

Before spawning the subagent in default (incremental) mode, the skill computes:

• PROCESSED_NODE_IDS — read from prior doc-gaps.md's frontmatter processed_node_ids:. Missing → --full fallback.
• NEW_SIDECAR_FILES — sidecars whose node_id is not in PROCESSED_NODE_IDS. Empty set → exit.
• PRIOR_HEAD — one line per existing DOC-GAP-NNN from prior doc-gaps.md, derived via grep -E '^## DOC-GAP-' + severity + category. Compact-head shape per the playbook.
• CURATED_ENTRIES — verbatim Markdown of every entry flagged maintainer_curated: true.
• NEXT_AVAILABLE_ID — max existing DOC-GAP-NNN + 1.

These get passed to the subagent in place of the legacy "full prior artefact" block. Live URLs are still re-verified per Rule 1 (the playbook does NOT relax the live-URL requirement — only the prior-artefact-reading cost).

Prerequisites

• lineage/{repo}/understanding/{slug}.md sidecars exist (i.e. /enrich has been run at least once).
• lineage/{repo}/concepts.yaml exists (i.e. /concepts has been run after the most recent enrichment).
• documentation/docs/SUMMARY.md is reachable (local at ../documentation/docs/SUMMARY.md preferred; live https://docs.opendatadiscovery.org/ fallback).
• WebFetch tool is available — every URL gets verified live; stale verification copied from sidecars is forbidden by the subagent's Rule 1.
• findings/docs-coverage-undocumented-features/2026-05-08.md is read for cross-reference (existing F-047..F-060 candidates) so the reducer doesn't duplicate.

Protocol

1. Orient

Read these (skip if loaded this session):

• CLAUDE.md — quality bar
• adrs/drafts/agentic-code-ontology.md — the layered ADR + reducer pattern
• .claude/agents/doc-gap-finder.md — the subagent's system prompt
• findings/docs-coverage-undocumented-features/2026-05-08.md — DOC-163 prior findings (cross-reference target so the reducer doesn't double-file)

2. Resolve inputs

• Sidecar set: Glob lineage/{repo}/understanding/*.md. Confirm at least one sidecar exists; otherwise report "no sidecars to walk — run /enrich first" and exit.
• Concepts catalog: lineage/{repo}/concepts.yaml. Confirm exists; if not, report "concepts.yaml missing — run /concepts first" and exit (the reducer joins concepts × SUMMARY.md).
• Existing doc-gaps: lineage/{repo}/doc-gaps.md. Capture maintainer-curated entries (maintainer_curated: true) for preservation.
• SUMMARY.md: prefer ../documentation/docs/SUMMARY.md (local sibling). Fallback: WebFetch https://docs.opendatadiscovery.org/.
• Substrate state: read lineage/{repo}/manifest.yaml's last_scan_commit so the produced report can record generated_at_commit.
• Existing F-NNN findings: read findings/docs-coverage-undocumented-features/*.md paths so the subagent can cross-reference (not duplicate).

3. Spawn the doc-gap-finder subagent

Invoke via Agent tool with subagent_type: doc-gap-finder (after .claude/agents/doc-gap-finder.md is loaded; in transient sessions general-purpose is the fallback). Construct the prompt as:

REPO: <repo>
WORKSPACE_ROOT_ABS: <absolute>
SIDECAR_DIR_ABS: /home/.../lineage/{repo}/understanding/
CONCEPTS_YAML_PATH: /home/.../lineage/{repo}/concepts.yaml
DOC_SUMMARY_PATH: <absolute path to ../documentation/docs/SUMMARY.md or live URL>
SUBSTRATE_LAST_SCAN_COMMIT: <from manifest.yaml>
EXISTING_DOC_GAPS: <verbatim content of lineage/{repo}/doc-gaps.md if present, else "(none)">
EXISTING_DOC_NNN_FINDINGS: <list of paths to findings/docs-coverage-undocumented-features/*.md for cross-reference>
TARGET_PATH: lineage/{repo}/doc-gaps.md
SIDECAR_COUNT: <N>

The subagent's tool surface per its frontmatter is Read, Glob, Grep, WebFetch, Write. It writes the report and replies with Wrote: ... + Findings: ....

4. Validate the resulting report

After completion:

• Confirm lineage/{repo}/doc-gaps.md exists.
• Parse YAML frontmatter (generated_at, total_findings, findings_by_severity, etc.). Missing keys are an error.
• Verify each finding entry has category, surfaced_by, evidence, proposed_doc_action, severity. Missing field = log warning + report.
• Spot-check 3-5 random findings: do their surfaced_by sidecar references resolve to real files? Do their evidence URLs resolve when re-fetched?
• HIGH-severity findings get an extra check: the maintainer triages these first; if the evidence is thin (single sidecar, no live-fetch confirmation), demote to MEDIUM and warn.

5. Report

Concise output:

• Report path
• Counts: <H> HIGH / <M> MEDIUM / <L> LOW = <N> total findings
• Categories: broken-url: n, missing-anchor: n, drift: n, missing-page: n, stale-page: n, coverage-gap: n
• Top-5 HIGH findings (one-liners with finding IDs)
• Cross-references to DOC-163's F-NNN: <count> findings overlap with prior cataloged gaps
• Suggested next: /triage findings/docs-coverage-undocumented-features/2026-05-08.md to catalog these as DOC-NNN backlog items, then /concepts to refresh the catalog if doc additions changed canonical-vocab.

Rules

• Live-URL-only re-verification. The doc-gap-finder MUST WebFetch every URL fresh in the session. Stale verifications copied from sidecars are forbidden — the subagent's prompt enforces this; the skill double-checks via spot-fetch on 3-5 sampled URLs.
• Cross-reference, don't duplicate. If a finding matches DOC-163's F-NNN catalog, the entry's cross_references field cites the F-NNN; the finding does NOT re-file the same gap as a new entry.
• Severity is anchored to operator impact. HIGH = operator follows the doc → broken/insecure deployment. MEDIUM = partial coverage / wrong-slug-but-resolvable. LOW = cosmetic. The skill rejects HIGH findings with thin evidence and warns to demote.
• Maintainer-curated entries preserved. Existing maintainer_curated: true entries in prior doc-gaps.md survive verbatim through refreshes (the subagent reads EXISTING_DOC_GAPS and preserves; the skill verifies preservation in step 4).
• Reducer doesn't fix. The subagent surfaces gaps; it doesn't author doc pages. Maintainer triages into DOC-NNN, then /implement slices ship the doc updates.

Failure modes to surface

• WebFetch fails repeatedly (network outage, rate-limit on docs.opendatadiscovery.org) → surface as a partial run; the existing doc-gaps.md is preserved; no auto-write.
• Subagent reports HIGH findings whose surfaced_by doesn't cite a sidecar → CRITICAL; reject the report; ask for prompt revision.
• More than 50% of findings cite the same single sidecar → likely sidecar-quality issue, not doc gap; surface to maintainer for sidecar refresh via /enrich --node <id>.
• Severity distribution skewed (e.g. >70% HIGH) → likely severity-inflation; surface for maintainer recalibration.

Cross-references

• Subagent: .claude/agents/doc-gap-finder.md
• Inputs: lineage/{repo}/understanding/*.md + lineage/{repo}/concepts.yaml
• Output: lineage/{repo}/doc-gaps.md
• Live source-of-truth: https://docs.opendatadiscovery.org/ + ../documentation/docs/SUMMARY.md
• Cross-reference target: findings/docs-coverage-undocumented-features/*.md (DOC-163 F-NNN catalog)
• ADR: adrs/drafts/agentic-code-ontology.md rev 2 (slice 7)
• Probe spec: adrs/drafts/research/agentic-code-ontology/PROBES.md (Type-5 bidirectional drift probe)
• Cornerstone enforced: documentation pillar Cornerstone 1 (discoverability without context)