DocGuard v0.31.0

Accuracy release — six research-backed detectors that make drift detection
change-aware and language-agnostic, built on one shared diff foundation. Every
new check was empirically tuned read-only against six real production repos
(TypeScript + Python) before shipping; all are deterministic (no LLM at
validation time) and soft (confidence: low, never break CI). Validator count
24 → 27.

Added

• docguard impact — doc→doc blast radius + agent-instruction files (feat 1).
  Agent-instruction files (AGENTS.md/CLAUDE.md/GEMINI.md) are now indexed, so a
  changed code file they reference is surfaced. New: when a canonical/agent doc
  changes, the docs that reference it — including agent-instruction files — are
  flagged as a "blast radius" ({ changedDocs, blastRadius } in JSON). No
  verified competitor propagates doc staleness across the doc graph. Proven on a
  real repo: an ARCHITECTURE.md change flags the AGENTS.md/CLAUDE.md that cite it.
• Diff-Suspicion validator (DSP001) (feat 3) — change-driven. A doc that BOTH
  references a code file changed since the ref AND shares domain tokens removed
  in that diff is flagged for review. Deterministic diff-overlap rule
  (arXiv 2010.01625, F1 74.7); path/module refs + domain-token filtering +
  per-doc cap keep it quiet at PR granularity.
• Reference-Existence validator (REF001) (feat 2) — two-revision check. A
  compound code identifier backticked in a doc that existed when the doc was last
  updated but has ZERO matches at HEAD is flagged as outdated (arXiv 2212.01479).
  In-memory HEAD identifier set + authoritative git-grep confirmation; zero false
  positives across the corpus.
• API-Doc-Smells validator (APS001 Bloated / APS002 Lazy) (feat 4) —
  deterministic length signals on signature-headed doc units (F1 0.90 / 0.95).
• IR-based traceability soft-matching (feat 5) — cli/shared-ir.mjs
  (zero-dep TF-IDF + cosine). An untraced requirement now surfaces the
  TF-IDF-closest test file ("X may already cover it — add @Req there"),
  reducing false "no coverage" for tests that lack the annotation.
• docguard verify --since <ref> — change-aware staging (feat 6). Attaches
  an activity-labeled (ordered replace/delete/add) structured diff to the staged
  agent-judgment tasks and flags which claims are about just-changed code —
  CARL-CCI showed the structured-diff representation drives judgment accuracy
  (arXiv 2512.19883).
• cli/shared-diff.mjs — zero-dependency unified-diff parser + identifier-
  aware tokenizer + activity-labeled diff, the shared foundation for feats 1/2/3/6.

Fixed

• hooks crash from a core.hooksPath edge and other pre-ship bugs caught by
  dogfooding DocGuard on itself (a walkFiles-vs-git grep dot-directory
  asymmetry that fabricated reference-existence false positives; a .map(basename)
  index-as-suffix crash in verify).
• Self-counting consistency — canonical-sync and metrics-consistency now
  agree on the validator count (both 27); a default-off validator previously made
  them disagree.

Changed

• New validators default ON except where noted; all are soft warnings.
• README, ARCHITECTURE.md, quickstart, CI-RECIPES, AGENTS.md updated to 27
  validators (historical version-log counts preserved).