feat(graceful-handoff): 2.0 — migrate to skills/ with disable-model-invocation [skip-docs]

Step 1 of v2.0 plan. Hard cut from commands/ to skills/ per Anthropic
recommendation for new plugins. Frontmatter sets disable-model-invocation:
true and pins model: claude-sonnet-4-6. Docs (README, CLAUDE.md, root
README) deferred to Step 9 per plan.

plugins/ultraplan-local/CLAUDE.md

@@ -90,6 +90,25 @@ If `{project_dir}/architecture/overview.md` exists (typically produced by the se
 | contrarian-researcher | sonnet | Counter-evidence, overlooked alternatives |
 | gemini-bridge | sonnet | Gemini Deep Research second opinion (conditional) |
 
+## Quality infrastructure (v3.1.0)
+
+`lib/` contains zero-dep validators and parsers wired into the four commands:
+
+- `lib/util/{frontmatter,result}.mjs` — shared YAML-frontmatter parser + Result helpers
+- `lib/parsers/{plan-schema,manifest-yaml,project-discovery,arg-parser,bash-normalize}.mjs` — pure parsers (no I/O), unit-tested
+- `lib/validators/{brief,research,plan,progress}-validator.mjs` — schema validators with CLI shims (`node lib/validators/X.mjs --json <path>`)
+- `lib/validators/architecture-discovery.mjs` — drift-WARN external-contract discovery for `architecture/overview.md`
+
+Wiring points (replaces previous prose-grep instructions):
+- `/ultrabrief-local` Phase 4g → `brief-validator` (post-write sanity check)
+- `/ultraplan-local` Phase 1 → `brief-validator --soft`, `research-validator --dir`, `architecture-discovery`
+- `planning-orchestrator` Phase 5.5 → `plan-validator --strict` (replaces 3 `grep -cE` calls)
+- `/ultraexecute-local --validate` → `plan-validator --strict` + `progress-validator`
+
+Tests under `tests/**/*.test.mjs` (109 tests, 0 deps). `npm test` is the fork-readiness gate.
+
+Doc-consistency test at `tests/lib/doc-consistency.test.mjs` pins agent-table count, command-table coverage, plan_version invariant, and settings.json scope cleanliness.
+
 ## Architecture
 
 **Brief:** 7-phase workflow: Parse mode → Create project dir → Phase 3 completeness loop (section-driven, no question cap) → Phase 4 draft/review/revise with `brief-reviewer` as stop-gate (max 3 iterations; gate = all dimensions ≥ 4 and research plan = 5) → Finalize (`brief.md` on pass, or `brief_quality: partial` on cap/force-stop) → Manual/auto opt-in → Stats. Always interactive. Auto mode runs research + plan inline in the main context (v2.4.0).