feat: adversarial spec review loop + skill chaining (v0.9.1.0) (#249)

* feat: add {{SPEC_REVIEW_LOOP}}, {{DESIGN_SKETCH}}, benefits-from resolvers

Three new resolvers in gen-skill-docs.ts:

- {{SPEC_REVIEW_LOOP}}: adversarial subagent reviews documents on 5
  dimensions (completeness, consistency, clarity, scope, feasibility)
  with convergence guard, quality score, and JSONL metrics
- {{DESIGN_SKETCH}}: generates rough HTML wireframes for UI ideas using
  DESIGN.md constraints and design principles, renders via $B
- {{BENEFITS_FROM}}: parses benefits-from frontmatter and generates
  skill chaining offer prose (one-hop-max, never blocks)

Also extends TemplateContext with benefitsFrom field and adds inline
YAML frontmatter parsing for the new field.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: /office-hours spec review loop + visual sketch phases

- Phase 4.5 ({{DESIGN_SKETCH}}): for UI ideas, generates rough HTML
  wireframe using design principles from {{DESIGN_METHODOLOGY}} and
  DESIGN.md, renders via $B, presents screenshot for iteration
- Phase 5.5 ({{SPEC_REVIEW_LOOP}}): adversarial subagent reviews the
  design doc before user sees it — catches gaps in completeness,
  consistency, clarity, scope, and feasibility
- Adds {{BROWSE_SETUP}} for $B availability in sketch phase

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* feat: skill chaining — plan reviews offer /office-hours

- plan-ceo-review: benefits-from office-hours, offers /office-hours when
  no design doc found, mid-session detection when user seems lost,
  spec review loop on CEO plan documents
- plan-eng-review: benefits-from office-hours, offers /office-hours when
  no design doc found
- One-hop-max chaining: never blocks, max one offer per session

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* test: add validation + E2E tests for spec review, sketch, benefits-from

Unit tests (32 new assertions):
- SPEC_REVIEW_LOOP: 5 dimensions, Agent dispatch, 3 iterations, quality
  score, metrics path, convergence guard, graceful failure
- DESIGN_SKETCH: DESIGN.md awareness, wireframe, $B goto/screenshot,
  rough aesthetic, skip conditions
- BENEFITS_FROM: prerequisite offer in CEO + eng review, graceful
  decline, skills without benefits-from don't get offer
- office-hours structure: spec review loop, adversarial dimensions,
  visual sketch section

E2E tests (2 new):
- office-hours-spec-review: verifies agent understands the spec review
  loop from SKILL.md
- plan-ceo-review-benefits: verifies agent understands the skill
  chaining offer

Touchfiles updated for diff-based test selection.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

* chore: bump version and changelog (v0.9.1.0)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -1,5 +1,14 @@
 # Changelog
 
+## [0.9.1.0] - 2026-03-20 — Adversarial Spec Review + Skill Chaining
+
+### Added
+
+- **Your design docs now get stress-tested before you see them.** When you run `/office-hours`, an independent AI reviewer checks your design doc for completeness, consistency, clarity, scope creep, and feasibility — up to 3 rounds. You get a quality score (1-10) and a summary of what was caught and fixed. The doc you approve has already survived adversarial review.
+- **Visual wireframes during brainstorming.** For UI ideas, `/office-hours` now generates a rough HTML wireframe using your project's design system (from DESIGN.md) and screenshots it. You see what you're designing while you're still thinking, not after you've coded it.
+- **Skills help each other now.** `/plan-ceo-review` and `/plan-eng-review` detect when you'd benefit from running `/office-hours` first and offer it — one-tap to switch, one-tap to decline. If you seem lost during a CEO review, it'll gently suggest brainstorming first.
+- **Spec review metrics.** Every adversarial review logs iterations, issues found/fixed, and quality score to `~/.gstack/analytics/spec-review.jsonl`. Over time, you can see if your design docs are getting better.
+
 ## [0.9.0.1] - 2026-03-19
 
 ### Changed