docs: update project documentation for v1.73.0.0

- README.md, docs/skills.md, AGENTS.md: /autoplan phase order corrected to
  CEO → design → DX → eng (eng always last); /review rows note the advisory
  simplification lens
- docs/PROJECT_STRUCTURE.md: add agents-digest/, gen-agents-digest.ts,
  sandbox-doctor.sh, test-free-shards.ts to the annotated tree
- CONTRIBUTING.md: document GSTACK_FREE_JOBS, GSTACK_FREE_RETRY_FLAKY, and
  the sandbox-doctor one-command fixer in the Tier 1 test section

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/PROJECT_STRUCTURE.md

@@ -20,11 +20,14 @@ gstack/
 │   └── index.ts     # Registry: exports all, derives Host type
 ├── scripts/         # Build + DX tooling
 │   ├── gen-skill-docs.ts  # Template → SKILL.md generator (config-driven)
+│   ├── gen-agents-digest.ts  # Generates the budget-capped instruction-tier digest (agents-digest/)
 │   ├── host-config.ts     # HostConfig interface + validator
 │   ├── host-config-export.ts  # Shell bridge for setup script
 │   ├── resolvers/   # Template resolver modules (preamble, design, review, gbrain, etc.)
 │   ├── skill-check.ts     # Health dashboard
+│   ├── test-free-shards.ts  # Strict parallel free-suite runner (GSTACK_FREE_JOBS, opt-in flaky retry)
 │   ├── test-paid-shards.ts  # Sharded paid-tier runner (one Bun process per shard)
+│   ├── sandbox-doctor.sh  # One-command cloud-sandbox fixer: makes the free suite run green
 │   └── dev-skill.ts       # Watch mode
 ├── test/            # Skill validation + eval tests
 │   ├── helpers/     # skill-parser.ts, session-runner.ts, llm-judge.ts, eval-store.ts
@@ -40,7 +43,7 @@ gstack/
 ├── review/          # PR review skill
 ├── plan-ceo-review/ # /plan-ceo-review skill
 ├── plan-eng-review/ # /plan-eng-review skill
-├── autoplan/        # /autoplan skill (auto-review pipeline: CEO → design → eng)
+├── autoplan/        # /autoplan skill (auto-review pipeline: CEO → design → DX → eng, eng always last)
 ├── benchmark/       # /benchmark skill (performance regression detection)
 ├── canary/          # /canary skill (post-deploy monitoring loop)
 ├── codex/           # /codex skill (multi-AI second opinion via OpenAI Codex CLI)
@@ -61,6 +64,7 @@ gstack/
 │   ├── src/         # CLI + commands (generate, variants, compare, serve, etc.)
 │   ├── test/        # Integration tests
 │   └── dist/        # Compiled binary
+├── agents-digest/   # Committed 2KB instruction-tier rules digest (gstack-AGENTS.md) for rules-reading hosts
 ├── extension/       # Chrome extension (side panel + activity feed + CSS inspector)
 ├── lib/             # Shared libraries (worktree.ts, egress-receipt.ts, context-bill.ts, redact-engine.ts, tracker-guard.ts, version-source.ts, code-intelligence/)
 ├── patches/         # bun `patchedDependencies` patches (playwright-core windowsHide)

docs/skills.md

@@ -10,7 +10,7 @@ Detailed guides for every gstack skill — philosophy, workflow, and examples.
 | [`/plan-eng-review`](#plan-eng-review) | **Eng Manager** | Lock in architecture, data flow, diagrams, edge cases, and tests. Forces hidden assumptions into the open. |
 | [`/plan-design-review`](#plan-design-review) | **Senior Designer** | Interactive plan-mode design review. Rates each dimension 0-10, explains what a 10 looks like, fixes the plan. Works in plan mode. |
 | [`/design-consultation`](#design-consultation) | **Design Partner** | Build a complete design system from scratch. Knows the landscape, proposes creative risks, generates realistic product mockups. Design at the heart of all other phases. |
-| [`/review`](#review) | **Staff Engineer** | Find the bugs that pass CI but blow up in production. Auto-fixes the obvious ones. Flags completeness gaps. |
+| [`/review`](#review) | **Staff Engineer** | Find the bugs that pass CI but blow up in production. Auto-fixes the obvious ones. Flags completeness gaps. Advisory simplification lens flags over-built code — never blocks, never auto-applies. |
 | [`/investigate`](#investigate) | **Debugger** | Systematic root-cause debugging. Iron Law: no fixes without investigation. Traces data flow, tests hypotheses, stops after 3 failed fixes. |
 | [`/design-review`](#design-review) | **Designer Who Codes** | Live-site visual audit + fix loop. 80-item audit, then fixes what it finds. Atomic commits, before/after screenshots. |
 | [`/design-shotgun`](#design-shotgun) | **Design Explorer** | Generate multiple AI design variants, open a comparison board in your browser, and iterate until you approve a direction. Taste memory biases toward your preferences. |
@@ -29,7 +29,7 @@ Detailed guides for every gstack skill — philosophy, workflow, and examples.
 | [`/retro`](#retro) | **Eng Manager** | Team-aware weekly retro. Per-person breakdowns, shipping streaks, test health trends, growth opportunities. |
 | [`/browse`](#browse) | **QA Engineer** | Give the agent eyes. Real Chromium browser, real clicks, real screenshots. ~100ms per command. |
 | [`/setup-browser-cookies`](#setup-browser-cookies) | **Session Manager** | Import cookies from your real browser (Chrome, Arc, Brave, Edge) into the headless session. Test authenticated pages. |
-| [`/autoplan`](#autoplan) | **Review Pipeline** | One command, fully reviewed plan. Runs CEO → design → eng → DX review automatically with encoded decision principles. Surfaces only taste decisions for your approval. |
+| [`/autoplan`](#autoplan) | **Review Pipeline** | One command, fully reviewed plan. Runs CEO → design → DX → eng review automatically (eng always last, so the shipping gate reviews the final amended plan) with encoded decision principles. Surfaces only taste decisions for your approval. |
 | [`/plan-devex-review`](#plan-devex-review) | **DX Reviewer** | Plan-stage DX review. TTHW (time-to-hello-world), magical moments, friction points, persona traces. Three modes: Expansion, Polish, Triage. |
 | [`/devex-review`](#devex-review) | **DX Reviewer (live)** | Live developer experience audit. Walks the actual onboarding flow, measures TTHW, catches the docs lies. |
 | [`/plan-tune`](#plan-tune) | **Question Tuner** | Self-tune AskUserQuestion sensitivity per question. Mark questions as never-ask, always-ask, or only-for-one-way. |
@@ -937,7 +937,7 @@ This is my **review autopilot mode**.
 
 Running `/plan-ceo-review`, then `/plan-design-review`, then `/plan-eng-review` individually means answering 15-30 intermediate questions. Each question is valuable, but sometimes you want the gauntlet to run without stopping for every decision.
 
-`/autoplan` reads all three review skills from disk and runs them sequentially: CEO → Design → Eng. It makes decisions automatically using six encoded principles (prefer completeness, match existing patterns, choose reversible options, prefer the option the user chose for similar past decisions, defer ambiguous items, and escalate security). Taste decisions (close approaches, borderline scope expansions, cross-model disagreements) get saved and presented at a final approval gate.
+`/autoplan` reads the review skills from disk and runs them sequentially: CEO → Design (if UI scope) → DX (if developer-facing scope) → Eng, always last — the required shipping gate reviews the final amended plan, not a stale one. It makes decisions automatically using six encoded principles (prefer completeness, match existing patterns, choose reversible options, prefer the option the user chose for similar past decisions, defer ambiguous items, and escalate security). Taste decisions (close approaches, borderline scope expansions, cross-model disagreements) get saved and presented at a final approval gate.
 
 One command, fully reviewed plan out.