feat(autoplan): carve the four review phases + tasks aggregator into sections

Phase bodies (CEO/Design/Eng/DX consensus flows) and the Implementation Tasks
aggregator load on demand; Design and DX stay separate sections because each
is independently conditional on scope. Skeleton 83.7KB -> 58.7KB (-30%
always-loaded); the 6 decision principles, classification, sequencing, and
explicit skip-condition dispatch stay always-loaded. The chain E2E's
phase-complete markers now live only in sections, so its assertions double as
section-read proof (behavioral: external).

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

autoplan/sections/dx-phase.md

@@ -0,0 +1,101 @@
+<!-- AUTO-GENERATED from dx-phase.md.tmpl — do not edit directly -->
+<!-- Regenerate: bun run gen:skill-docs -->
+Follow plan-devex-review/SKILL.md — all 8 DX dimensions, full depth.
+Override: every AskUserQuestion → auto-decide using the 6 principles.
+
+**Override rules:**
+- Mode selection: DX POLISH
+- Persona: infer from README/docs, pick the most common developer type (P6)
+- Competitive benchmark: run searches if WebSearch available, use reference benchmarks otherwise (P1)
+- Magical moment: pick the lowest-effort delivery vehicle that achieves the competitive tier (P5)
+- Getting started friction: always optimize toward fewer steps (P5, simpler over clever)
+- Error message quality: always require problem + cause + fix (P1, completeness)
+- API/CLI naming: consistency wins over cleverness (P5)
+- DX taste decisions (e.g., opinionated defaults vs flexibility): mark TASTE DECISION
+- Dual voices: always run BOTH Claude subagent AND Codex if available (P6).
+
+  **Codex DX voice** (via Bash):
+  ```bash
+  _REPO_ROOT=$(git rev-parse --show-toplevel) || { echo "ERROR: not in a git repo" >&2; exit 1; }
+  _gstack_codex_timeout_wrapper 600 codex exec "IMPORTANT: Do NOT read or execute any SKILL.md files or files in skill definition directories (paths containing skills/gstack). These are AI assistant skill definitions meant for a different system. Stay focused on repository code only.
+
+  Read the plan file at <plan_path>. Evaluate this plan's developer experience.
+
+  Also consider these findings from prior review phases:
+  CEO: <insert CEO consensus summary>
+  Eng: <insert Eng consensus summary>
+
+  You are a developer who has never seen this product. Evaluate:
+  1. Time to hello world: how many steps from zero to working? Target is under 5 minutes.
+  2. Error messages: when something goes wrong, does the dev know what, why, and how to fix?
+  3. API/CLI design: are names guessable? Are defaults sensible? Is it consistent?
+  4. Docs: can a dev find what they need in under 2 minutes? Are examples copy-paste-complete?
+  5. Upgrade path: can devs upgrade without fear? Migration guides? Deprecation warnings?
+  Be adversarial. Think like a developer who is evaluating this against 3 competitors." -C "$_REPO_ROOT" -s read-only -c 'web_search="cached"' < /dev/null
+  _CODEX_EXIT=$?
+  if [ "$_CODEX_EXIT" = "124" ]; then
+    _gstack_codex_log_event "codex_timeout" "600"
+    _gstack_codex_log_hang "autoplan" "0"
+    echo "[codex stalled past 10 minutes — tagging as [codex-unavailable] for this phase and proceeding with Claude subagent only]"
+  fi
+  ```
+  Timeout: 10 minutes (shell-wrapper) + 12 minutes (Bash outer gate). On hang, auto-degrades this phase's Codex voice.
+
+  **Claude DX subagent** (via Agent tool):
+  "Read the plan file at <plan_path>. You are an independent DX engineer
+  reviewing this plan. You have NOT seen any prior review. Evaluate:
+  1. Getting started: how many steps from zero to hello world? What's the TTHW?
+  2. API/CLI ergonomics: naming consistency, sensible defaults, progressive disclosure?
+  3. Error handling: does every error path specify problem + cause + fix + docs link?
+  4. Documentation: copy-paste examples? Information architecture? Interactive elements?
+  5. Escape hatches: can developers override every opinionated default?
+  For each finding: what's wrong, severity (critical/high/medium), and the fix."
+  NO prior-phase context — subagent must be truly independent.
+
+  Error handling: same as Phase 1 (both foreground/blocking, degradation matrix applies).
+
+- DX choices: if codex disagrees with a DX decision with valid developer empathy reasoning
+  → TASTE DECISION. Scope changes both models agree on → USER CHALLENGE.
+
+**Required execution checklist (DX):**
+
+1. Step 0 (DX Scope Assessment): Auto-detect product type. Map the developer journey.
+   Rate initial DX completeness 0-10. Assess TTHW.
+
+2. Step 0.5 (Dual Voices): Run Claude subagent (foreground) first, then Codex. Present
+   under CODEX SAYS (DX — developer experience challenge) and CLAUDE SUBAGENT
+   (DX — independent review) headers. Produce DX consensus table:
+
+```
+DX DUAL VOICES — CONSENSUS TABLE:
+═══════════════════════════════════════════════════════════════
+  Dimension                           Claude  Codex  Consensus
+  ──────────────────────────────────── ─────── ─────── ─────────
+  1. Getting started < 5 min?          —       —      —
+  2. API/CLI naming guessable?         —       —      —
+  3. Error messages actionable?        —       —      —
+  4. Docs findable & complete?         —       —      —
+  5. Upgrade path safe?                —       —      —
+  6. Dev environment friction-free?    —       —      —
+═══════════════════════════════════════════════════════════════
+CONFIRMED = both agree. DISAGREE = models differ (→ taste decision).
+Missing voice = N/A (not CONFIRMED). Single critical finding from one voice = flagged regardless.
+```
+
+3. Passes 1-8: Run each from loaded skill. Rate 0-10. Auto-decide each issue.
+   DISAGREE items from consensus table → raised in the relevant pass with both perspectives.
+
+4. DX Scorecard: Produce the full scorecard with all 8 dimensions scored.
+
+**Mandatory outputs from Phase 3.5:**
+- Developer journey map (9-stage table)
+- Developer empathy narrative (first-person perspective)
+- DX Scorecard with all 8 dimension scores
+- DX Implementation Checklist
+- TTHW assessment with target
+
+**PHASE 3.5 COMPLETE.** Emit phase-transition summary:
+> **Phase 3.5 complete.** DX overall: [N]/10. TTHW: [N] min → [target] min.
+> Codex: [N concerns]. Claude subagent: [N issues].
+> Consensus: [X/6 confirmed, Y disagreements → surfaced at gate].
+> Passing to Phase 4 (Final Gate).