docs(18-04): create initiative detail page assembly summary and update state

Phase 18 (Initiative Detail) complete — all 4 plans finished.

.planning/phases/18-initiative-detail/18-04-SUMMARY.md

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+---
+phase: 18-initiative-detail
+plan: 04
+subsystem: ui
+tags: [react, trpc, tanstack-router, tailwind]
+
+# Dependency graph
+requires:
+  - plan: 18-01
+    provides: InitiativeHeader, ProgressPanel
+  - plan: 18-02
+    provides: PhaseAccordion, TaskRow, DependencyIndicator
+  - plan: 18-03
+    provides: DecisionList, TaskDetailModal
+provides:
+  - Fully assembled Initiative Detail page with data fetching and component wiring
+affects: [initiative detail route, /initiatives/$id]
+
+# Tech tracking
+tech-stack:
+  added: []
+  patterns: [PhaseWithTasks helper component for stable hooks, PlanTasksFetcher data component]
+
+key-files:
+  created: []
+  modified:
+    - packages/web/src/routes/initiatives/$id.tsx
+
+key-decisions:
+  - "18-04: PhaseWithTasks helper component pattern solves hooks-in-loops problem for nested data fetching"
+  - "18-04: PlanTasksFetcher renders null — data-only component for per-plan task fetching with stable hook count"
+  - "18-04: Task counts aggregated via callback from PhaseWithTasks to page-level state"
+  - "18-04: DecisionList passed empty array — no backend endpoint for decisions yet"
+  - "18-04: Phase/task dependencies simplified (empty arrays) for v1 — full dependency resolution deferred"
+
+patterns-established:
+  - "Data-fetching component pattern: render null, report data via callback props"
+  - "Nested tRPC fetching: parent fetches list, child component fetches per-item details"
+
+# Metrics
+duration: 4min
+completed: 2026-02-04
+---
+
+# Phase 18 Plan 04: Initiative Detail Page Assembly Summary
+
+**Wire all Phase 18 components into the $id.tsx route with tRPC data fetching, queue actions, and full build verification**
+
+## Performance
+
+- **Duration:** 4 min
+- **Started:** 2026-02-04
+- **Completed:** 2026-02-04
+- **Tasks:** 2
+- **Files modified:** 1
+
+## Accomplishments
+- Replaced placeholder Initiative Detail page with full implementation
+- Data fetching via tRPC: getInitiative, listPhases, listPlans (per phase), listTasks (per plan)
+- PhaseWithTasks helper component solves the hooks-in-loops problem by giving each phase its own component instance with stable hook count
+- PlanTasksFetcher data component fetches tasks per plan and reports upward via callbacks
+- Two-column layout: phases on left, progress panel + decisions on right (lg:grid-cols-[1fr_340px])
+- Task counts aggregated from PhaseWithTasks children into page-level state for ProgressPanel
+- TaskDetailModal opens on task click with phase name, dependencies, and queue/stop actions
+- Queue All button dispatches all pending phases; Queue Task button in modal dispatches single task
+- Loading/error states matching InitiativeList patterns
+- First incomplete phase expanded by default
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Wire Initiative Detail page with data fetching and all components** - `1e26bfa` (feat)
+2. **Task 2: Verify full build and integration** - No code changes needed; all builds passed
+
+## Files Created/Modified
+- `packages/web/src/routes/initiatives/$id.tsx` - Full initiative detail page with data fetching, component wiring, queue actions, and modal
+
+## Decisions Made
+- 18-04: PhaseWithTasks helper component pattern solves hooks-in-loops problem for nested data fetching
+- 18-04: PlanTasksFetcher renders null — data-only component for per-plan task fetching with stable hook count
+- 18-04: Task counts aggregated via callback from PhaseWithTasks to page-level state
+- 18-04: DecisionList passed empty array — no backend endpoint for decisions yet
+- 18-04: Phase/task dependencies simplified (empty arrays) for v1 — full dependency resolution deferred
+
+## Deviations from Plan
+
+- Skipped `instanceof Date` checks for serialization — tRPC serializes Date to string over JSON, so `String()` wrapping is sufficient
+- No separate commit for Task 2 since no code changes were needed
+
+## Issues Encountered
+None
+
+## User Setup Required
+None — no external service configuration required.
+
+## Verification
+
+- [x] `npx tsc --noEmit -p packages/web/tsconfig.app.json` passes
+- [x] `npx vite build` in packages/web succeeds
+- [x] `npm run build` in root succeeds
+- [x] Route registered in routeTree.gen.ts for /initiatives/$id
+
+## Next Phase Readiness
+- Phase 18 (Initiative Detail) is complete
+- Ready for Phase 19 (next phase in ROADMAP)
+
+---
+*Phase: 18-initiative-detail*
+*Completed: 2026-02-04*