docs(21-03): complete cross-screen navigation & mobile responsive plan

Tasks completed: 2/2
- Add cross-screen navigation links
- Fix mobile responsive layout for detail panels

SUMMARY: .planning/phases/21-polish-integration/21-03-SUMMARY.md

.planning/ROADMAP.md

@@ -324,7 +324,7 @@ Plans:
 Plans:
 - [ ] 21-01: Error Boundary & Toast Notifications
 - [ ] 21-02: Skeleton Loading States
-- [ ] 21-03: Cross-Screen Navigation & Mobile Responsive
+- [x] 21-03: Cross-Screen Navigation & Mobile Responsive
 - [ ] 21-04: Subscription Error Handling
 - [ ] 21-05: Code Splitting & Performance
 - [ ] 21-06: Integration Smoke Test
@@ -358,7 +358,7 @@ Phases execute in numeric order: 1 → 1.1 → 2 → 3 → 4 → 5 → 6 → 7
 | 18. Initiative Detail | v2.0 | 4/4 | Complete | 2026-02-04 |
 | 19. Agent Inbox | v2.0 | 4/4 | Complete | 2026-02-04 |
 | 20. Real-time Subscriptions | v2.0 | 2/2 | Complete | 2026-02-04 |
-| 21. Polish & Integration | v2.0 | 0/6 | Not started | - |
+| 21. Polish & Integration | v2.0 | 3/6 | In progress | - |
 
 ---
 *Roadmap created: 2026-01-30*

.planning/STATE.md

@@ -9,10 +9,10 @@ See: .planning/PROJECT.md (updated 2026-02-04)
 
 ## Current Position
 
-Phase: 20 of 21 (Real-Time Subscriptions) - COMPLETE
+Phase: 21 of 21 (Polish & Integration) - In progress
-Plan: 2 of 2 in current phase (all complete)
+Plan: 3 of 6 in current phase
-Status: Completed 20-02 (Frontend SSE Subscription Hooks)
+Status: Completed 21-03 (Cross-Screen Navigation & Mobile Responsive)
-Last activity: 2026-02-04 - Completed 20-02-PLAN.md (frontend subscriptions)
+Last activity: 2026-02-05 - Completed 21-03-PLAN.md (navigation links + mobile responsive)
 
 Progress: █████████░ 99%
 
@@ -233,6 +233,10 @@ Recent decisions affecting current work:
 - 20-02: Subscription-driven invalidation (not local state) — simplest approach, reuses existing React Query cache
 - 20-02: Silent onError callbacks — pages degrade to manual refresh when backend is not running
 - 20-02: No new packages needed — splitLink and httpSubscriptionLink ship with @trpc/client v11
+- 21-03: Removed disabled nav stubs (Agents, Tasks, Settings) — stubs create false promises for v2.0
+- 21-03: TaskRow agent names link to /inbox — simplest cross-screen navigation for agent context
+- 21-03: Inbox task links go to /initiatives — no direct task-to-initiative mapping on frontend
+- 21-03: Mobile drill-down pattern hides list on mobile when detail selected, shows back button
 
 ### Pending Todos
 
@@ -254,6 +258,6 @@ None.
 
 ## Session Continuity
 
-Last session: 2026-02-04
+Last session: 2026-02-05
-Stopped at: Completed 20-02 (Frontend SSE Subscription Hooks) — Phase 20 complete
+Stopped at: Completed 21-03 (Cross-Screen Navigation & Mobile Responsive)
 Resume file: None

.planning/phases/21-polish-integration/21-03-SUMMARY.md

@@ -0,0 +1,95 @@
+---
+phase: 21-polish-integration
+plan: 03
+subsystem: ui
+tags: [react, tanstack-router, tailwind, responsive, navigation]
+
+# Dependency graph
+requires:
+  - phase: 19-agent-inbox
+    provides: InboxList, MessageCard, QuestionForm components and inbox page
+  - phase: 18-initiative-detail
+    provides: TaskRow, PhaseAccordion, initiative detail page
+provides:
+  - Cross-screen navigation between inbox and initiative detail
+  - Mobile-responsive inbox detail panel with drill-down pattern
+affects: [21-polish-integration]
+
+# Tech tracking
+tech-stack:
+  added: []
+  patterns: [mobile drill-down pattern for list-detail views]
+
+key-files:
+  modified:
+    - packages/web/src/layouts/AppLayout.tsx
+    - packages/web/src/components/TaskRow.tsx
+    - packages/web/src/routes/inbox.tsx
+
+key-decisions:
+  - "Removed disabled nav stubs (Agents, Tasks, Settings) — stubs create false promises for v2.0"
+  - "TaskRow agent names link to /inbox — simplest cross-screen navigation for agent context"
+  - "Inbox task links go to /initiatives — no direct task-to-initiative mapping on frontend"
+  - "Mobile drill-down hides list when detail selected — standard mobile pattern"
+
+patterns-established:
+  - "Mobile drill-down: hide list on mobile when detail selected, show back button with lg:hidden"
+
+# Metrics
+duration: 4min
+completed: 2026-02-05
+---
+
+# Phase 21 Plan 03: Cross-Screen Navigation & Mobile Responsive Summary
+
+**Cross-screen navigation links between inbox and initiatives, mobile drill-down pattern for inbox detail panel**
+
+## Performance
+
+- **Duration:** 4 min
+- **Started:** 2026-02-05T07:50:00Z
+- **Completed:** 2026-02-05T07:54:00Z
+- **Tasks:** 2
+- **Files modified:** 3
+
+## Accomplishments
+- Removed disabled nav stubs (Agents, Tasks, Settings) from AppLayout to eliminate visual clutter
+- TaskRow agent names are now clickable links to the inbox page
+- Inbox detail panel shows linked taskId and "View in context" link to initiatives
+- Mobile users can access inbox detail panel via drill-down pattern with back button
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Add cross-screen navigation links** - `c52c6f1` (feat)
+2. **Task 2: Fix mobile responsive layout for detail panels** - `1e1aada` (feat)
+
+## Files Created/Modified
+- `packages/web/src/layouts/AppLayout.tsx` - Removed disabled nav items, simplified nav rendering
+- `packages/web/src/components/TaskRow.tsx` - Agent name is now a Link to /inbox
+- `packages/web/src/routes/inbox.tsx` - Task link, "View in context" link, mobile back button, list hiding
+
+## Decisions Made
+- Removed Agents/Tasks/Settings disabled nav items — they were stubs that will never be implemented in v2.0
+- Task links in inbox go to /initiatives (no direct task-to-initiative mapping on frontend)
+- Mobile drill-down pattern: hide list column on mobile when agent selected, show back button
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+## Issues Encountered
+None
+
+## User Setup Required
+None - no external service configuration required.
+
+## Next Phase Readiness
+- Plan 21-03 complete, ready for 21-04 (Subscription Error Handling)
+- All cross-screen navigation in place
+- Mobile responsive inbox working
+
+---
+*Phase: 21-polish-integration*
+*Completed: 2026-02-05*