docs: update roadmap with phase 7 plan details

- Phase 6 marked complete (2/2 plans)
- Phase 7 breakdown: 3 TDD plans (Redux, API, WebSocket)
- Progress table updated

.planning/ROADMAP.md

@@ -126,10 +126,12 @@ Plans:
 **Goal**: Build Redux state management and API integration for chat
 **Depends on**: Phase 6
 **Research**: Unlikely (following established Redux/WebSocket patterns from JamTrack)
-**Plans**: TBD
+**Plans**: 3 plans (TDD)
 
 Plans:
-- [ ] 07-01: TBD (run /gsd:plan-phase 7 to break down)
+- [ ] 07-01: Redux Slice & Core Reducers (TDD) - sessionChatSlice with 7 reducers, message deduplication, unread tracking
+- [ ] 07-02: Async Thunks & API Integration (TDD) - REST methods, fetchChatHistory, sendMessage with optimistic updates
+- [ ] 07-03: WebSocket Integration & Selectors (TDD) - CHAT_MESSAGE handler, 8 memoized selectors, localStorage persistence
 
 #### Phase 8: Chat Window UI & Message Display
 **Goal**: Build modeless chat dialog with message list and user information display
@@ -179,8 +181,8 @@ Phases execute in numeric order: 1 → 2 → 3 → 4 → 5 → 6 → 7 → 8 →
 | 3. Backing Track Finalization | v1.0 | 3/3 | Complete | 2026-01-14 |
 | 4. JamTrack Research & Design | v1.0 | 2/2 | Complete | 2026-01-14 |
 | 5. JamTrack Implementation | v1.0 | 5/5 | Complete | 2026-01-14 |
-| 6. Session Chat Research & Design | v1.1 | 1/TBD | In progress | 2026-01-26 |
-| 7. Chat Infrastructure & State Management | v1.1 | 0/TBD | Not started | - |
+| 6. Session Chat Research & Design | v1.1 | 2/2 | Complete | 2026-01-26 |
+| 7. Chat Infrastructure & State Management | v1.1 | 0/3 | Not started | - |
 | 8. Chat Window UI & Message Display | v1.1 | 0/TBD | Not started | - |
 | 9. Message Composition & Sending | v1.1 | 0/TBD | Not started | - |
 | 10. Read/Unread Status Management | v1.1 | 0/TBD | Not started | - |