docs(04-06): complete live-sync SSE vertical slice plan

.planning/STATE.md

@@ -3,15 +3,15 @@ gsd_state_version: 1.0
 milestone: v1.0
 milestone_name: milestone
 status: executing
-stopped_at: Completed 04-03-PLAN.md
-last_updated: "2026-06-09T17:19:23.873Z"
+stopped_at: Completed 04-06-PLAN.md
+last_updated: "2026-06-09T17:35:35.144Z"
 last_activity: 2026-06-09
 progress:
   total_phases: 15
-  completed_phases: 3
+  completed_phases: 4
   total_plans: 27
-  completed_plans: 26
-  percent: 20
+  completed_plans: 27
+  percent: 27
 ---
 
 # Project State
@@ -26,7 +26,7 @@ See: .planning/PROJECT.md (updated 2026-06-07)
 ## Current Position
 
 Phase: 04 (shared-lists-live-sync) — EXECUTING
-Plan: 5 of 6
+Plan: 6 of 6
 Status: Ready to execute
 Last activity: 2026-06-09
 
@@ -63,6 +63,7 @@ Progress: [█████████░] 93%
 | Phase 04 P03 | 12 | 2 tasks | 9 files |
 | Phase 04 P04 | 11 | 2 tasks | 10 files |
 | Phase 04 P05 | 10 | 2 tasks | 4 files |
+| Phase 04 P06 | 11 | 2 tasks | 7 files |
 
 ## Accumulated Context
 
@@ -95,6 +96,7 @@ Recent decisions affecting current work:
 - [Phase 04-04]: listItemsRouter separate from listsRouter, mounted at /api/list-items for PATCH/DELETE item routes per RESEARCH architecture diagram
 - [Phase 04-04]: Uncheck rank recomputed to active-bottom (generateKeyBetween(lastActiveRank, null)) in same DB write (Open Question 2 resolved)
 - [Phase 04-04]: Delete-wins no-rollback: deleteMutation has no onError handler; item removal from cache is final (D-09)
+- [Phase ?]: LIST-04: SSE connection lives in ListDetail (not hoisted to Lists route); Phase 5 push will own session lifecycle
 
 ### Roadmap Evolution
 
@@ -135,6 +137,6 @@ Recent decisions affecting current work:
 
 ## Session Continuity
 
-Last session: 2026-06-09T17:19:23.865Z
-Stopped at: Completed 04-03-PLAN.md
+Last session: 2026-06-09T17:35:35.134Z
+Stopped at: Completed 04-06-PLAN.md
 Resume file: None