docs(02-01): complete thread backend API plan

- Created 02-01-SUMMARY.md with execution results
- Updated STATE.md with phase 2 position and decisions
- Updated ROADMAP.md with plan progress
- Marked THRD-01 through THRD-04 requirements complete

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.planning/STATE.md

@@ -2,16 +2,16 @@
 gsd_state_version: 1.0
 milestone: v1.0
 milestone_name: milestone
-status: completed
-stopped_at: Phase 2 context gathered
-last_updated: "2026-03-15T10:18:27.410Z"
-last_activity: 2026-03-14 — Completed 01-04 onboarding wizard and visual verification
+status: in-progress
+stopped_at: Completed 02-01-PLAN.md
+last_updated: "2026-03-15T10:39:24Z"
+last_activity: 2026-03-15 — Completed 02-01 thread backend API
 progress:
   total_phases: 3
   completed_phases: 1
-  total_plans: 4
-  completed_plans: 4
-  percent: 100
+  total_plans: 7
+  completed_plans: 5
+  percent: 71
 ---
 
 # Project State
@@ -21,16 +21,16 @@ progress:
 See: .planning/PROJECT.md (updated 2026-03-14)
 
 **Core value:** Make it effortless to manage gear and plan new purchases — see how a potential buy affects your total setup weight and cost before committing.
-**Current focus:** Phase 1: Foundation and Collection
+**Current focus:** Phase 2: Planning Threads
 
 ## Current Position
 
-Phase: 1 of 3 (Foundation and Collection)
-Plan: 4 of 4 in current phase (complete)
-Status: Phase 1 complete
-Last activity: 2026-03-14 — Completed 01-04 onboarding wizard and visual verification
+Phase: 2 of 3 (Planning Threads)
+Plan: 1 of 3 in current phase
+Status: In progress
+Last activity: 2026-03-15 — Completed 02-01 thread backend API
 
-Progress: [██████████] 100%
+Progress: [███████---] 71%
 
 ## Performance Metrics
 
@@ -53,6 +53,7 @@ Progress: [██████████] 100%
 | Phase 01 P02 | 3min | 2 tasks | 13 files |
 | Phase 01 P03 | 3min | 2 tasks | 16 files |
 | Phase 01 P04 | 3min | 2 tasks | 5 files |
+| Phase 02 P01 | 5min | 2 tasks | 9 files |
 
 ## Accumulated Context
 
@@ -71,6 +72,9 @@ Recent decisions affecting current work:
 - [Phase 01-03]: CategoryPicker uses native ARIA combobox pattern with keyboard navigation
 - [Phase 01-04]: Onboarding state persisted in SQLite settings table, not Zustand (source of truth in DB)
 - [Phase 01-04]: Settings API is generic key-value store usable beyond onboarding
+- [Phase 02-01]: Drizzle sql template literals use raw table.column refs in correlated subqueries (not interpolated)
+- [Phase 02-01]: Thread deletion collects candidate image filenames before cascade for filesystem cleanup
+- [Phase 02-01]: Resolution validates categoryId existence, falls back to Uncategorized (id=1)
 
 ### Pending Todos
 
@@ -83,6 +87,6 @@ None yet.
 
 ## Session Continuity
 
-Last session: 2026-03-15T10:18:27.408Z
-Stopped at: Phase 2 context gathered
-Resume file: .planning/phases/02-planning-threads/02-CONTEXT.md
+Last session: 2026-03-15T10:39:24Z
+Stopped at: Completed 02-01-PLAN.md
+Resume file: .planning/phases/02-planning-threads/02-01-SUMMARY.md