chore: mark US-006 complete in prd.json and update progress log

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

prd.json

@@ -104,8 +104,8 @@
         "Typecheck passes"
       ],
       "priority": 6,
-      "passes": false,
-      "notes": ""
+      "passes": true,
+      "notes": "Completed: projects.list (filters by clientId + includeArchived via drizzle and()), projects.listAll (id+name only), projects.get (returns null if not found), projects.create (UUID + status='active' + createdAt), projects.update (partial set object), projects.delete (nulls tasks.projectId then deletes project)"
     },
     {
       "id": "US-007",

progress.txt

@@ -51,6 +51,24 @@
   - The `writingMode: 'vertical-rl'` + `transform: 'rotate(180deg)'` CSS pattern creates bottom-to-top text for vertical affordance labels
 ---
 
+## 2026-02-19 - US-006
+- What was implemented:
+  - Full `projectsRouter` replacing stubs in `src/main/router/index.ts`
+  - Added `and` to drizzle-orm imports
+  - `projects.list`: uses `and()` with optional conditions for `clientId` filter and archived filter (defaults to active only)
+  - `projects.listAll`: returns only `{ id, name }` columns for dropdown use
+  - `projects.get`: `.all()` then `result[0] ?? null` pattern for nullable single-record lookup
+  - `projects.create`: inserts with UUID, status='active', createdAt=Date.now()
+  - `projects.update`: partial set object — only sets defined fields
+  - `projects.delete`: nulls `tasks.projectId` for all tasks in the project, then deletes the project
+- Files changed: `src/main/router/index.ts`, `prd.json`, `progress.txt`
+- **Learnings for future iterations:**
+  - `and(...conditions)` from drizzle-orm accepts `(SQL | undefined)[]` — pass `undefined` for optional conditions and drizzle filters them out automatically
+  - For nullable single-record queries: use `.all()` and `result[0] ?? null` (strict mode forbids `.get()` direct null return without this pattern)
+  - `and()` returns `SQL<unknown> | undefined` which `.where()` accepts directly (no extra wrapping needed)
+
+---
+
 ## 2026-02-19 - US-005
 - What was implemented:
   - Full clients tRPC router replacing stubs in `src/main/router/index.ts`