docs: update CLAUDE.md and migration plan for local-first architecture

- CLAUDE.md: new Local-First Architecture section with data flow, migrated apps,
  dev commands, and step-by-step guide for adding local-first to new apps
- Migration plan: Phase 1-3 marked as done, status updated to "in progress"

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

.claude/plans/local-first-architecture-migration.md

@@ -1,7 +1,8 @@
 # Local-First Architektur & Stack-Migration
 
-> **Status**: 🔵 In Planung
+> **Status**: 🟢 In Umsetzung (Phase 1-3 abgeschlossen)
 > **Erstellt**: 2026-03-26
+> **Zuletzt aktualisiert**: 2026-03-27
 > **Autor**: Claude Code + Till Schneider
 > **Ziel**: Alle ManaCore-Apps auf Local-First umstellen, Backend-Stack modernisieren
 
@@ -72,7 +73,7 @@ Dieser Plan beschreibt den Umbau der gesamten ManaCore-Architektur von einem kla
 
 ---
 
-## Phase 1: Foundation (2-3 Wochen)
+## Phase 1: Foundation (2-3 Wochen) — DONE 2026-03-27
 
 ### 1.1 `@manacore/local-store` Package
 
@@ -264,7 +265,7 @@ Die Todo-App wird als erste auf Local-First umgebaut:
 
 ---
 
-## Phase 2: Todo komplett auf Hono/Bun (2-3 Wochen)
+## Phase 2: Todo komplett auf Hono/Bun (2-3 Wochen) — DONE 2026-03-27
 
 ### 2.1 Todo Backend: NestJS → Hono/Bun
 
@@ -312,7 +313,7 @@ apps/todo/apps/backend/     # Oder: services/todo/ (umstrukturieren?)
 
 ---
 
-## Phase 3: Rollout auf alle Apps (4-6 Wochen)
+## Phase 3: Rollout auf alle Apps (4-6 Wochen) — 6/8 DONE 2026-03-27
 
 Reihenfolge nach Komplexität:
 

CLAUDE.md

@@ -502,10 +502,67 @@ let count = 0;
 $: doubled = count * 2;
 ```
 
+## Local-First Architecture
+
+All web apps use a **local-first** data layer: reads/writes go to IndexedDB (Dexie.js) first, sync to server in the background. This enables guest mode, offline CRUD, and instant UI.
+
+### Key Components
+
+| Component | Location | Purpose |
+|-----------|----------|---------|
+| `@manacore/local-store` | `packages/local-store/` | Dexie.js collections, sync engine, Svelte 5 reactive queries |
+| `mana-sync` | `services/mana-sync/` | Go sync server (WebSocket push, field-level LWW conflict resolution) |
+| Todo Hono Server | `apps/todo/apps/server/` | Lightweight compute server (RRULE, reminders, admin) on Bun |
+
+### Data Flow
+
+```
+Guest:      App → IndexedDB (Dexie.js) → UI            (no sync)
+Logged in:  App → IndexedDB → UI → SyncEngine → mana-sync (Go) → PostgreSQL
+                                  ← WebSocket push ←
+```
+
+### Migrated Apps
+
+| App | Collections | Status |
+|-----|------------|--------|
+| Todo | tasks, projects, labels, taskLabels, reminders | Done |
+| Zitare | favorites, lists | Done |
+| Calendar | calendars, events | Done |
+| Clock | alarms, timers, worldClocks | Done |
+| Contacts | contacts | Done |
+| ManaDeck | decks, cards | Done |
+| Picture | — | Not yet |
+| Presi | — | Not yet |
+
+### Dev Commands (Local-First Stack)
+
+```bash
+pnpm dev:sync              # Go sync server (port 3050)
+pnpm dev:sync:build        # Compile Go binary
+pnpm dev:todo:server       # Hono/Bun compute server (port 3019)
+pnpm dev:todo:local        # Web + sync + Hono (no auth/NestJS needed)
+pnpm dev:todo:full         # Everything incl. auth + NestJS legacy
+```
+
+### Adding Local-First to a New App
+
+1. Create `apps/{app}/apps/web/src/lib/data/local-store.ts` — define collections with `createLocalStore()`
+2. Create `apps/{app}/apps/web/src/lib/data/guest-seed.ts` — onboarding data
+3. Rewrite stores to use `collection.getAll()` / `collection.insert()` instead of API calls
+4. In layout: `await store.initialize()`, `store.startSync()` on login, `allowGuest={true}` on AuthGate
+5. Set `userEmail = ''` for guests so PillNav shows login button
+6. Add `GuestWelcomeModal` for first-visit experience
+
+### Architecture Plan
+
+Full migration plan: `.claude/plans/local-first-architecture-migration.md`
+
 ## Shared Packages (`packages/`)
 
 | Package                         | Purpose                                         |
 | ------------------------------- | ----------------------------------------------- |
+| `@manacore/local-store`         | Local-first data layer (Dexie.js + sync engine) |
 | `@manacore/shared-nestjs-auth`  | NestJS JWT validation guards via mana-core-auth |
 | `@mana-core/nestjs-integration` | NestJS module with auth guards + credit client  |
 | `@manacore/shared-auth`         | Client-side auth service for web/mobile apps    |