docs(02-01): complete config loader & Gemini API client plan

- SUMMARY.md with 18 tests, 6 files, 3min execution
- STATE.md advanced to plan 2/5, 70% progress
- ROADMAP.md updated with plan progress
- Requirements GAPI-01, GAPI-02, GAPI-03, GAPI-06 marked complete

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

.planning/phases/02-gemini-integration-asset-pipeline/02-01-SUMMARY.md

@@ -0,0 +1,135 @@
+---
+phase: 02-gemini-integration-asset-pipeline
+plan: 01
+subsystem: api
+tags: [gemini, rest-api, fetch, indexeddb, rate-limiting, config-loader]
+
+# Dependency graph
+requires:
+  - phase: 01-grundgeruest-tippmechanik
+    provides: "IndexedDB wrapper (openDB, getSettings, saveSettings) and Settings type"
+provides:
+  - "GeminiConfig interface and loadConfig() with caching"
+  - "generateText() with 3x exponential backoff retry"
+  - "generateImage() with reference image support as base64 inlineData"
+  - "checkRateLimit() and incrementApiCall() for daily API call tracking"
+  - "Extended Settings type with apiCallsToday and lastApiCallDate"
+affects: [02-02, 02-03, 02-04, 02-05, asset-pipeline, companion-system, forest-rewards]
+
+# Tech tracking
+tech-stack:
+  added: []
+  patterns: [gemini-rest-client, exponential-backoff-retry, config-caching, rate-limit-via-settings-store]
+
+key-files:
+  created:
+    - src/api/config.ts
+    - src/api/config.test.ts
+    - src/api/gemini.ts
+    - src/api/gemini.test.ts
+  modified:
+    - src/types.ts
+    - src/storage/db.test.ts
+
+key-decisions:
+  - "Rate limiting stored in Settings singleton via getSettings/saveSettings (no new store)"
+  - "Image generation has no retry (too expensive), text generation retries 3x with [1s, 2s, 4s] backoff"
+  - "Config loader caches after first successful fetch, resetConfigCache() for testing"
+  - "loadConfigFromObject() provided for Node.js build script usage"
+
+patterns-established:
+  - "Gemini REST pattern: POST to v1beta/models/{model}:generateContent with key param"
+  - "Null-return pattern: all API functions return null on failure, callers use fallback"
+  - "Daily reset pattern: compare lastApiCallDate to today, reset counters if different"
+
+requirements-completed: [GAPI-01, GAPI-02, GAPI-03, GAPI-06]
+
+# Metrics
+duration: 3min
+completed: 2026-03-29
+---
+
+# Phase 02 Plan 01: Config Loader & Gemini API Client Summary
+
+**Isomorphic Gemini REST client with config caching, text/image generation, exponential backoff retry, and per-day rate limiting via IndexedDB Settings store**
+
+## Performance
+
+- **Duration:** 3 min
+- **Started:** 2026-03-29T09:52:49Z
+- **Completed:** 2026-03-29T09:56:41Z
+- **Tasks:** 1 (TDD: RED + GREEN)
+- **Files modified:** 6
+
+## Accomplishments
+- Config loader fetches and caches public/config.json with typed GeminiConfig interface
+- generateText sends correct Gemini REST request with systemInstruction, retries 3x on failure with exponential backoff [1s, 2s, 4s]
+- generateImage converts reference Blobs to base64 inlineData parts, sets responseModalities: ["IMAGE"]
+- Rate limiting tracks text/image API calls per day in Settings store with automatic daily reset
+- 18 tests across config.test.ts and gemini.test.ts, all passing (55 total project tests)
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1 (RED): Failing tests** - `b31b9fd` (test)
+2. **Task 1 (GREEN): Implementation** - `2bea324` (feat)
+
+_TDD task with RED (failing tests) and GREEN (implementation) commits._
+
+## Files Created/Modified
+- `src/api/config.ts` - GeminiConfig interface, loadConfig() with caching, resetConfigCache()
+- `src/api/config.test.ts` - 6 tests for config loader (fetch, errors, caching)
+- `src/api/gemini.ts` - generateText(), generateImage(), checkRateLimit(), incrementApiCall()
+- `src/api/gemini.test.ts` - 12 tests for text/image generation and rate limiting
+- `src/types.ts` - Extended Settings with apiCallsToday and lastApiCallDate
+- `src/storage/db.test.ts` - Updated Settings test fixture with new fields
+
+## Decisions Made
+- Rate limiting stored in existing Settings singleton (no new IndexedDB store needed)
+- Image generation has no retry logic (too expensive per plan spec), only text retries
+- Config loader includes loadConfigFromObject() for future Node.js build script usage
+- Blob-to-base64 conversion uses arrayBuffer + manual binary encoding (no FileReader needed)
+
+## Deviations from Plan
+
+### Auto-fixed Issues
+
+**1. [Rule 1 - Bug] Fixed TypeScript strict null errors in array indexing**
+- **Found during:** Task 1 GREEN phase
+- **Issue:** TypeScript strict mode flagged RETRY_DELAYS[attempt] and split("T")[0] as possibly undefined
+- **Fix:** Added nullish coalescing fallbacks (e.g., `?? 1000`, `?? ""`)
+- **Files modified:** src/api/gemini.ts, src/api/gemini.test.ts
+- **Verification:** `npx tsc --noEmit` passes for all api/ files
+- **Committed in:** 2bea324
+
+**2. [Rule 1 - Bug] Updated db.test.ts Settings fixture for extended type**
+- **Found during:** Task 1 GREEN phase
+- **Issue:** Existing db.test.ts Settings object missing new apiCallsToday and lastApiCallDate fields
+- **Fix:** Added missing fields to test fixture
+- **Files modified:** src/storage/db.test.ts
+- **Verification:** All 55 tests pass
+- **Committed in:** 2bea324
+
+---
+
+**Total deviations:** 2 auto-fixed (2 bugs)
+**Impact on plan:** Both fixes required for type safety and test correctness. No scope creep.
+
+## Issues Encountered
+- Pre-existing TypeScript errors in src/companion/fallbacks.ts (not caused by this plan, out of scope)
+
+## Known Stubs
+None - all functions are fully implemented with real logic.
+
+## User Setup Required
+None - no external service configuration required.
+
+## Next Phase Readiness
+- Gemini API client ready for use by prompt templates (02-02), image pipeline (02-03), and companion dialog (02-04)
+- Config must exist at public/config.json with geminiApiKey, geminiModel, imageModel fields
+- No blockers for subsequent plans
+
+---
+*Phase: 02-gemini-integration-asset-pipeline*
+*Completed: 2026-03-29*