[Developer] #218 Real Gemma 4 E2B integration via flutter_gemma 0.16.5
Implements the OQ-1 follow-up to #215 v0.2.0: replace the placeholder
GemmaLlmService stub with a real flutter_gemma 0.16.5 backend driving
Gemma 4 E2B (litert-community/gemma-4-E2B-it-litert-lm, 2.41GB).
Highlights:
- GemmaLlmService.load → FlutterGemma.initialize + installModel.fromFile +
getActiveModel; idempotent + FileSystemException on missing file.
- generateStructured uses Gemma 4 native function calling via
createChat(tools: [Tool(...)], toolChoice: required). Stream parsed by
collectFunctionCall — first FCR wins, ParallelFCR first-call wins,
TextResponse/ThinkingResponse skipped, errors sanitized to prevent
prompt leakage.
- main.dart wires _LazyLlmService adapter that resolves to GemmaLlmService
when ModelLifecycle reports ready, MockLlmService otherwise.
- ai_providers.dart pins real model URL + SHA-256 (181938...39a63c).
- F2 hardening: ModelLifecycle.purge wraps each delete + meta remove in
try/catch so a single OS-level flake cannot block opt-out.
- Android: INTERNET / FOREGROUND_SERVICE / POST_NOTIFICATIONS permissions
+ R8 proguard-rules.pro keeping MediaPipe / LiteRT / TFLite / protobuf
JNI entry points (release builds otherwise crash on first inference).
Design-First: fn-gemma_llm_service.md updated to v2 — §C
(_appendSchemaInstruction) deprecated after reading flutter_gemma
0.16.5 source (Gemma 4 SDK injects tool declarations via template;
prompt-side append would double-wrap).
Tests:
- 10 new unit tests for collectFunctionCall covering all 8 fn-spec
cases + 2 ParallelFunctionCallResponse paths.
- All 81 existing tests still pass.
- flutter analyze: 0 issues.
Refs #218
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
joungmin
9a9eb2abd5