v3.12.0: gRPC auto-fallback for Antigravity (PR #13)

CHANGELOG.md

@@ -1,5 +1,22 @@
 # Changelog
 
+## v3.12.0 (2026-05-27)
+
+**gRPC Auto-Fallback for Antigravity Provider (PR #13)**
+
+### New Features
+- **gRPC auto-fallback**: When REST API returns 404 (model not found), automatically retries via gRPC
+- **New `antigravity_grpc` module**: Full protobuf client with CloudCode PredictionService stubs
+- **Display name remapping**: gRPC uses display names (e.g. "Gemini 3.5 Flash (High)") instead of REST slugs
+- **Streaming and unary support**: gRPC fallback works for both streaming and non-streaming requests
+- **Dynamic version fetch with validation**: Probes fetched versions to ensure they work before caching
+- **Antigravity v2 handler rewrite**: Based on anti-api approach with proper safety settings, stopSequences, sessionId
+- **Lazy import**: grpcio is only imported when needed — zero impact if not installed
+
+### Bug Fixes
+- Antigravity 404 caused by invalid version — now validates with probe requests
+- Version fallback: auto-retries with re-fetched version if all endpoints return 404
+
 ## v3.11.12 (2026-05-26)
 
 **New Antigravity v2 Handler (Mimicking anti-api)**