- Add open-sse/services/thoughtSignatureStore.js managing LRU Map (2k) + SQLite kv table - Store thoughtSignature with sessionId namespace and toolCallId fallback - Replay cached signature by sessionId:tool_call_id to prevent multi-process collisions - Normalize Antigravity sessionId to numeric int64 format Co-Authored-By: Claude Code <noreply@anthropic.com>