Imp-15: Session Reuse for Repeated Operations
Adds a SHA-256 fingerprint-based operation cache as layer 0 before HNSW
early exit. Exact-match lookups run in O(1) before O(log n) similarity
search, catching repeated operations instantly.
- SessionOperationCache with TTL, capacity eviction, and kv_store persistence
- Wired into TokenOptimizerService.checkEarlyExit() as first check
- cacheOperationResult() stores results after successful LLM execution
- session_cache_stats MCP tool for monitoring hit rates
- CLI: aqe token-usage --cache-stats for cache performance
- Cross-session persistence via existing kv_store table
- 26 new tests covering fingerprinting, TTL, eviction, stats, degradation
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Dragan Spiridonov