Module metadata_cache 

SQLite metadata cache for session files

Caches session metadata with mtime-based invalidation for 90% startup speedup. Also caches activity analysis (tool calls, alerts) per session on demand.

Schema:

• session_metadata: parsed metadata + mtime + cache_version
• activity_cache: serialized ActivitySummary + mtime per session file
• activity_alerts: searchable alert records (severity/category) across all sessions
• Indexes: project, mtime, session_id, severity for fast queries

Invalidation:

• File watcher detects modification → delete session + activity cache entries
• Startup: compare mtime → rescan if stale
• Startup: compare cache_version → auto-clear ALL tables if mismatch

Cache Version History:

• v1: Initial version (pre-TokenUsage fix)
• v2: Fixed TokenUsage::total() to include cache_read_tokens + cache_write_tokens
• v3: Added token breakdown fields (input_tokens, output_tokens, cache_creation_tokens, cache_read_tokens) to SessionMetadata + real pricing calculation
• v4: Added branch field to SessionMetadata
• v5: Added activity_cache + activity_alerts tables for Phase 2 activity module
• v6: Added aggregate_stats table with triggers + FTS5 session_fts table
• v7: Added tool_token_usage field to SessionMetadata (Phase K analytics)

Structs

ActivityCacheStats

Activity cache statistics

AggregateStats

Aggregate statistics from O(1) table

CacheStats

Session metadata cache statistics

MetadataCache

SQLite-based metadata cache (thread-safe)

SearchResult

A single FTS5 search result

StoredAlert

A single alert record from the activity_alerts table