GET /api/sessions (and every session lookup) re-read and JSON.parsed every
.jsonl session file synchronously on each request, blocking the agent's
event loop. Parsed metadata is now cached per path (bounded to 500 entries)
and invalidated when mtime or size changes.
Add characterization tests first, then split the hot spots into small helpers:
- STT/TTS settings updates move to extensions/piagentui-speech-settings.ts (rule tables)
- defaultExtractData is split into diff/diagnostic/output extractors
- getToolSummaryCategory becomes an ordered rule table (toolSummary.ts)
- sanitizePersistedTerminalLayoutMap is split per level
- duplicated diff stats helpers are merged into utils/diffStats.ts
evandro