Read sessions-index.json from a project directory. Falls back to scanning .jsonl files directly if the index doesn't exist.
Parallelizes all I/O: stats every JSONL for fresh mtime, only parses JSONL content for sessions with messageCount=0 (small/new sessions).
Read sessions-index.json from a project directory. Falls back to scanning .jsonl files directly if the index doesn't exist.
Parallelizes all I/O: stats every JSONL for fresh mtime, only parses JSONL content for sessions with messageCount=0 (small/new sessions).