POST /api/personal/add_directory called rag.index_personal_documents
inline from an async handler, so the whole indexing job (os.walk, file
reads, per-chunk embedding, Chroma inserts) ran on the event loop and
every other request queued behind it. Indexing a real directory froze
the UI and API for 25+ minutes with no sign of life.
Move the blocking section into the threadpool via run_in_threadpool.
personal_docs_manager.add_directory stays inside it because its
refresh_index() re-extracts text across tracked directories, which is
also blocking work. A module-level lock serializes index jobs so the
threadpool move does not introduce parallel jobs racing
PersonalDocsManager's unsynchronized list mutations and file writes;
they previously serialized on the blocked loop, so one-at-a-time is
behavior parity.
StressTestor
b91f48f50a