Five hottest BQ-touching endpoints were `async def` but invoked synchronous
DuckDB / BQ-extension calls inside the body. Under uvicorn's single event
loop that meant a single heavy `agnes query --remote` (waiting up to
~200 s for BQ's jobs.query) froze EVERY other request — /api/health,
dashboard, auth, even another query — for the full BQ wait. Operators
saw "VM idle, app frozen" during PR #188's testing.
Convert to plain `def` so FastAPI auto-offloads the body to the anyio
thread pool. Event loop stays free for non-BQ requests.
- app/api/query.py:execute_query
- app/api/v2_scan.py:scan_estimate_endpoint, scan_endpoint
- app/api/v2_sample.py:sample
- app/api/v2_schema.py:schema
Audit: 0 `await` statements in any converted handler (verified file-by-
file), so the rename is safe. Tests in tests/test_v2_*.py called the
handlers via `asyncio.run(...)` which now fails on a non-coroutine return;
swapped for direct calls (asyncio.run( -> ( ) — keeps paren balance).
Plus AGNES_THREADPOOL_SIZE env var (default 200, was anyio's stock 40)
in app/main.py:lifespan. Set via
anyio.to_thread.current_default_thread_limiter().total_tokens. 200 is
comfortable headroom for <50 concurrent analysts; bump for more.
480/480 impacted tests pass (the 2 remaining errors are a pre-existing
fixture setup issue in test_reader_smoke_matrix.py unrelated to this
change).
e5fb913cec