Devin Review iter #2 found 2 new issues (after iter #1's 5 fixes
landed). Both real, both addressed.
🔴 Quota user_id key mismatch defeated shared daily budget. /api/query
computed `user.get("id") or user.get("email")` while /api/v2/scan uses
`user.get("email") or "anon"` (app/api/v2_scan.py:327). Same user → two
different keys in the singleton QuotaTracker. BQ bytes consumed via
/api/query were tracked under UUID; via /api/v2/scan under email; the
`check_daily_budget` pre-flight on either endpoint never saw the
other's recorded bytes — per-user cap was effectively doubled. Match
v2/scan's email-first ordering.
🟡 QuotaExceededError(KIND_CONCURRENT) → 400 instead of 429.
`quota.acquire(user_id)` raises this from __enter__ when the per-user
concurrent-scan slot is at cap. The exception propagated through the
@contextlib.contextmanager generator, the caller's `with guard:`
block, and was caught by execute_query's generic `except Exception`
handler → mapped to 400 with a flattened "Query error: concurrent_scans:
N/M" string, dropping the typed retry_after_seconds field. Wrap the
`with quota.acquire(...)` in a try/except QuotaExceededError that maps
to 429 with the same typed-detail shape used for the daily-budget
rejection — consistent with /api/v2/scan:392-402.
Tests: test_api_query_quota.py user_id strings updated to
"admin@test.com" (the seeded_app admin's email) to match the new
email-first ordering. 40 affected tests pass.