AZ-291 — FileFdrWriter: single writer thread draining every registered
FdrClient SPSC ring buffer to per-flight segment files; per-segment
size rotation; cross-process fcntl.flock filelock on flight_root;
ENOSPC degraded mode with rate-capped ERROR logs and one GCS alert.
AZ-292 — FlightHeader/FlightFooter dataclasses + open_flight /
close_flight lifecycle methods; four per-flight monotonic counters
(records_written, records_dropped_overrun, bytes_written,
rollover_count) reported by the footer; flight_id mismatch and
close-without-open are typed errors.
AZ-293 — CapacityCapPolicy (post-rotation hook): walks the flight
directory, drops the oldest CLOSED segment when total > cap (default
64 GiB), emits a kind="segment_rollover" record per drop. Never drops
the currently-open segment or segment 0 alone; cap_misconfigured path
logs ERROR + GCS alert. No config flag disables emission (C13-ST-01).
Schema: bumped fdr_record_schema flight_header / flight_footer payload
key sets to match the AZ-292 task spec (effective 1.0.0 -> 1.1.0; no
prior producer); KNOWN_PAYLOAD_KEYS updated. Added FdrWriterConfig
nested in FdrConfig (segment_size_bytes, batch_size, flight_cap_bytes,
debug_log_per_record).
Tests: 29 new unit tests (8 AC + 1 invariant per task); full suite
323 passed, 2 pre-existing skips, 0 regressions.
Co-authored-by: Cursor <cursoragent@cursor.com>