The 10s hygiene_max_turn_hold_seconds budget (#92318) releases the arriving
user turn while the summary model is still streaming. For thinking summary
models (DeepSeek-V4-Flash etc.) whose reasoning prefix alone exceeds 10s,
the abandonment path ALWAYS cancelled the commit fence — 100% of the summary
attempt (including the full thinking prefix) was discarded on every turn,
permanently disabling auto-compression while paying the summary model 10s
of thinking per turn, and the flat 60s retry-after then blocked the
agent-side preflight from a fresh chance.
Structural fix (maintainer-chosen direction in #97963): decouple the turn
from the compression instead of holding the turn longer or making the hold
progress-aware (which would reintroduce the #90845 frozen-turn bug):
- CompressionCommitFence gains mark_commit_watermark_fenced() /
commit_watermark_fenced; compress_context marks the fence right after
capturing get_active_message_watermark() under the durable compression
lock (#75316/#87484) — the property that makes a LATE commit safe: rows
appended after compression start survive both commit paths verbatim as
cloned concurrent tail (archive_and_compact watermark= and
publish_compression_child watermark/watermark_ceiling).
- gateway hygiene turn-hold handler: when the fence is watermark-fenced,
the detached worker (already kept alive via
_defer_agent_cleanup_until_future_done) KEEPS its commit admission; the
user's turn proceeds on the uncompressed transcript at the same 10s
budget, and the summary is adopted at the worker's own watermark-fenced
commit boundary. Unfenced workers are cancelled exactly as before —
never worse than the status quo.
- No retry-after is armed while the kept-admission attempt runs (it would
block preflight adoption via the same-session cooldown); re-attempt
spacing is covered by the durable compression lock
(_session_has_compression_in_flight). If the worker ends WITHOUT
committing, a done-callback restores the flat non-escalating 60s
retry-after; a successful adoption resets the hygiene failure streak.
The streak never advances for a deferral either way.
- Docs: configuration.md hygiene_max_turn_hold_seconds one-liner updated
to describe deferred adoption and the thinking-model case;
config_defaults.py comment updated. Knob stays config.yaml-only.
Invariants preserved:
- 10s user-latency cap stays hard (#90845/#92318):
test_session_hygiene_turn_hold_budget_abandons_streaming_wait passes
UNMODIFIED (its worker is not watermark-fenced, so it pins the cancel
path through the public surface).
- Stale-clobber impossible: adoption only rides commits bounded by the
start watermark; the fence still gates admission and unfenced/late
results are discarded.
New regression tests (tests/gateway/test_session_hygiene_turnhold_adoption.py):
- watermark-fenced worker keeps admission, late summary is committed,
turn still released at the budget, no cooldown while running,
streak reset on adoption;
- kept-admission worker that ends without committing restores the flat
turn-hold retry-after (<=120s, names turn-hold, streak untouched);
- unfenced worker still cancelled and discarded (status quo).
Sabotage-verified: disabling the keep-admission branch fails the two new
adoption tests and leaves the unfenced-cancel test green.
Fixes#97963
Teknium
9de9d7613c