Review folds from the formal gate battery:
- _SPLIT_FAILURE_COOLDOWN_SECONDS = 60 replaces the bare literal, with a
comment pinning WHY it is the timeout ladder's first rung (transient
lease/DB condition) rather than the 600s summary-provider cooldown.
- publish_compression_child docstring now states the compression_lock_holder
condition on the refresh guard.
- Dropped 2 of 3 extracted unit tests as duplicates of existing coverage in
test_compression_rotation_state.py / test_context_compressor.py; kept the
force-bypass test (only site pinning that behavior for split failures) and
the E2E test (now asserting the named constant).
Two narrow repairs for #97948 symptom B (large-session rotation aborts with
'Compression lease lost before publication' / session_split_failed, then the
next turn re-runs the identical doomed compression):
1. publish_compression_child gains require_lease_refresh: the lease is
extended inside the same transaction as the expiry check (same conn, no
TOCTOU), giving a worker whose refresher thread died from transient DB
failures one final chance to keep its completed work.
2. A failed compression split now records a 60s failure cooldown, so the
next turn cannot immediately re-trigger the same compression.
Salvaged from #98137 (author: vsd2807). The timeout-reconciliation half of
that PR is NOT carried: it has a blocking review (runtime sid vs persisted
session_key, one-shot check cannot observe a 6-minute commit, no identity
projection) and needs a redesign.
kshitijk4poor