The gateway pre-compression hygiene valve force-compressed any session
crossing 400 messages regardless of token usage. On large-context (1M+)
models doing many short, message-dense turns, a healthy session at ~16%
token usage could hit 400 messages and get force-compressed — and the
compression summary's stale Active Task could then bleed into the next
turn.
The valve's actual purpose is to break a death spiral: when API calls
keep disconnecting on an oversized session, no token-usage data arrives,
the token threshold never fires, and the transcript grows unbounded.
It's a count-based floor for that pathological case only. 400 was tuned
for ~200K-context models and is far too low for modern large-context
sessions. Raise the default to 5000 — still well clear of any death
spiral, but no longer firing on legitimate long conversations.
The value remains fully configurable via compression.hygiene_hard_message_limit.