pub fn context_window_trigger(window: u64, percent: u32) -> TriggerFnExpand description
Build a trigger closure that fires when the most recent transcript item’s
reported usage.tokens.input_tokens reaches window * percent / 100.
Only fires at MutationPoint::AfterTurnEnded; other points return
None. percent is clamped to 1..=100.
Plug into StrategyCompactorBuilder::trigger (or use it directly as a
TriggerFn).