Type Alias: OnCostFn

type OnCostFn = (event: CompactionCostEvent) => void;

Defined in: src/batteries/context/compact/contracts.ts:121

Optional per-summarization cost callback — fired once per SummarizeFn call that actually runs, replacing the production flagship agent's globalThis.__agentCompactionCost ring buffer with an injectable, testable seam that leaves no global state behind.

Parameters

Parameter	Type	Description
event	CompactionCostEvent	See CompactionCostEvent.

Returns

void

Remarks

Never invoked when the threshold hasn't been crossed (no summarization call made — see @nhtio/adk/batteries/context/compact/summarizer!assembleCompactedTurns's below-threshold pass-through path). A caller who wants a running total across a whole session's worth of dispatches accumulates across onCost firings themselves; this battery holds no cross-call state of its own beyond what a single assembleCompactedTurns invocation's caller threads through (the rolling prior summary is passed in and returned explicitly, never stashed on globalThis).