src/compact/demote.rs

This file decides where compaction’s evicted messages go instead of the void. CompactionOutcome.evicted is handed to a DemotionSink after the history rewrite, so evicted content stays recallable. It is always compiled.

Key items

DemotionSink is your object-safe trait: it receives the evicted messages with their context as a DemotionContext.

MemoryDemotionSink::new(store, max_chars) is the shipped implementation. It renders each evicted exchange into a Trajectory-category memory entry in any LoopMemory store you hand it.

render_evicted(messages, max_chars) is the renderer behind that: role lines, tool one-liners, and per-part truncation. It is the same transcript renderer the QA summarizer feeds its prompts, and it is public so you can reuse it in your own sink.

NoopDemotionSink is your default, where evicted content is dropped.

Behavior notes

The handoff rides the compaction pass’s cancel race, so a cancel during a hanging sink ends your run typed Cancelled, never wedged.

Your prune pass, see context accounting, hands its cleared tool outputs to the same sink under CompactReason::Prune.

Combine this with SearchMemoriesTool and you close the loop: what compaction evicts, your model can recall on demand.

Deep dive: Compaction demotion