A compaction capability family (see [capability seams](../../.agents/notes/implemented/architecture/2026-06-13-capability-seams.md)): an abstract interface, a summarizing backend, a model-free tool-result pruning companion, and a human command adapter. All **product** packages.
The backend, optional pruner, and human command compose through the seam; token measurement remains a separate LLM-family service. The [compaction capability-seam Agent Note](../../.agents/notes/implemented/feature/2026-06-18-compaction-capability-seam.md) owns the dependency rationale.