Compact the current conversation into a handover document a fresh agent can pick up and continue seamlessly. Invoke when only 5-10% of the session limit remains, when context usage passes 40% (less than 60% of the context window remaining), when context is about to cross an agent or session boundary, when work is blocked, or on explicit user request — never haphazardly mid-task. Covers decisions, shipped changes, key files, running state, verification, deferrals, and open questions.
