Claude API adds on-demand compaction for long agent runs
Anthropic added a Messages API beta that lets a client request compaction at a chosen point and receive a signed summary block. The request can run in the background, and callers can replace older messages with that block while preserving recent turns verbatim.
Why it matters: Agent runtimes can move context compression out of an in-band response and schedule it before a long task reaches a hard limit. That improves orchestration control, but it also creates a new signed-state handoff and a separately billed model sampling step…