Anthropic::SummarizeCompaction

Request a server-side compaction summary instead of a sampled reply.

Sending compaction compacts the whole conversation and returns a signed compaction block, alone, that a later request sends back first in messages in place of the messages it summarizes. There is no trigger and no pause flag: sending the parameter compacts, and nothing is sampled after the block. Requires the compact-2026-09-04 beta (see Anthropic::COMPACT_2026_09_04_BETA); the beta Messages methods attach it automatically when compaction is set.