Anthropic API 2026-09-14

+ 신기능 2개

• `compact-2026-09-04` 베타 헤더를 사용해 필요할 때 대화를 압축하는 기능을 추가한다 # 세션·컨텍스트
  원문

  The Messages API can now compact a conversation on demand on the Claude API, in beta with the `compact-2026-09-04` beta header. Send the top-level `compaction` parameter, and the API returns a signed `compaction` block that summarizes the messages you sent. On later requests, send that block first, in place of those messages. You choose when to compact, the request can run in the background, and you can keep recent turns word for word after the summary. On models with preserved thinking, the thinking in those kept turns can stay valid.

• `thinking-binding-controls-2026-08-01` 베타 헤더와 함께 `input_transformations` 응답 필드에 `thinking_mismatch_allowed` 항목을 추가한다 # 모델·요금
  원문

  With the `thinking-binding-controls-2026-08-01` beta header, the `input_transformations` response field gains a second entry type, `thinking_mismatch_allowed`. It names a thinking block that failed the prefix check on a request where the API doesn't enforce that check: on Claude Fable 5.1, for example, a request from an account created before August 31, 2026, with `prefix_mismatch_behavior` unset. The block still reaches the model unchanged. Log these entries to find history edits in production traffic before you opt into enforcement. See Set the mismatch behavior and read `input_transformations`.