For an API partner acting for your brokerage (a token carrying the partner claim, with broker_submit) on a submission that partner created, before or after finalize. Any other caller, or a submission the partner did not create, gets 404.

Each answer is checked, and only a key a question carries is ever recorded. An api_program answer is checked against the program's questions (GET /broker/programs/{program_id}/application-schema): by question_id, whose question's key it must send, or by key alone when one question carries it. Option values are the program's own JSON values and are compared exactly (300000 is not "300000"). A hedge_questions answer is checked against the Hedge questions (POST /broker/hedge-questions) by key; a select there takes an option value or its label. Values are type-checked. Program answers may address only the programs of a rater file, or of a standard file's own lanes. An accepted answer is recorded on the submission as the agency's own answer under its key, which every Hedge model, carrier application and rendered supplemental reads. A program answer also reaches that program's live carrier session once one exists. Limits: 500 answers per request, 4,000 characters per text answer, 20,000 characters of JSON per value (250,000 for a list value such as a carrier's location rows).

Idempotency-Key (at most 128 characters) is required. Retrying the same key with the same body returns the first result; the same key with a different body is a 409.