userActionResponse

Response to a UI prompt (not a text conversation message). Operator App SDK clients set this to the control-string sentinel "APPROVAL_ACTION" when the request is resuming a paused tool call after an operator approval decision; in that case the structured decision context lives on the sibling approvalAction member and the chat agent reads from there. Preserved as a String for back-compat: pre-typed-approval clients still encode arbitrary UI-prompt responses as JSON in this field, and the chat agent parses them out during the transition.