Send private reply

Send a direct message to the author of a comment. Supported on Instagram and Facebook only. One reply per comment, must be sent within 7 days. Optionally attach interactive elements: quickReplies (chips above the keyboard, max 13) or buttons (1-3 inline postback/url buttons rendered in the same bubble via Meta's button_template). Chips do not render in the Instagram Message Requests folder. Instagram can refuse buttons, cards and attachments to commenters who do not follow the account (Meta code 2, subcode 1545133, returned here as a non-retryable 400 that says so). The refusal is uneven: most accounts do not get it, an affected account gets it on many of its non-followers, and only that account's own past refusals show whether it is affected. The failed call still consumes the comment's single private reply. On an affected account, send plain text to reach non-followers and add buttons once they reply. quickReplies and buttons are mutually exclusive. When the comment's single private reply is spent (by this call or an earlier one) the 400 carries details.privateReplyConsumed: true; never retry it. A 502 means Meta answered a server error after receiving the reply; it carries details.privateReplyOutcome: "unknown", the reply is usually delivered and the comment's private reply spent, so check the conversation before retrying. The reply is recorded in the inbox conversation with the commenter (sentVia api for key auth, human for a session) and fires message.sent once.