422 invalid_request; the exceptions are called out on their rows and in
Errors.
Rate limits
Message writes use a fixed window per conversation. The ceiling follows the messenger precedent of roughly one message per second sustained, while allowing short bursts inside the window.
A
429 response carries Retry-After in seconds. Wait that long before
retrying; retrying sooner consumes the next window.
Messages
Quick replies
Message components
See message components for the per-kind schemas.
Attachments
Message edit and unsend
Groups
See group conversations.