The commercial dependency
Sendblue’s AI Agent plan is $100 per line monthly and inbound-first. Full outbound belongs to Enterprise custom pricing. Put message direction in the requirements document: answering a message, starting a reminder and contacting a newly created CRM lead are different actions to confirm.
The test dependency
The sandbox has ten verified contacts and does not provide webhooks. It can expose part of the developer experience, but it will not prove your full inbound event handling. Request a supported production-like evaluation before building assumptions around callback delivery.
The implementation question
Ask for current event identifiers, authentication requirements and retry behavior. Keep the provider’s acceptance response separate from delivery and read states in your own data model. The public integration pages advertise possible connections; they do not establish the behavior of every connector or the latency your application will observe.