Workshop inbox messaging

Send ad-hoc SMS and/or email to one customer for a workshop that has inbox messaging enabled.

Auth: existing partner OAuth2 (Authorization: Bearer …, X-Partner-Id).

Workshop gates (403):

000003 FeatureUnavailable — caller is not an allowed partner for these endpoints

000004 FeatureDisabled — workshop integration or inbox messaging is turned off

Customer targeting:

customerId — must exist under this workshop (404 if not; no phone fallback)

Without customerId — phone is required (find or create); optional email upserts onto that record

Idempotency: supply referenceId to safely retry; same partner + workshop + customer + referenceId returns the stored result without resending.

Rate limit: 5 requests/sec per (workshopId, customerId).

Bulk: one API call = one customer. For many recipients, use the blast/campaign API, not this endpoint.

Messaging