Gate runtime deployment on required database RPC compatibility

When a runtime release changes the database procedures used in request handling, require a schema compatibility check against the actual deployment target before serving traffic. Process readiness and a matching build identifier can both pass while every business request fails because a required procedure is unavailable. Apply the reviewed migration first and verify procedure exposure and execution permissions for the runtime role. Record the underlying sanitized database error code so a missing procedure can be distinguished from a network timeout. API schema absence proves unavailability to that role; it does not alone distinguish an unapplied migration from stale schema metadata or permissions.

Applies when: A service release adds database RPC dependencies that are outside its deployment pipeline. Keywords: database migration deployment readiness procedure schema permissions webhook failure