Dispatch a real (non-test) Sierra voice-agent call. For mammogram-member-availability, dispatched to Sierra's Playbook API directly, in-request; for the direct-agent purposes, queued for dispatch by OutboundCallWorker (GE-2565/GE-2832). No dry-run/confirm gate -- once a dispatch is actually attempted, the response is always 202 {"status": "queued"} regardless of purpose or outcome; the real outcome (dispatched, failed, or a Sierra-reported disposition) is only ever visible via POST .../results. A request that can't even be attempted -- ENABLE_CA_VOICE_CALLS off, or a missing SIERRA_PLAYBOOKS_API_TOKEN -- returns 502 instead, before any audit row exists.

Requires scope: voice_calls:write

For the direct-agent purposes, inputs may override the standard member fields MC2 derives from the member record: patient_first_name, patient_last_name, patient_dob, patient_address, patient_email_address, patient_phone and language_preference (member_id is never overridable). Each must be a non-blank string; patient_phone must be a dialable US or Canadian E.164 number and, for the agents that call the member, is also the number dialed; language_preference is passed through as sent (for example chinese), not checked against a list of languages. An invalid override is a 422.

The Idempotency-Key request header is required. Replaying the same key for the same api_client returns the original queued response rather than dispatching again -- but only if the request body is unchanged; reusing a key with a different body returns 409 instead.