Cancel Truemed Session

Abandon a pending Truemed session — call this when the shopper never finished the flow or you withdrew the offer. The endpoint takes no request body and is naturally idempotent: re-canceling a canceled session is a no-op that returns the same `canceled` state. A session is cancelable while nothing has been captured: from creation, through the survey, an authorization hold, and clinical review. A canceled session reads `qualification_info.qualification_status` = `canceled` and stops accepting survey completion and holds. The rest of `qualification_info` is preserved — a canceled session with `eligible_amount_cents` > 0 in `qualification_info` was approved before it was canceled. Once a capture has been reported, the session can no longer be canceled and the call returns a `400` — money going back to the shopper after capture is a [refund](/v2/api-reference/truemed-sessions/create-truemed-session-refund).