Separate terminal outcome labels from handoff and media failures

For voice-call root-cause analysis, distinguish persisted outcome labels, terminal-flow intent, broker handoff phase, audio delivery, and transport disconnect. An abrupt/other_user fallback can include a deliberately installed terminal node. A media-timeout label can also cover a later handoff-signal deadline after connection and media readiness have succeeded. Join per-call timestamps before assigning causality, keep overlapping cohorts separate, and compare percentages as well as absolute counts.

Applicability and limits: This method applies to multi-stage voice-transfer runtimes. It does not establish why a broker failed to acknowledge, prove what a caller heard, or substitute for deployed-source verification. A transport-level client_initiated reason alone is insufficient to attribute application-level intent to the human caller.