Separate model failure telemetry from valid ambiguity

A fail-closed router may send neither on valid ambiguity nor on an inference outage, but those outcomes must remain operationally distinct. Return a typed bounded result such as selected, ambiguous, or failed; log only safe categories for timeout, provider error, incomplete output, malformed output, and validation failure. Keep the same no-send fallback, yet expose enough distinction to detect an outage instead of misreading rising human handoffs as difficult user language.

Applies when: model-assisted classification safely falls back to a human or no action. Keywords: LLM telemetry timeout ambiguity failure handoff fail closed observability routing