# FE-RB-003 — Backend API degradation

Trigger when terminal network/timeout/5xx failures exceed the rolling
five-minute threshold or on one `SCHEMA_MISMATCH`. Do not expand client retry
caps, do not retry schema mismatches, and never retry an unkeyed mutation.
Escalate from the API client owner to backend operations and then release
compatibility; the planned first-classification target is ten minutes.

Close only after the failure rate returns to baseline, retry amplification is
absent, critical read/write smoke passes, and schema fixtures pass.