When a systemic failure (provider outage, auth expiry, OOM) crashes
multiple workers simultaneously, detect_crashed_workers increments
each task failure counter independently. The circuit breaker only
trips after N × failure_limit retries across the fleet.
Fingerprint crash errors by normalizing host-specific details (PIDs,
timestamps). When 3+ tasks crash with the same fingerprint in a
single detection cycle, immediately trip the circuit breaker
(failure_limit=1) instead of waiting for repeated failures.
Isolated crashes (unique fingerprints) retain their normal retry
budget. Protocol violations continue to trip immediately.
Includes regression tests for systemic and isolated crash paths.
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