Attempt And Age Dead Letter Policy • AI Agent SDK

AttemptAndAgeDeadLetterPolicy: Default dead-letter policy: require BOTH attempt-exhaustion AND age.

AttemptAndAgeDeadLetterPolicy

Defined in the protocols module.

Default dead-letter policy: require BOTH attempt-exhaustion AND age.

Distinguishes a poison message (fails repeatedly over a long time) from a transient outage (fails a few times quickly, then recovers). A recoverable/transient failure is dead-lettered only once it satisfies

both:

1. `attempts >= max_attempts`, and
2. `age >= min_age_seconds` (wall-clock age since first receipt).

Until an entry is genuinely old it keeps retrying under capped backoff rather than being discarded, so a brief channel incident results in delayed-but-delivered messages rather than a DLQ full of manual-replay work. A truly poisoned entry still dead-letters — it keeps failing past both thresholds.

An error whose `error_class is known-permanent (see :data:PERMANENT_ERROR_CLASSES` — a revoked credential or a permanently invalid target) short-circuits to dead-letter immediately regardless of age, since retrying can never recover it.

`min_age_seconds=0` restores the legacy attempt-count-only behaviour, keeping the knob fully backward-compatible for callers that opt in.

Example::

AttemptAndAgeDeadLetterPolicy(max_attempts=5, min_age_seconds=6*3600)

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