Review follow-up (egilewski): the previous commit only hedged the guidance
text; the exact Anthropic 400 was still classified, persisted, and surfaced
as confirmed billing exhaustion. Carry the ambiguity all the way through:
- agent/error_classifier.py: 'out of extra usage' matches on the 400 and
status-less paths now attach error_context {billing_unverified,
possible_content_filter}. Reason stays FailoverReason.billing (rotation +
fallback remain the right recovery either way); ClassifiedError grows a
billing_unverified property.
- agent/credential_pool.py: new FAILURE_REASON_BILLING_UNVERIFIED. An
unverified billing exhaustion gets the short transient cooldown instead of
the one-hour bench, regardless of pool size: a content-filter rejection
leaves the credential healthy and fails identically on every key, and the
hour-long sole-credential latch is what replayed the stored error and made
real fixes look ineffective. A true 402 keeps the full bench. The marker
persists with the entry so a restart cannot upgrade it back to a bench.
- agent/agent_runtime_helpers.py + run_agent.py: recover_with_credential_pool
threads billing_unverified and hands the pool 'billing_unverified' as the
persisted failure_reason.
- agent/conversation_loop.py: the fallback-switch status, max-retries status,
terminal label, and both structured terminal results hedge when the verdict
is unverified. New _billing_terminal_label + _billing_failure_result build
the returned terminal response in one place; the result dict now carries
billing_unverified and the billing_block gains 'unverified': true. The
confirmed-billing path (a real 402 or an API-key credit depletion) keeps
the original assertive wording, so the caveat no longer dilutes it.
Regression tests: classifier marking (400 + status-less + unambiguous-body
negative), pool cooldown TTLs + persistence round-trip, pool failure_reason
plumbing, and the returned terminal response for both unverified and
confirmed verdicts.
Note: tests/agent/test_credential_pool_routing.py::TestFailureAttribution::
test_unmatched_key_does_not_retry_only_pool_entry fails identically on
current main without this change (pre-existing, unrelated).
f57209bc9f