[Fix] Fast parent events repeatedly retry exhausted OpenRouter accounts

[roomote-roomote]

​Opened on behalf of @mrubens. Follow up by mentioning @roomote-roomote, in the web UI, or in Slack.

What changed

• Recognize OpenRouter credit exhaustion only from the observed structured 402 metadata (limit_source=openrouter_credits) and stop both OpenCode and Fast inference retries immediately.
• Keep arbitrary 402 responses retryable when they lack that evidence, while preserving the existing terminal handling for errors providers explicitly mark non-retryable.
• Discard durable Fast parent events after typed non-retryable inference failures so PostgreSQL recovery does not recreate exhausted BullMQ jobs indefinitely.
• Preserve transient provider retries and the separate missing-session fallback rebuild path.
• Add regression coverage across provider recovery, Fast inference, durable parent-event delivery, and cold-session recovery.

Why this change was made

Fast parent platform events could exhaust their bounded inference and BullMQ retries after an OpenRouter account-credit failure, then be recreated every minute because the durable PostgreSQL event remained pending. That turned a terminal account condition into an unbounded production retry storm.

Impact

Explicit OpenRouter credit-limit failures now settle once at the inference and durable queue boundaries. Temporary provider outages, rate limits, unknown 402 responses, and missing OpenCode sessions retain their recovery behavior.

[roomote-community]

1 issue outstanding. See task

• Durable parent events still retry non-retryable inference failures because their FastAgentInferenceError is wrapped before the new predicate runs. (packages/sdk/src/server/lib/fast-agent-parent-event-queue.ts:449)

_{Reviewed 2491ca1}

[roomote-community]

deliverFastAgentParentEventWithLock wraps failures from answerFastAgentQuestion in FastAgentParentEventDeliveryError before they reach this catch block (fast-agent-parent-event.ts:1862). The new predicate only accepts a direct FastAgentInferenceError, so it returns false for this wrapper and the row is left pending and retried by recovery. Inspect the error cause (or unwrap it here) so an OpenRouter credit failure is actually discarded.