Manual Grok connection tests previously surfaced upstream HTTP 402 errors without changing account availability. Persist the same 30-minute payment-required cooldown used by the live forwarding path so refreshed account lists no longer present the account as schedulable.
Constraint: Keep manual-test HTTP 402 handling aligned with existing Grok forwarding semantics.
Rejected: Mark the account permanently error | payment state can recover and the forwarding path intentionally uses a bounded cooldown.
Confidence: high
Scope-risk: narrow
Directive: Keep the manual-test cooldown reason and duration aligned with handleGrokAccountUpstreamError.
Tested: go test -tags=unit ./internal/service -count=1; go vet -tags=unit ./internal/service; production package compile check
Not-tested: Live xAI account with an exhausted subscription
Related: #4794
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