When the billing lookup failed, metering answered with a provisional
fallback plan, so the relay refused the session with
`subscription_required` or, against the fallback's allowance,
`insufficient_funds`, both terminal 1008 closes, and the SDK showed the
upgrade prompt to a paying account. A plan or funds refusal decided on a
provisional plan now sends `internal_error` and closes with 1011, at
connection and mid-session, so the client retries once the lookup
recovers.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>