Server-sent events. On connect, a snapshot event with the last 20 request log rows, the credit balance, the server-authoritative month-to-date totals (monthToDate: tokens, spentCredits, requests) and their read-time cutoff; then one request event per settled or failed request. Live request frames carry balanceCredits; a request replayed just after the snapshot omits it. Event data is JSON with v: 1. Heartbeat comments every 25s. Log rows only, payloads are never streamed.
Gateway API key (imp-rt-...) from POST /v1/accounts or /v1/keys.
A text/event-stream of snapshot and request events