{"version":"2.1.251","anchor":"relay-checks-whether-its-runtime-reports-websocket-backpress","canonical_anchor":"relay-checks-whether-its-runtime-reports-websocket-backpress","heading":"Relay checks whether its runtime reports WebSocket backpressure","tier":"internal","area":"Agent Proxy","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.251\/e\/relay-checks-whether-its-runtime-reports-websocket-backpress","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.251","markdown":"### Relay checks whether its runtime reports WebSocket backpressure\n\nThe relay tests at startup that its runtime reports backpressure, warning if it doesn't.\n\n**What**\n\nWhen the agent-proxy relay starts with a reachability probe configured, it opens a loopback WebSocket, pushes enough data that backpressure should register, and verifies the runtime actually reports queued bytes. If it does not, the relay logs a warning and sends telemetry, because the tunnel's upload throttling relies on that number.\n\n**Details**\n\n- Runs whenever the relay's startup probe is set, not behind a separate feature flag.\n- Warning states the upload gate cannot engage on that runtime; the relay still starts.\n\n**Evidence**\n\n`WebSocket.bufferedAmount stays 0 with bytes queued: the upload gate cannot engage on this runtime`\n\n- Area: Agent Proxy\n- Tier: Under the hood\n- Useful: 1\/5\n- Signal: 3\/5"}