[lavaman131]

Two connector log bugs seen while a build ran through a two-and-a-half-minute Chopin outage. Both are in the chopin CLI, so they ship with the next CLI release. No protocol change.

"Still trying to reach Chopin" said "no answer" behind a 502 gateway

While Chopin was down, the proxy in front of it answered every request with 502 within about 50 ms. Every retry line said no answer instead of the status.

Once the run's connection drops, each heartbeat registers the machine again before it calls Chopin. The proxy's 502 has an empty body sent with Content-Length: 0, and Bun's response.json() reads that as null, not a parse error. So post() in machine.ts threw TypeError: null is not an object (evaluating 'value.error'). It did not throw the ConnectorError("http-502", …, 502) it was meant to throw. That TypeError happened to be classified as retryable, but it has no status or code, so failureKind fell back to no answer. A 502 with an HTML body, or a refused connection, never showed the problem.

• post() now treats any body that is not a JSON object as empty, so registration refuses with the HTTP status.
• failureKind now reads the status of a refused registration (HTTP 502, the same wording as the MCP client's errors, or HTTP 503 unavailable when there is a server code). It also finds a status, server code or network code in anything the error wraps as its cause. It still never reports message text.

False "Lost the connection" / "Lost contact" right after "✓ Finished"

When a run ends, runWork stops its heartbeat, which cancels a renew_* call that is still in flight. The MCP client rejects that with MCP error -32001: AbortError. link.call only checked the connector's own stop signal, and classifyConnectorError treats -32001 as retryable. So the connector printed "Lost the connection to Chopin during a run" and dropped the healthy shared connection, and runReports.attempt printed "Lost contact with Chopin".

Now a call that its own caller gave up is not a connection failure: it keeps the connection and prints nothing. A call that timed out (its signal's reason is a TimeoutError) still counts as a failure, as before.

Tests

Each test failed on the unfixed code for the reason above:

• run.test.ts: "a run behind a gateway answering 502 with no body says HTTP 502 while it retries". It runs the real serveWork → runWork heartbeat with a connect that registers and then opens MCP, the way chopin connect does, against a gateway that sends an empty 502. Before the fix the lines said no answer.
• run.test.ts: "a heartbeat in flight when a run finishes is cancelled without losing the connection". Before the fix it printed the same MCP error -32001: AbortError lines and registered the machine a second time.
• connection.test.ts: failureKind for wrapped refusals and network errors.