08 Troubleshooting

Most Fastify issues come from missing body validation, plugin ordering, or streams being buffered by infrastructure.

Auth Is Not Available In Routes

Register auth plugins before support routes:

await app.register(authPlugin);
await app.register(supportRoutes, { prefix: "/api" });

Validation Returns 500

Validate unknown bodies with safeParse and return a 400 from the route.

const parsed = SupportRequest.safeParse(request.body);

if (!parsed.success) {
  return reply.status(400).send({ error: { code: "bad_request" } });
}

Stream Does Not Flush

Set the NDJSON content type and check proxy buffering.

return reply
  .header("Content-Type", "application/x-ndjson")
  .send(agent.prompt(message).readableStream());

Provider Failures Leak Details

Install a Fastify error handler that logs internal details and returns a stable application error shape.

Long Runs Time Out

Increase application, proxy, and platform timeouts. For reviewer waits, store approvals and resume through a decision endpoint.

Next

Add reviewer workflows in Human in the Loop. Related guides: Tool Errors, Readable Streams, and Tracing.