Debug Mode

When your agent isn't behaving as expected — events are missing, state isn't updating, or tool calls aren't executing — you need visibility into what's happening in the event pipeline. Debug mode gives you that visibility with detailed logging on both the server (runtime) and client (React) side.

Enable it to see:

• What events your agent is emitting and whether they reach the client
• Where in the pipeline events are being dropped or failing validation
• The full lifecycle of a request from start to finish

Enabling Debug Mode

Server-Side (Runtime)

Pass debug: true to the CopilotRuntime constructor:

const runtime = new CopilotRuntime({
  agents: {
    // your agents
  },
  debug: true, // [!code highlight]
});

This produces structured Pino logs (formatted by pino-pretty) with a copilotkit-debug component label:

[14:32:01.123] DEBUG (copilotkit-debug): Agent run started
    agentName: "default"
    threadId: "abc-123"
[14:32:01.130] DEBUG (copilotkit-debug): SSE stream opened
[14:32:01.145] DEBUG (copilotkit-debug): Event emitted
    type: "TEXT_MESSAGE_START"
    messageId: "msg-1"
    role: "assistant"
[14:32:01.200] DEBUG (copilotkit-debug): Event emitted
    type: "TEXT_MESSAGE_CONTENT"
    deltaLength: 42
[14:32:01.250] DEBUG (copilotkit-debug): Event emitted
    type: "TEXT_MESSAGE_END"
[14:32:01.260] DEBUG (copilotkit-debug): Event emitted
    type: "RUN_FINISHED"
[14:32:01.261] DEBUG (copilotkit-debug): SSE stream completed
    eventCount: 4
    loggedEventCount: 4

Client-Side (React)

Pass debug={true} to the <CopilotKit> provider:

<CopilotKit
  runtimeUrl="/api/copilotkit"
  debug={true} // [!code highlight]
>
  <YourApp />
</CopilotKit>

This forwards the debug configuration to the AG-UI client transport layer (transformChunks), which may produce transport-level debug output depending on the AG-UI library version. Note that the richest debug logging comes from the server-side CopilotRuntime — enable debug: true there for full structured Pino logs of every AG-UI event.

Granular Configuration

Instead of true, you can pass an object for fine-grained control over what gets logged:

debug: {
  events: true,     // Log every event emitted/received
  lifecycle: true,  // Log request/run lifecycle (start, finish, error)
  verbose: false,   // Log full payloads instead of summaries
}

This works the same way on both the server and client.

Defaults

Input	events	lifecycle	verbose
debug: true	true	true	false
debug: {}	true	true	false
debug: { events: false }	false	true	false

When debug is a boolean (true), events and lifecycle logging are enabled but verbose mode is off by default (to avoid leaking PII in logs). To get full event payloads, explicitly opt in with debug: { verbose: true }.

Examples

Log only lifecycle events (no per-event logs):

debug: { events: false, lifecycle: true }

Log events with full payloads but skip lifecycle:

debug: { events: true, lifecycle: false, verbose: true }

Troubleshooting with Debug Mode

Events Not Reaching the Client

Enable debug on the server side for the most detailed visibility:

1. Check server logs for Event emitted — are the expected events being sent?
2. Verify SSE stream completed shows the expected eventCount.
3. Use the browser Network tab to confirm SSE events are arriving over the wire.

Tool Calls Not Executing

Enable server-side debug and look for:

1. TOOL_CALL_START events being emitted on the server
2. TOOL_CALL_ARGS and TOOL_CALL_END events following correctly
3. Confirm the events appear in the SSE stream via the browser Network tab

State Not Updating

Look for STATE_SNAPSHOT or STATE_DELTA events in server logs. If they appear on the server but not in the browser's SSE stream, there may be a connection issue.

What Gets Logged

Server-Side Logs

Category	Log Message	Description
Lifecycle	Agent run started	An agent run was initiated, includes agent name and thread ID
Lifecycle	SSE stream opened	The SSE response stream was created
Lifecycle	SSE stream completed	The stream finished, includes total event count
Lifecycle	SSE stream errored	The stream encountered an error
Events	Event emitted	Each AG-UI event as it's written to the stream

In summary mode (verbose off), event logs include key identifiers like messageId, toolCallId, toolCallName, role, and content lengths instead of full payloads.

Client-Side

On the client, the debug configuration is passed through to the AG-UI transport layer. The AG-UI client library controls what (if any) debug output is produced. CopilotKit itself does not emit console.debug calls — the debug flag configures the underlying AG-UI event pipeline.