How it works
Read the stream in order.
MESSAGE_NOT_STARTED means content or end arrived without a matching start. TOOL_CALL_NOT_STARTED means args, end or result cannot be associated with a call. RUN_ID_MISMATCH means a finishing event changed the thread or run identifier. PATCH_PATH means an RFC 6902 path did not start with a slash.
Fix the earliest error first because later lifecycle errors may be consequences. Replace deprecated THINKING_* names with their REASONING_* equivalents and include the fields required by the current schema.
Useful next steps
- Paste the stream into the free validator.
- Check SSE framing and JSON payload parsing.
- Look up common lifecycle diagnostics.
- Compare behavior with the official AG-UI SDK used by your application.
AG-UI Event Lab is independent and is not affiliated with the AG-UI project or CopilotKit.