🐛 Bug: Generative UI not working properly with useCopilotAction

[rohan-nerdster]

♻️ Reproduction Steps

When using useCopilotAction with actions from a remote python endpoint or TypeScript actions with CopilotChat.

✅ Expected Behavior

Ideally once the handler returns the response the UI should be shown persistently and the data should be added to the messages and be used by the LLM for context.

❌ Actual Behavior

The UI renders for the inProgress status but once it is complete, the result UI appears for a split second before being reset and disappearing and the response from the handler is not added to the message either.
This works with the LangGraph coagent but this is not working as expected with the other methods as mentioned above. This is despite following the code as shown in the documentation and examples.

𝌚 CopilotKit Version

1.8.13

📄 Logs (Optional)

[linear]

CPK-2815 🐛 Bug: Generative UI not working properly with useCopilotAction

[copilotkit-support]

Thanks for reporting this bug — we're looking into it now. If this is blocking production, please book a 15‑minute call here: https://cal.com/nathan-tarbert-copilotkit/15min.

[tylerslaton]

Hey @rohan-nerdster - would you mind giving this a try with our latest versions? The version you are on is pretty old and it'll help us know if this persists.

[rohan-nerdster]

Hey @rohan-nerdster - would you mind giving this a try with our latest versions? The version you are on is pretty old and it'll help us know if this persists.

Hey @tylerslaton , Thank you for getting back to me. Sure, I will try upgrading to the latest versions and let you know if it works.

[rohan-nerdster]

Hey @rohan-nerdster - would you mind giving this a try with our latest versions? The version you are on is pretty old and it'll help us know if this persists.

I tried with copilotkit==0.1.51 in the backend Python remote endpoint and

    "@copilotkit/react-core": "^1.9.1",
    "@copilotkit/react-ui": "^1.9.1",
    "@copilotkit/runtime": "^1.9.1",

in the Next.js app but I am still encountering the same issue. The result gets reset and the response doesn't get added to the messages when using the copilot action.

[copilotkit-support-bot]

There is an architectural limitation in CopilotKit that causes generative UI to not persist when using regular useCopilotAction with remote Python endpoints or TypeScript actions, unlike with LangGraph coagents where it works as expected.

Root Cause Analysis

The core issue is a fundamental difference in how LangGraph coagents and regular useCopilotAction handle generative UI:

• LangGraph CoAgents use a coAgentStateRenders system that properly persists generative UI in the message history
• Regular useCopilotAction uses a renderAndWaitRef system that doesn't persist UI after completion
• Message conversion logic only attaches generativeUI functions when coAgentStateRenders exists

Technical Details

The issue stems from the message conversion logic in the runtime client:

• For LangGraph CoAgents: The agui-to-gql.ts file preserves generativeUI in coAgentStateRenders system, which then gets properly restored in gql-to-agui.ts
• For Regular Actions: The renderAndWaitRef system in use-copilot-action.ts doesn't have the same persistence mechanism, causing UI to disappear and messages not to persist

Current Status & Workarounds

Unfortunately, there's no direct fix available as this appears to be a fundamental architectural difference between the two systems. The current CopilotKit architecture doesn't provide the same generative UI persistence for regular useCopilotAction that it does for LangGraph coagents.

Recommended Approaches

• Primary Recommendation: Use LangGraph coagents for generative UI functionality, as they have proper persistence mechanisms
• Alternative: Consider restructuring your remote Python endpoints to work through the LangGraph coagent system instead of direct useCopilotAction
• Monitoring: Keep an eye on CopilotKit updates, as this may be addressed in future releases

Documentation References

• LangGraph Integration Guide
• Generative UI Documentation
• CoAgent Architecture

Confidence Level: High - This analysis is based on direct examination of the message conversion and action handling code within CopilotKit's core packages.

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