AG UI data model incompatibility issues #311
Description
TanStack AI version
0.5.0
Framework/Library version
react
Describe the bug and the steps to reproduce it
I'm having a rough time pointing my tanstack ai (generated using tanstack builder) to my ag-ui compatible backend. I think this stems from possible data model incompatibility issues between tanstack ai and ag-ui
As an example, tanstack ai sends:
{ "messages": [ { "id": "msg-1771876311632-1djsf", "role": "user", "parts": [ { "type": "text", "content": "test" } ], "createdAt": "2026-02-23T19:51:51.632Z" } ], "data": { "conversationId": "_R_la_" } }
However my ag-ui backend expects:
type RunAgentInput = { threadId: string runId: string parentRunId?: string state: any messages: Message[] tools: Tool[] context: Context[] forwardedProps: any }
And message is also inaccurate:
type UserMessage = { id: string role: "user" content: string | InputContent[] name?: string }
Missing fields in RunAgentInput:
threadId, runId, state?, tools, context?, forwardedProps? (adding ? as they're marked as any in spec but not as optional like parentRunId is.)
Missing/misnamed fields in UserMessage:
"parts": this seems quite similar to "content" from spec
"parts" in tanstack contains an array of an object with fields "type" and "content", in ag-ui this object maps to "TextInputContent" which has "type" and "text" fields
"createdAt": this field does not exist in the specification, not sure if it'll matter to keep/remove it
Reproducing this:
- Create a new tanstack ai app
- Check out ag-ui server-starter and run it
- Point your tanstack ai hook to your ag-ui server (should be as easy as
connection: fetchServerSentEvents('http://localhost:8000/agentic_chat'), - Try sending messages using tanstack ai chat
Your Minimal, Reproducible Example - (Sandbox Highly Recommended)
dont have a codesandbox
Screenshots or Videos (Optional)
No response
Do you intend to try to help solve this bug with your own PR?
None
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