Message corruption

[solid grove]

Version: npx copilotkit create -f mcp-apps

[brittle ermine]

This solution has been AI generated

This is a known streaming/join issue in the mcp-apps template: adjacent text chunks can be concatenated without spaces (e.g., today?I'd). It happens when Streamdown renders back‑to‑back chunks (reasoning → answer) that lack explicit whitespace.

Why this happens

The mcp-apps starter (V2) renders assistant content with Streamdown:

// CopilotChatAssistantMessage.tsx
export const MarkdownRenderer = ({ content, ...props }) => (
  <Streamdown {...props}>{content ?? ""}</Streamdown>
);

In MCP Apps flows, agents often emit a "reasoning" block followed immediately by the final answer. If those events don’t include a trailing newline/space, Streamdown joins them visually.

Fixes (in order of recommendation)

1. Add explicit separators in the agent output
   Ensure your agent logic/prompt inserts a newline between blocks, e.g. end reasoning with \n\n before the final response. This applies to LangGraph or the Built‑in Agent used by MCP Apps.

2. Update CopilotKit/Streamdown packages

npm install @copilotkit/react-ui@latest @copilotkit/react-core@latest @copilotkit/runtime@latest

Early V2 stream handlers occasionally dropped delimiters; latest versions improve chunk joining.

3. Optional visual tweak (CSS)
   If spacing still looks off due to typography styles, add:

[data-copilotkit] .prose p + p { margin-top: 1em; }

If after adding a newline and upgrading packages you still see concatenation, the remaining cause is likely in how Streamdown or MCP Apps events are joined and may require a library fix.

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[brittle ermine]

Thank you for your feedback! Our team will provide additional assistance. 🔄

[solid grove]

need help

[brittle ermine]

Hi @solid grove, Could you open an issue with the details - versions and steps to reproduce? That would really help the team look into it. Thanks!

[solid grove]

yes https://github.com/CopilotKit/CopilotKit/issues/3351

[brittle ermine]

Thanks for opening the issue. I'll follow up with the team and get back to you!

[solid grove]

very need help, i have change many models