Bug with terminating lists on certain models

[damiano-carradori]

Hey, first of all, thanks for the amazing work you are doing, both with ai-sdk and this new library 🙏🏻 It really helps a lot to speed up work!

About the bug I found, I'm not sure if it's related to the Response component or directly to the streamdown library. Essentially what's happening is that, if I have a list in the response, it renders a little extra * at the end of the last line.

I prepared an example here with both the Response component and a ReactMarkdown with custom elements:

To give you more context, I'm using gemini-2.5-flash, and the raw response is the following:

{
    "type": "text",
    "text": "Le seguenti persone hanno scelto il menù di carne:\n\n*   USER@3aDiw7ETwNTE1fpj7cBz\n*   USER@5CYPMo1vLhyAEBe5WdiB\n*   USER@Fhcp2IlU03qD4wwhSiiu\n*   USER@L1B2PV0VxeHjersK3Odn\n*   USER@jXURfsIVkjPyLF5ccqWy\n*   USER@liF1hJrhKxDsEvhYcxA0\n*   USER@mOo9SGEY2T2peXWg9BYa",
    "state": "done"
}

Thank you very much 🙏🏻

[damiano-carradori]

PS: I tried with gpt-5-nano as well, and it looks like it's not happening there. Maybe it's only related to gemini models? some hidden character?

[jolbol1]

It happens because gemini is using asterisks for the list. Streamdown tries to fix incomplete markdown, and in this case its unfinished italics so it appends a closing one.

Code from streamdown:

streamdown/packages/streamdown/lib/parse-incomplete-markdown.ts

Line 71 in dff0eef

const handleIncompleteSingleAsteriskItalic = (text: string): string => {

You can disable parsingIncompleteMarkdown if you want, via <Response parseIncompleteMarkdown={false}> but obviously you will lose the nice effect.

[damiano-carradori]

Got it, thanks 🙏🏻 I’d prefer not to disable parsingIncompleteMarkdown for now, but let’s see how it goes.

Another option could be to tweak the system prompt so Gemini uses - instead of * for lists. I’ll play around with that and see what works best 💪🏻

[haydenbleasel]

Fixed! Will be available in the next release. Thanks for letting us know 🙏