markdown headings change by themselves

[hopezh]

Describe the bug

As shown below, extra/duplicated text is added to the words in the headings by themselves.

This has happened several times recently, even after I tidy up the headings.

Environment

{
"marimo": "0.10.6",
"OS": "Darwin",
"OS Version": "24.1.0",
"Processor": "arm",
"Python Version": "3.11.8",
"Binaries": {
"Browser": "131.0.6778.205",
"Node": "v22.12.0"
},
"Dependencies": {
"click": "8.1.7",
"docutils": "0.21.2",
"itsdangerous": "2.2.0",
"jedi": "0.19.2",
"markdown": "3.7",
"narwhals": "1.19.0",
"packaging": "24.2",
"psutil": "6.1.0",
"pygments": "2.18.0",
"pymdown-extensions": "10.12",
"pyyaml": "6.0.2",
"ruff": "0.8.4",
"starlette": "0.42.0",
"tomlkit": "0.13.2",
"typing-extensions": "4.12.2",
"uvicorn": "0.34.0",
"websockets": "14.1"
},
"Optional Dependencies": {
"pandas": "2.2.3",
"polars": "1.16.0"
}
}

Code to reproduce

import marimo as mo

@app.cell
def _(mo):
mo.md(r"""### create dataclass for Frame""")
return

[akshayka]

Thanks for reporting, and sorry for the inconvenience!

Are there any steps required in the UI to duplicate this? If you could send a video that shows how to reproduce this that would help.

[hopezh]

Thanks for the reply.

It happens randomly, usually after I reopen the marimo python file with these kind of errors in the headings already corrected previously, especially the text highlighted by one pair of the backticks: `

An example code is attached below which is stripped down to the headings having issue frequently.

import marimo

__generated_with = "0.10.6"
app = marimo.App(width="medium", css_file="style.css")


@app.cell
def _():
    import marimo as mo

    return (mo,)


@app.cell
def _(mo):
    mo.md(r"""# Top level keys""")
    return


@app.cell
def _(mo):
    mo.md(r"""### create **_dataclass_** for **Frame**""")
    return


@app.cell
def _(mo):
    mo.md(r"""### create a list of **Frame** objects""")
    return


@app.cell
def _(mo):
    mo.md("""### create **_dataframe_** for **frames**""")
    return


@app.cell
def _():
    return


if __name__ == "__main__":
    app.run()

[akshayka]

Thanks for the additional context. I'm unable to reproduce this somehow, but I don't doubt you're facing the issue ... We'll get to the bottom of this eventually.

[dmadisetti]

Possibly related? #2087

[akshayka]

@hopezh does this issue only affect headings?

[hopezh]

Hi @dmadisetti, the issue I encountered seems to be different from the one u mentioned.

Hi @akshayka, yes, this issue only affect the headings.

I managed to capture one such instance when it happened. Unfortunately, the code contains proprietary content that I cannot share.

So, I can only show the image below when this happens in a marimo notebook which includes a button to select a JSON file and read its contents.

The issue only happens to the word in the heading that is highlighted by the backticks.

I.e. this...

... is changed to this: