[bug]: Notebook marked as stale when saved after kernel restart in watch mode

[Antyos]

Describe the bug

I described this behavior in #7098, where it seemed like it was related to a VS Code extension, however, I have noticed that it happens even outside of VS Code. It is still possible the behavior for the #7098 is still related to the old extension, so I am making a new issue.

When running a Marimo notebook in watch mode, the first time the user saves the notebook after a kernel restart marks all the cells as stale. I don't think it should do this.

Example:

https://github.com/user-attachments/assets/8b5d7699-cfbe-412b-a642-bd995ff12615

Will you submit a PR?

• [ ] Yes

Environment

{
  "marimo": "0.17.7",
  "editable": false,
  "location": "C:/Users/avg170002/AppData/Local/uv/cache/archive-v0/y6F1X84CPUXxWLfYY4ewn/Lib/site-packages/marimo",
  "OS": "Windows",
  "OS Version": "11",
  "Processor": "Intel64 Family 6 Model 198 Stepping 2, GenuineIntel",
  "Python Version": "3.13.9",
  "Locale": "en_US",
  "Binaries": {
    "Browser": "--",
    "Node": "v22.21.1"
  },
  "Dependencies": {
    "click": "8.3.0",
    "docutils": "0.22.3",
    "itsdangerous": "2.2.0",
    "jedi": "0.19.2",
    "markdown": "3.10",
    "narwhals": "2.11.0",
    "packaging": "25.0",
    "psutil": "7.1.3",
    "pygments": "2.19.2",
    "pymdown-extensions": "10.16.1",
    "pyyaml": "6.0.3",
    "starlette": "0.50.0",
    "tomlkit": "0.13.3",
    "typing-extensions": "missing",
    "uvicorn": "0.38.0",
    "websockets": "15.0.1"
  },
  "Optional Dependencies": {
    "loro": "1.8.2"
  },
  "Experimental Flags": {}
}

Code to reproduce

import marimo

__generated_with = "0.17.7"
app = marimo.App(width="medium")


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


@app.cell
def _():
    print("Hello")
    return


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

[dmadisetti]

I don't think this is related to #7098 but it is weird (the markdown actively changed- meaning that the cell is stale because the contents were different). Thanks for reporting

[mscolnick]

@Antyos im having trouble even reproducing this simple example. can you verify in the top right hamburger menu that you are running on 0.17.7

EDIT: I can reproduce this with watcher_on_save = "lazy" set

EDIT-2: I do think this is fixed on latest though. I will keep testing around if I can reproduce this otherwise.