Cursor Randomly Jumps to Top of Cell When Using --watch

[undeMalum]

Describe the bug

I've noticed a strange behavior when editing notebooks locally.
While typing in a cell, the cursor randomly jumps to the top of the cell.

This issue does not occur:

• In any other application (so it’s not a keyboard issue)
• In Jupyter notebooks
• When running Marimo via uvx run marimo edit

However, the problem does appear when developing local notebooks.

---

After discussing on Discord, we’ve narrowed the issue down to the --watch flag.
The cursor jump only happens when Marimo is started with:

marimo edit --watch notebook.py

When running without the flag, everything works as expected.

---

Things I’ve already checked:

• No issues when using molab
• No Vim mode enabled
• No custom keybindings or shortcuts
• Keyboard works fine in all other contexts

---

I’m attaching a short video demonstrating the issue.

2025-10-15.13-28-19.mp4

Will you submit a PR?

• Yes

Environment

{
  "marimo": "0.16.5",
  "editable": false,
  "location": "C:/Users/Mateusz/Desktop/Minerva_general/Obesrvability/.venv/Lib/site-packages/marimo",
  "OS": "Windows",
  "OS Version": "11",
  "Processor": "AMD64 Family 25 Model 80 Stepping 0, AuthenticAMD",
  "Python Version": "3.11.6",
  "Locale": "en_US",
  "Binaries": {
    "Browser": "141.0.7390.66",
    "Node": "v24.8.0"
  },
  "Dependencies": {
    "click": "8.3.0",
    "docutils": "0.22.2",
    "itsdangerous": "2.2.0",
    "jedi": "0.19.2",
    "markdown": "3.9",
    "narwhals": "2.8.0",
    "packaging": "25.0",
    "psutil": "7.1.0",
    "pygments": "2.19.2",
    "pymdown-extensions": "10.16.1",
    "pyyaml": "6.0.3",
    "starlette": "0.48.0",
    "tomlkit": "0.13.3",
    "typing-extensions": "4.15.0",
    "uvicorn": "0.35.0",
    "websockets": "15.0.1"
  },
  "Optional Dependencies": {
    "pandas": "2.3.3",
    "loro": "1.8.1"
  },
  "Experimental Flags": {}
}

Code to reproduce

No response

[mscolnick]

Thanks for filing this - i have a fix out: #6792