File name change in the file panel is not propagated to the opened notebook

[teristam]

Describe the bug

When you opened a notebook in the browser, and then change its filename in the File side panel, the name change is not being reflected in the opened notebook. Any modification in the originally opened notebook, will be saved silently in a new file with the original name. And if you change the filename of the opened notebook, it will appear as being saved successfully, but actually no file is being saved.

Changing the file name directly in the opened notebook has no problem though.

Will you submit a PR?

• Yes

Environment

Environment

{
  "marimo": "0.24.0",
  "editable": false,
  "location": "~/code/trialexp_notebook_learning/.venv/lib/python3.12/site-packages/marimo",
  "OS": "Linux",
  "OS Version": "6.14.0-33-generic",
  "Processor": "x86_64",
  "Python Version": "3.12.3",
  "Locale": "en_US",
  "Binaries": {
    "Browser": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/152.0.0.0 Safari/537.36 Edg/152.0.0.0",
    "Node": "v24.8.0",
    "uv": "0.12.9 (x86_64-unknown-linux-gnu)"
  },
  "Dependencies": {
    "click": "8.1.7",
    "docutils": "0.21.2",
    "itsdangerous": "2.2.0",
    "jedi": "0.19.1",
    "markdown": "3.6",
    "narwhals": "2.25.0",
    "packaging": "24.1",
    "psutil": "6.0.0",
    "pygments": "2.21.0",
    "pymdown-extensions": "11.0.2",
    "pyyaml": "6.0.1",
    "starlette": "0.41.3",
    "tomlkit": "0.13.2",
    "typing-extensions": "4.16.0",
    "uvicorn": "0.30.1",
    "websockets": "17.0.1"
  },
  "Optional Dependencies": {
    "altair": "6.2.2",
    "duckdb": "1.5.5",
    "loro": "1.13.2",
    "nbformat": "5.10.4",
    "openai": "2.54.0",
    "pandas": "2.1.4",
    "polars": "1.44.1",
    "pyarrow": "17.0.0",
    "ruff": "0.16.5",
    "sqlglot": "30.17.0"
  },
  "Experimental Flags": {}
}

Code to reproduce

No response

[tevinch]

Both sequences still reproduce with the unmodified 0.24.2 package (Python 3.12, macOS, Chrome 152). They need separate fresh notebooks:

1. Open a.py, rename it to b.py in the File sidebar, then add a comment to the cell and wait for autosave. The browser title and URL still say a.py. Autosave recreates a.py with the edit; b.py keeps the earlier content.
2. Start again with a fresh a.py, rename it to b.py in the sidebar, then rename through the notebook header to c.py before editing. /api/kernel/rename returns HTTP 200 with {"success":true}, and the title/URL switch to c.py, but c.py does not exist; b.py remains on disk.

Editing between the two renames can mask the second failure because it recreates the missing source file.

Two places appear relevant in 0.24.2: the sidebar move endpoint moves the file without updating the active session, while the header rename endpoint ignores the (success, error) result from rename_session and returns success. A fix would need to keep the editor and session paths aligned and surface a failed rename before changing the displayed name.

[simonether]

I looked into this on current main. The file browser renames and moves files through the generic /api/files/move endpoint (requesting-tree.tsx → file_explorer.py), so the session keeps the old path: autosave recreates a.py, and since #10728 a later rename from the title returns a 400 instead of a false success. I'd route renames and moves of the open notebook through the same /api/kernel/rename flow the title uses, and update the ?file= URL only after that rename succeeds. I have this working locally with regression tests in requesting-tree.test.ts and file-explorer-navigation.test.tsx. Since the issue is assigned to @Light2Dark, would it be OK if I opened a PR?