The skill has no guidance for creating new notebooks in folder mode.
The skill docs cover discovering servers, executing code, and mutating cells via code_mode — but all of that assumes a session already
exists. When marimo runs in folder mode (marimo edit ./books), there's no active session until the user opens a notebook in the browser.
The gap I hit:
1. discover-servers.sh found the server on 2719, but execute-code.sh failed with "No active sessions."
2. The skill says "If there's no .py file yet, pick a descriptive filename" and start marimo — but marimo was already running. I couldn't
start a second instance on the same port.
3. My first instinct was to write the .py file directly, but the skill explicitly says "NEVER write to the .py file directly while a session
is running." Even though no session was active yet, the server owned that directory.
4. I had to dig through marimo's server source code to find the /api/files/create endpoint with type: "notebook" — that's not documented
anywhere in the skill.
Suggestions for the skill:
- Document the folder-mode workflow: how to create a new notebook via the API (POST /api/files/create with type: "notebook"), and that the
user then needs to open it from the browser before code_mode works.
- Clarify that "no active sessions" ≠ "server not running" — in folder mode it's the expected state until a notebook is opened.
- Consider adding a create-notebook.sh script alongside discover-servers.sh and execute-code.sh.
As mentioned in marimo-team/marimo#8103 (comment), my LLM was not quite able to easily figure out how to create a new notebook when a server is running but there are no existing notebook sessions.