Marimo Screenshot

Capture a marimo notebook's rendered output (charts, tables, markdown) as a PNG screenshot that Claude can view and analyze.

Usage

When the user wants you to see notebook output, or when you need to analyze charts/visualizations in a marimo notebook.

Workflow

1. •

   Start the notebook in run mode (executes cells, serves rendered output):

   bash

   uv run marimo run notebooks/<notebook>.py --port 2719 --headless &
   

2. •

   Wait for server to start:

   bash

   sleep 10
   

3. •

   Take screenshot with JS render time (Altair/Vega charts need ~15s):

   bash

   npx playwright screenshot --wait-for-timeout 15000 --full-page \
     "http://localhost:2719" /tmp/marimo_output.png
   

4. •

   Read the screenshot using the Read tool:

   code

   Read /tmp/marimo_output.png
   

5. •

   Kill the server when done:

   bash

   pkill -f "marimo run.*2719"
   

Key Details

• •Use marimo run (not edit) - this executes cells and renders output
• •--headless runs server-only without opening a browser
• •--wait-for-timeout 15000 gives charts time to render via JavaScript
• •--full-page captures the entire scrollable notebook
• •Port 2719 avoids conflict with the user's edit server on 2718

Troubleshooting

Charts not appearing:

• •Cells must return their output (e.g., mo.vstack([chart]) as the last expression)
• •If inside if/else, ensure all branches return a value

Blank screenshot:

• •Increase --wait-for-timeout to 20000 or more
• •Check that the notebook runs without errors: uv run marimo run notebook.py

Port in use:

• •Kill existing process: pkill -f "marimo run.*2719"
• •Or use a different port