debugging-streamlit

# Debugging Streamlit Apps ## Quick Start ```bash make debug my_app.py ``` This starts both backend (Streamlit/Python) and frontend (Vite/React) with hot-reload. The app URL is printed on startup (default `http://localhost:3001`; `3000` is reserved for manual `make frontend-dev`; it may use `3002+` if other debug sessions are running). Avoid pinning `VITE_PORT` unless you have a specific hard requirement (last resort). **Hot-reload behavior:** - **Frontend**: Changes to `frontend/` code are applied within seconds. - **Backend**: Only changes to the **app script** trigger a rerun. Changes to the Streamlit library itself (`lib/streamlit/`) require restarting `make debug`. ## Log Files Each `make debug` run writes logs to a per-session directory under `work-tmp/debug/` and updates `work-tmp/debug/latest/` to point at the most recent session. Because `latest/*` is a symlink, **it can move** if multiple debug sessions are starting/stopping concurrently—prefer using the session directory path printed by `make debug` when you need stable log references. You can find the exact session directory in the `make debug` startup output under the `Log files` section. | File | Content | |------|---------| | `work-tmp/debug/latest/backend.log` | Python `print()` statements, Streamlit logs, errors | | `work-tmp/debug/latest/frontend.log` | Browser `console.log()`, React errors, Vite output | Logs are cleared at the start of each session and persist after exit for post-mortem analysis. ...