Streamlit Apps in Wizard

Apps live in apps/wizard/app_pages/. Run with make wizard or .venv/bin/etlwiz <alias>.

Creating a New App

1. Create apps/wizard/app_pages/your_app/app.py:

import streamlit as st
st.set_page_config(page_title="Wizard: Your App", page_icon="🪄", layout="wide")

def main():
    st.title("Your App")

main()

2. Register in apps/wizard/config/config.yml under a section's apps list:

- title: "Your App"
  alias: your-app
  entrypoint: app_pages/your_app/app.py
  description: "What it does"
  maintainer: "@slack-handle"
  icon: ":material/icon:"

Key Utilities

# Caching (supports ttl, show_time, works outside Streamlit too)
from apps.wizard.utils.components import st_cache_data
@st_cache_data(custom_text="Loading...", ttl="1h")

# URL-synced widgets (shareable state)
from apps.wizard.utils.components import url_persist
url_persist(st.selectbox)(label="Option", options=["a", "b"], key="my_key")
# ⚠️ Booleans stored as "True"/"False" strings in URL

# Charts
from apps.wizard.utils.components import grapher_chart, grapher_chart_from_url
grapher_chart(catalog_path="grapher/ns/ver/ds#var")
grapher_chart(variable_id=123, selected_entities=["France"], tab="map")

# Data loading
from apps.wizard.utils.cached import load_variables_in_dataset, load_variable_data

# Environment & DB
from etl.config import OWID_ENV  # .base_site, .indicators_url, .data_api_url
from etl.db import get_engine
from sqlalchemy.orm import Session

Components (apps.wizard.utils.components)

• Pagination(items, items_per_page, pagination_key) — paginated lists
• grapher_chart() / grapher_chart_from_url() — OWID charts
• st_wizard_page_link(alias) — link to another Wizard page
• tag_in_md(name, color, icon) — colored badge markup for st.markdown (or use native st.badge)
• st_toast_error() — error toast
• preview_file(path) — code preview in expander

Rules

• st.set_page_config() must be the first Streamlit command
• Use @st_cache_data for expensive operations
• Use url_persist() for shareable widget state
• Material icons: :material/icon_name: (Google Material Symbols)
• HTTP requests: always timeout=30 and .raise_for_status()
• Layout: use native st.container(horizontal=True, vertical_alignment=..., horizontal_alignment=...) for rows, st.columns(..., border=True) for grids. No CSS/HTML hacks (st.markdown(..., unsafe_allow_html=True) with <style>) — they break silently across Streamlit versions.
• Sections in config.yml need title, description and apps; the home page is generated from them (no images).