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name: setting-up-streamlit-environment description: Setting up Python environments for Streamlit apps. Use when creating a new project or managing dependencies. Covers uv for dependency management and running apps. license: Apache-2.0

Streamlit environment

Use whatever dependency management the project already has (pip, poetry, conda, etc.). If starting fresh and uv is available, it's a good default—fast, reliable, and creates isolated environments automatically.

If uv is not installed, ask the user before installing it.

CRITICAL: Always Use Latest Streamlit

Always specify streamlit>=1.53.0 (or latest) in dependencies. Many Streamlit features and patterns in these skills require recent versions. Older streamlit versions will cause errors with:

• Material icons (:material/icon_name:)
• st.pills(), st.segmented_control()
• Modern caching decorators
• Navigation APIs

When setting up a new project or fixing an existing one, always check and update the streamlit version.

Using uv

If uv is available, here's how to set up a Streamlit project.

Quick start (venv only)

For simple apps, just create a virtual environment:

uv venv
source .venv/bin/activate  # or .venv\Scripts\activate on Windows
uv pip install streamlit

Run with:

streamlit run streamlit_app.py

Full project setup

For larger projects or when you need reproducible builds:

uv init my-streamlit-app
cd my-streamlit-app
uv add streamlit

This creates:

• pyproject.toml with dependencies
• uv.lock for reproducible builds
• .venv/ virtual environment

Run with:

uv run streamlit run streamlit_app.py

With options

Avoid setting options unless you have a specific reason:

streamlit run streamlit_app.py --server.headless true  # Only for automated/CI environments

Add dependencies

# With venv approach
uv pip install plotly snowflake-connector-python

# With full project (uv init)
uv add plotly snowflake-connector-python

Project structure

Keep it simple. For most apps:

my-streamlit-app/
├── .venv/
└── streamlit_app.py

Only add more when needed:

• app_pages/ → Only for multi-page apps
• .streamlit/config.toml → Only if customizing theme or settings
• .streamlit/secrets.toml → Only if using secrets (add to .gitignore)
• pyproject.toml → Only if using uv init for reproducible builds

Convention

Name your main file streamlit_app.py for consistency. This is what Streamlit expects by default.

What goes in the main module:

• When using navigation: it's a router that defines pages and runs them
• When there's no navigation: it's the home page with your main content

pyproject.toml Example

[project]
name = "my-streamlit-app"
version = "0.1.0"
requires-python = ">=3.11"
dependencies = [
    "streamlit>=1.53.0",
    "plotly>=5.0.0",
    "snowflake-connector-python>=3.0.0",
]

[tool.uv]
dev-dependencies = [
    "pytest>=8.0.0",
]

References

• uv documentation
• Streamlit installation