Developing With Streamlit

1---2name: developing-with-streamlit3description: "**[REQUIRED]** Use for ALL Streamlit tasks: creating, editing, debugging, beautifying, styling, theming, optimizing, or deploying Streamlit applications. Also required for building custom components (inline or packaged), using st.components.v2, or any HTML/JS/CSS component work. Triggers: streamlit, st., dashboard, app.py, beautify, style, CSS, color, background, theme, button, widget styling, custom component, st.components, packaged component, pyproject.toml, asset_dir, CCv2, HTML/JS component."4---5 6# Developing with Streamlit7 8This is a **routing skill** that directs you to specialized sub-skills for Streamlit development.9 10## When to Use11 12Invoke this skill when the user's request involves:13- Creating a new Streamlit app14- Editing or modifying an existing Streamlit app15- Debugging Streamlit issues (errors, session state bugs, performance problems)16- Beautifying or improving the visual design of a Streamlit app17- Optimizing Streamlit performance (caching, fragments, reruns)18- Deploying Streamlit apps (locally or to Snowflake)19- Styling widgets (button colors, backgrounds, CSS customization)20- Any question about Streamlit widgets, layouts, or components21 22**Trigger phrases:** "streamlit", "st.", "dashboard", "app.py", "beautify app", "make it look better", "style", "CSS", "color", "background", "theme", "button", "slow rerun", "session state", "performance", "faster", "cache", "deploy"23 24## Workflow25 26```27Step 1: Locate the Streamlit source code28    ↓29Step 2: Identify task type and load appropriate sub-skill(s)30    ↓31Step 3: Apply guidance from sub-skill to edit code32    ↓33Step 4: Check if app is running and offer to run it34```35 36### Step 1: Locate the Streamlit Source Code (if needed)37 38**Goal:** Identify the app file(s) to edit. **Skip this step if already clear from context.**39 40**When to skip:**41- User mentioned a specific file path (e.g., "edit `src/app.py`")42- User has file(s) already in conversation context43- Working directory has an obvious single entry point (`app.py`, `streamlit_app.py`)44 45**When to search:**46- User says "my streamlit app" without specifying which file47- Multiple Python files exist and it's unclear which is the entry point48 49**If searching is needed:**50 511. **Quick scan** for Streamlit files:52   ```bash53   find . -name "*.py" -type f | xargs grep -l "import streamlit\|from streamlit" 2>/dev/null | head -1054   ```55 562. **Apply entry point heuristics** (in priority order):57   - `streamlit_app.py` at root → **this is the entry point** (canonical name)58   - `app.py` at root → likely entry point59   - File using `st.navigation` → entry point for multi-page apps60   - Single `.py` file at root with streamlit import → entry point61   - Files in `pages/` or `app_pages/` subdirectory → **NOT entry points** (these are sub-pages)62 633. **If entry point is obvious** → use it, no confirmation needed64 65   Example: Found `streamlit_app.py` and `pages/metrics.py` → use `streamlit_app.py`66 674. **Only ask if genuinely ambiguous** (e.g., multiple root-level candidates, none named `streamlit_app.py`):68   ```69   Found multiple potential entry points:70   - dashboard.py71   - main.py72 73   Which is your main app?74   ```75 76**Output:** Path to the main Streamlit source file(s)77 78### Step 2: Identify Task Type and Route to Sub-Skill79 80**Goal:** Determine what the user needs and load the appropriate guidance.81 82Use this routing table to select sub-skill(s). **Always read the sub-skill file** before making changes:83 84| User Need | Sub-skill to Read |85|-----------|-------------------|86| **Performance issues, slow apps, caching** | `read skills/optimizing-streamlit-performance/SKILL.md` |87| **Building a dashboard with KPIs/metrics** | `read skills/building-streamlit-dashboards/SKILL.md` |88| **Improving visual design, icons, polish** | `read skills/improving-streamlit-design/SKILL.md` |89| **Choosing widgets (selectbox vs radio vs pills)** | `read skills/choosing-streamlit-selection-widgets/SKILL.md` |90| **Styling widgets (button colors, backgrounds, CSS)** | `read skills/creating-streamlit-themes/SKILL.md` |91| **Layouts (columns, tabs, sidebar, containers)** | `read skills/using-streamlit-layouts/SKILL.md` |92| **Displaying data (dataframes, charts)** | `read skills/displaying-streamlit-data/SKILL.md` |93| **Multi-page app architecture** | `read skills/building-streamlit-multipage-apps/SKILL.md` |94| **Session state and callbacks** | `read skills/using-streamlit-session-state/SKILL.md` |95| **Markdown, colored text, badges** | `read skills/using-streamlit-markdown/SKILL.md` |96| **Custom themes and colors** | `read skills/creating-streamlit-themes/SKILL.md` |97| **Comprehensive theme design and brand alignment** | `read skills/creating-streamlit-themes/SKILL.md` |98| **Chat interfaces and AI assistants** | `read skills/building-streamlit-chat-ui/SKILL.md` |99| **Connecting to Snowflake** | `read skills/connecting-streamlit-to-snowflake/SKILL.md` |100| **Building or packaging a custom component, triggering events back to Python from JS/HTML, custom HTML/JS with event handling (CCv2), OR any UI element that doesn't exist as a native Streamlit widget** (e.g., drag-and-drop, custom interactive visualization, canvas drawing) | `read skills/building-streamlit-custom-components-v2/SKILL.md` — **IMPORTANT: `st.components.v1` is deprecated. Never use v1 for new components; always use `st.components.v2.component()`.** |101| **Third-party components** | `read skills/using-streamlit-custom-components/SKILL.md` |102| **Code organization** | `read skills/organizing-streamlit-code/SKILL.md` |103| **Environment setup** | `read skills/setting-up-streamlit-environment/SKILL.md` |104| **CLI commands** | `read skills/using-streamlit-cli/SKILL.md` |105 106**Fallback — "this widget doesn't exist in Streamlit":**107 108If the user asks for a UI element or interaction that **has never been part of Streamlit's API** and cannot be built with any combination of native widgets (e.g., drag-and-drop, canvas drawing, custom interactive visualizations), **route to the CCv2 sub-skill** (`skills/building-streamlit-custom-components-v2/SKILL.md`). **Do not** route to CCv2 for features that exist in newer Streamlit versions (e.g., `st.connection`, `st.segmented_control`) — suggest upgrading instead.109 110**Common combinations:**111 112For **beautifying/improving an app**, read in order:1131. `skills/improving-streamlit-design/SKILL.md`1142. `skills/using-streamlit-layouts/SKILL.md`1153. `skills/choosing-streamlit-selection-widgets/SKILL.md`116 117For **building a dashboard**, read:1181. `skills/building-streamlit-dashboards/SKILL.md`1192. `skills/displaying-streamlit-data/SKILL.md`120 121**IMPORTANT - Use templates:**122 123When creating a **new dashboard app**, prefer starting from a template in `templates/apps/`:124- If a template closely matches the request, copy it and adapt:125  - `dashboard-metrics` / `dashboard-metrics-snowflake` — KPI cards with time-series charts126  - `dashboard-companies` — company/entity comparison127  - `dashboard-compute` / `dashboard-compute-snowflake` — resource/credit monitoring128  - `dashboard-feature-usage` — feature adoption tracking129  - `dashboard-seattle-weather` — public dataset exploration (local only)130  - `dashboard-stock-peers` / `dashboard-stock-peers-snowflake` — financial peer analysis131- If no template is a close match, start from scratch but borrow relevant patterns from the templates (e.g., caching with `@st.cache_data`, `filter_by_time_range()`, `st.set_page_config()`, chart utilities, layout structure)132- See `templates/apps/README.md` for template descriptions133 134When **editing an existing app**, use templates as reference for best practices:135- Check `templates/apps/` for caching patterns, layout structure, and Snowflake integration136- Apply consistent patterns from templates to improve the existing code137 138When applying a **custom theme**, use a template from `templates/themes/`:139- Copy a theme directory (snowflake, dracula, nord, stripe, solarized-light, spotify, github, minimal)140- Themes use Google Fonts for easy setup141- See `templates/themes/README.md` for theme previews142 143For **performance optimization**, read:1441. `skills/optimizing-streamlit-performance/SKILL.md`145 146### Step 3: Apply Guidance to Edit Code147 148**Goal:** Make changes to the Streamlit app following sub-skill best practices.149 150**Actions:**151 1521. Apply the patterns and recommendations from the loaded sub-skill(s)1532. Make edits to the source file(s) identified in Step 11543. Preserve existing functionality while adding improvements155 156### Step 4: Check Running Apps and Offer to Run157 158**Goal:** Help the user see their changes by checking if their app is running.159 160**Actions:**161 1621. **Check** for running Streamlit apps on ports 850*:163   ```bash164   lsof -nP -iTCP -sTCP:LISTEN 2>/dev/null | grep -i python | awk '{print $2, $9}' | grep ':85' || echo "No Streamlit apps detected on ports 850*"165   ```166 1672. **Present** findings to user:168 169   **If app is running:**170   ```171   Found Streamlit app running:172   - PID: [pid] at http://localhost:[port]173 174   Your changes should be visible after a page refresh (Streamlit hot-reloads on file save).175   ```176 177   **If no app is running:**178   ```179   No Streamlit app detected on ports 850*.180 181   Would you like me to run the app? I can start it with:182     streamlit run [app_file.py]183   ```184 1853. **If user wants to run the app**, start it:186   ```bash187   streamlit run [path/to/app.py] --server.port 8501188   ```189 190## Stopping Points191 192- **Step 2**: If multiple sub-skills seem relevant, ask user which aspect to focus on first193- **Step 4**: Ask before starting the Streamlit app194 195## Skill map196 197| Skill | Covers |198|-------|--------|199| [building-streamlit-chat-ui](skills/building-streamlit-chat-ui/SKILL.md) | Chat interfaces, streaming responses, message history |200| [building-streamlit-dashboards](skills/building-streamlit-dashboards/SKILL.md) | KPI cards, metrics, dashboard layouts |201| [building-streamlit-multipage-apps](skills/building-streamlit-multipage-apps/SKILL.md) | Page structure, navigation, shared state |202| [building-streamlit-custom-components-v2](skills/building-streamlit-custom-components-v2/SKILL.md) | Streamlit Custom Components v2 (inline and template-based packaged), bidirectional state/trigger callbacks, bundling, theme CSS variables |203| [choosing-streamlit-selection-widgets](skills/choosing-streamlit-selection-widgets/SKILL.md) | Selectbox vs radio vs segmented control vs pills vs multiselect |204| [connecting-streamlit-to-snowflake](skills/connecting-streamlit-to-snowflake/SKILL.md) | st.connection, query caching, credentials |205| [creating-streamlit-themes](skills/creating-streamlit-themes/SKILL.md) | Theme configuration, colors, fonts, light/dark modes, professional brand alignment, CSS avoidance |206| [displaying-streamlit-data](skills/displaying-streamlit-data/SKILL.md) | Dataframes, column config, charts |207| [improving-streamlit-design](skills/improving-streamlit-design/SKILL.md) | Icons, badges, colored text, visual polish |208| [optimizing-streamlit-performance](skills/optimizing-streamlit-performance/SKILL.md) | Caching, fragments, forms, static vs dynamic widgets |209| [organizing-streamlit-code](skills/organizing-streamlit-code/SKILL.md) | When to split into modules, separating UI from logic |210| [setting-up-streamlit-environment](skills/setting-up-streamlit-environment/SKILL.md) | Python environment, dependency management |211| [using-streamlit-custom-components](skills/using-streamlit-custom-components/SKILL.md) | Third-party components from the community |212| [using-streamlit-cli](skills/using-streamlit-cli/SKILL.md) | CLI commands, running apps |213| [using-streamlit-layouts](skills/using-streamlit-layouts/SKILL.md) | Sidebar, columns, containers, tabs, expanders, dialogs, alignment, spacing |214| [using-streamlit-markdown](skills/using-streamlit-markdown/SKILL.md) | Colored text, badges, icons, LaTeX, and all markdown features |215| [using-streamlit-session-state](skills/using-streamlit-session-state/SKILL.md) | Session state, widget keys, callbacks, state persistence |216 217## Resources218 219- [Streamlit API Reference](https://docs.streamlit.io/develop/api-reference)220- [Streamlit Gallery](https://streamlit.io/gallery)