Databricks Apps Development

FIRST: Use the parent databricks skill for CLI basics, authentication, profile selection, and data exploration commands.

Build apps that deploy to Databricks Apps platform.

Required Reading by Phase

Generic Guidelines

These apply regardless of framework:

• •Deployment: databricks apps deploy --profile <PROFILE> (⚠️ USER CONSENT REQUIRED)
• •Validation: databricks apps validate before deploying
• •App name: Must be ≤26 characters, lowercase letters/numbers/hyphens only (no underscores). dev- prefix adds 4 chars, max 30 total.
• •Smoke tests: ALWAYS update tests/smoke.spec.ts selectors BEFORE running validation. Default template checks for "Minimal Databricks App" heading and "hello world" text — these WILL fail in your custom app. See testing guide.
• •Authentication: covered by parent databricks skill

Project Structure (after databricks apps init --features analytics)

• •client/src/App.tsx — main React component (start here)
• •config/queries/*.sql — SQL query files (queryKey = filename without .sql)
• •server/server.ts — backend entry (tRPC routers)
• •tests/smoke.spec.ts — smoke test (⚠️ MUST UPDATE selectors for your app)
• •client/src/appKitTypes.d.ts — auto-generated types (npm run typegen)

Development Workflow (FOLLOW THIS ORDER)

1. •Create SQL files in config/queries/
2. •Run npm run typegen — verify all queries show ✓
3. •Read client/src/appKitTypes.d.ts to see generated types
4. •THEN write App.tsx using the generated types
5. •Update tests/smoke.spec.ts selectors
6. •Run databricks apps validate

DO NOT write UI code before running typegen — types won't exist and you'll waste time on compilation errors.

When to Use What

• •Read data → display in chart/table: Use visualization components with queryKey prop
• •Read data → custom display (KPIs, cards): Use useAnalyticsQuery hook
• •Read data → need computation before display: Still use useAnalyticsQuery, transform client-side
• •Call ML model endpoint: Use tRPC
• •Write/update data (INSERT/UPDATE/DELETE): Use tRPC
• •⚠️ NEVER use tRPC to run SELECT queries — always use SQL files in config/queries/

Frameworks

AppKit (Recommended)

TypeScript/React framework with type-safe SQL queries and built-in components.

Official Documentation — the source of truth for all API details:

npx @databricks/appkit docs              # ← ALWAYS start here to see available pages
npx @databricks/appkit docs <path>       # then use paths from the index

DO NOT guess doc paths. Run without args first, pick from the index. Docs are the authority on component props, hook signatures, and server APIs — skill files only cover anti-patterns and gotchas.

Scaffold (requires --warehouse-id, see parent skill; DO NOT use npx):

databricks apps init --description "<DESC>" --features analytics --warehouse-id <ID> --name <NAME> --run none --profile <PROFILE>

READ AppKit Overview for project structure, workflow, and pre-implementation checklist.

Other Frameworks

Databricks Apps supports any framework that can run as a web server (Flask, FastAPI, Streamlit, Gradio, etc.). Use standard framework documentation - this skill focuses on AppKit.