Journey Frontend Agent Skill

Journey: Frontend

Stage 3j of the guided journey. Build (or adopt) and deploy the frontend.

When to use

• Dispatched by journey when current_stage: frontend.
• Directly via /butterbase-skills:journey-frontend.
• Skipped (annotated (n/a)) if frontend_stack: none in 00-state.md.

Preflight

If docs/butterbase/03-preflight.md is missing, older than 24 hours, or 00-state.md has app_id: null, invoke butterbase-skills:journey-preflight first. Wait for it to return successfully before proceeding.

Inputs

• docs/butterbase/02-plan.md — the Frontend section.
• docs/butterbase/00-state.md — for app_id, api_base, frontend_stack.

Procedure

• Refresh docs. Call butterbase_docs with topic: "frontend". For framework-specific deploy patterns, also WebFetch https://docs.butterbase.ai/frontend. Skip if cache is fresh.

Use @butterbase/sdk

Any frontend that talks to the deployed Butterbase app should use @butterbase/sdk:

• Install: npm install @butterbase/sdk inside the frontend project.
• Initialize: import { createClient } from '@butterbase/sdk'; const bb = createClient({ apiUrl: import.meta.env.VITE_API_URL, appId: import.meta.env.VITE_APP_ID });
• Auth: bb.auth.signInWithOAuth({ provider: 'google' }), bb.auth.signOut(), bb.auth.getSession().
• Data: bb.db.from('posts').select('*').eq('user_id', userId).
• Storage: bb.storage.upload(file), persist the returned object_id, resolve download URLs via the SDK at render time.
• Realtime: bb.realtime.from('posts').on('insert', cb).subscribe().

Do NOT hand-roll fetch() against the REST API in a Butterbase frontend — the SDK handles auth headers, presigned URL refresh, realtime reconnection, and type-narrowing. The MCP tools are not for runtime code.

For framework-specific patterns (Next.js Server Components, SvelteKit load functions, etc.), call butterbase_docs with topic: "sdk".

Build and deploy

• Read the Frontend section and frontend_stack from 00-state.md. Print: "About to deploy a <stack> frontend for app_id <id>. Proceed?". Wait for yes.
• Invoke butterbase-skills:deploy-frontend via the Skill tool with the frontend spec, app_id, and api_base. The wrapped skill scaffolds (if no package.json exists in ./web or chosen path), sets VITE_API_URL and VITE_APP_ID, builds, calls create_frontend_deployment, then manage_frontend action: start_deployment.
• Capture the live URL from the response. Show it to the user.
• Append one line to docs/butterbase/04-build-log.md:

<ISO timestamp> frontend manage_frontend <live-url> ok

• Also write the live URL into a new deployed_url: field in 00-state.md front-matter.
• Tick - [x] frontend in 00-state.md, set current_stage: deploy.
• Return to journey orchestrator (or ask "Continue to deploy verification? (yes/no)").

Outputs

• Live deployed frontend URL.
• deployed_url: in 00-state.md.
• One line in 04-build-log.md.

Anti-patterns

• ❌ Forgetting to set VITE_API_URL and VITE_APP_ID — frontend will load blank.
• ❌ Wrong MIME types — let deploy-frontend handle the bundling; do not hand-roll.