contributing

name	contributing
description	Use when contributing to the Butterbase codebase, adding new MCP tools, creating API routes, writing migrations, or understanding the monorepo architecture

1. Overview

Contributor guide for the Butterbase monorepo. Covers architecture, how to add MCP tools, API routes, database migrations, and coding conventions.

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2. Monorepo Map

Directory	Package	Purpose
packages/cli	@butterbase/cli (v0.1.3)	Published CLI tool (Commander.js). Commands: init, apps, schema, functions, storage, deploy, data, env, keys, realtime, status, open
packages/sdk	@butterbase/sdk (v1.2.1)	Published TypeScript SDK. Modules: auth, storage, functions, AI, billing, realtime, admin
packages/shared	@butterbase/shared	Internal shared types, constants, schema DSL, error types
packages/plugin	@butterbase/plugin	Claude Code plugin (this package — skills for AI agents)
services/control-api	@butterbase/control-api	Fastify API server — the brain. Routes, plugins, services. Port 4000
services/mcp-server	@butterbase/mcp-server	MCP server with ~28 tools (consolidated manage_* action-based tools + a few standalone ones like init_app, deploy_function, select_rows). Runs via stdio or HTTP (served by control-api at /mcp)
services/deno-runtime	—	Serverless function executor. Deno-based worker isolation. Port 7133
services/cron-scheduler	@butterbase/cron-scheduler	Cron job runner using node-cron + cron-parser
services/dashboard	—	React management UI (Vite + Radix UI)
services/dashboard-api	—	Dashboard backend proxy. Port 4100
services/docs	@butterbase/docs	Astro/Starlight documentation site
services/storage-indexer	—	Cloudflare Worker for S3 event indexing
db/control-plane	—	SQL migrations (sequential numbering, 001_ upward). Control plane database schema
db/data-plane	—	Per-app database initialization scripts

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3. Adding a New MCP Tool (4 Steps)

Step 1: Create tool file at services/mcp-server/src/tools/my-new-tool.ts

Decide whether the new capability is a standalone tool (single, self-contained operation like init_app) or another action on an existing umbrella tool (manage_schema, manage_function, etc). Most new operations should be added as actions on an existing manage_* tool — this keeps the surface area small for AI agents.

For a brand-new standalone tool, follow the pattern from init-app.ts:

import type { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
import { z } from 'zod';
import { apiPost } from '../api-client.js';

interface MyResponse {
  // response shape
}

export function registerMyNewTool(server: McpServer) {
  server.tool(
    'my_new_tool',      // snake_case name
    `Tool description.   // Multi-line description with examples

Example:
  Input: { ... }
  Output: { ... }

Common errors:
  - ERROR_CODE: Description`,
    {
      // Zod schema for parameters
      app_id: z.string().describe('The app ID'),
      param: z.string().describe('Parameter description'),
    },
    async ({ app_id, param }) => {
      const result = await apiPost<MyResponse>(`/v1/${app_id}/my-endpoint`, { param });
      return {
        content: [{
          type: 'text' as const,
          text: JSON.stringify(result, null, 2),
        }],
      };
    }
  );
}

API client functions available: apiGet, apiPost, apiPatch, apiDelete (from ../api-client.js).

Step 2: Register in services/mcp-server/src/create-server.ts

import { registerMyNewTool } from './tools/my-new-tool.js';
// ...
registerMyNewTool(server);

Step 3: Create the backing API route in services/control-api/src/routes/

• Fastify route handler matching the endpoint your tool calls
• Register in services/control-api/src/index.ts

Step 4: Update documentation in services/mcp-server/src/docs/user-documentation.ts

• Add tool to the relevant section's table in the SECTIONS object

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4. Adding a Database Migration

• IMPORTANT: Use scripts/migrate.ts or scripts/backfill-migrations.ts, NEVER raw psql
• Migration files: db/control-plane/NNN_description.sql (sequential numbering, starting at 001_initial_schema.sql)
• Pick the next free three-digit prefix; never edit a committed migration
• Run migrations: npx tsx scripts/migrate.ts

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5. Coding Conventions

Convention	Example
MCP tool names	snake_case. Two flavours: standalone (init_app, deploy_function, select_rows) and manage_* umbrella tools that take an action enum (manage_schema, manage_rls, manage_function, manage_frontend, etc.)
App IDs	app_ prefix: app_abc123
Service keys	bb_sk_ prefix: bb_sk_a1b2c3...
Environment variables	BUTTERBASE_ prefix: BUTTERBASE_API_KEY
Response metadata	_meta.next_actions (suggested next tool calls), _meta.resource_info (quota/state)
Error codes	UPPERCASE_WITH_UNDERSCORES: AUTH_RLS_POLICY_VIOLATION, QUOTA_TABLE_LIMIT
Domain	butterbase.ai (never "nira")

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6. Running Locally

docker-compose -f docker-compose.local.yml up

Service	Port	URL
Control API	4000	http://localhost:4000
Dashboard API	4100	http://localhost:4100
Deno Runtime	7133	http://localhost:7133
Control Plane DB	5433	postgres://localhost:5433
Data Plane DB	5435	postgres://localhost:5435
PgBouncer	6432	postgres://localhost:6432
LocalStack (S3)	4566	http://localhost:4566

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7. Testing

• Framework: Vitest
• Run tests per workspace: cd services/control-api && npm test
• Test files: __tests__/ directory or co-located *.test.ts
• Build all workspaces: npm run build (from repo root)
• Type check: npx tsc --noEmit in each workspace