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local-prisma-postgres-handling.md

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Local Prisma Postgres (aka ppg dev) Handling

The extension supports running local Prisma Postgres instances using @prisma/dev. Since these servers are long-running processes that shouldn't block the VS Code extension host, they run in a separate forked process.

Architecture

┌─────────────────────────────────────────┐
│           VS Code Extension             │
│                                         │
│  PrismaDevRepository.startInstance()    │
│            │                            │
│            │ fork()                     │
│            ▼                            │
│  ┌─────────────────────────────────┐    │
│  │   dist/workers/ppgDevServer.js  │    │
│  │                                 │    │
│  │   ┌─────────────────────────┐   │    │
│  │   │     @prisma/dev         │   │    │
│  │   │                         │   │    │
│  │   │  ┌───────────────────┐  │   │    │
│  │   │  │ @electric-sql/    │  │   │    │
│  │   │  │    pglite         │  │   │    │
│  │   │  └───────────────────┘  │   │    │
│  │   └─────────────────────────┘   │    │
│  └─────────────────────────────────┘    │
└─────────────────────────────────────────┘

Worker Entry Point

The worker is defined in src/workers/ppgDevServer.ts. It:

  1. Receives the database name as a CLI argument
  2. Starts the @prisma/dev server
  3. Communicates status back to the parent process via IPC (process.send())
  4. Handles graceful shutdown on SIGTERM/SIGINT
// Simplified flow
const { unstable_startServer } = await import('@prisma/dev')
server = await unstable_startServer({ name, persistenceMode: 'stateful' })
process.send?.({ type: 'started' })

Build Configuration

The worker is bundled separately by esbuild (see packages/vscode/esbuild.mjs):

const ppgDevServerConfig = {
  entryPoints: ['src/workers/ppgDevServer.ts'],
  outfile: 'dist/workers/ppgDevServer.js',
  // ...
}

Runtime Assets

PGlite (used internally by @prisma/dev) requires runtime assets that cannot be bundled:

  • pglite.data — PostgreSQL data file (~5MB)
  • pglite.wasm — WebAssembly module (~11MB)

These are copied to dist/workers/ during the build process so they're in the same directory as the worker bundle and can be loaded via __dirname-relative paths.

Forking the Worker

PrismaDevRepository.startInstance() forks the worker:

const { fsPath } = Uri.joinPath(this.context.extensionUri, ...['dist', 'workers', 'ppgDevServer.js'])

const child = fork(fsPath, [name], {
  detached: true,
  stdio: ['ignore', 'ignore', 'ignore', 'ipc'],
})

// Wait for startup confirmation
child.once('message', (message) => {
  if (message.type === 'started') {
    // Server is ready
  }
})

// Detach so the server keeps running after extension closes
child.disconnect()
child.unref()

File Structure

plugins/prisma-postgres-manager/
├── ai-tools/                    # AI tool implementations
├── commands/                    # VS Code command handlers
│   ├── createProjectInclDatabase.ts
│   ├── createRemoteDatabase.ts
│   ├── deployPrismaDevInstance.ts
│   ├── launchStudio.ts
│   └── ...
├── management-api/              # Prisma Platform API client
├── shared-ui/                   # Shared UI utilities
├── ConnectionStringStorage.ts   # Secure credential storage
├── PrismaDevRepository.ts       # Local instance management
├── PrismaDevTreeDataProvider.ts # Tree view for local instances
├── PrismaPostgresRepository.ts  # Remote database management
├── PrismaPostgresTreeDataProvider.ts
└── index.ts                     # Plugin entry point

Related Files

  • src/workers/ppgDevServer.ts — Worker entry point (separate bundle)
  • esbuild.mjs — Build configuration for worker bundle and asset copying