Moose Dev

The moose dev command starts a local development environment with hot-reload, containerized infrastructure (ClickHouse, Redpanda, Temporal, Redis), and automatic schema synchronization.

What Happens When You Run moose dev

1. Infrastructure starts - Docker containers spin up for ClickHouse, Redpanda, Redis, and Temporal
2. Code compiles - Your data models, streams, and functions are compiled and validated
3. Schema syncs - Tables, views, and topics are created/updated in local infrastructure
4. Server starts - The Moose runtime serves your APIs and processes data
5. Watcher activates - Changes to your code trigger automatic reloads (see TypeScript compilation for TypeScript behavior)

Key Capabilities

TypeScript projects: compilation and hot reload

For TypeScript projects, moose dev uses a compilation-driven workflow:

• Initial compile – Before planning or starting the server, Moose compiles your TypeScript once. The runtime loads pre-compiled JavaScript (we used to run TypeScript via ts-node at runtime; we no longer do). If this initial compilation fails, moose dev exits with an error.
• Incremental compilation (watch) – The compiler runs in watch mode and watches your source files. When you save changes, it performs an incremental compile. Only after a successful compile does Moose run planning and apply infrastructure changes (tables, APIs, etc.). Compilation errors block reloads until fixed; warnings do not block reloads but are shown in the terminal.
• Output directory – Compiled output is written to your tsconfig.json outDir if set, otherwise to .moose/compiled. Moose reads this directory when loading your app; do not delete it while moose dev is running.

This replaces the previous file-watcher approach so that TypeScript benefits from incremental compilation and reloads only when the project compiles successfully.

Development Topics

• CDC Managed Tables - Work locally with tables managed by CDC pipelines like ClickPipes, PeerDB, or Debezium