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@objectstack/types

Shared runtime type definitions for the ObjectStack ecosystem.

Overview

This package provides common TypeScript interfaces and types used across the ObjectStack runtime environment. It serves as a minimal, dependency-light package that defines the core contracts between different parts of the system.

Purpose

The @objectstack/types package exists to:

  1. Break Circular Dependencies - Provides shared types without creating circular imports between packages
  2. Define Runtime Contracts - Establishes interfaces that plugins and kernel must satisfy
  3. Enable Type Safety - Ensures type compatibility across the ObjectStack ecosystem
  4. Minimal Footprint - Ultra-lightweight with minimal dependencies

🤖 AI Development Context

Role: Shared Type Definitions Usage:

  • Use this to import interfaces like IKernel, RuntimePlugin.
  • Helps avoid circular dependencies.
  • Do not add implementation code here, only types.

Installation

pnpm add @objectstack/types

Type Definitions

IKernel

Core interface for the ObjectStack kernel that plugins interact with.

export interface IKernel {
  /**
   * ObjectQL instance (optional to support initialization phase)
   */
  ql?: any;
  
  /**
   * Start the kernel and all registered plugins
   */
  start(): Promise<void>;
  
  /**
   * Additional kernel methods and services
   */
  [key: string]: any;
}

Usage:

import type { IKernel } from '@objectstack/types';

export class MyPlugin {
  async onStart(kernel: IKernel) {
    // Access ObjectQL if available
    if (kernel.ql) {
      await kernel.ql.find('user', {});
    }
  }
}

RuntimeContext

Context object passed to runtime plugins during their lifecycle.

export interface RuntimeContext {
  /**
   * Reference to the kernel instance
   */
  engine: IKernel;
}

Usage:

import type { RuntimeContext } from '@objectstack/types';

export const myPlugin = {
  name: 'my-plugin',
  
  async install(ctx: RuntimeContext) {
    // Use kernel through context
    await ctx.engine.start();
  }
};

RuntimePlugin

Interface for plugins that integrate with the ObjectStack runtime.

export interface RuntimePlugin {
  /**
   * Unique plugin identifier
   */
  name: string;
  
  /**
   * Optional: Called when plugin is registered
   */
  install?: (ctx: RuntimeContext) => void | Promise<void>;
  
  /**
   * Optional: Called when kernel starts
   */
  onStart?: (ctx: RuntimeContext) => void | Promise<void>;
}

Usage:

import type { RuntimePlugin, RuntimeContext } from '@objectstack/types';

export const myPlugin: RuntimePlugin = {
  name: 'my-custom-plugin',
  
  async install(ctx: RuntimeContext) {
    console.log('Plugin installed');
    // Register services, hooks, etc.
  },
  
  async onStart(ctx: RuntimeContext) {
    console.log('Plugin started');
    // Initialize connections, start background tasks, etc.
  }
};

Architecture

Design Philosophy

The @objectstack/types package follows these principles:

  1. Interface Segregation - Only define what's absolutely necessary
  2. Loose Coupling - Enable interoperability without tight dependencies
  3. Progressive Enhancement - Allow plugins to implement optional interfaces
  4. Type Safety - Provide compile-time guarantees where possible

Dependency Graph

@objectstack/types (Layer 0)
├── Dependencies: @objectstack/spec (protocols only)
└── Used By:
    ├── @objectstack/core (kernel implementation)
    ├── @objectstack/runtime (plugin utilities)
    ├── @objectstack/objectql (query engine)
    └── All plugins

The types package sits at the foundation of the architecture, depended upon by nearly all other packages but depending on very few itself.

Use Cases

1. Plugin Development

When building plugins, import types for proper typing:

import type { RuntimePlugin, RuntimeContext } from '@objectstack/types';

export const authPlugin: RuntimePlugin = {
  name: 'auth',
  
  async install(ctx: RuntimeContext) {
    // Setup authentication
  },
  
  async onStart(ctx: RuntimeContext) {
    // Start auth service
  }
};

2. Kernel Extensions

When extending the kernel with custom functionality:

import type { IKernel } from '@objectstack/types';

export class CustomKernel implements IKernel {
  ql?: any;
  
  async start(): Promise<void> {
    // Custom kernel implementation
  }
}

3. Runtime Integration

When integrating with the ObjectStack runtime:

import type { RuntimeContext } from '@objectstack/types';

export function setupRuntime(ctx: RuntimeContext) {
  const kernel = ctx.engine;
  
  // Access kernel functionality
  kernel.start();
}

TypeScript Configuration

This package is designed to work with TypeScript 5.0+:

{
  "compilerOptions": {
    "target": "ES2020",
    "module": "ESNext",
    "moduleResolution": "bundler",
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "declaration": true,
    "declarationMap": true
  }
}

Best Practices

1. Use Type-Only Imports

When importing types, use the type keyword to ensure they're erased at runtime:

import type { IKernel, RuntimePlugin } from '@objectstack/types';

2. Don't Import Implementation

This package contains only types. Never import implementation details:

// ✅ Good - type-only import
import type { RuntimePlugin } from '@objectstack/types';

// ❌ Bad - trying to import implementation
import { RuntimePlugin } from '@objectstack/types'; // Won't work

3. Extend Interfaces When Needed

Plugins can extend these interfaces for custom requirements:

import type { RuntimePlugin, RuntimeContext } from '@objectstack/types';

interface MyPluginContext extends RuntimeContext {
  customProperty: string;
}

export const myPlugin: RuntimePlugin = {
  name: 'my-plugin',
  
  async install(ctx: RuntimeContext) {
    const myCtx = ctx as MyPluginContext;
    // Use custom context
  }
};

4. Maintain Backward Compatibility

The types in this package should be stable. Use optional properties for new features:

export interface RuntimePlugin {
  name: string;
  install?: (ctx: RuntimeContext) => void | Promise<void>;
  onStart?: (ctx: RuntimeContext) => void | Promise<void>;
  // New optional methods are OK
  onDestroy?: () => void | Promise<void>;
}

Version Compatibility

This package follows semantic versioning:

  • Patch: Documentation updates, internal refactoring
  • Minor: New optional properties/methods
  • Major: Breaking changes to existing interfaces

FAQ

Why a separate types package?

To avoid circular dependencies between @objectstack/core and plugins, we extract shared interfaces into a neutral package.

Can I use this in my plugin?

Yes! This package is designed to be used by all ObjectStack plugins and extensions.

Do I need this for application development?

Usually not. Application developers typically use @objectstack/spec for type definitions. This package is primarily for plugin and runtime developers.

What's the difference from @objectstack/spec?

  • @objectstack/spec: Protocol definitions, schemas, and data types (what you configure)
  • @objectstack/types: Runtime interfaces and contracts (how the system runs)

Migration Guide

From Direct Kernel Access

Before:

import { ObjectKernel } from '@objectstack/core';

function myFunction(kernel: ObjectKernel) {
  // Tight coupling to concrete class
}

After:

import type { IKernel } from '@objectstack/types';

function myFunction(kernel: IKernel) {
  // Loose coupling to interface
}

From Inline Types

Before:

interface MyPlugin {
  name: string;
  install: (ctx: any) => Promise<void>;
}

After:

import type { RuntimePlugin } from '@objectstack/types';

const myPlugin: RuntimePlugin = {
  name: 'my-plugin',
  install: async (ctx) => {
    // Implementation
  }
};

Related Packages

Contributing

When adding new types to this package:

  1. Keep interfaces minimal and focused
  2. Use optional properties for extensibility
  3. Document all public types with JSDoc
  4. Avoid breaking changes
  5. Consider backward compatibility

License

MIT