feat: add minimal SDK example

[prosdev]

Implements #8 : Create Minimal Example SDK

Summary

A complete, working example SDK that demonstrates all core features of SDK Kit through three well-documented plugins.

Example SDK Plugins

1. Logger Plugin

• Console logging with configurable levels
• Exposes: debug(), info(), warn(), error(), getLogs()
• Emits logger:logged events
• Demonstrates namespace, defaults, expose, events

2. Analytics Plugin

• Event tracking with batching
• Auto-flush after batch size or interval
• Exposes: track(), identify(), page(), flush()
• Emits analytics:tracked, analytics:identified, analytics:page
• Demonstrates timers, async operations, cleanup

3. Monitor Plugin

• Cross-plugin event monitoring
• Wildcard subscriptions (analytics:*)
• Exposes: getStats(), resetStats()
• Demonstrates plugin communication, statistics

What It Demonstrates

✅ Plugin System

• Three functional plugins working together
• Each with unique namespace
• Proper capability injection

✅ Configuration

• Hierarchical config with defaults
• Dot-notation access
• Runtime updates
• Underwrite pattern (user config wins)

✅ Events

• Pub/sub pattern for loose coupling
• Wildcard subscriptions (analytics:*)
• Lifecycle events (sdk:init, sdk:ready, sdk:destroy)
• Custom events for plugin communication

✅ API Exposure

• 11 public methods exposed from plugins
• Type-safe module augmentation
• Clean, intuitive API

✅ Lifecycle

• Proper init/destroy flow
• Timer cleanup
• Data flushing on destroy
• Event-based hooks

Usage Example

import { createMySDK } from './index';

const sdk = createMySDK({
  logger: { level: 'debug' },
  analytics: { batchSize: 3 },
});

await sdk.init();

// Use exposed methods
sdk.info('Hello world');
sdk.track('button_clicked', { button: 'sign_up' });
sdk.identify('user-123', { name: 'John' });

// Check stats
const stats = sdk.getStats();
console.log(stats); // { trackedEvents: 1, ... }

await sdk.destroy();

File Structure

examples/minimal-sdk/
├── src/
│   ├── index.ts              # Main SDK (157 lines)
│   └── plugins/
│       ├── logger.ts         # Logging (104 lines)
│       ├── analytics.ts      # Tracking (148 lines)
│       └── monitor.ts        # Monitoring (98 lines)
├── README.md                 # Walkthrough (282 lines)
├── package.json
└── tsconfig.json

Documentation

The README includes:

• Step-by-step code walkthrough
• Expected console output
• Key takeaways for each feature
• How to extend with more plugins
• Links to full API docs

Building & Running

cd examples/minimal-sdk
pnpm install
pnpm build    # ✅ Builds successfully

Key Takeaways

This example proves SDK Kit can be used to build real-world SDKs with:

• Clean plugin architecture
• Type-safe APIs
• Flexible configuration
• Event-driven communication
• Proper lifecycle management

Perfect reference for developers building their own SDKs!

Closes #8