OmniRoute/docs/plugins/PLUGIN_SDK.md

# OmniRoute Plugin SDK

## Quick Start

```ts
import { definePlugin } from "omniroute/plugins/sdk";

export default definePlugin({
  name: "my-plugin",
  priority: 50,
  onRequest: async (ctx) => {
    console.log(`Request ${ctx.requestId} for ${ctx.model}`);
  },
  onResponse: async (ctx, response) => {
    console.log(`Response for ${ctx.requestId}`);
    return response;
  },
  onError: async (ctx, error) => {
    console.error(`Error: ${error.message}`);
  },
});
```

## API Reference

### `definePlugin(def: PluginDefinition): Plugin`

Factory function that creates a Plugin object with defaults.

**Parameters:**
- `name` (string, required) — Plugin name in kebab-case
- `priority` (number, optional, default: 100) — Lower runs first
- `enabled` (boolean, optional, default: true) — Start enabled?
- `onRequest` (function, optional) — Runs before chat handler
- `onResponse` (function, optional) — Runs after chat handler
- `onError` (function, optional) — Runs on handler error

### `blockRequest(response?): BlockingHookResult`

Block the request and optionally return a custom response.

```ts
onRequest: (ctx) => {
  if (!ctx.headers["authorization"]) {
    return blockRequest({ error: "Unauthorized", status: 401 });
  }
};
```

### `modifyBody(body): PluginResult`

Modify the request body before it reaches the provider.

```ts
onRequest: (ctx) => {
  return modifyBody({ ...ctx.body, temperature: 0.7 });
};
```

### `addMetadata(metadata): PluginResult`

Attach metadata to the request context.

```ts
onRequest: (ctx) => {
  return addMetadata({ source: "my-plugin", version: "1.0.0" });
};
```

## Plugin Context (`PluginContext`)

| Field | Type | Description |
|---|---|---|
| `requestId` | `string` | Unique request identifier |
| `model` | `string` | Requested model name |
| `provider` | `string` | Target provider ID |
| `body` | `Record<string, unknown>` | Request body |
| `headers` | `Record<string, string>` | Request headers |
| `metadata` | `Record<string, unknown>` | Mutable metadata |
| `timestamp` | `number` | Request timestamp |

## Manifest (`plugin.json`)

```json
{
  "name": "my-plugin",
  "version": "1.0.0",
  "description": "A sample plugin",
  "author": "your-name",
  "main": "index.js",
  "hooks": {
    "onRequest": { "enabled": true, "priority": 50 },
    "onResponse": true,
    "onError": false
  },
  "requires": {
    "permissions": ["network", "file-read"]
  },
  "enabledByDefault": false,
  "configSchema": {
    "apiKey": { "type": "string", "description": "API key for external service" },
    "maxRetries": { "type": "number", "min": 1, "max": 10, "default": 3 },
    "debug": { "type": "boolean", "default": false },
    "mode": { "type": "string", "enum": ["fast", "slow"], "default": "fast" }
  }
}
```

### Hook Priority

Hooks can be configured with priority (lower = runs first):

```json
{
  "hooks": {
    "onRequest": { "enabled": true, "priority": 10 },
    "onResponse": { "enabled": true, "priority": 100 }
  }
}
```

Or as simple booleans (default priority 100):

```json
{
  "hooks": {
    "onRequest": true,
    "onResponse": true
  }
}
```

## Permission System

Plugins run in a sandboxed VM context. Access to external resources requires explicit permissions:

| Permission | Grants |
|---|---|
| `network` | `fetch`, `AbortController`, `Headers`, `Request`, `Response` |
| `file-read` | `fs.readFile`, `fs.readdir`, `fs.stat` |
| `file-write` | `fs.writeFile`, `fs.mkdir`, `fs.rm` |
| `env` | Read-only `process.env` proxy |
| `exec` | `child_process.exec`, `child_process.execSync` |

Without a permission, the corresponding globals are simply not available in the sandbox.

## Config Schema

Define configurable settings in `configSchema`:

```json
{
  "configSchema": {
    "apiKey": { "type": "string", "description": "External API key" },
    "maxRetries": { "type": "number", "min": 1, "max": 10, "default": 3 },
    "debug": { "type": "boolean", "default": false },
    "mode": { "type": "string", "enum": ["fast", "slow"], "default": "fast" }
  }
}
```

Field types: `string`, `number`, `boolean`, `select`

Field options: `default`, `min`, `max`, `enum`, `description`

Config values are persisted in the database and accessible via the dashboard config page.

## Built-in Events

| Event | When | Payload |
|---|---|---|
| `onRequest` | Before chat handler | Request context |
| `onResponse` | After chat handler | Response data |
| `onError` | On handler error | Error object |
| `onModelSelect` | Model selected for routing | Model info |
| `onComboResolve` | Combo routing resolved | Combo targets |
| `onRateLimit` | Rate limit hit | Limit info |
| `onQuotaExhaust` | Quota exhausted | Quota info |
| `onProviderError` | Provider returned error | Error details |
| `onStreamStart` | SSE stream started | Stream info |
| `onStreamEnd` | SSE stream ended | Stream stats |

## Examples

### Request Logger

```ts
import { definePlugin } from "omniroute/plugins/sdk";

export default definePlugin({
  name: "request-logger",
  onRequest: async (ctx) => {
    console.log(`[${new Date().toISOString()}] ${ctx.method} ${ctx.model} -> ${ctx.provider}`);
  },
});
```

### Rate Limiter

```ts
import { definePlugin, blockRequest } from "omniroute/plugins/sdk";

const requests = new Map<string, number[]>();

export default definePlugin({
  name: "rate-limiter",
  priority: 10,
  onRequest: async (ctx) => {
    const key = ctx.headers["x-api-key"] || "anonymous";
    const now = Date.now();
    const window = 60000; // 1 minute
    const maxRequests = 100;

    const timestamps = (requests.get(key) || []).filter(t => t > now - window);
    timestamps.push(now);
    requests.set(key, timestamps);

    if (timestamps.length > maxRequests) {
      return blockRequest({ error: "Rate limit exceeded", status: 429 });
    }
  },
});
```

### Response Transformer

```ts
import { definePlugin } from "omniroute/plugins/sdk";

export default definePlugin({
  name: "response-transformer",
  onResponse: async (ctx, response) => {
    if (response.choices) {
      response.choices = response.choices.map((c: any) => ({
        ...c,
        message: { ...c.message, content: c.message.content.trim() },
      }));
    }
    return response;
  },
});
```