posthog-replicate

PostHog LLM observability for the Replicate SDK. Drop-in replacement that automatically tracks all your AI model calls.

Install

``bash
npm install posthog-replicate posthog-node
`

Usage

`typescript
import { Replicate } from 'posthog-replicate';
import { PostHog } from 'posthog-node';

const posthog = new PostHog('');
const replicate = new Replicate({ posthog });

const output = await replicate.run('stability-ai/sdxl', {
input: { prompt: 'A sunset over mountains' },
posthogDistinctId: 'user_123'
});

await posthog.shutdown();
`

Every call sends a $ai_generation event to PostHog with model, latency, and input/output.

What's Tracked

- run() - full execution with output
- stream() - streaming responses
- predictions.create() - async prediction creation
- predictions.get() - prediction status polling (captures output when complete)

$3

Tracking options are automatically linked between create() and get() calls:

`typescript
// Pass tracking options once at creation
const prediction = await replicate.predictions.create({
model: 'stability-ai/sdxl',
input: { prompt: 'A sunset' },
posthogDistinctId: 'user_123'
});

// Options are automatically inherited - no need to pass them again
const result = await replicate.predictions.get(prediction.id);
`

What's Not Tracked

- predictions.list(), predictions.cancel()
- models., deployments., hardware.* and other non-generation methods

Caveats

- Call posthog.shutdown() before your app exits to flush pending events
- Input/output is tracked by default - use posthogPrivacyMode: true` to disable
- Requires Node.js 20+