posthog-core-workflow-a

What this skill does

# PostHog Core Workflow A — Product Analytics

## Overview

Primary PostHog workflow covering event capture, user identification, group analytics, and person properties. This is the foundation for all PostHog analytics: capturing what users do, linking events to identified users, and grouping users by company/team for B2B analytics.

## Prerequisites

- Completed `posthog-install-auth` setup
- `posthog-js` (browser) and/or `posthog-node` (server) installed
- Project API key (`phc_...`) configured

## Instructions

### Step 1: Define Event Taxonomy

```typescript
// src/analytics/events.ts
// Define all events as typed constants for consistency
export const EVENTS = {
  // User lifecycle
  USER_SIGNED_UP: 'user_signed_up',
  USER_LOGGED_IN: 'user_logged_in',
  USER_ONBOARDING_COMPLETED: 'user_onboarding_completed',

  // Core product actions
  FEATURE_USED: 'feature_used',
  ITEM_CREATED: 'item_created',
  ITEM_UPDATED: 'item_updated',
  ITEM_DELETED: 'item_deleted',
  SEARCH_PERFORMED: 'search_performed',
  EXPORT_COMPLETED: 'export_completed',

  // Revenue events
  SUBSCRIPTION_STARTED: 'subscription_started',
  SUBSCRIPTION_UPGRADED: 'subscription_upgraded',
  SUBSCRIPTION_CANCELED: 'subscription_canceled',
  PAYMENT_COMPLETED: 'payment_completed',
} as const;

// Standard property schema for consistency across events
interface BaseProperties {
  source?: 'web' | 'mobile' | 'api' | 'webhook';
  plan_tier?: 'free' | 'pro' | 'enterprise';
  duration_ms?: number;
}
```

### Step 2: Capture Events (Browser)

```typescript
import posthog from 'posthog-js';
import { EVENTS } from './events';

// Custom event with properties
posthog.capture(EVENTS.ITEM_CREATED, {
  item_type: 'document',
  source: 'web',
  plan_tier: 'pro',
});

// Timed event (measure duration)
const start = performance.now();
await doExpensiveOperation();
posthog.capture(EVENTS.EXPORT_COMPLETED, {
  format: 'csv',
  row_count: 1500,
  duration_ms: Math.round(performance.now() - start),
});

// Pageview with custom properties (if capture_pageview: false)
posthog.capture('$pageview', {
  page_title: document.title,
  referrer: document.referrer,
});
```

### Step 3: Identify Users and Set Properties

```typescript
// After user logs in — links anonymous events to this user
posthog.identify('user-456', {
  // $set properties (persist, overwrite on change)
  email: '[email protected]',
  name: 'Jane Smith',
  plan: 'enterprise',
  signup_date: '2025-06-15',
});

// Update properties later without re-identifying
posthog.people.set({
  last_active: new Date().toISOString(),
  total_items: 42,
});

// Set properties only if not already set ($set_once)
posthog.people.set_once({
  first_seen: new Date().toISOString(),
  original_referrer: document.referrer,
});

// Unset properties
posthog.people.unset(['deprecated_field']);

// Reset on logout (clears distinct_id, starts new anonymous session)
posthog.reset();
```

### Step 4: Group Analytics (B2B Company Tracking)

```typescript
// Associate user with a company group
posthog.group('company', 'company-789', {
  name: 'Acme Corp',
  industry: 'SaaS',
  plan: 'enterprise',
  employee_count: 150,
  arr: 250000,
});

// Events now automatically include company context
posthog.capture(EVENTS.FEATURE_USED, {
  feature_name: 'bulk-export',
});
// This event is attributed to both user-456 AND company-789

// Multiple group types
posthog.group('team', 'team-alpha', { name: 'Alpha Team' });
```

### Step 5: Server-Side Event Capture (posthog-node)

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

const posthog = new PostHog(process.env.NEXT_PUBLIC_POSTHOG_KEY!, {
  host: 'https://us.i.posthog.com',
});

// Server-side capture (e.g., in API route or webhook handler)
function trackServerEvent(userId: string, event: string, properties?: Record<string, any>) {
  posthog.capture({
    distinctId: userId,
    event,
    properties: {
      ...properties,
      source: 'api',
    },
  });
}

// Identify with server-side properties
posthog.identify({
  distinctId: 'user-456',
  properties: {
    subscription_status: 'active',
    mrr: 99,
  },
});

// Group identify from server
posthog.groupIdentify({
  groupType: 'company',
  groupKey: 'company-789',
  properties: {
    plan: 'enterprise',
    total_seats: 50,
  },
});

// CRITICAL: Flush in serverless/edge functions
await posthog.flush();
```

### Step 6: Create Annotations for Context

```bash
set -euo pipefail
# Mark a deployment or product change in PostHog
curl -X POST "https://app.posthog.com/api/projects/$POSTHOG_PROJECT_ID/annotations/" \
  -H "Authorization: Bearer $POSTHOG_PERSONAL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "content": "v2.5.0 deployed — new checkout flow",
    "date_marker": "'$(date -u +%Y-%m-%dT%H:%M:%SZ)'",
    "scope": "project"
  }'
```

## Error Handling

| Error | Cause | Solution |
|-------|-------|----------|
| Events not appearing | `posthog.init` not called | Ensure init runs before any capture |
| Anonymous/identified split | Different `distinct_id` across platforms | Use consistent user ID from your auth system |
| Group data missing | `posthog.group()` not called | Call `group()` before capture for group attribution |
| Server events lost | No `flush()` in serverless | Always call `await posthog.flush()` before response |
| Properties not updating | Using `$set_once` for mutable data | Use `posthog.people.set()` for values that change |

## Output

- Typed event taxonomy for consistent tracking
- Browser event capture with user identification
- B2B group analytics linking users to companies
- Server-side event capture with proper flushing
- Annotations marking deployments and product changes

## Resources

- [Capture Events](https://posthog.com/docs/product-analytics/capture-events)
- [Identifying Users](https://posthog.com/docs/product-analytics/identify)
- [Group Analytics](https://posthog.com/docs/product-analytics/group-analytics)
- [Annotations API](https://posthog.com/docs/api/annotations)

## Next Steps

For feature flags and experiments, see `posthog-core-workflow-b`.