Instrument Product Analytics

PostHogOfficialCreated by PostHog

Skill
Tool integration
Data and AI
MIT
Low risk

From the author

Add PostHog product analytics events to track user behavior. Use after implementing new features or reviewing PRs to ensure meaningful user actions are captured. Also handles initial PostHog SDK setup if not yet installed.

— the description by PostHog

AutoGineer summary

Written by AutoGineer from the skill’s own files, not by the author

This skill provides a structured, multi-step workflow to integrate PostHog product analytics into a wide variety of software projects. It guides the user through detecting the project's framework, installing the appropriate SDK, initializing the service, and strategically placing event capture calls. The skill emphasizes non-intrusive implementation, requiring that new analytics code be added alongside existing logic without altering the project's fundamental architecture. It also covers user identification, error tracking, and secure environment variable management.

What it does

Detects the project's framework and language to determine the correct PostHog SDK.
Handles initial SDK installation and initialization based on framework-specific patterns.
Identifies key user actions and business-critical events for tracking.
Implements event capture calls and user identification logic.
Configures environment variables securely for API tokens and host URLs.
Verifies the integration and performs targeted linting on modified files.

When to use it

After implementing new features that require tracking for product analytics.
When reviewing pull requests to ensure meaningful user behaviors are captured.
During the initial setup of a new project that needs product analytics.
When migrating or adding analytics to an existing application.

Advantages

Supports a broad range of frontend, backend, and mobile frameworks.
Ensures consistent event naming and property usage across the codebase.
Prioritizes non-breaking changes and minimal impact on existing code structure.
Automates the complex setup of environment variables and SDK initialization.

Usage examples

“Add PostHog analytics to my Next.js project.”: The agent will analyze the project structure, install the PostHog SDK, initialize it in the appropriate client/server files, and prompt you to identify key events to track.
“I need to track user signups and errors in my Django backend.”: The agent will locate your authentication logic, add identify calls, implement exception capture, and ensure the PostHog project tokens are managed via environment variables.

Install

Download the skill as a ZIP:
https://autogineer.com/agent-skills/posthog/instrument-product-analytics/download

Unzip it into the cross-client skills folder of your project:

mkdir -p .agents/skills && unzip instrument-product-analytics.zip -d .agents/skills

Documentation by PostHog

Add PostHog product analytics events

Use this skill to add product analytics events (capture calls) that track meaningful user actions in new or changed code. Use it after implementing features or reviewing PRs to ensure key user behaviors are captured. If PostHog is not yet installed, this skill also covers initial SDK setup. Supports any framework or language.

Supported frameworks and languages: Next.js, React Router, Nuxt, Vue, TanStack Start, SvelteKit, Astro, Angular, Django, Flask, FastAPI, Laravel, PHP, Ruby on Rails, Go, Elixir, Android, iOS, Flutter, React Native, Expo, and more.

Instructions

Follow these steps IN ORDER:

STEP 1: Analyze the codebase and detect the platform.

Look for dependency files (package.json, pubspec.yaml, Podfile, Package.swift, requirements.txt, Gemfile, composer.json, go.mod, mix.exs, etc.) to determine the framework and language.

Look for lockfiles (pnpm-lock.yaml, package-lock.json, yarn.lock, bun.lockb, go.sum, pubspec.lock, Podfile.lock, Package.resolved, mix.lock) to determine the package manager.

Check for existing PostHog setup. If PostHog is already installed and initialized, skip to STEP 5.

STEP 2: Research integration. (Skip if PostHog is already set up.) 2.1. Find the reference file below that matches the detected framework — it is the source of truth for SDK initialization, provider setup, and event capture patterns. Read it now. 2.2. If no reference matches, fall back to your general knowledge and web search. Use posthog.com/docs as the primary search source.

STEP 3: Install the PostHog SDK. (Skip if PostHog is already set up.)

Add the PostHog SDK package for the detected platform. Do not manually edit package.json — use the package manager's install command.

STEP 4: Initialize PostHog. (Skip if PostHog is already set up.)

Follow the framework reference for where and how to initialize. This varies significantly by framework (e.g., instrumentation-client.ts for Next.js 15.3+, AppConfig.ready() for Django, create_app() for Flask).

STEP 5: Plan event tracking.

From the project's file list, select between 10 and 15 files that might have interesting business value for event tracking, especially conversion and churn events.
Also look for files related to login that could be used for identifying users, along with error handling.
Find any existing posthog.capture() code. Make note of event name formatting. Don't duplicate existing events; supplement them.
Track actions only, not pageviews (those can be captured automatically). Exceptions can be made for "viewed"-type events at the top of a conversion funnel.
Server-side events are REQUIRED if the project includes any instrumentable server-side code (API routes, server actions, webhook handlers, payment/checkout completion, authentication endpoints).

STEP 6: Implement event capture.

For each planned event, add posthog.capture() calls with useful properties.
If a file already has existing integration code for other tools or services, don't overwrite or remove that code. Place PostHog code below it.
Do not alter the fundamental architecture of existing files. Make additions minimal and targeted.
You must read a file immediately before attempting to write it.

STEP 7: Identify users.

Add PostHog identify() calls on the client side during login and signup events. Use the contents of login and signup forms to identify users on submit.
If both frontend and backend exist, pass the client-side session and distinct ID using X-POSTHOG-DISTINCT-ID and X-POSTHOG-SESSION-ID headers to the server-side code. On the server side, make sure events have a matching distinct ID.

STEP 8: Add error tracking.

Add PostHog exception capture error tracking to relevant files, particularly around critical user flows and API boundaries.

STEP 9: Set up environment variables.

Check if the project already has PostHog environment variables configured (e.g. in .env, .env.local, or framework-specific env files). If valid values already exist, skip this step.
If the PostHog project token is missing, use the PostHog MCP server's projects-get tool to retrieve the project's api_token. If multiple projects are returned, ask the user which project to use. If the MCP server is not connected or not authenticated, ask the user for their PostHog project token instead.
For the PostHog host URL: check the projects-get MCP response for a region field — US maps to https://us.i.posthog.com, EU maps to https://eu.i.posthog.com. If the region is not available from the MCP response or from existing project configuration, ask the user: "Are you on PostHog US Cloud or EU Cloud?" Do not assume US Cloud.
Write these values to the appropriate env file using the framework's naming convention.
Reference these environment variables in code instead of hardcoding them.

STEP 10: Verify and clean up.

Check the project for errors. Look for type checking or build scripts in package.json.
Ensure any components created were actually used.
Run any linter or prettier-like scripts found in the package.json, but ONLY on the files you have edited or created during this session. Never run formatting or linting across the entire project's codebase.

Reference files

references/EXAMPLE-next-app-router.md - next-app-router example project code
references/EXAMPLE-next-pages-router.md - next-pages-router example project code
references/EXAMPLE-react-react-router-6.md - react-react-router-6 example project code
references/EXAMPLE-react-react-router-7-framework.md - react-react-router-7-framework example project code
references/EXAMPLE-react-react-router-7-data.md - react-react-router-7-data example project code
references/EXAMPLE-react-react-router-7-declarative.md - react-react-router-7-declarative example project code
references/EXAMPLE-nuxt-3-6.md - nuxt-3-6 example project code
references/EXAMPLE-nuxt-4.md - nuxt-4 example project code
references/EXAMPLE-vue-3.md - vue-3 example project code
references/EXAMPLE-react-tanstack-router-file-based.md - react-tanstack-router-file-based example project code
references/EXAMPLE-react-tanstack-router-code-based.md - react-tanstack-router-code-based example project code
references/EXAMPLE-tanstack-start.md - tanstack-start example project code
references/EXAMPLE-sveltekit.md - sveltekit example project code
references/EXAMPLE-astro-static.md - astro-static example project code
references/EXAMPLE-astro-view-transitions.md - astro-view-transitions example project code
references/EXAMPLE-astro-ssr.md - astro-ssr example project code
references/EXAMPLE-astro-hybrid.md - astro-hybrid example project code
references/EXAMPLE-angular.md - angular example project code
references/EXAMPLE-django.md - django example project code
references/EXAMPLE-flask.md - flask example project code
references/EXAMPLE-fastapi.md - fastapi example project code
references/EXAMPLE-python.md - python example project code
references/EXAMPLE-laravel.md - laravel example project code
references/EXAMPLE-php.md - php example project code
references/EXAMPLE-ruby-on-rails.md - ruby-on-rails example project code
references/EXAMPLE-ruby.md - ruby example project code
references/EXAMPLE-android.md - android example project code
references/EXAMPLE-swift.md - swift example project code
references/EXAMPLE-react-native.md - react-native example project code
references/EXAMPLE-expo.md - expo example project code
references/next-js.md - Next.js
references/react-router-v6.md - React router v6
references/react-router-v7-framework-mode.md - React router v7 framework mode (remix v3)
references/react-router-v7-data-mode.md - React router v7 data mode
references/react-router-v7-declarative-mode.md - React router v7 declarative mode
references/nuxt-js-3-6.md - Nuxt.js (v3.0 to v3.6)
references/nuxt-js.md - Nuxt.js
references/vue-js.md - Vue.js
references/tanstack-start.md - Tanstack start
references/svelte.md - Svelte
references/astro.md - Astro
references/angular.md - Angular
references/django.md - Django
references/flask.md - Flask
references/python.md - Python
references/posthog-python.md - PostHog python SDK
references/dotnet.md - .net
references/elixir.md - Elixir
references/go.md - Go
references/laravel.md - Laravel
references/php.md - Php
references/ruby-on-rails.md - Ruby on rails
references/ruby.md - Ruby
references/android.md - Android
references/ios.md - Ios
references/usage.md - Ios SDK usage
references/configuration.md - Ios SDK configuration
references/flutter.md - Flutter
references/react-native.md - React native
references/identify-users.md - Identify users
references/COMMANDMENTS.md - Framework-specific rules the integration must follow

Each framework reference contains SDK-specific installation, initialization, and usage patterns. Find the one matching the user's stack.

Key principles

Environment variables: Always use environment variables for PostHog keys. Never hardcode them.
Minimal changes: Add PostHog code alongside existing integrations. Don't replace or restructure existing code.
Match the docs: Follow the framework reference's initialization and capture patterns exactly.

Files

ATTRIBUTION.mdAdded by AutoGineer970 B
LICENSELicence file added by AutoGineer1.0 KiB
SKILL.md9.6 KiB
references/COMMANDMENTS.md1.5 KiB
references/EXAMPLE-android.md49.8 KiB
references/EXAMPLE-angular.md23.1 KiB
references/EXAMPLE-astro-hybrid.md27.5 KiB
references/EXAMPLE-astro-ssr.md27.6 KiB
references/EXAMPLE-astro-static.md19.6 KiB
references/EXAMPLE-astro-view-transitions.md23.3 KiB
references/EXAMPLE-django.md30.7 KiB
references/EXAMPLE-expo.md35.1 KiB
references/EXAMPLE-fastapi.md40.9 KiB
references/EXAMPLE-flask.md32.4 KiB
references/EXAMPLE-laravel.md59.3 KiB
references/EXAMPLE-next-app-router.md17.6 KiB
references/EXAMPLE-next-pages-router.md19.1 KiB
references/EXAMPLE-nuxt-3-6.md22.3 KiB
references/EXAMPLE-nuxt-4.md28.9 KiB
references/EXAMPLE-php.md13.0 KiB
references/EXAMPLE-python.md11.6 KiB
references/EXAMPLE-react-native.md46.0 KiB
references/EXAMPLE-react-react-router-6.md13.5 KiB
references/EXAMPLE-react-react-router-7-data.md20.1 KiB
references/EXAMPLE-react-react-router-7-declarative.md15.0 KiB
references/EXAMPLE-react-react-router-7-framework.md32.5 KiB
references/EXAMPLE-react-tanstack-router-code-based.md19.6 KiB
references/EXAMPLE-react-tanstack-router-file-based.md18.3 KiB
references/EXAMPLE-ruby-on-rails.md38.0 KiB
references/EXAMPLE-ruby.md10.0 KiB
references/EXAMPLE-sveltekit.md18.6 KiB
references/EXAMPLE-swift.md18.8 KiB
references/EXAMPLE-tanstack-start.md29.9 KiB
references/EXAMPLE-vue-3.md17.9 KiB
references/android.md33.3 KiB
references/angular.md16.5 KiB
references/astro.md15.8 KiB
references/configuration.md17.2 KiB
references/django.md14.9 KiB
references/dotnet.md25.8 KiB
references/elixir.md17.6 KiB
references/flask.md8.1 KiB
references/flutter.md42.8 KiB
references/go.md20.1 KiB
references/identify-users.md12.2 KiB
references/ios.md8.0 KiB
references/laravel.md13.1 KiB
references/next-js.md18.3 KiB
references/nuxt-js-3-6.md11.4 KiB
references/nuxt-js.md15.1 KiB
references/php.md23.7 KiB
references/posthog-python.md69.3 KiB
references/python.md52.2 KiB
references/react-native.md59.9 KiB
references/react-router-v6.md13.6 KiB
references/react-router-v7-data-mode.md13.5 KiB
references/react-router-v7-declarative-mode.md13.7 KiB
references/react-router-v7-framework-mode.md20.2 KiB
references/ruby-on-rails.md19.7 KiB
references/ruby.md25.5 KiB
references/svelte.md14.6 KiB
references/tanstack-start.md12.8 KiB
references/usage.md29.2 KiB
references/vue-js.md13.4 KiB

references/tanstack-start.md

AI agents: this is one page from PostHog's docs. Full index of Markdown docs for LLMs: https://posthog.com/llms.txt

TanStack Start

Canonical URL: https://posthog.com/docs/libraries/tanstack-start

Cloud region: This page uses US Cloud hosts. For an EU Cloud project, use https://eu.i.posthog.com instead of https://us.i.posthog.com (ingestion host).

Install with the wizard

Run this command in your project directory to add PostHog to your TanStack Start project. The wizard detects your framework, installs the SDK, and sets up your first events.

npx @posthog/wizard

Or set it up manually by following the rest of this guide.

Installation

Install the required packages:

npm install @posthog/react posthog-node

@posthog/react - React package for our JS Web SDK for client-side usage
posthog-node - PostHog Node.js SDK for server-side event capture

If your site sets a Content-Security-Policy, it needs to allow PostHog. This applies to the snippet and to package installs alike: the SDK lazy-loads extra bundles (session replay, surveys) from PostHog's CDN, and sends events to the ingestion host. PostHog serves from subdomains of posthog.com that change over time, so allow the wildcard:
script-src 'self' https://*.posthog.com;
connect-src 'self' https://*.posthog.com;
worker-src 'self' blob: data:;
script-src covers the snippet and the lazy-loaded bundles, connect-src covers event ingestion and feature flags, and worker-src covers session replay. The toolbar needs a few more, or use a reverse proxy so everything is first-party. Failing to do so causes silent failures where capture and identify calls never send, so the integration looks complete while zero events arrive. Remember connect-src falls back to default-src, so default-src 'self' blocks event delivery even when the script itself is bundled.

Identifying users

Identifying users is required. Call posthog.identify('your-user-id') after login to link events to a known user. This is what connects frontend event captures, session replays, LLM traces, and error tracking to the same person — and lets backend events link back too.
Use a stable ID from your auth system when possible, not an email or display name. Send those as person properties instead. If your app has no other stable key, email works as a fallback if they are unique. Never a shared literal like "anonymous" or "user", which pools many people onto one person and corrupts their data. When no ID is available at all, skip the identify and retain the anonymous distinct ID that's automatically assigned.
Call posthog.reset() on logout, so the next person to use the browser doesn't inherit the last one's identity.
See our guide on identifying users for how to set this up.

If your app calls your own backend, tracing_headers adds X-POSTHOG-DISTINCT-ID and X-POSTHOG-SESSION-ID to matching fetch and XMLHttpRequest requests. This lets server-side SDKs link backend events, errors, and LLM traces back to frontend sessions and replays. Use hostnames only, without protocols or paths.

posthog.init('<ph_project_token>', {
  api_host: 'https://us.i.posthog.com',
  // Optional: send PostHog session/user context to your backend
  tracing_headers: ['api.example.com'],
})

This works in local development too, but match on the hostname alone: use 'localhost', not 'localhost:3000'. Ports are never part of a hostname, so a value with one in it never matches anything. localhost and 127.0.0.1 are also different hostnames — use whichever your app actually calls.

Tracing headers help you attribute events across front and backend consistently. When this isn't available, use your server-side stable IDs to deduce the matching distinctId, and pass it in when capturing the event.

Initialize PostHog on the client

Wrap your app with PostHogProvider in your root route with your project token, host, and other options.

src/routes/__root.tsx

// src/routes/__root.tsx
import { HeadContent, Scripts, createRootRoute } from '@tanstack/react-router'
import { PostHogProvider } from '@posthog/react'

export const Route = createRootRoute({
  head: () => ({
    meta: [
      { charSet: 'utf-8' },
      { name: 'viewport', content: 'width=device-width, initial-scale=1' },
    ],
  }),
  shellComponent: RootDocument,
})

function RootDocument({ children }: { children: React.ReactNode }) {
  return (
    <html lang="en">
      <head>
        <HeadContent />
      </head>
      <body>
        <PostHogProvider
          apiKey="<ph_project_token>"
          options={{
            api_host: 'https://us.i.posthog.com',
            defaults: '2026-08-30',
            capture_exceptions: true
          }}
        >
          {children}
        </PostHogProvider>
        <Scripts />
      </body>
    </html>
  )
}

Once the provider is in place, PostHog automatically captures pageviews, sessions, and web vitals.

Capture events on the client

Use the usePostHog hook from @posthog/react in any component to capture custom events:

src/routes/checkout.tsx

import { usePostHog } from '@posthog/react'

function CheckoutButton({ orderId, total }: { orderId: string; total: number }) {
  const posthog = usePostHog()

  const handleClick = () => {
    posthog.capture('checkout_started', {
      order_id: orderId,
      total: total,
    })
  }

  return <button onClick={handleClick}>Checkout</button>
}

Identify users

Call posthog.identify() when a user logs in to link their events to a user ID:

import { usePostHog } from '@posthog/react'

function LoginForm() {
  const posthog = usePostHog()

  const handleLogin = async (userId: string, email: string) => {
    // ... your login logic

    posthog.identify(userId, {
      email: email,
    })

    posthog.capture('user_logged_in')
  }
}

Call posthog.reset() on logout to clear the identified user.

Initialize PostHog on the server

Create a server-side PostHog client using posthog-node. Use a singleton pattern so you reuse the same client across requests:

src/utils/posthog-server.ts

// src/utils/posthog-server.ts
import { PostHog } from 'posthog-node'

let posthogClient: PostHog | null = null

export function getPostHogClient() {
  if (!posthogClient) {
    posthogClient = new PostHog(
      '<ph_project_token>',
      {
        host: 'https://us.i.posthog.com',
        flushAt: 1,
        flushInterval: 0,
      },
    )
  }
  return posthogClient
}

Capture events on the server

Use the server client in TanStack Start API routes to capture events server-side. Server-side capture is useful for tracking events that shouldn't be spoofable from the client, like purchases or authentication:

src/routes/api/checkout.ts

// src/routes/api/checkout.ts
import { createFileRoute } from '@tanstack/react-router'
import { getPostHogClient } from '../../utils/posthog-server'

export const Route = createFileRoute('/api/checkout')({
  server: {
    handlers: {
      POST: async ({ request }) => {
        const body = await request.json()

        const posthog = getPostHogClient()

        posthog.capture({
          distinctId: body.userId,
          event: 'item_purchased',
          properties: {
            item_id: body.itemId,
            price: body.price,
            source: 'api',
          },
        })

        return Response.json({ success: true })
      },
    },
  },
})

The server-side capture call requires a distinctId (the user identifier), an event name, and optional properties.

Add request context to backend spans

For a Node.js deployment with OpenTelemetry, reuse getPostHogClient() for both request context and the span processor. Add this processor to your existing tracing provider before the server accepts requests:

import { PostHogContextSpanProcessor } from 'posthog-node/otel'
import { getPostHogClient } from './src/utils/posthog-server'

const posthogSpanProcessor = new PostHogContextSpanProcessor(getPostHogClient())

Include posthogSpanProcessor in that provider's spanProcessors configuration. Keep your existing exporter, sampler, and instrumentation. See the Node.js tracing setup for provider setup. Keep this setup on the server. Shut down the provider and the PostHog client through your application's shutdown hook, after requests finish.

Add global request middleware in src/start.ts. If that file already exists, add the middleware to its existing configuration. Keep your existing CSRF and authentication middleware. This example includes TanStack Start's CSRF middleware because defining src/start.ts replaces its default setup.

src/start.ts

import {
  createCsrfMiddleware,
  createMiddleware,
  createStart,
} from '@tanstack/react-start'
import { enrichCurrentSpan } from 'posthog-node/otel'
import { getPostHogClient } from './utils/posthog-server'

function tracingHeader(request: Request, name: string): string | undefined {
  const value = request.headers.get(name)
  return value?.replace(/[\x00-\x1f\x7f-\x9f]/g, '').trim().slice(0, 1000) || undefined
}

const posthogContext = createMiddleware().server(async ({ request, next }) => {
  const posthog = getPostHogClient()
  const existing = posthog.getContext()

  return posthog.withContext(
    {
      distinctId:
        existing?.distinctId ??
        tracingHeader(request, 'X-POSTHOG-DISTINCT-ID'),
      sessionId:
        existing?.sessionId ??
        tracingHeader(request, 'X-POSTHOG-SESSION-ID'),
    },
    async () => {
      enrichCurrentSpan(posthog)
      return await next()
    },
    { fresh: true }
  )
})

export const startInstance = createStart(() => ({
  requestMiddleware: [createCsrfMiddleware({ filter: ({ handlerType }) => handlerType === 'serverFn' }), posthogContext],
}))

This setup was checked with TanStack Start 1.169.3 on Node.js. It runs for SSR, server routes, and server functions. It reads the two browser tracing headers without copying other headers or request data. The header helper removes control characters, trims whitespace, and limits each ID to 1,000 characters. An identity already set by application code takes precedence. Treat browser IDs as analytics data, not authentication. Set authenticated identity before this middleware when you need it to take precedence.

The processor fills missing sessionId and posthogDistinctId span attributes. Explicit canonical attributes stay unchanged, including non-string values. user.id alone is not an override. At request entry, the helper also fills missing attributes on the nearest recording server ancestor whose parent chain the processor observed. A sampler-dropped intermediate breaks that chain, so the earlier server span stays unchanged.

Work that the request starts, including detached tasks, keeps the IDs after next() returns or throws. This example does not support the edge runtime. Give separately owned background work that needs its own IDs an explicit context.

TanStack handles some route and server-function errors before middleware can see them. Capture an error once at the application handler that owns it, while request context is active:

try {
  await savePurchase()
} catch (error) {
  getPostHogClient().captureException(error)
  throw error
}

Do not add a second capture if an existing error handler already reports the same error. This middleware does not enable automatic error capture.

Next steps

Installing the JS Web SDK and Node SDK means all of their functionality is available in your TanStack Start project. To learn more about this, have a look at our JS Web SDK docs and Node SDK docs.

Requirements and compatibility

Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta

“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.

Needs: Needs an MCP server, Needs Python, Needs Node.js

Security

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Attribution and licence

Created by

PostHog

Publisher

PostHog (Official)

Source

PostHog/skills · skills/omnibus/instrument-product-analytics · commit a5d30e7

Licence

MIT License (redistribution allowed)

LICENSE (added by AutoGineer from LICENSE)
ATTRIBUTION.md (written by AutoGineer)

Synced

2026-11-09

AutoGineer is not affiliated with or endorsed by PostHog or PostHog.

Download ZIP

The ZIP holds the skill’s files, its licence files and an ATTRIBUTION.md. Download instrument-product-analytics.zip