instrument-logs

Sends an app's log lines to PostHog as records with named fields you can search and filter, rather than leaving them as loose text nobody can ask questions of.

WHEN TO USE

SCOPE

USE FOR

Start sending an app's logs to PostHog for the first time.
Give new log lines named fields so they can be filtered later.
Use a phone SDK's own log capture instead of a separate exporter.
Review a pull request to check new log lines carry useful fields.

This is a saved copy of the skill's SKILL.md instructions. It may differ from the upstream file or the version you install.

In this document (4)

Add PostHog log capture

Use this skill to add PostHog log capture for new or changed code. Use it after implementing features or reviewing PRs to ensure meaningful log events are captured with structured properties. If PostHog log export is not yet configured, this skill also covers initial OTLP exporter setup. Supports any platform or language.

Supported platforms: Next.js, Node.js, Python, Go, Java, Datadog, Android, React Native, iOS, and any language via OpenTelemetry.

Instructions

Follow these steps IN ORDER:

STEP 1: Analyze the codebase and detect the platform.

Detect the language, framework, and existing logging setup.
Look for dependency files and project files (package.json, Podfile, Package.swift, requirements.txt, go.mod, pom.xml, etc.).
Look for log libraries (winston, pino, logging module, logrus, log4j, serilog, os_log, Logger, etc.).
Look for lockfiles (pnpm-lock.yaml, package-lock.json, yarn.lock, bun.lockb, go.sum, Podfile.lock, Package.resolved, etc.) to determine the package manager.
Check for existing PostHog log export setup. If the OTLP exporter is already configured, skip to STEP 5 to add log capture for new code.

STEP 2: Research log capture. (Skip if PostHog log export is already configured.) 2.1. Find the reference file below that matches the detected platform — it is the source of truth for OTLP exporter configuration and integration with existing logging. Read it now. 2.2. If no reference matches, use the "Other Languages" reference as a fallback — it covers the generic OpenTelemetry approach.

STEP 3: Install dependencies. (Skip if PostHog log export is already configured.)

Install the OpenTelemetry SDK and OTLP exporter packages for the detected platform.
Do not manually edit dependency files — use the package manager's install command.

STEP 4: Configure the OTLP exporter. (Skip if PostHog log export is already configured.)

PostHog logs use the OpenTelemetry protocol. Set up an OTLP exporter pointed at PostHog's ingest endpoint.
For SDK-native log support such as Android, React Native, and iOS, follow the platform reference instead of adding a separate OTLP exporter.
Follow the platform-specific reference for the exact configuration.

STEP 5: Integrate with existing logging.

Add the PostHog log exporter alongside existing logging. Don't replace existing log handlers or outputs.
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 6: Add structured properties.

Ensure logs include structured key-value properties for filtering and search in PostHog.
Prefer structured log formats with key-value properties over plain text messages.

STEP 7: 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.
For the OpenTelemetry endpoint, use https://us.i.posthog.com/v1 (US) or https://eu.i.posthog.com/v1 (EU), matching the region determined above.
Write these values to the appropriate env file using the framework's naming convention.
Reference these environment variables in code instead of hardcoding them.

Reference files

references/nextjs.md - Next.js logs installation - docs
references/nodejs.md - Node.js logs installation - docs
references/python.md - Python logs installation - docs
references/go.md - Go logs installation - docs
references/java.md - Java logs installation - docs
references/datadog.md - Datadog logs installation - docs
references/android.md - Android logs installation - docs
references/react-native.md - React native logs installation - docs
references/ios.md - Ios logs installation - docs
references/flutter.md - Flutter logs installation - docs
references/other.md - Other languages logs installation - docs
references/start-here.md - Getting started with logs - docs
references/search.md - Search logs - docs
references/best-practices.md - Logging best practices - docs
references/troubleshooting.md - Logs troubleshooting - docs
references/link-session-replay.md - Link session replay - docs
references/mcp.md - Use logs over PostHog mcp - docs
references/COMMANDMENTS.md - Framework-specific rules the integration must follow

Each platform reference contains specific OTLP configuration, SDK setup, and integration patterns. Find the one matching the user's stack.

Key principles

Environment variables: Always use environment variables for PostHog keys and OpenTelemetry endpoints. Never hardcode them.
Minimal changes: Add log export alongside existing logging. Don't replace or restructure existing logging code.
OpenTelemetry: PostHog logs use the OpenTelemetry protocol. Configure an OTLP exporter pointed at PostHog's ingest endpoint unless the platform SDK provides native log capture.
SDK-native logs: For Android, React Native, and iOS, use the SDK logger/capture APIs from the platform reference instead of adding a separate OTLP exporter.
Structured logging: Prefer structured log formats with key-value properties over plain text messages.

This skill ships inside the PostHog AI Plugin. Listed package contents include 3 slash commands, 1 agent, hooks and an MCP server. Installed components and skill versions may vary by AI tool.

Install just this skill

Run this outside your AI tool, using Node.js 22.20.0 or newer. Skills CLI 1.7.2 skips skill selection; prompts cancel installation without an interactive terminal. If choosing Project when asked about installation scope, open your project's folder before running this.

Install checklist

Check selected tools if a picker appears; Claude Code may be unchecked under Additional agents. ↑/↓ moves, Space toggles selections, Enter confirms.
Without a tool picker, check Installing to: for your intended tool. Stop if it names a different tool.
If asked, choose Symlink (Recommended) for shared files or Copy to all agents for separate copies; review the summary before confirming installation.
Install the find-skills skill? defaults to Yes, adding another skill for all projects. Choose No if you don't want that extra installation.

Skills CLI 1.7.2 sends install data to skills.sh by default, including the source, skill names, target tools and file details; GitHub sources are reported only when GitHub confirms the repository is public, while other remote sources can also be reported. Confirmed-public GitHub sources also trigger a security-audit request. Before installing, set the environment variable DO_NOT_TRACK=1 or DISABLE_TELEMETRY=1 to disable both.

npx skills add posthog/ai-plugin --skill "instrument-logs" --full-depth

After installing for Claude Code, open it in the installation project if you chose Project; Global makes the skill available across projects on this computer. Once Claude Code loads the skill, its description helps Claude decide when to use it.

If installation created a top-level skills folder that did not exist when your Claude Code session started, run /reload-skills in that session. Run it again after later changes in that folder.

Install the whole plugin

This route installs the posthog plugin package selected for your AI tool.

Claude Code

Add PostHog's marketplace, then install the plugin

Run both lines in a terminal. They install PostHog's posthog plugin: this skill, PostHog's other skills, and a connection to PostHog's hosted MCP server.

claude plugin marketplace add PostHog/ai-plugin

02
```
claude plugin install posthog@posthog
```

Installation and loading

The plugin installs for you in every project and loads the next time you start Claude Code, or after /reload-plugins in an open session.
To connect your PostHog account, start claude, type /mcp, select plugin:posthog:posthog and follow the browser prompts.

Good to know

The plugin includes PostHog's session-capture hook; PostHog's README says it sends sessions to LLM Analytics only when POSTHOG_LLMA_CC_ENABLED=true and POSTHOG_API_KEY are both set.
If you use the separate posthog-telemetry plugin, PostHog says to keep only one of the two, because both register the same hook.
On a self-hosted PostHog, this route's MCP connection won't reach your instance: the plugin's config is fixed to https://mcp.posthog.com/mcp, which routes to PostHog's US or EU region. POSTHOG_MCP_URL works only for the Gemini CLI extension.

What's inside

Files included with this skill.

View on GitHub

Same repository

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Add PostHog log capture

Instructions

Reference files

Key principles

Account or credentials required

Install just this skill

Install the whole plugin

Add PostHog's marketplace, then install the plugin

What's inside

More skills

adding-warehouse-person-properties

analyzing-expensive-users

analyzing-experiment-session-replays

assessing-heatmaps

auditing-endpoints

auditing-experiments-flags