/metrics-track

Set up a metrics tracking plan for a project. Defines PostHog event funnel, KPI benchmarks, and kill/iterate/scale decision thresholds based on lean startup principles.

MCP Tools (use if available)

• kb_search(query) — find PostHog methodology, analytics patterns

If MCP tools are not available, fall back to Grep + Read.

Methodology Reference

This skill implements metrics tracking based on lean startup principles:

• Relative metrics vs niche benchmarks — compare against your own trajectory, not vanity averages
• Kill/iterate/scale decision rules — data-driven thresholds for product decisions (see step 7 below)

Steps

1. Parse project from $ARGUMENTS.

   • Read PRD for features, ICP, monetization model.
   • Read CLAUDE.md for stack (iOS/Web/both).
   • If empty: ask via AskUserQuestion.

2. Detect platform:

   • iOS app → PostHog iOS SDK events
   • Web app → PostHog JS SDK events
   • Both → cross-platform identity (shared user ID across platforms)

3. Load PostHog methodology:

   • If MCP available: kb_search("PostHog analytics events funnel identity")
   • Otherwise: check project docs for existing analytics configuration
   • Extract: event naming conventions, identity resolution, funnel pattern

4. Define event funnel based on PRD features:

   Standard funnel: Awareness → Acquisition → Activation → Revenue → Retention → Referral

   See references/kpi-benchmarks.md for the full event table, KPI thresholds, PostHog code snippets, and A/B test template. Adapt events to the specific product.

5. Forced reasoning — metrics selection: Before defining KPIs, write out:

   • North Star Metric: The ONE number that matters most (e.g., "weekly active users who completed core action")
   • Leading indicators: What predicts the North Star? (e.g., "activation rate D1")
   • Lagging indicators: What confirms success? (e.g., "MRR", "retention D30")
   • Vanity metrics to AVOID: (e.g., total downloads without activation)

6. Set KPI benchmarks per stage:

   Use thresholds from references/kpi-benchmarks.md as starting point. Adjust for product type (B2B has lower volume/higher conversion, B2C mobile has higher volume/lower retention).

7. Define decision rules — use kill/iterate/scale framework from references/kpi-benchmarks.md. Adapt thresholds to project-specific values from step 6.

8. Generate PostHog implementation snippets — use platform-specific examples from references/kpi-benchmarks.md. Adapt event names and properties to the funnel defined in step 4.

9. A/B Test Analysis Template — copy template from references/kpi-benchmarks.md into the metrics plan. Include decision rules (SHIP / KEEP / EXTEND / INCONCLUSIVE).

10. Write metrics plan to docs/metrics-plan.md:

# Metrics Plan: {Project Name}

**Generated:** {YYYY-MM-DD}
**Platform:** {iOS / Web / Both}
**North Star:** {north star metric}

## Event Funnel

| Stage | Event | Properties |
|-------|-------|------------|
{event table from step 4}

## KPIs & Thresholds

| KPI | Target | Kill | Scale |
|-----|--------|------|-------|
{benchmark table from step 6}

## Decision Rules

{framework from step 7}

## Implementation

### PostHog Setup
- Project: {project name} (EU region)
- SDK: {posthog-ios / posthog-js}
- Identity: {anonymous → identified on signup}

### Code Snippets
{snippets from step 8}

## A/B Test Template
{template from step 9}

## Dashboard Template
- Funnel: {stage1} → {stage2} → ... → {stageN}
- Retention: D1 / D7 / D30 cohort chart
- Revenue: MRR trend + trial conversion

---
*Generated by /metrics-track. Implement events, then review weekly.*

11. Output summary — North Star metric, key thresholds, first event to implement, A/B template included.

Notes

• PostHog EU hosting for privacy compliance
• Use $set for user properties, capture for events
• Identity: start anonymous, identify() on signup with user ID
• Cross-platform: same PostHog project, same user ID → unified journey
• Review dashboard weekly, make kill/iterate/scale decision monthly

Common Issues

Wrong platform detected

Cause: Project has both web and iOS indicators. Fix: Skill checks package manifests. If both exist, it generates cross-platform identity setup. Verify the detected platform in the output.

KPI thresholds too aggressive

Cause: Default thresholds are industry averages. Fix: Adjust thresholds in docs/metrics-plan.md based on your niche. B2B typically has lower volume but higher conversion.

PostHog SDK not in project

Cause: Metrics plan generated but SDK not installed. Fix: This skill generates the PLAN only. Install PostHog SDK separately: pnpm add posthog-js (web) or add posthog-ios via SPM (iOS).