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PR Evaluation Report

Summary

Adds comprehensive PostHog analytics integration to a Next.js 15 todo app with event tracking for user actions, page views, and error handling

Files Changed Lines Added Lines Removed
8 +151 -0

PostHog Integration: 9/10

Events Tracked: todo_created, todo_completed, todo_uncompleted, todo_deleted, todo_create_failed, todo_update_failed, todo_delete_failed, todo_fetch_failed, todo_form_submitted, about_page_viewed
Error Tracking: ✅ Configured

Issues

LOW: Missing user identification setup - no posthog.identify() calls found (in instrumentation-client.ts)

Consider adding user identification when user data is available

Strengths

  • ⭐ Comprehensive event tracking covering all major user actions
  • ⭐ Proper error tracking with captureException calls
  • ⭐ Well-structured events JSON documentation
  • ⭐ Good event properties with contextual data
  • ⭐ Proper client and server-side setup
  • ⭐ Correct proxy configuration for PostHog endpoints
  • ⭐ Prevention of duplicate page view tracking with useRef

Runnability: 8/10

  • Can Build:
  • Can Run:

Issues

  • ⚠️ Environment variables (NEXT_PUBLIC_POSTHOG_KEY, NEXT_PUBLIC_POSTHOG_HOST) need to be configured but are not documented

Code Quality: 9/10

Aspect Status
Minimal Changes
Understandable
Maintainable
Disruption Level low

Overall Score: 9/10

Recommendation:APPROVE


Generated by PR Evaluation Agent

@edwinyjlim
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PR Evaluation Report

Summary

This PR adds comprehensive PostHog analytics integration to a Next.js 15 App Router todo application. It includes client-side initialization via instrumentation-client.ts, server-side PostHog client setup, reverse proxy configuration to avoid ad-blockers, and event tracking for all core todo CRUD operations plus page views. The implementation also includes a .posthog-events.json manifest documenting all tracked events.

Files Changed Lines Added Lines Removed
8 +151 -0

PostHog Integration: 4/5

Events Tracked: todo_created, todo_completed, todo_uncompleted, todo_deleted, todo_create_failed, todo_update_failed, todo_delete_failed, todo_fetch_failed, todo_form_submitted, about_page_viewed
Error Tracking: ✅ Configured

Issues

🟡 MEDIUM: Missing user identification - no posthog.identify() call to link events to users (in instrumentation-client.ts)

Add posthog.identify() when user authentication state is available to enable user-level analytics

LOW: No automatic pageview tracking configured - only manual about_page_viewed event (in instrumentation-client.ts)

Consider adding capture_pageview: true or implementing a route change listener for automatic pageview tracking

LOW: Server-side PostHog client is created but never used in the PR (in lib/posthog-server.ts)

Either use the server client for server-side events or remove if not needed

Strengths

  • ⭐ Excellent reverse proxy setup in next.config.ts to circumvent ad-blockers
  • ⭐ Proper use of instrumentation-client.ts for Next.js 15 initialization pattern
  • ⭐ Exception capture enabled with capture_exceptions: true and posthog.captureException() calls
  • ⭐ Good use of defaults: '2025-05-24' for modern SDK defaults
  • ⭐ Debug mode enabled for development environment
  • ⭐ Well-documented events in .posthog-events.json manifest
  • ⭐ Proper use of useRef to prevent duplicate page view tracking in React strict mode

Code Quality: 5/5

Aspect Status
Breaks App ✅ No
Overwrites Existing Code ✅ No
Changes App Logic ✅ No
Minimal Changes
Understandable
Disruption Level low

Quality of Insights: 5/5

Aspect Status
Meaningful Events
Enriched Properties
Answers Product Questions

Strengths

  • ⭐ Events capture both success and failure states for all CRUD operations
  • ⭐ Error events include error_message property for debugging
  • ⭐ todo_form_submitted includes has_description, title_length, description_length for form engagement analysis
  • ⭐ todo_created includes has_description and title_length to understand user behavior
  • ⭐ todo_update_failed includes attempted_completed_state for debugging context
  • ⭐ Events enable funnel analysis: form submission -> todo creation -> completion
  • ⭐ Failure tracking enables error rate monitoring and reliability insights

Overall Score: 4/5

Recommendation:APPROVE


Generated by PR Evaluation Agent

@edwinyjlim
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PR Evaluation Report

Summary

This PR implements a comprehensive PostHog analytics integration for a Next.js 15 App Router todo application. It includes client-side initialization using the modern instrumentation-client.ts pattern, reverse proxy setup to circumvent ad-blockers, server-side PostHog client setup, and extensive event tracking across core todo CRUD operations (create, complete, delete) with error tracking. The implementation also includes a page view tracker component and documents all events in a .posthog-events.json manifest file.

Files Changed Lines Added Lines Removed
8 +151 -0

Important Files Changed

Filename Score Overview
apps/next-js/15-app-router-todo/.posthog-events.json 5/5 Comprehensive event manifest documenting 10 tracked events with clear descriptions and file locations. Provides excellent documentation for the analytics implementation and enables event discovery for other team members.
apps/next-js/15-app-router-todo/app/about/page.tsx 5/5 Minimal, non-invasive change adding the AboutPageTracker component. Preserves all existing page structure and only adds the import and component usage at the top of the page content.
apps/next-js/15-app-router-todo/components/about/about-page-tracker.tsx 4/5 Clean page view tracking component using useRef to prevent duplicate tracking. Uses the 'use client' directive correctly. The pattern is solid, though a more reusable generic page tracker could be considered for future pages.
apps/next-js/15-app-router-todo/components/todos/todo-form.tsx 5/5 Well-integrated form submission tracking with meaningful properties (has_description, title_length, description_length). The tracking is placed at the right moment before the actual action, preserving existing form logic entirely.
apps/next-js/15-app-router-todo/components/todos/todo-list.tsx 5/5 Comprehensive event tracking covering all CRUD operations with both success and failure cases. Each action (create, toggle, delete) has corresponding error tracking with captureException for stack traces. Properties include relevant context like todo_id, error messages, and state information.
apps/next-js/15-app-router-todo/instrumentation-client.ts 5/5 Correct Next.js 15 initialization pattern using instrumentation-client.ts. Configures reverse proxy via '/ingest', enables exception capture, sets modern SDK defaults ('2025-05-24'), and includes debug mode for development.
apps/next-js/15-app-router-todo/lib/posthog-server.ts 4/5 Proper server-side PostHog client setup with singleton pattern and shutdown function. Uses flushAt: 1 and flushInterval: 0 for immediate flushing in serverless environments. Note: This client is set up but not actively used in the PR, which could be intentional for future server-side tracking.
apps/next-js/15-app-router-todo/next.config.ts 5/5 Correct reverse proxy rewrites for PostHog to circumvent ad-blockers. Includes both the main ingest path and static assets path, plus skipTrailingSlashRedirect for PostHog API compatibility. Clean integration with existing config.

PostHog Integration: 4/5

Events Tracked: todo_created, todo_completed, todo_uncompleted, todo_deleted, todo_create_failed, todo_update_failed, todo_delete_failed, todo_fetch_failed, todo_form_submitted, about_page_viewed
Error Tracking: ✅ Configured

Issues

  • 🟡 MEDIUM: Missing user identification (posthog.identify()). Without user identification, events cannot be attributed to specific users across sessions. (in apps/next-js/15-app-router-todo/instrumentation-client.ts)
    • Add posthog.identify() call when user authentication state is available
  • LOW: Server-side PostHog client is configured but not used anywhere in the codebase (in apps/next-js/15-app-router-todo/lib/posthog-server.ts)
    • Either use the server client for server-side event tracking or remove if not needed
  • LOW: No automatic pageview tracking configured. Only the about page has manual page view tracking. (in apps/next-js/15-app-router-todo/instrumentation-client.ts)
    • Consider adding capture_pageview: true or implementing a PageViewTracker component for all pages

Criteria met

  • ✅ Reverse proxy setup to circumvent ad-blockers
  • ✅ Proper initialization pattern for Next.js 15 App Router
  • ✅ Exception capture enabled with capture_exceptions: true
  • ✅ posthog.captureException() used for error tracking
  • ✅ Custom events with enriched properties
  • ✅ Both success and failure events tracked
  • ✅ Environment variable configuration for API key
  • ✅ Debug mode enabled for development

Code Quality: 5/5

Aspect Status
Breaks App ✅ No
Overwrites Existing Code ✅ No
Changes App Logic ✅ No
Minimal Changes
Understandable
Disruption Level none

Quality of Insights: 5/5

Aspect Status
Meaningful Events
Enriched Properties
Answers Product Questions

Strengths

  • ✅ Events tied to actual user actions (create, complete, delete todos)
  • ✅ Error events capture failure points for debugging and reliability monitoring
  • ✅ Properties provide actionable context (todo_id, has_description, title_length)
  • ✅ Success/failure pairs enable conversion funnel analysis
  • ✅ Form submission event with content metadata enables form optimization
  • ✅ Page view tracking for funnel awareness analysis
  • ✅ Comprehensive CRUD coverage allows full user journey analysis

Overall Score: 5/5

Recommendation:APPROVE


Generated by PR Evaluation Agent

@edwinyjlim
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Now I have all the information I need to provide a thorough evaluation. Here's my review:


PR Evaluation Report

Summary

This PR adds PostHog analytics integration to a Next.js 15 App Router todo application. It implements client-side tracking via instrumentation-client.ts, adds custom event tracking for all CRUD operations on todos, sets up a reverse proxy to circumvent ad blockers, and creates a server-side PostHog client. However, critical dependencies are missing from package.json, which will cause the application to fail at build time.

Files Changed Lines Added Lines Removed
8 +151 -0

Important Files Changed

Filename Score Overview
instrumentation-client.ts 4/5 PostHog client initialization with proper config, uses reverse proxy, but defaults property is unusual
next.config.ts 5/5 Clean reverse proxy setup for ad-blocker circumvention
components/todos/todo-list.tsx 4/5 Comprehensive event tracking for all todo CRUD operations with error tracking
components/todos/todo-form.tsx 4/5 Form submission tracking with useful metadata properties
components/about/about-page-tracker.tsx 4/5 Page view tracking with deduplication via useRef
lib/posthog-server.ts 3/5 Server client setup but never used in the PR; singleton pattern is fragile in serverless
app/about/page.tsx 5/5 Minimal change to add tracker component
.posthog-events.json 4/5 Good event documentation, but note file path inconsistency for about_page_viewed
package.json 1/5 Missing posthog-js and posthog-node dependencies

PostHog Integration: 2/5

Events Tracked: todo_created, todo_completed, todo_uncompleted, todo_deleted, todo_create_failed, todo_update_failed, todo_delete_failed, todo_fetch_failed, todo_form_submitted, about_page_viewed

Error Tracking: ✅ Configured via capture_exceptions: true and explicit captureException() calls

Issues

  • 🔴 HIGH: posthog-js and posthog-node are not listed in package.json dependencies
    • The application will fail to build/run. Add: "posthog-js": "^1.x.x" and "posthog-node": "^4.x.x" to dependencies
  • 🔴 HIGH: No user identification (posthog.identify()) implemented
    • Anonymous users cannot be linked across sessions. Consider adding identification when user context is available
  • 🟡 MEDIUM: The defaults: '2025-05-24' property in initialization is non-standard
    • This doesn't appear to be a valid PostHog configuration option. May cause warnings or be ignored
  • 🟡 MEDIUM: Server-side PostHog client (lib/posthog-server.ts) is created but never used
    • Dead code that adds confusion. Either remove or implement server-side tracking
  • 🟡 MEDIUM: Automatic pageview tracking is not explicitly enabled
    • Consider adding capture_pageview: true or implementing manual page tracking across all routes
  • 🟡 MEDIUM: .env file contains hardcoded API key that should not be committed
    • Move to .env.example with placeholder values

Criteria Met

  • ✅ PostHog initialization with API key (assuming deps are added)
  • ✅ Correct API host configuration via reverse proxy
  • ✅ Reverse proxy setup to circumvent ad blockers
  • ✅ Exception capture enabled
  • ✅ Custom event tracking with posthog.capture()
  • ✅ Event properties enriched with contextual data
  • ✅ No PII in event properties
  • ✅ Proper deduplication in page tracker (useRef pattern)

Code Quality: 3/5

Aspect Status
Breaks App ❌ Yes (missing dependencies)
Overwrites Existing Code ✅ No
Changes App Logic ✅ No
Minimal Changes ✅ Yes
Understandable ✅ Yes
Disruption Level high (due to missing deps)

Issues

  • 🔴 Critical: Missing posthog-js and posthog-node in package.json - app will not build
  • 🟡 Medium: .posthog-events.json lists app/about/page.tsx as filePath for about_page_viewed but the actual tracking is in components/about/about-page-tracker.tsx
  • 🟡 Medium: Unused lib/posthog-server.ts - dead code in the PR
  • ⚠️ Minor: .env file committed with actual key value (security concern, should be in .env.example)

Quality of Insights: 4/5

Aspect Status
Meaningful Events ✅ Yes
Enriched Properties ✅ Yes
Answers Product Questions ✅ Yes

Strengths

  • ✅ Complete coverage of todo CRUD lifecycle (create, complete, uncomplete, delete)
  • ✅ Error events paired with success events enables funnel analysis
  • ✅ Form submission tracking with useful metadata (has_description, title_length, description_length)
  • ✅ Exception tracking via captureException() provides debugging context
  • ✅ Events can answer: "What % of todo creations fail?", "How long are typical todo titles?", "Do users use descriptions?"

Issues

  • ⚠️ No automatic pageview tracking means limited funnel visibility across pages
  • ⚠️ Missing session replay or feature flag setup (not required but valuable)
  • ⚠️ No tracking on successful todo fetch (only failure) - asymmetric observability

Overall Score: 3/5

Recommendation:REQUEST CHANGES

Required Changes Before Merge:

  1. Add PostHog dependencies to package.json:
    "posthog-js": "^1.165.0",
    "posthog-node": "^4.3.0"
  2. Remove or implement the unused lib/posthog-server.ts
  3. Move .env contents to .env.example with placeholder values
  4. Fix the defaults property in instrumentation-client.ts (appears to be invalid config)

Recommended Improvements:

  • Add posthog.identify() when user context is available
  • Enable automatic pageview tracking or implement manual tracking across all routes
  • Correct the .posthog-events.json file path for about_page_viewed

Generated by PR Evaluation Agent

@edwinyjlim
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Now I have all the information needed to provide a comprehensive evaluation. Let me create the PR review:


PR Evaluation Report

Summary

This PR adds PostHog analytics integration to a Next.js 15 App Router todo application. It implements client-side event tracking for todo CRUD operations, page views, and error capture, along with a reverse proxy configuration to bypass ad blockers. However, the PostHog SDK dependencies are missing from package.json.

Files Changed Lines Added Lines Removed
8 +151 -0

Important Files Changed

Filename Score Description Events
instrumentation-client.ts 3/5 PostHog client initialization with exception capture, but uses undocumented defaults option None (initialization only)
next.config.ts 5/5 Correctly configured reverse proxy for PostHog to bypass ad blockers None
lib/posthog-server.ts 2/5 Server-side PostHog client setup, but never used anywhere in the codebase None
components/todos/todo-list.tsx 4/5 Good event tracking for CRUD operations with error capture todo_created, todo_completed, todo_uncompleted, todo_deleted, todo_fetch_failed, todo_create_failed, todo_update_failed, todo_delete_failed
components/todos/todo-form.tsx 4/5 Form submission tracking with useful properties todo_form_submitted
components/about/about-page-tracker.tsx 4/5 Manual page view tracking with deduplication, but hacky approach about_page_viewed
app/about/page.tsx 4/5 Minimal change to include tracker component None directly
.posthog-events.json 4/5 Good documentation of tracked events Documentation only

PostHog Integration: 3/5

Criteria Result
PostHog SDKs Installed ❌ Neither posthog-js nor posthog-node in package.json
Events Tracked todo_created, todo_completed, todo_uncompleted, todo_deleted, todo_form_submitted, about_page_viewed, todo_fetch_failed, todo_create_failed, todo_update_failed, todo_delete_failed
Error Tracking ✅ Configured with capture_exceptions: true and posthog.captureException() calls
Reverse Proxy ✅ Properly configured in next.config.ts

Issues

  • 🔴 Missing PostHog dependencies: posthog-js and posthog-node are not listed in package.json. The app will fail to build/run without these packages installed.
    • SUGGESTION: Add to dependencies: "posthog-js": "^1.165.0" and "posthog-node": "^4.3.0"
  • 🔴 Unused server-side PostHog client: lib/posthog-server.ts creates a PostHog Node.js client that is never imported or used anywhere. Dead code.
    • SUGGESTION: Either remove this file or implement server-side tracking where appropriate
  • 🟠 Unknown defaults configuration option: instrumentation-client.ts uses defaults: '2025-05-24' which is not a documented PostHog configuration option. This may cause issues or be silently ignored.
    • SUGGESTION: Remove this option or verify it's a valid PostHog configuration
  • 🟠 No user identification: posthog.identify() is never called, meaning all events are attributed to anonymous users without the ability to link sessions to user accounts.
    • SUGGESTION: Implement user identification when users log in or register
  • 🟠 Manual page view tracking is fragmented: The AboutPageTracker component manually tracks page views for one page only. No automatic pageview capture is configured, and other pages don't have tracking.
    • SUGGESTION: Enable capture_pageview: true in initialization or implement consistent tracking across all pages

Other completed criteria

  • Proper reverse proxy configuration for ad blocker bypass
  • Exception capture properly configured
  • No PII exposed in event properties
  • Deduplication logic in AboutPageTracker prevents double-firing

Code quality: 3/5

Criteria Result
App runs ❌ No - missing dependencies
Preserves Existing Code ✅ Yes
Minimal Changes ❌ No - includes unused server-side code
Understandable ✅ Yes
Disruption Level medium

Issues

  • 🔴 Application will not build: Missing posthog-js and posthog-node in package.json means the app cannot be built or run. The imports will fail.
    • SUGGESTION: Run npm install posthog-js posthog-node and commit the updated package.json
  • 🟠 Unused code committed: lib/posthog-server.ts is complete dead code - never imported or used. This adds maintenance burden.
    • SUGGESTION: Either integrate server-side tracking or remove the file
  • 🟡 Environment variable in .env: The .env file contains what appears to be an actual API key (sTMFPsFhdP1Ssg). Should use .env.example with placeholder values.
    • SUGGESTION: Create .env.example with placeholder values, add .env to .gitignore if not already

Quality of insights: 4/5

PostHog insights enabled

  • Todo funnel analysis: Track complete user journey from form submission → creation → completion → deletion
  • Error rate monitoring: Capture failure events for all CRUD operations with error messages, enabling debugging and reliability insights
  • Feature usage patterns: Distinguish between simple todos (title only) vs detailed todos (with description) via has_description property
  • User engagement metrics: Track about page views as top-of-funnel awareness metric
  • Completion rates: Separate todo_completed and todo_uncompleted events allow tracking task completion behavior

Issues

  • 🟠 Redundant event tracking: Both todo_form_submitted (in TodoForm) and todo_created (in TodoList) fire for successful todo creation. This creates duplicate/overlapping data.
    • SUGGESTION: Keep only todo_created which fires on successful creation, or rename todo_form_submitted to track specifically validation/intent vs outcome
  • 🟡 Limited page view tracking: Only the about page has view tracking. No visibility into main todo page visits, navigation patterns, or user flow.
    • SUGGESTION: Add consistent page view tracking across all routes

Overall score: 3/5

Recommendation:REQUEST CHANGES

Required changes:

  1. Add PostHog dependencies to package.json:
    "posthog-js": "^1.165.0",
    "posthog-node": "^4.3.0"
  2. Remove unused lib/posthog-server.ts or implement actual server-side tracking
  3. Remove or verify the defaults: '2025-05-24' configuration option in instrumentation-client.ts

Recommended improvements:

  • Implement posthog.identify() for user identification when authentication is added
  • Add automatic pageview capture or extend manual tracking to all pages
  • Consider removing todo_form_submitted event as it overlaps with todo_created
  • Create .env.example with placeholder values instead of committing actual API keys

@posthog-contributions-bot
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This issue has 3216 words at 5 comments. Issues this long are hard to read or contribute to, and tend to take very long to reach a conclusion. Instead, why not:

  1. Write some code and submit a pull request! Code wins arguments
  2. Have a sync meeting to reach a conclusion
  3. Create a Request for Comments and submit a PR with it to the meta repo or product internal repo

Is this issue intended to be sprawling? Consider adding label epic or sprint to indicate this.

@edwinyjlim
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edwinyjlim commented Dec 7, 2025

Now I have a complete picture. Let me provide the evaluation:


PR Evaluation Report

Summary

This PR adds PostHog analytics integration to a Next.js 15 App Router todo application. It implements client-side tracking via instrumentation-client.ts, configures a reverse proxy, creates a server-side PostHog client, and tracks various todo-related events (create, complete, delete, errors) along with an about page view. However, critical dependency installation is missing - neither posthog-js nor posthog-node are in package.json.

Files Changed Lines Added Lines Removed
8 +151 -0

Overall confidence score: 2/5 ❌

Required changes:

  • Add posthog-js and posthog-node to package.json dependencies - without these, the app will fail at runtime with import errors
  • Add NEXT_PUBLIC_POSTHOG_KEY and NEXT_PUBLIC_POSTHOG_HOST to .env.example or documentation so developers know which environment variables are required
  • Fix inconsistent host configuration - server client uses NEXT_PUBLIC_POSTHOG_HOST env var but client uses hardcoded /ingest

Recommended improvements:

  • Add posthog.identify() calls for user identification (currently no user association)
  • Consider adding automatic pageview tracking via capture_pageview: true option instead of manual page trackers
  • The posthog-server.ts is created but never used anywhere in the codebase

Important Files Changed

Filename Score Description Captured events
package.json 1/5 Missing PostHog dependencies - neither posthog-js nor posthog-node added N/A
instrumentation-client.ts 3/5 PostHog client initialization with proxy and exception capture N/A (init only)
next.config.ts 5/5 Correctly configured reverse proxy rewrites for adblock bypass N/A
components/todos/todo-list.tsx 4/5 Good event tracking for CRUD operations with properties todo_created, todo_completed, todo_uncompleted, todo_deleted, todo_fetch_failed, todo_create_failed, todo_update_failed, todo_delete_failed
components/todos/todo-form.tsx 4/5 Form submission tracking with useful properties todo_form_submitted
components/about/about-page-tracker.tsx 3/5 Manual page view with React Strict Mode protection about_page_viewed
lib/posthog-server.ts 2/5 Server client setup but never used in codebase N/A
.posthog-events.json 4/5 Good documentation of events N/A

PostHog Integration: 2/5

Criteria Result
PostHog SDKs Installed Neither posthog-js nor posthog-node in package.json
Events Tracked: todo_created, todo_completed, todo_uncompleted, todo_deleted, todo_form_submitted, about_page_viewed, todo_fetch_failed, todo_create_failed, todo_update_failed, todo_delete_failed
Error Tracking: ✅ Configured (capture_exceptions: true + captureException() calls)
Reverse Proxy: ✅ Configured correctly in next.config.ts

Issues

  • [CRITICAL] Missing PostHog dependencies: posthog-js and posthog-node are not in package.json. The app will crash with Cannot find module 'posthog-js' errors. SUGGESTION: Run npm install posthog-js posthog-node and commit the updated package.json
  • [CRITICAL] Missing environment variable documentation: NEXT_PUBLIC_POSTHOG_KEY and NEXT_PUBLIC_POSTHOG_HOST are required but not documented
    • SUGGESTION: Add .env.example file or update README with required environment variables
  • [MEDIUM] Server client unused: lib/posthog-server.ts creates a PostHog Node client but it's never imported or used anywhere
    • SUGGESTION: Either use it for server-side analytics or remove it to avoid dead code
  • 🟠 No user identification: No posthog.identify() calls to associate events with users
    • SUGGESTION: Add identify calls when user session is established
  • 🟡 Inconsistent host configuration: Client uses hardcoded ui_host: 'https://us.posthog.com' while server uses NEXT_PUBLIC_POSTHOG_HOST env var
    • SUGGESTION: Use consistent configuration approach

Other completed criteria

#### Other completed criteria
  • Correct instrumentation-client.ts pattern for Next.js 15
  • Events enriched with relevant properties (todo_id, error_message, has_description, etc.)
  • Exception capture properly configured
  • Reverse proxy with skipTrailingSlashRedirect for trailing slash support
  • Events documented in .posthog-events.json

Code quality: 3/5

Criteria Result
App runs ❌ No - missing dependencies will cause runtime failures
Preserves existing code ✅ Yes - existing logic unchanged, only additions
Minimal changes ✅ Yes - focused PostHog additions only

Issues

  • 🔴 App will not build/run: Missing npm dependencies means immediate failure
    • SUGGESTION: Add dependencies to package.json
  • 🟠 Dead code: posthog-server.ts is unused
    • SUGGESTION: Remove or implement server-side tracking
  • 🟡 Non-null assertion on env var: process.env.NEXT_PUBLIC_POSTHOG_KEY! will throw unclear errors if not set
    • SUGGESTION: Add runtime validation or provide clearer error messages

Quality of PostHog insights: 4/5

Insights Enabled Description
Todo Conversion Funnel Track form submission → todo creation success rate to measure friction
Task Completion Rate Analyze todo_completed vs todo_created to understand user engagement
Error Impact Analysis All failure events captured with error messages enable error rate dashboards
Feature Usage Patterns has_description and title_length properties enable analysis of how users create todos
Page View Funnel About page view tracking enables awareness funnel analysis

Issues

  • 🟠 No session/user correlation: Events lack distinct_id setup, making user journey analysis impossible
    • SUGGESTION: Implement posthog.identify() with anonymous IDs at minimum
  • 🟡 Limited page tracking: Only about page is tracked manually; main todo page has no view event
    • SUGGESTION: Enable capture_pageview: true for automatic pageview tracking or add tracker to main page
  • 🟡 No time-to-complete tracking: Could track time between todo creation and completion
    • SUGGESTION: Add timestamp properties or use feature flags for cohort analysis

Sequence diagram

sequenceDiagram
    participant User
    participant Browser
    participant NextJS as Next.js App
    participant Proxy as /ingest (Reverse Proxy)
    participant PostHog as PostHog Cloud

    Note over Browser: App loads instrumentation-client.ts
    Browser->>Browser: posthog.init() with capture_exceptions: true
    
    User->>Browser: Visit About Page
    Browser->>Browser: AboutPageTracker mounts
    Browser->>Proxy: capture('about_page_viewed')
    Proxy->>PostHog: Forward to us.i.posthog.com
    
    User->>Browser: Submit Todo Form
    Browser->>Browser: capture('todo_form_submitted', {has_description, title_length})
    Browser->>NextJS: POST /api/todos
    NextJS-->>Browser: 200 OK (newTodo)
    Browser->>Proxy: capture('todo_created', {todo_id, has_description})
    Proxy->>PostHog: Forward event
    
    User->>Browser: Toggle Todo Complete
    Browser->>NextJS: PATCH /api/todos/:id
    NextJS-->>Browser: 200 OK
    Browser->>Proxy: capture('todo_completed', {todo_id})
    Proxy->>PostHog: Forward event
    
    User->>Browser: Delete Todo
    Browser->>NextJS: DELETE /api/todos/:id
    NextJS-->>Browser: 200 OK
    Browser->>Proxy: capture('todo_deleted', {todo_id})
    Proxy->>PostHog: Forward event
    
    Note over Browser,PostHog: Error Flow
    Browser->>NextJS: API Request
    NextJS-->>Browser: Error/Exception
    Browser->>Proxy: capture('todo_*_failed', {error_message})
    Browser->>Proxy: captureException(error)
    Proxy->>PostHog: Forward error events
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@edwinyjlim
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Now I have all the information needed to provide a comprehensive PR evaluation. Here's the report:


PR Evaluation Report

Summary

This PR adds PostHog analytics integration to a Next.js 15 App Router todo application. It includes client-side tracking via instrumentation-client.ts, a reverse proxy setup in next.config.ts, event tracking for CRUD operations in the todo components, and server-side PostHog client setup. However, the PostHog SDK dependencies (posthog-js and posthog-node) are missing from package.json, which will cause the build to fail.

Files Changed Lines Added Lines Removed
8 +151 -0

Confidence score: 2/5 ❌

Recommended changes and improvements (in order of most urgent):

  1. [CRITICAL] Add PostHog SDK dependencies to package.json - The PR imports posthog-js and posthog-node but neither package is listed in package.json. The app will fail to build with Module not found errors. Add:

    "posthog-js": "^1.165.0",
    "posthog-node": "^4.3.0"
  2. [CRITICAL] Invalid PostHog init option - defaults: '2025-05-24' is not a valid PostHog configuration option. This should be removed or replaced with a valid option.

  3. [MEDIUM] Missing user identification - No posthog.identify() calls are present. Users will be tracked as anonymous, limiting analytics value for user-level insights and cohort analysis.

  4. [MEDIUM] Server-side client unused - lib/posthog-server.ts is created but never used anywhere in the codebase. Either remove it or implement server-side event tracking.

  5. [LOW] Missing .env.example - While .env exists with the PostHog keys, there's no .env.example file to document required environment variables for other developers.

  6. [LOW] Duplicate form submission tracking - Both todo_form_submitted (in todo-form.tsx) and todo_created (in todo-list.tsx) fire on successful todo creation, which may cause analytics redundancy.


Important files changed

Filename Score Description
package.json 1/5 Missing PostHog dependencies - posthog-js and posthog-node imports will fail
instrumentation-client.ts 2/5 PostHog init with invalid defaults option; otherwise correct pattern for Next.js 15
next.config.ts 4/5 Correct reverse proxy setup for ad-blocker circumvention
components/todos/todo-list.tsx 4/5 Good CRUD event tracking with error capture
components/todos/todo-form.tsx 4/5 Form submission tracking with useful properties
components/about/about-page-tracker.tsx 4/5 Page view tracking with proper deduplication via useRef
lib/posthog-server.ts 2/5 Created but unused; dead code
.posthog-events.json 4/5 Good event documentation with descriptions

App sanity check

Criteria Result
App builds and runs ❌ No - Build will fail due to missing posthog-js and posthog-node dependencies
Preserves existing env vars & configs ✅ Yes - Existing code preserved, PostHog env vars added to .env
No syntax or type errors ❌ No - Invalid PostHog config option defaults: '2025-05-24' will cause TypeScript error
Correct imports/exports ✅ Yes - Import statements are syntactically correct (but dependencies missing)
Minimal, focused changes ✅ Yes - Changes are focused on PostHog integration only

Issues

  • [CRITICAL] Missing npm dependencies: posthog-js and posthog-node are imported but not in package.json. Build will fail with Module not found: Can't resolve 'posthog-js'.
  • [CRITICAL] Invalid configuration option: defaults: '2025-05-24' in instrumentation-client.ts is not a valid PostHog init option and will cause TypeScript errors.
  • [MEDIUM] Unused server-side code: lib/posthog-server.ts creates a PostHog Node client but is never imported or used anywhere.

Other completed criteria

  • Environment variables documented in .env file
  • No PII captured in event properties
  • Consistent event naming convention (snake_case)
  • Error messages captured without stack traces

PostHog Integration: 2/5

Criteria Result
PostHog SDKs installed ❌ Not installed - missing from package.json
PostHog client initialized ⚠️ Partially - Uses instrumentation-client.ts (Next.js 15 pattern) but has invalid config option
capture(): ✅ Configured - 10 events tracked across components
identify(): ❌ Not configured - No user identification implemented
Error tracking: ✅ Configured - capture_exceptions: true and posthog.captureException() calls
Reverse proxy: ✅ Configured - Correct rewrites in next.config.ts for /ingest/*

Issues

  • [CRITICAL] Missing dependencies: The integration imports posthog-js and posthog-node but neither is added to package.json. The app cannot build.
  • [CRITICAL] Invalid init config: The defaults: '2025-05-24' option is not a valid PostHog configuration parameter.
  • [MEDIUM] No user identification: Without posthog.identify(), all events are attributed to anonymous users, limiting cohort analysis and user journey tracking.
  • [MEDIUM] Dead server code: lib/posthog-server.ts exports getPostHogClient() and shutdownPostHog() but they're never called.

Other completed criteria

  • Reverse proxy correctly routes /ingest/* to us.i.posthog.com
  • Static assets proxy configured for /ingest/static/*
  • skipTrailingSlashRedirect: true added for PostHog compatibility
  • ui_host correctly set to https://us.posthog.com
  • Debug mode enabled for development environment
  • Exception capture enabled globally

Quality of PostHog insights: 4/5

Filename Captured events Description
todo-list.tsx todo_created, todo_completed, todo_uncompleted, todo_deleted, todo_fetch_failed, todo_create_failed, todo_update_failed, todo_delete_failed + captureException Comprehensive CRUD tracking with success/failure states; enables funnel analysis for todo completion rates
todo-form.tsx todo_form_submitted Form submission with has_description, title_length, description_length properties for input analysis
about-page-tracker.tsx about_page_viewed Page view tracking with deduplication; useful for awareness funnel

Issues

  • [LOW] Redundant event tracking: todo_form_submitted and todo_created both fire on successful todo creation. Consider tracking only one or differentiating their purposes (intent vs. success).
  • [LOW] Missing page view for main page: Only the About page has explicit tracking. The main todo list page has no $pageview equivalent.

Other completed criteria

  • Events capture meaningful user actions (create, complete, delete todos)
  • Error events include error_message property for debugging
  • todo_id included for correlation across events
  • Boolean properties (has_description) enable segmentation
  • Numeric properties (title_length) enable distribution analysis
  • Separate events for todo_completed vs todo_uncompleted enable completion rate analysis
  • .posthog-events.json documents all events with descriptions for team reference

Reviewed by wizard workbench PR evaluator

@edwinyjlim
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Now I have all the information needed to provide a comprehensive evaluation. Here is my PR review:


PR Evaluation Report

Summary

This PR adds PostHog analytics integration to a Next.js 15 App Router todo application. It implements client-side tracking via instrumentation-client.ts, sets up a reverse proxy via Next.js rewrites, creates a server-side PostHog client utility, and adds event tracking for all CRUD operations on todos plus page view tracking for the about page.

Files Changed Lines Added Lines Removed
8 +151 -0

Confidence score: 2/5 ❌

Top recommended changes:

  • Missing PostHog SDK dependencies: posthog-js and posthog-node are not added to package.json. The app will fail to build/run. [CRITICAL]
  • No user identification: posthog.identify() is never called, making all events anonymous and reducing analytics value significantly. [MEDIUM]
  • Server-side client created but never used: lib/posthog-server.ts exports utilities that are never imported anywhere. [MEDIUM]

Important files changed

Filename Score Description
package.json 1/5 Missing critical PostHog dependencies - posthog-js and posthog-node packages are not installed
instrumentation-client.ts 3/5 Client init with correct proxy config, but uses non-existent defaults option
next.config.ts 5/5 Correctly configured reverse proxy rewrites for PostHog
components/todos/todo-list.tsx 4/5 Good event tracking for CRUD operations with error handling
components/todos/todo-form.tsx 4/5 Form submission tracking with useful properties
components/about/about-page-tracker.tsx 4/5 Page view tracking with proper deduplication
lib/posthog-server.ts 2/5 Server client setup is correct but never used in the codebase
.posthog-events.json 4/5 Good documentation of tracked events

App sanity check

Criteria Result
App builds and runs No - Missing posthog-js and posthog-node dependencies will cause build failure
Preserves existing env vars & configs Yes - Existing configs preserved, new PostHog env vars added to .env
No syntax or type errors No - Import of posthog-js and posthog-node will fail without packages
Correct imports/exports Yes - Import statements are syntactically correct
Minimal, focused changes Yes - Only adds PostHog integration, no unnecessary modifications

Issues

  • Missing PostHog SDK packages: posthog-js and posthog-node must be added to package.json dependencies. Without these, import posthog from 'posthog-js' will fail and the app won't build. [CRITICAL]
  • Invalid defaults option: In instrumentation-client.ts, defaults: '2025-05-24' is not a valid PostHog configuration option. This may cause warnings or errors. [MEDIUM]
  • Unused server-side client: lib/posthog-server.ts creates a server-side PostHog client but it's never imported or used anywhere. [LOW]

Other completed criteria

  • Existing app logic preserved intact
  • New files follow existing project patterns
  • TypeScript types are appropriate
  • No PII captured in events

PostHog Integration: 2/5

Criteria Result
PostHog SDKs installed No - posthog-js and posthog-node not in package.json
PostHog client initialized Partial - instrumentation-client.ts has init code but uses invalid defaults option
capture() Yes - Multiple capture calls for todo CRUD and page views
identify() No - No user identification implemented
Error tracking Yes - capture_exceptions: true and posthog.captureException() calls
Reverse proxy Yes - Correctly configured in next.config.ts with /ingest rewrites

Issues

  • Missing SDK installation: Add to package.json: "posthog-js": "^1.x.x" and "posthog-node": "^4.x.x". [CRITICAL]
  • No user identification: Add posthog.identify(userId) when user context is available to link events to users. [MEDIUM]
  • Invalid defaults option: Remove defaults: '2025-05-24' from init config or replace with valid options like persistence: 'localStorage'. [MEDIUM]
  • Server client unused: Either implement server-side tracking or remove lib/posthog-server.ts to avoid dead code. [LOW]

Other completed criteria

  • API host points to reverse proxy (/ingest)
  • UI host correctly set to https://us.posthog.com
  • Debug mode enabled in development
  • Exception capture enabled
  • Environment variables documented in .env
  • Proper error message extraction in catch blocks

Quality of PostHog insights: 4/5

Filename Captured events Description
todo-list.tsx todo_created, todo_completed, todo_uncompleted, todo_deleted, todo_fetch_failed, todo_create_failed, todo_update_failed, todo_delete_failed + captureException Comprehensive CRUD tracking with success/failure states, enables funnel analysis and error monitoring
todo-form.tsx todo_form_submitted Tracks form submissions with useful properties (has_description, title_length)
about-page-tracker.tsx about_page_viewed Page view tracking with deduplication via ref

Issues

  • Missing automatic pageview tracking: Consider enabling capture_pageview: true or implementing pageviews for all routes, not just the about page. [MEDIUM]
  • No session recording setup: Consider adding enable_recording_console_log or session replay for debugging. [LOW]

Other completed criteria

  • Events follow consistent snake_case naming convention
  • Events are enriched with contextual properties (todo_id, error_message, has_description, title_length)
  • Error events paired with captureException for full error context
  • Events map to real user actions (create, complete, delete)
  • Events enable funnel analysis (form_submitted → created vs created_failed)
  • Event documentation in .posthog-events.json provides good discoverability

Reviewed by wizard workbench PR evaluator

@edwinyjlim
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Member Author

Now I have all the information needed to evaluate this PR. Let me compile the review:


PR Evaluation Report

Summary

This PR adds PostHog analytics integration to a Next.js 15 App Router todo application. It includes client-side initialization via instrumentation-client.ts, a reverse proxy configuration for ad-blocker circumvention, and event tracking for todo CRUD operations and page views. A server-side PostHog client is also created but unused.

Files Changed Lines Added Lines Removed
8 +151 -0

Confidence score: 2/5 ❌

Top recommended changes:

  • Missing PostHog dependencies: posthog-js and posthog-node are not in package.json. The app will fail to build/run. [CRITICAL]
  • Server-side client unused: lib/posthog-server.ts is created but never imported or used anywhere. Remove or implement. [MEDIUM]
  • Missing posthog.identify(): No user identification is implemented, limiting analytics value. [MEDIUM]

Important files changed

Filename Score Description
instrumentation-client.ts 3/5 PostHog client initialization with reverse proxy and exception capture, but uses undocumented defaults option
next.config.ts 4/5 Proper reverse proxy rewrites for ad-blocker circumvention
components/todos/todo-list.tsx 4/5 Comprehensive CRUD event tracking with error handling
components/todos/todo-form.tsx 4/5 Form submission event with useful properties
lib/posthog-server.ts 2/5 Server client created but never used
package.json 1/5 Missing required PostHog dependencies
.posthog-events.json 4/5 Good documentation of events
components/about/about-page-tracker.tsx 4/5 Proper page view tracking with deduplication

App sanity check score: 2/5

Criteria Result Description
App builds and runs No Missing posthog-js and posthog-node dependencies will cause build failures
Preserves existing env vars & configs Yes Existing .env preserved, new PostHog vars added
No syntax or type errors No Import errors due to missing dependencies
Correct imports/exports Partial Imports are syntactically correct but will fail at runtime
Minimal, focused changes Yes Changes are focused on PostHog integration

Issues

  • Missing PostHog dependencies: package.json does not include posthog-js or posthog-node. The application will fail to build with "Cannot find module 'posthog-js'" errors. Add both packages: npm install posthog-js posthog-node. [CRITICAL]
  • Unused server-side client: lib/posthog-server.ts creates a server-side PostHog client that is never imported or used anywhere in the codebase. Either implement server-side analytics or remove the file. [MEDIUM]
  • Environment variable in .env: The PostHog API key is committed in .env file. Consider using .env.example with placeholder values and adding .env to .gitignore. [LOW]

Other completed criteria

  • Consistent code patterns with existing codebase
  • Clear, readable code
  • Appropriate error handling in components
  • Environment variables documented in .env

PostHog implementation score: 3/5

Criteria Result Description
PostHog SDKs installed No Neither posthog-js nor posthog-node are in package.json
PostHog client initialized Partial instrumentation-client.ts initializes client correctly but uses undocumented defaults: '2025-05-24' option
capture() Yes Multiple events captured: todo_created, todo_completed, todo_deleted, etc.
identify() No No posthog.identify() calls for user identification
Error tracking Yes captureException() used in all error handlers with capture_exceptions: true in init
Reverse proxy Yes Proper /ingest rewrites in next.config.ts with skipTrailingSlashRedirect

Issues

  • Missing posthog-js dependency: The package is not installed. Run npm install posthog-js. [CRITICAL]
  • Missing posthog-node dependency: The package is not installed. Run npm install posthog-node. [CRITICAL]
  • No posthog.identify() implementation: User identification is missing, which limits the ability to track user journeys and build cohorts. Add posthog.identify(userId) when users are authenticated. [MEDIUM]
  • Undocumented defaults option: instrumentation-client.ts uses defaults: '2025-05-24' which is not a documented PostHog option. This may cause unexpected behavior or be ignored. [MEDIUM]
  • Server client inconsistent host config: lib/posthog-server.ts uses process.env.NEXT_PUBLIC_POSTHOG_HOST directly while client uses /ingest proxy. Server should use the direct PostHog host. [LOW]

Other completed criteria

  • Correct API host configuration via reverse proxy
  • capture_exceptions: true enabled for automatic error tracking
  • Debug mode enabled in development
  • ui_host correctly set for US region
  • Proper deduplication in AboutPageTracker using useRef
  • No PII in event properties

PostHog insights score: 4/5

Filename PostHog events Description
todo-list.tsx todo_created, todo_completed, todo_uncompleted, todo_deleted, todo_fetch_failed, todo_create_failed, todo_update_failed, todo_delete_failed Comprehensive CRUD tracking with error states. Enables funnel analysis for todo lifecycle and error rate monitoring.
todo-form.tsx todo_form_submitted Form submission with has_description, title_length, description_length properties. Enables analysis of user input patterns.
about-page-tracker.tsx about_page_viewed Page view tracking for awareness funnel analysis.

Issues

  • Duplicate form submission tracking: Both todo_form_submitted and todo_created fire on successful todo creation. Consider removing todo_form_submitted or making it capture intent regardless of success. [LOW]
  • Missing automatic pageview tracking: No capture_pageview option set in init. Relies on custom about_page_viewed event only. Consider enabling automatic pageviews or adding manual tracking to all pages. [MEDIUM]
  • No session replay or feature flag setup: Could enhance analytics with session replay for debugging user flows. [LOW]

Other completed criteria

  • Events enriched with relevant properties (todo_id, has_description, title_length, etc.)
  • Error events include error_message for debugging
  • Events represent real user actions (create, complete, delete)
  • Success/failure states tracked separately
  • .posthog-events.json provides good documentation for all events

Reviewed by wizard workbench PR evaluator

@edwinyjlim
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Member Author

Now I have all the information needed to evaluate this PR. Let me compile my review:


PR Evaluation Report

Summary

This PR adds PostHog analytics integration to a Next.js 15 App Router todo application. It implements client-side tracking via instrumentation-client.ts, configures a reverse proxy through Next.js rewrites, and adds event capture for todo CRUD operations, form submissions, error tracking, and page views.

Files changed Lines added Lines removed
8 +151 -0

Confidence score: 2/5 ❌

  • Missing PostHog dependencies in package.json: Neither posthog-js nor posthog-node are listed in dependencies. The app will fail to build/run. [CRITICAL]
  • Server-side PostHog client is unused: lib/posthog-server.ts creates a server-side PostHog client but it's never imported or used anywhere in the codebase. [MEDIUM]
  • No posthog.identify() implementation: User identification is completely missing, limiting analytics value. [MEDIUM]

Files changed

Filename Score Description
.posthog-events.json 4/5 Well-structured event documentation with names, descriptions, and file paths. Good reference for the integration.
app/about/page.tsx 4/5 Cleanly adds the tracker component without disrupting existing code.
components/about/about-page-tracker.tsx 4/5 Proper client component with useRef to prevent duplicate tracking on re-renders.
components/todos/todo-form.tsx 4/5 Good event capture with relevant properties (has_description, title_length).
components/todos/todo-list.tsx 4/5 Comprehensive CRUD event tracking with error capture via captureException().
instrumentation-client.ts 3/5 Correct Next.js 15 initialization pattern, but uses defaults: '2025-05-24' which may not be a valid config option.
lib/posthog-server.ts 2/5 Dead code - server client is never used. Uses flushAt: 1 and flushInterval: 0 which is inefficient for production.
next.config.ts 5/5 Correct reverse proxy configuration for ad-blocker circumvention with proper trailing slash handling.

App sanity check score: 2/5 ❌

Criteria Result Description
App builds and runs No Missing posthog-js and posthog-node in package.json dependencies will cause build/runtime failures
Preserves existing env vars & configs Yes Adds new env vars without modifying existing ones
No syntax or type errors Yes TypeScript syntax is correct
Correct imports/exports Yes All imports use correct paths and posthog-js API
Minimal, focused changes No lib/posthog-server.ts is unused dead code

Issues

  • Missing PostHog dependencies: posthog-js and posthog-node are not in package.json. App will fail with "Cannot find module" errors. Add both packages to dependencies. [CRITICAL]
  • Unused server-side module: lib/posthog-server.ts is created but never imported anywhere. Either remove it or integrate it for server-side analytics. [MEDIUM]
  • Environment variables in committed .env: The .env file contains an API key (sTMFPsFhdP1Ssg). Should use .env.example with placeholder values instead. [LOW]

Other completed criteria

  • Clean, readable code with proper TypeScript typing
  • Consistent with existing codebase patterns
  • Proper error handling with try/catch blocks
  • No syntax errors in any file

PostHog implementation score: 3/5 ⚠️

Criteria Result Description
PostHog SDKs installed No Neither posthog-js nor posthog-node appear in package.json dependencies
PostHog client initialized Yes Client initialized in instrumentation-client.ts using Next.js 15 instrumentation pattern with api_host pointing to reverse proxy
capture() Yes Events captured for all CRUD operations, form submission, page view, and errors
Identify() No No user identification implemented anywhere
Error tracking Yes Uses posthog.captureException(error) in all catch blocks plus capture_exceptions: true in init
Reverse proxy Yes Properly configured via Next.js rewrites to /ingest/*us.i.posthog.com with static asset handling

Issues

  • Missing NPM dependencies: posthog-js and posthog-node must be added to package.json for the integration to work. [CRITICAL]
  • No user identification: posthog.identify() is not called anywhere. User sessions won't be linked across devices or to user accounts. Add identification after authentication. [MEDIUM]
  • Suspicious defaults config option: defaults: '2025-05-24' in init is not a standard PostHog config option. May be ignored or cause issues. [LOW]
  • Server client configured but unused: lib/posthog-server.ts creates a PostHog Node client but it's never used for server-side tracking. [LOW]

Other completed criteria

  • Uses correct US region endpoints (us.i.posthog.com, us-assets.i.posthog.com)
  • Debug mode enabled only in development
  • Proper skipTrailingSlashRedirect for PostHog API compatibility
  • Uses environment variables for API key configuration
  • No PII in event properties (only has todo_id, lengths, error messages)

PostHog insights score: 4/5 ✅

Filename PostHog events Description
todo-list.tsx todo_created, todo_completed, todo_uncompleted, todo_deleted Core product engagement metrics for todo lifecycle - enables funnel analysis and completion rates
todo-list.tsx todo_fetch_failed, todo_create_failed, todo_update_failed, todo_delete_failed Error tracking events with error messages - enables reliability monitoring and debugging
todo-list.tsx captureException Exception capture for all CRUD failures - provides stack traces for debugging
todo-form.tsx todo_form_submitted Form submission with has_description, title_length, description_length - enables analysis of user input patterns
about-page-tracker.tsx about_page_viewed Page view tracking - enables awareness funnel analysis

Issues

  • No automatic pageview tracking: Only about_page_viewed is manually tracked. Consider enabling capture_pageview: true or implementing a pageview capture in the layout for comprehensive navigation analytics. [MEDIUM]
  • Limited property enrichment on success events: todo_completed and todo_deleted only capture todo_id. Could include more context like time_since_creation for completion analysis. [LOW]

Other completed criteria

  • Events capture real user actions (create, complete, delete todos)
  • Error events include error messages for debugging
  • Success events include relevant properties (todo_id, has_description, title_length)
  • Events documented in .posthog-events.json for reference
  • Events enable key product questions: "What % of todos get completed?", "How often do users add descriptions?", "What errors are users encountering?"

Reviewed by wizard workbench PR evaluator

@edwinyjlim
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Member Author

Now I have all the information needed to write the PR evaluation. Let me produce the comprehensive review:


PR Evaluation Report

Summary

This PR adds PostHog analytics integration to a Next.js 15 App Router todo application. It implements client-side initialization via instrumentation-client.ts, adds event tracking for all CRUD operations on todos, captures page views on the About page, sets up a reverse proxy to avoid ad blockers, and creates a server-side PostHog client (though unused). The implementation captures both success and error events with appropriate context.

Files changed Lines added Lines removed
8 +151 -0

Confidence score: 3/5 🤔

  • PostHog SDK packages not added to dependencies: posthog-js and posthog-node are imported but not listed in package.json. The app will fail to build/run. [CRITICAL]
  • Server-side PostHog client is unused: lib/posthog-server.ts creates a server-side client that is never used anywhere in the application. Dead code that adds complexity. [MEDIUM]
  • No user identification implemented: posthog.identify() is never called, so all events are captured anonymously without linking to user sessions. [MEDIUM]

File changes

Filename Score Description
.posthog-events.json 4/5 Well-structured event documentation listing 10 events with names, descriptions, and file paths. Good for maintainability.
app/about/page.tsx 4/5 Clean integration of tracker component at top of page. Minimal change.
components/about/about-page-tracker.tsx 4/5 Properly implements a client-side page view tracker using useRef to prevent duplicate tracking in React Strict Mode.
components/todos/todo-form.tsx 4/5 Adds form submission tracking with useful properties (has_description, title_length, description_length).
components/todos/todo-list.tsx 4/5 Comprehensive tracking of all CRUD operations with success/failure events. Uses captureException for error tracking. Good error context.
instrumentation-client.ts 3/5 Correct Next.js 15 pattern for client instrumentation. Uses defaults: '2025-05-24' which is nonstandard (should be persistence). Missing capture_pageview: true for automatic pageviews.
lib/posthog-server.ts 2/5 Creates a singleton server-side client but it's never imported or used. flushAt: 1 and flushInterval: 0 are overly aggressive settings.
next.config.ts 5/5 Properly configured reverse proxy for PostHog to bypass ad blockers. Includes required skipTrailingSlashRedirect.

App sanity check: 2/5 ❌

Criteria Result Description
App builds and runs No Missing posthog-js and posthog-node in dependencies will cause build failure
Preserves existing env vars & configs Yes Added .env with PostHog keys without removing existing config
No syntax or type errors Yes All TypeScript code is syntactically correct
Correct imports/exports Yes All imports use correct paths and named exports
Minimal, focused changes No lib/posthog-server.ts is unused dead code

Issues

  • Missing PostHog SDK dependencies: posthog-js and posthog-node are imported but not listed in package.json. Add them: "posthog-js": "^1.x.x" and "posthog-node": "^4.x.x". [CRITICAL]
  • Unused server-side client: lib/posthog-server.ts is never imported anywhere. Either use it for server-side events or remove it. [MEDIUM]
  • Environment variables documented in .env but not .env.example: The .env file contains actual keys. Should use .env.example with placeholder values for documentation. [LOW]

Other completed criteria

  • Existing app code preserved (todo functionality unchanged)
  • Import statements follow existing patterns
  • New components follow existing file structure conventions
  • No breaking changes to existing API or component interfaces

PostHog implementation: 3/5 ⚠️

Criteria Result Description
PostHog SDKs installed No Packages imported but not in package.json dependencies
PostHog client initialized Yes Uses instrumentation-client.ts with posthog.init(), api_host pointing to reverse proxy
capture() Yes 10 events tracked across todo CRUD and page views
identify() No No user identification implemented
Error tracking Yes Uses posthog.captureException() for caught errors plus capture_exceptions: true in config
Reverse proxy Yes Properly configured in next.config.ts with /ingest route to us.i.posthog.com

Issues

  • Missing SDK packages in dependencies: Without adding posthog-js and posthog-node to package.json, the app will fail to build. [CRITICAL]
  • No posthog.identify() calls: User sessions are anonymous. Add identification when user context is available (e.g., after authentication or using distinct_id). [MEDIUM]
  • Nonstandard defaults option: defaults: '2025-05-24' is not a valid PostHog init option. This may be ignored or cause unexpected behavior. Consider removing or using valid options like persistence. [MEDIUM]
  • No automatic pageview capture: Missing capture_pageview: true in init options. Currently only the About page tracks views explicitly. [LOW]

Other completed criteria

  • Correct API host configuration using reverse proxy (/ingest)
  • UI host configured separately (ui_host: 'https://us.posthog.com')
  • Debug mode enabled in development
  • Exception auto-capture enabled
  • skipTrailingSlashRedirect: true set for PostHog API compatibility
  • Proper cleanup pattern using useRef to prevent duplicate event firing

PostHog insights and events: 4/5 ✅

Filename PostHog events Description
todo-list.tsx todo_created, todo_completed, todo_uncompleted, todo_deleted, todo_fetch_failed, todo_create_failed, todo_update_failed, todo_delete_failed Full CRUD lifecycle with success/failure tracking. Includes todo_id, error_message, and contextual properties. Enables funnel analysis (create → complete → delete) and error rate monitoring.
todo-form.tsx todo_form_submitted Captures form submission intent with has_description, title_length, description_length. Useful for understanding user input patterns.
about-page-tracker.tsx about_page_viewed Tracks About page engagement. Useful for awareness funnel.

Issues

  • Duplicate event for todo creation: Both todo_form_submitted (in form) and todo_created (in list) fire when creating a todo. This is intentional (form submission vs. API success) but may cause confusion in analysis. [LOW]
  • No session/user context: Events lack user identifiers, making cohort analysis and user journey tracking impossible. [MEDIUM]

Other completed criteria

  • Events represent real user actions (create, complete, delete todos)
  • Error events capture actionable context (error_message, todo_id)
  • Properties are non-PII safe (lengths, booleans, IDs)
  • Event naming follows snake_case convention consistently
  • Success and failure states tracked separately for operational insights
  • Events enable building insights: completion rate, error rate, user engagement

Reviewed by wizard workbench PR evaluator

@edwinyjlim
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Now I have all the information needed to evaluate this PR. Let me compile the evaluation report.


PR Evaluation Report

Summary

This PR adds PostHog analytics integration to a Next.js 15 todo application. It implements client-side initialization via instrumentation-client.ts, server-side client setup, reverse proxy rewrites, and event tracking for CRUD operations on todos plus page views. However, the PostHog dependencies are missing from package.json, which will cause the app to fail at build time.

Files changed Lines added Lines removed
8 +151 -0

Confidence score: 2/5 ❌

  • PostHog dependencies missing from package.json: Neither posthog-js nor posthog-node are listed in dependencies. The app will fail to build. [CRITICAL]
  • Server-side client never used: lib/posthog-server.ts creates a PostHog Node client that is never imported or called anywhere. [MEDIUM]

File changes

Filename Score Description
.posthog-events.json 4/5 New documentation file cataloging 10 tracked events with descriptions and file paths. Well-organized but notes file path inaccuracy (lists app/about/page.tsx but event is in tracker component)
app/about/page.tsx 4/5 Minimal change: imports and renders AboutPageTracker component. Clean integration
components/about/about-page-tracker.tsx 4/5 New client component for page view tracking with proper useRef guard to prevent double-firing. Returns null (no UI)
components/todos/todo-form.tsx 4/5 Adds todo_form_submitted event with useful properties (has_description, title_length, description_length). Clean integration
components/todos/todo-list.tsx 4/5 Adds comprehensive event tracking for all CRUD operations (create, complete, uncomplete, delete) plus error tracking with captureException. Well-implemented
instrumentation-client.ts 3/5 Client-side PostHog initialization with proxy host, exception capture enabled. Uses defaults: '2025-05-24' which is a valid config option
lib/posthog-server.ts 2/5 Server-side PostHog client setup but never used anywhere. Dead code
next.config.ts 5/5 Correct reverse proxy rewrites for PostHog to bypass ad blockers. Includes both static assets and API paths

App sanity check: 2/5 ❌

Criteria Result Description
App builds and runs No Missing posthog-js and posthog-node in dependencies will cause build failure
Preserves existing env vars & configs Yes No existing configs modified destructively
No syntax or type errors Yes Code syntax is valid assuming dependencies exist
Correct imports/exports Yes All imports/exports are correctly structured
Minimal, focused changes No Server-side client (posthog-server.ts) is unused dead code

Issues

  • Missing dependencies: posthog-js and posthog-node are not in package.json. Run npm install posthog-js posthog-node or add them to dependencies. [CRITICAL]
  • Dead code: lib/posthog-server.ts defines getPostHogClient() and shutdownPostHog() but neither is imported anywhere. Either remove this file or integrate server-side tracking. [MEDIUM]
  • Environment variables undocumented: NEXT_PUBLIC_POSTHOG_KEY and NEXT_PUBLIC_POSTHOG_HOST are required but not documented in README or .env.example. [LOW]

Other completed criteria

  • Existing app logic in todo-form.tsx and todo-list.tsx preserved
  • No destructive changes to existing functionality
  • TypeScript types preserved
  • Event tracking added in appropriate locations (after successful operations)

PostHog implementation: 3/5 ⚠️

Criteria Result Description
PostHog SDKs installed No posthog-js and posthog-node are imported but not in package.json dependencies
PostHog client initialized Yes Client initialized in instrumentation-client.ts using Next.js 15 instrumentation pattern with /ingest proxy host
capture() Yes Multiple posthog.capture() calls for user actions (form submit, CRUD operations)
identify() No No user identification implemented
Error tracking Yes posthog.captureException(error) called on all catch blocks, capture_exceptions: true in init config
Reverse proxy Yes Correct rewrites in next.config.ts for /ingest to us.i.posthog.com and static assets

Issues

  • PostHog packages not installed: Dependencies are imported but not added to package.json. App will crash on import. [CRITICAL]
  • No user identification: posthog.identify() is never called. User analytics will be anonymous only. [MEDIUM]
  • Server-side client unused: posthog-node client configured but never utilized for server-side event tracking. [MEDIUM]

Other completed criteria

  • Uses instrumentation-client.ts which is the correct Next.js 15 pattern
  • ui_host correctly set to https://us.posthog.com
  • Debug mode enabled in development
  • Reverse proxy includes both API and static asset paths
  • skipTrailingSlashRedirect: true correctly set for PostHog compatibility
  • Exception capture enabled via capture_exceptions: true
  • Uses useRef guard in AboutPageTracker to prevent React Strict Mode double-fire

PostHog insights and events: 4/5 ✅

Filename PostHog events Description
todo-form.tsx todo_form_submitted Captures form submission with properties: has_description, title_length, description_length. Useful for understanding input behavior
todo-list.tsx todo_created, todo_completed, todo_uncompleted, todo_deleted Full CRUD lifecycle tracking with todo_id property. Enables funnel analysis
todo-list.tsx todo_fetch_failed, todo_create_failed, todo_update_failed, todo_delete_failed Error events with error_message property plus captureException for stack traces. Good error monitoring
about-page-tracker.tsx about_page_viewed Page view tracking for navigation analytics

Issues

  • No page view on main page: The home/todo list page doesn't track page views, only the About page does. [LOW]
  • Missing funnel completion context: Events like todo_completed don't include time-based properties (e.g., time since creation) that would enable richer funnel analysis. [LOW]

Other completed criteria

  • Events represent real user actions (create, complete, delete todos)
  • Error events capture failure context with error messages
  • Event properties are relevant and non-PII (lengths, booleans, IDs)
  • Events documented in .posthog-events.json for team reference
  • Both success and failure paths are tracked
  • captureException used for full error stack traces

Reviewed by wizard workbench PR evaluator

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