[CI] (7f79337) next-js/15-pages-router-todo

[wizard-ci-bot]

Automated wizard CI run

Source: context-mill-pr
Trigger ID: 7f79337
App: next-js/15-pages-router-todo
App directory: apps/next-js/15-pages-router-todo
Workbench branch: wizard-ci-7f79337-next-js-15-pages-router-todo
Wizard branch: main
Context Mill branch: clarify-next-provider
PostHog (MCP) branch: master
Timestamp: 2026-02-12T21:00:35.666Z
Duration: 425.2s

[wizard-ci-bot]

Now I have all the information I need. Let me write my evaluation report:

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PR Evaluation Report

Summary

This PR adds PostHog analytics integration to a Next.js 15 Pages Router todo application. It includes client-side event tracking for CRUD operations, server-side error tracking in API routes, a reverse proxy configuration to bypass ad blockers, and automatic exception capture. However, the implementation has a critical issue: instrumentation-client.ts is not imported or executed anywhere, making the client-side PostHog initialization non-functional.

Files changed	Lines added	Lines removed
10	+531	-2

Confidence score: 2/5 ❌

• PostHog client never initialized: The instrumentation-client.ts file exists but is never imported. For Next.js Pages Router, PostHog must be initialized in _app.tsx or a custom component, not via instrumentation-client.ts which is an App Router feature. This means no client-side events will be captured. [CRITICAL]
• No user identification: No posthog.identify() calls exist in the codebase, making all events anonymous with no way to tie them to specific users. [MEDIUM]
• Missing pageview tracking: Without proper initialization, automatic pageviews won't be tracked. Additionally, the SPA router events are not being tracked for client-side navigation. [MEDIUM]

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File changes

Filename	Score	Description
instrumentation-client.ts	2/5	Creates PostHog client initialization with correct config, but this file is never imported in Pages Router apps. It's an App Router pattern.
lib/posthog-server.ts	4/5	Proper singleton pattern for server-side PostHog client. Missing shutdown() calls in API routes.
next.config.ts	5/5	Correct reverse proxy rewrites for PostHog ingest endpoint to bypass ad blockers.
components/todos/todo-list.tsx	3/5	Adds posthog.capture() calls for CRUD events, but since PostHog is never initialized, these will fail silently or throw errors.
pages/api/todos/index.ts	4/5	Adds server-side error tracking for todo creation failures. Good pattern but uses 'anonymous' fallback for distinctId.
pages/api/todos/[id].ts	4/5	Adds server-side error tracking for update/delete failures. Same anonymous fallback pattern.
package.json	5/5	Correctly adds posthog-js and posthog-node dependencies.
.gitignore	5/5	Correctly ignores .env.local.
pnpm-lock.yaml	5/5	Lock file updated with PostHog dependencies.
posthog-setup-report.md	4/5	Good documentation but describes a setup that won't work as implemented.

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App sanity check: 3/5 ⚠️

Criteria	Result	Description
App builds and runs	Yes	Build completes successfully with pnpm build
Preserves existing env vars & configs	Yes	Existing code preserved, new configs added
No syntax or type errors	Yes	TypeScript compilation passes
Correct imports/exports	No	instrumentation-client.ts is never imported anywhere
Minimal, focused changes	Yes	Changes are focused on PostHog integration

Issues

• PostHog client import missing: instrumentation-client.ts is not imported in _app.tsx or any other file. In Pages Router, you must import the PostHog initialization in _app.tsx to ensure it runs. The current implementation will result in posthog calls failing or using an uninitialized client. [CRITICAL]
• Missing .env.local in commit: The .env.local file is mentioned but not committed (correctly gitignored). However, no .env.example or documentation shows required env vars NEXT_PUBLIC_POSTHOG_KEY and NEXT_PUBLIC_POSTHOG_HOST. [LOW]

Other completed criteria

• App structure preserved
• No unnecessary file modifications
• Clean, readable code additions
• Consistent with existing patterns
• Appropriate error handling added

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PostHog implementation: 2/5 ❌

Criteria	Result	Description
PostHog SDKs installed	Yes	posthog-js@^1.347.0 and posthog-node@^5.24.15 added to package.json
PostHog client initialized	No	instrumentation-client.ts exists but is never imported. For Pages Router, initialization must be in _app.tsx.
capture()	Partial	Calls exist in todo-list.tsx but will fail without initialization
identify()	No	No posthog.identify() calls anywhere in the codebase
Error tracking	Partial	capture_exceptions: true set but won't work without initialization; server-side error tracking works
Reverse proxy	Yes	Correctly configured in next.config.ts with /ingest rewrites

Issues

• Client-side PostHog never runs: The instrumentation-client.ts pattern is for Next.js App Router. For Pages Router, you need to import PostHog initialization in _app.tsx:

  import '@/instrumentation-client'; // Add this import

  Or initialize directly in _app.tsx. Without this, all client-side posthog.capture() calls will fail. [CRITICAL]
• No user identification: No posthog.identify() calls exist. Users remain anonymous, limiting analytics value for user journey analysis. [MEDIUM]
• Server-side client never shutdown: shutdownPostHog() is exported but never called. In serverless environments, this can cause event loss. Consider using flushAt: 1 (already set) or ensuring flush happens. [LOW]

Other completed criteria

• API key via environment variable (not hardcoded)
• capture_exceptions: true for error tracking (when initialized)
• Debug mode in development
• Reverse proxy with correct PostHog US endpoints
• Server-side singleton pattern

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PostHog insights and events: 3/5 ⚠️

Filename	PostHog events	Description
todo-list.tsx	todo_created, todo_completed, todo_uncompleted, todo_deleted, captureException	Tracks full CRUD lifecycle with relevant properties (todo_id, has_description)
pages/api/todos/index.ts	todo_create_failed	Server-side error tracking with error message and source
pages/api/todos/[id].ts	todo_update_failed, todo_delete_failed	Server-side error tracking with todo_id, error message, and source

Issues

• Events won't fire client-side: Since PostHog is not initialized, client-side events (todo_created, todo_completed, etc.) won't actually be captured. [CRITICAL]
• No pageview tracking: Missing SPA page navigation tracking. For Pages Router, you'd want to track route changes. [MEDIUM]
• Limited event properties: Events could include more context like todo_title_length, timestamp, or session_id. [LOW]

Other completed criteria

• Events represent meaningful user actions (create, complete, delete)
• Good event naming convention (todo_* prefix)
• Server-side error events include error context
• has_description property useful for understanding user behavior
• Distinct events for completion vs uncompletion

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Reviewed by wizard workbench PR evaluator