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Project	Deployment	Actions	Updated (UTC)
docs	Skipped		Apr 3, 2026 8:21am

PR Summary

Low Risk
Low risk Next.js config/doc change that only affects requests under /ingest and optional analytics initialization; main app logic is unchanged.

Overview
Fixes client-side PostHog event delivery by adding Next.js rewrites to proxy /ingest/* (and /ingest/static/*) to PostHog’s US endpoints, avoiding the previous 404s when the client sent events to a local /ingest path.

Documents the optional analytics env vars in apps/sim/.env.example (NEXT_PUBLIC_POSTHOG_KEY and NEXT_PUBLIC_POSTHOG_ENABLED), including behavior when analytics is disabled.

^{Written by Cursor Bugbot for commit 14dd40c. Configure here.}

Closing — the /ingest proxy is already handled at the infrastructure level since session recordings are flowing correctly. The next.config.ts rewrite is only needed when Next.js itself needs to proxy PostHog traffic. Keeping the .env.example docs only.

Greptile Summary

This PR attempts to fix client-side PostHog event 404s by adding /ingest reverse-proxy rewrites to next.config.ts and documenting the NEXT_PUBLIC_POSTHOG_KEY / NEXT_PUBLIC_POSTHOG_ENABLED env vars in .env.example. The env var documentation is a clean, accurate improvement. However, the next.config.ts rewrite entries directly conflict with prior deliberate architecture.

• Dead-code rewrites: PR fix(posthog): replace proxy rewrite with route handler for reliable body streaming #3187 (c471627ce) explicitly replaced these exact same Next.js rewrites with a dedicated App Router Route Handler at app/ingest/[[...path]]/route.ts for "reliable body streaming." Because rewrites() returns a plain array (treated as afterFiles by Next.js), rewrites only fire when no matching filesystem route exists — and the route handler covers all /ingest/* paths, so the new rewrites will never execute.
• Risk of regression: If the route handler is ever removed (e.g., someone assumes the rewrites cover it), PostHog proxying would fall back to raw Next.js rewrites that don't strip auth cookies and don't guarantee reliable streaming of POST bodies.
• .env.example changes: Accurate and well-documented; matches actual usage in posthog-provider.tsx and lib/core/config/env.ts.

Confidence Score: 4/5

Safe to merge as-is (behavior is unchanged since the route handler wins), but the rewrites should be removed to prevent future confusion and regression risk.

The .env.example change is straightforwardly correct. The next.config.ts rewrites are currently dead code (the existing route handler handles all /ingest/* traffic first), so they don't break anything today. However, they directly contradict a deliberate prior fix (PR #3187) and create a latent regression risk if the route handler is ever removed. A P1 issue warrants a 4/5 rather than 5/5.

apps/sim/next.config.ts — the two new /ingest rewrites are redundant with app/ingest/[[...path]]/route.ts and should be removed.

Important Files Changed

Sequence Diagram

sequenceDiagram
    participant Browser
    participant NextJS as Next.js Router
    participant RH as app/ingest/[[...path]]/route.ts
    participant Rewrite as next.config.ts rewrites
    participant PH as PostHog (us.i.posthog.com)

    Browser->>NextJS: POST /ingest/decide
    Note over NextJS: Checks filesystem routes first (afterFiles)
    NextJS->>RH: Route Handler matches /ingest/[[...path]]
    Note over RH: Strips cookie & connection headers<br/>Sets Host header<br/>Streams body with duplex:'half'
    RH->>PH: Proxied request (no cookies)
    PH-->>RH: Response
    RH-->>Browser: Forwarded response

    Note over Rewrite: These rewrites never fire —<br/>shadowed by the route handler above

_{Reviews (1): Last reviewed commit: "fix(analytics): add posthog ingest proxy..." | Re-trigger Greptile}