From 2d4137073c0d71a09009ba69af80631c97efe92f Mon Sep 17 00:00:00 2001
From: Yaacov <coryacos1@gmail.com>
Date: Tue, 8 Sep 2026 19:51:48 +0300
Subject: [PATCH] Fix PostHog transport in Cloudflare Workers

---
 workers/events/src/readiness.test.ts | 14 ++++++++++++--
 workers/events/src/transport.ts      |  6 +++++-
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/workers/events/src/readiness.test.ts b/workers/events/src/readiness.test.ts
index af2c42c..975e81d 100644
--- a/workers/events/src/readiness.test.ts
+++ b/workers/events/src/readiness.test.ts
@@ -5,7 +5,7 @@ import worker, {
   pruneExpiredAnalyticsEvents,
 } from "./index";
 import { testDatabase } from "./sqlite.testSupport";
-import { posthogEventUuid, readBoundedJson } from "./transport";
+import { posthogEventUuid, posthogRequest, readBoundedJson } from "./transport";
 import { withExportLease } from "./exportLease";
 
 const installation = "installation:10000000-0000-4000-8000-000000000001";
@@ -73,6 +73,16 @@ afterEach(() => {
   for (const db of databases.splice(0)) db.close();
 });
 
+it("does not follow PostHog redirects or turn them into network failures", async () => {
+  const fetcher = vi.fn().mockResolvedValue(new Response(null, { status: 302 }));
+  vi.stubGlobal("fetch", fetcher);
+
+  await expect(
+    posthogRequest("https://eu.i.posthog.com/batch", { method: "POST" }),
+  ).rejects.toThrow("http");
+  expect(fetcher.mock.calls[0]![1].redirect).toBe("manual");
+});
+
 describe("inactive gateway readiness with real SQL", () => {
   it("keeps diagnostic events queryable in D1 without exporting them to PostHog", async () => {
     const f = fixture();
@@ -423,7 +433,7 @@ describe("inactive gateway readiness with real SQL", () => {
     expect(first.uuid).toMatch(
       /^[a-f0-9]{8}-[a-f0-9]{4}-8[a-f0-9]{3}-[89ab][a-f0-9]{3}-[a-f0-9]{12}$/,
     );
-    expect(fetcher.mock.calls[0]![1].redirect).toBe("error");
+    expect(fetcher.mock.calls[0]![1].redirect).toBe("manual");
     expect(fetcher.mock.calls[0]![1].signal).toBeInstanceOf(AbortSignal);
   });
 
diff --git a/workers/events/src/transport.ts b/workers/events/src/transport.ts
index 1a88a3b..21fe433 100644
--- a/workers/events/src/transport.ts
+++ b/workers/events/src/transport.ts
@@ -45,7 +45,11 @@ export async function posthogRequest(url: string, init: RequestInit): Promise<Re
   try {
     const response = await fetch(url, {
       ...init,
-      redirect: "error",
+      // A manual redirect response is never followed, so credentials remain
+      // scoped to the configured PostHog origin. Cloudflare's runtime rejects
+      // `redirect: "error"` as a failed subrequest before a response is
+      // available, which prevents otherwise valid exports.
+      redirect: "manual",
       signal: AbortSignal.timeout(5_000),
     });
     if (!response.ok) {