From 2a2224b26760d4b4a92d2bad14ad66cd0f6d909b Mon Sep 17 00:00:00 2001
From: aliferous3 <noamanm19@gmail.com>
Date: Wed, 30 Sep 2026 02:42:41 +0400
Subject: [PATCH] fix: beacon-transport login_start so the event survives OAuth
 navigation

The GitHub login button immediately navigates to /api/auth/login; a
batched gtag send races the unload and can drop login_start.
transport_type:'beacon' is a gtag control field (consumed by the tag,
never sent as an event param) that flushes via sendBeacon at emit time.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>
---
 src/analytics/ga4.ts        |  2 +-
 src/analytics/ga4Model.mjs  |  7 +++++--
 src/ledger/shared.tsx       |  2 +-
 test/ga4-analytics.test.mjs | 10 ++++++++--
 4 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/src/analytics/ga4.ts b/src/analytics/ga4.ts
index b65aa88..9b1b0e7 100644
--- a/src/analytics/ga4.ts
+++ b/src/analytics/ga4.ts
@@ -41,7 +41,7 @@ export {
 export type GA4EventName = 'login_start' | 'login' | 'select_content';
 
 export interface GA4EventProps {
-  login_start: { method: 'github' };
+  login_start: { method: 'github'; transport_type: 'beacon' };
   login: { method: 'github' };
   select_content: { content_type: 'product_cta'; item_id: string };
 }
diff --git a/src/analytics/ga4Model.mjs b/src/analytics/ga4Model.mjs
index 62492c5..93f4923 100644
--- a/src/analytics/ga4Model.mjs
+++ b/src/analytics/ga4Model.mjs
@@ -29,8 +29,11 @@
 export const GA4_EVENT_PROPERTIES = {
   // Google recommended `login` event — method only, never any identity.
   login: { method: ['github'] },
-  // Funnel step: the GitHub OAuth button was activated.
-  login_start: { method: ['github'] },
+  // Funnel step: the GitHub OAuth button was activated. transport_type is
+  // a gtag control field (consumed by the tag, never sent as an ep param)
+  // — beacon sends immediately instead of batching, so the event survives
+  // the OAuth navigation that follows the click.
+  login_start: { method: ['github'], transport_type: ['beacon'] },
   // Google recommended `select_content` — used for the blog/product CTA.
   // item_id carries a slug-like identifier only (validated below).
   select_content: { content_type: ['product_cta'], item_id: null },
diff --git a/src/ledger/shared.tsx b/src/ledger/shared.tsx
index c0d1c64..98df053 100644
--- a/src/ledger/shared.tsx
+++ b/src/ledger/shared.tsx
@@ -43,7 +43,7 @@ export function GithubButton({ large = false, onLogin, remember = false }: { lar
     // pending flag lets the post-callback boot emit login_succeeded once.
     markLoginPending();
     captureEvent('github_login_started', {});
-    captureGoogleEvent('login_start', { method: 'github' });
+    captureGoogleEvent('login_start', { method: 'github', transport_type: 'beacon' });
     window.location.assign(remember ? '/api/auth/login?remember=1' : '/api/auth/login');
   };
   return (
diff --git a/test/ga4-analytics.test.mjs b/test/ga4-analytics.test.mjs
index 6966ea8..f359be8 100644
--- a/test/ga4-analytics.test.mjs
+++ b/test/ga4-analytics.test.mjs
@@ -177,7 +177,13 @@ test('GA4 event set is exactly the acquisition funnel', () => {
 
 test('login events carry method:github only — never identity', () => {
   assert.deepEqual(validateGA4Event('login', { method: 'github' }), { method: 'github' });
-  assert.deepEqual(validateGA4Event('login_start', { method: 'github' }), { method: 'github' });
+  assert.deepEqual(
+    validateGA4Event('login_start', { method: 'github', transport_type: 'beacon' }),
+    { method: 'github', transport_type: 'beacon' },
+  );
+  // beacon is required — a missing it falls back to batched sends that lose
+  // the event to the OAuth navigation
+  assert.equal(validateGA4Event('login_start', { method: 'github' }), null);
   assert.equal(validateGA4Event('login', { method: 'github', user_id: 'x' }), null);
   assert.equal(validateGA4Event('login', { method: 'github', email: 'a@b.c' }), null);
   assert.equal(validateGA4Event('login', { method: 'google' }), null);
@@ -266,7 +272,7 @@ test('GA4 wiring: boot init + pageview, popstate, navigate, login events', () =>
   assert.ok((pages.match(/captureGooglePageview\(\)/g) || []).length >= 2,
     'navigate + popstate must each emit a GA4 pageview');
   const shared = src('src/ledger/shared.tsx');
-  assert.match(shared, /captureGoogleEvent\('login_start', \{ method: 'github' \}\)/);
+  assert.match(shared, /captureGoogleEvent\('login_start', \{ method: 'github', transport_type: 'beacon' \}\)/);
 });
 
 test('GA4 and PostHog are separate modules — no cross-import', () => {