From ee7cf29f44fdd338d95f073b1e1fa88fb87dbf56 Mon Sep 17 00:00:00 2001
From: Tanner Linsley <tannerlinsley@gmail.com>
Date: Thu, 10 Sep 2026 11:28:00 -0600
Subject: [PATCH] Fix browser Crypto invocation when opening saved Builder
 projects

---
 src/utils/builder-project-sync.client.ts  |  4 +--
 tests/builder-project-sync-client.test.ts | 43 +++++++++++++++++++++++
 2 files changed, 45 insertions(+), 2 deletions(-)

diff --git a/src/utils/builder-project-sync.client.ts b/src/utils/builder-project-sync.client.ts
index f1b4a5878..3bd6ba517 100644
--- a/src/utils/builder-project-sync.client.ts
+++ b/src/utils/builder-project-sync.client.ts
@@ -495,7 +495,7 @@ export type BuilderProjectSyncCollection = ReturnType<
 
 export function getBuilderProjectBrowserSessionId({
   storage = getSessionStorage(),
-  createId = crypto.randomUUID,
+  createId = () => crypto.randomUUID(),
 }: {
   storage?: Pick<Storage, 'getItem' | 'setItem'>
   createId?: () => string
@@ -512,7 +512,7 @@ export function getBuilderProjectBrowserSessionId({
 async function claimBuilderProjectBrowserSession({
   storage = getSessionStorage(),
   lockManager = getBrowserSessionLockManager(),
-  createId = crypto.randomUUID,
+  createId = () => crypto.randomUUID(),
 }: {
   storage?: Pick<Storage, 'getItem' | 'setItem'>
   lockManager?: BuilderProjectBrowserSessionLockManager
diff --git a/tests/builder-project-sync-client.test.ts b/tests/builder-project-sync-client.test.ts
index 0d8403f58..ef3109ce4 100644
--- a/tests/builder-project-sync-client.test.ts
+++ b/tests/builder-project-sync-client.test.ts
@@ -131,6 +131,49 @@ test('Builder project browser sessions remain stable in session storage', () =>
   )
 })
 
+test('the default browser session generator preserves the Crypto receiver', (context) => {
+  const original = crypto.randomUUID
+  context.mock.method(crypto, 'randomUUID', function (this: Crypto) {
+    if (this !== crypto) throw new TypeError('Illegal invocation')
+    return original.call(this)
+  })
+  const storage = memoryStorage()
+  const id = getBuilderProjectBrowserSessionId({ storage })
+  assert.match(id, /^[a-f0-9-]{36}$/)
+  assert.equal(getBuilderProjectBrowserSessionId({ storage }), id)
+})
+
+test('saved project sync starts with the browser-native session generator', async (context) => {
+  const original = crypto.randomUUID
+  context.mock.method(crypto, 'randomUUID', function (this: Crypto) {
+    if (this !== crypto) throw new TypeError('Illegal invocation')
+    return original.call(this)
+  })
+  await withFakeIndexedDb(async () => {
+    const storage = memoryStorage()
+    const client = await createBuilderProjectSyncClient({
+      projectId,
+      sessionStorage: storage,
+      browserSessionLockManager: memoryLockManager(),
+      fetch: async () => jsonSnapshotPage(snapshot),
+      createEventSource: () => ({
+        readyState: 1,
+        addEventListener: () => undefined,
+        removeEventListener: () => undefined,
+        close: () => undefined,
+      }),
+    })
+    try {
+      assert.equal(
+        client.browserSessionId,
+        getBuilderProjectBrowserSessionId({ storage }),
+      )
+    } finally {
+      await client.cleanup()
+    }
+  })
+})
+
 test('durable project revisions enter the outbox before upload', async () => {
   await withFakeIndexedDb(async (indexedDb) => {
     const nextRevisionId = uuid(50)