From ab928e3fffe107eeb35bcdfd32f0a4f3775c6cf3 Mon Sep 17 00:00:00 2001
From: Waleed Latif <walif6@gmail.com>
Date: Thu, 21 May 2026 22:57:28 -0700
Subject: [PATCH 1/2] fix(oauth): follower last-chance read after poll deadline

---
 .../concurrency/__tests__/leader-lock.test.ts | 22 +++++++++++++++++++
 apps/sim/lib/concurrency/leader-lock.ts       |  4 ++++
 2 files changed, 26 insertions(+)

diff --git a/apps/sim/lib/concurrency/__tests__/leader-lock.test.ts b/apps/sim/lib/concurrency/__tests__/leader-lock.test.ts
index 8e0cbcc6cd..5153862c2e 100644
--- a/apps/sim/lib/concurrency/__tests__/leader-lock.test.ts
+++ b/apps/sim/lib/concurrency/__tests__/leader-lock.test.ts
@@ -117,6 +117,28 @@ describe('withLeaderLock', () => {
     expect(onFollower.mock.calls.length).toBeGreaterThanOrEqual(2)
   })
 
+  it('follower does a final read after timeout to catch a just-finished leader', async () => {
+    redisConfigMockFns.mockAcquireLock.mockResolvedValueOnce(false)
+
+    let polls = 0
+    const onFollower = vi.fn(async () => {
+      polls += 1
+      // Return null during the poll loop, value on the post-deadline read.
+      if (polls <= 2) return null
+      return 'late-leader'
+    })
+
+    const result = await withLeaderLock<string>({
+      key: 'k',
+      pollIntervalMs: 5,
+      maxWaitMs: 12,
+      onLeader: async () => 'should-not-run',
+      onFollower,
+    })
+
+    expect(result).toBe('late-leader')
+  })
+
   it('follower returns null after timeout', async () => {
     redisConfigMockFns.mockAcquireLock.mockResolvedValueOnce(false)
 
diff --git a/apps/sim/lib/concurrency/leader-lock.ts b/apps/sim/lib/concurrency/leader-lock.ts
index dd0ed0402a..567abd1c8a 100644
--- a/apps/sim/lib/concurrency/leader-lock.ts
+++ b/apps/sim/lib/concurrency/leader-lock.ts
@@ -64,6 +64,10 @@ export async function withLeaderLock<T>(opts: LeaderLockOptions<T>): Promise<T |
     if (value !== null) return value
   }
 
+  // The leader may have persisted between our final poll and now; one last check.
+  const lastChance = await onFollower()
+  if (lastChance !== null) return lastChance
+
   logger.warn('Follower timed out waiting for leader', { key, maxWaitMs })
   return null
 }

From f3120cf5279b032da73417ca3ee86a23d5b93434 Mon Sep 17 00:00:00 2001
From: Waleed Latif <walif6@gmail.com>
Date: Thu, 21 May 2026 23:02:38 -0700
Subject: [PATCH 2/2] test(oauth): exercise last-chance read in follower
 timeout test

---
 apps/sim/lib/concurrency/__tests__/leader-lock.test.ts | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/apps/sim/lib/concurrency/__tests__/leader-lock.test.ts b/apps/sim/lib/concurrency/__tests__/leader-lock.test.ts
index 5153862c2e..8b3e2a3a06 100644
--- a/apps/sim/lib/concurrency/__tests__/leader-lock.test.ts
+++ b/apps/sim/lib/concurrency/__tests__/leader-lock.test.ts
@@ -120,10 +120,11 @@ describe('withLeaderLock', () => {
   it('follower does a final read after timeout to catch a just-finished leader', async () => {
     redisConfigMockFns.mockAcquireLock.mockResolvedValueOnce(false)
 
+    // pollInterval=5, maxWait=9 → loop exits after 2 in-loop polls (T+5, T+10);
+    // the third call (polls=3) is the post-deadline last-chance read.
     let polls = 0
     const onFollower = vi.fn(async () => {
       polls += 1
-      // Return null during the poll loop, value on the post-deadline read.
       if (polls <= 2) return null
       return 'late-leader'
     })
@@ -131,12 +132,13 @@ describe('withLeaderLock', () => {
     const result = await withLeaderLock<string>({
       key: 'k',
       pollIntervalMs: 5,
-      maxWaitMs: 12,
+      maxWaitMs: 9,
       onLeader: async () => 'should-not-run',
       onFollower,
     })
 
     expect(result).toBe('late-leader')
+    expect(onFollower).toHaveBeenCalledTimes(3)
   })
 
   it('follower returns null after timeout', async () => {