From d073065f6d91fecad3c475dbb5fbd3b5e59b44a2 Mon Sep 17 00:00:00 2001
From: Waleed Latif <walif6@gmail.com>
Date: Sat, 31 Oct 2026 22:16:08 -0700
Subject: [PATCH] fix(oauth): default a leader-lock follower's wait to the
 lease so its takeover can land

---
 apps/sim/lib/concurrency/leader-lock.test.ts | 21 ++++++++++++++++++++
 apps/sim/lib/concurrency/leader-lock.ts      |  7 +++++--
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/apps/sim/lib/concurrency/leader-lock.test.ts b/apps/sim/lib/concurrency/leader-lock.test.ts
index ce83c6e39bc..4e278f70e5b 100644
--- a/apps/sim/lib/concurrency/leader-lock.test.ts
+++ b/apps/sim/lib/concurrency/leader-lock.test.ts
@@ -136,6 +136,27 @@ describe('withLeaderLock', () => {
       expect(redisConfigMockFns.mockReleaseLock).toHaveBeenCalledOnce()
     })
 
+    it('waits out a dead leader’s lease by default before taking over', async () => {
+      /** A Redis `SET NX EX` lease on fake time: acquiring succeeds only once the holder's lapses. */
+      let leaseExpiresAt = 0
+      redisConfigMockFns.mockAcquireLock.mockImplementation(async (_key, _owner, ttlSec) => {
+        if (Date.now() < leaseExpiresAt) return false
+        leaseExpiresAt = Date.now() + ttlSec * 1000
+        return true
+      })
+      vi.useFakeTimers()
+      try {
+        leaseExpiresAt = Date.now() + 10_000
+        const onLeader = vi.fn(async () => 'took-over')
+        const result = withLeaderLock<string>({ key: 'k', onLeader, onFollower: async () => null })
+        await vi.advanceTimersByTimeAsync(10_200)
+        await expect(result).resolves.toBe('took-over')
+        expect(onLeader).toHaveBeenCalledOnce()
+      } finally {
+        vi.useRealTimers()
+      }
+    })
+
     it('returns the follower result when a live holder still has the lease', async () => {
       redisConfigMockFns.mockAcquireLock.mockResolvedValue(false)
       const onLeader = vi.fn(async () => 'should-not-run')
diff --git a/apps/sim/lib/concurrency/leader-lock.ts b/apps/sim/lib/concurrency/leader-lock.ts
index 69949ad98fa..53a29203bdb 100644
--- a/apps/sim/lib/concurrency/leader-lock.ts
+++ b/apps/sim/lib/concurrency/leader-lock.ts
@@ -8,12 +8,15 @@ const logger = createLogger('LeaderLock')
 
 const DEFAULT_TTL_SEC = 10
 const DEFAULT_POLL_INTERVAL_MS = 100
-const DEFAULT_MAX_WAIT_MS = 3_000
 
 export interface LeaderLockOptions<T> {
   key: string
   ttlSec?: number
   pollIntervalMs?: number
+  /**
+   * How long a follower polls before its takeover try. Defaults to the lease TTL so that try comes
+   * after a dead leader's lease has lapsed; a shorter wait can only take over a released lease.
+   */
   maxWaitMs?: number
   onLeader: () => Promise<T | null>
   onFollower: () => Promise<T | null>
@@ -31,7 +34,7 @@ export async function withLeaderLock<T>(opts: LeaderLockOptions<T>): Promise<T |
     key,
     ttlSec = DEFAULT_TTL_SEC,
     pollIntervalMs = DEFAULT_POLL_INTERVAL_MS,
-    maxWaitMs = DEFAULT_MAX_WAIT_MS,
+    maxWaitMs = ttlSec * 1000,
     onLeader,
     onFollower,
   } = opts