diff --git a/src/backend/services/events/workerInvoker.integration.test.ts b/src/backend/services/events/workerInvoker.integration.test.ts
index e9fef6506..98c874bfd 100644
--- a/src/backend/services/events/workerInvoker.integration.test.ts
+++ b/src/backend/services/events/workerInvoker.integration.test.ts
@@ -39,7 +39,6 @@ import {
     describe,
     expect,
     it,
-    type MockInstance,
     vi,
 } from 'vitest';
 import {
@@ -317,14 +316,15 @@ const heldForMs = async (subId: string): Promise<number> => {
 };
 
 /**
- * Wait until `count` failed attempts have had their holds written. A future
- * score alone can't tell a hold from the in-flight claim's lease.
+ * Wait until this subscription has `count` failed attempts on record. The
+ * counter moves only after the attempt's hold or gap marker is written, so it
+ * can't be the in-flight claim's lease or another test's late attempt.
  */
-const holdsWritten = (deferred: MockInstance, count: number): Promise<void> =>
-    waitUntil(() =>
-        expect(
-            deferred.mock.settledResults.filter((r) => r.type === 'fulfilled'),
-        ).toHaveLength(count),
+const failuresRecorded = (subId: string, count: number): Promise<void> =>
+    waitUntil(async () =>
+        expect(await env.server.clients.redis.get(`ev:qf:{${subId}}`)).toBe(
+            String(count),
+        ),
     );
 
 beforeAll(async () => {
@@ -599,11 +599,7 @@ describe('what each answer does to the delivery', () => {
         // It counted: a refusal is still a handler that did not work. Counted
         // only once the marker is in, so it is also what says the answer was
         // handled — the depth alone reads 1 while the event is still leased.
-        await waitUntil(async () =>
-            expect(await env.server.clients.redis.get(`ev:qf:{${subId}}`)).toBe(
-                '1',
-            ),
-        );
+        await failuresRecorded(subId, 1);
 
         // The event is gone and a marker stands in its place, so the
         // subscription learns there was one rather than reading silence.
@@ -626,16 +622,14 @@ describe('what each answer does to the delivery', () => {
         await touch('unmarked.txt');
         await invoked(1);
 
-        await waitUntil(async () =>
-            expect(await heldForMs(subId)).toBeGreaterThan(0),
-        );
+        await failuresRecorded(subId, 1);
+        expect(await heldForMs(subId)).toBeGreaterThan(0);
         expect(await pending().depth(subId)).toBe(1);
     });
 
     it('holds one it could not answer, for longer each time', async () => {
         answer = 500;
         const subId = await subscribe();
-        const deferred = vi.spyOn(pending(), 'deferAfterFailure');
         // Freeze the clock so every hold is read against the same instant it
         // was written from.
         jump(0);
@@ -649,7 +643,7 @@ describe('what each answer does to the delivery', () => {
             attempt < EVENTS_CONSECUTIVE_FAILURES;
             attempt++
         ) {
-            await holdsWritten(deferred, attempt);
+            await failuresRecorded(subId, attempt);
             waits.push(await heldForMs(subId));
 
             // Nothing may take it while it is held.
@@ -672,7 +666,6 @@ describe('what each answer does to the delivery', () => {
             ),
         );
         expect(calls).toHaveLength(EVENTS_CONSECUTIVE_FAILURES);
-        deferred.mockRestore();
     });
 
     it('tells the developer their handler stopped working', async () => {
@@ -686,7 +679,7 @@ describe('what each answer does to the delivery', () => {
             attempt < EVENTS_CONSECUTIVE_FAILURES;
             attempt++
         ) {
-            await invoked(attempt);
+            await failuresRecorded(subId, attempt);
             jump(deliveryBackoffMs(attempt) + 50);
             await events().sweepPending();
         }
@@ -710,9 +703,8 @@ describe('what each answer does to the delivery', () => {
         await invoked(1);
 
         // Still owed, and held rather than dropped: nobody said no.
-        await waitUntil(async () =>
-            expect(await heldForMs(subId)).toBeGreaterThan(0),
-        );
+        await failuresRecorded(subId, 1);
+        expect(await heldForMs(subId)).toBeGreaterThan(0);
         expect(await pending().depth(subId)).toBe(1);
         answer = 200;
     });
@@ -724,9 +716,8 @@ describe('what each answer does to the delivery', () => {
         await touch('busy.txt');
         await invoked(1);
 
-        await waitUntil(async () =>
-            expect(await heldForMs(subId)).toBeGreaterThan(0),
-        );
+        await failuresRecorded(subId, 1);
+        expect(await heldForMs(subId)).toBeGreaterThan(0);
         expect(await pending().depth(subId)).toBe(1);
     });
 });
@@ -794,7 +785,6 @@ describe('with no events worker to address', () => {
         // Unpublished after the fact: the app's set now hashes to nothing, so
         // there is no script to name and nowhere to send the delivery.
         await env.server.stores.eventHandler.remove(appUid, HANDLER);
-        const deferred = vi.spyOn(pending(), 'deferAfterFailure');
 
         try {
             await touch('unresolved.txt');
@@ -803,7 +793,7 @@ describe('with no events worker to address', () => {
                 attempt < EVENTS_CONSECUTIVE_FAILURES;
                 attempt++
             ) {
-                await holdsWritten(deferred, attempt);
+                await failuresRecorded(subId, attempt);
                 jump(deliveryBackoffMs(attempt) + 50);
                 await events().sweepPending();
             }
@@ -816,7 +806,6 @@ describe('with no events worker to address', () => {
             // Nothing was ever called: there was nowhere to call.
             expect(calls).toEqual([]);
         } finally {
-            deferred.mockRestore();
             await env.server.stores.eventHandler.publish({
                 appUid,
                 name: HANDLER,
@@ -835,9 +824,10 @@ describe('with no events worker to address', () => {
 
         try {
             await touch('suspended-owner.txt');
-            await waitUntil(async () =>
-                expect(await heldForMs(subId)).toBeGreaterThan(0),
-            );
+            // Not just the claim's lease: un-suspending the owner while the
+            // attempt is still in flight would let it address and call out.
+            await failuresRecorded(subId, 1);
+            expect(await heldForMs(subId)).toBeGreaterThan(0);
             expect(await pending().depth(subId)).toBe(1);
             // A suspended owner is nobody to address: nothing was called.
             expect(calls).toEqual([]);