diff --git a/packages/api/src/schedules/service.spec.ts b/packages/api/src/schedules/service.spec.ts
index 3d36547a4f..7b6945864c 100644
--- a/packages/api/src/schedules/service.spec.ts
+++ b/packages/api/src/schedules/service.spec.ts
@@ -950,6 +950,15 @@ describe('scheduled resume capacity', () => {
     });
     expect(methods.markRunResumeClaimed).not.toHaveBeenCalled();
   });
+
+  it('normalizes an exhausted slot-collision retry to public capacity conflict', async () => {
+    const { service, methods } = makeResumeService({ takenSlots: [], unslotted: 0 });
+    methods.markRunResumeClaimed.mockResolvedValue({ conflict: 'slot-taken' });
+
+    await expect(service.claimScheduleResume('s1', '2026-08-17T12:00:00.000Z')).resolves.toEqual({
+      conflict: 'capacity',
+    });
+  });
 });
 
 describe('deployment-wide limits', () => {
diff --git a/packages/api/src/schedules/service.ts b/packages/api/src/schedules/service.ts
index 0d790c0d54..2e508d6f41 100644
--- a/packages/api/src/schedules/service.ts
+++ b/packages/api/src/schedules/service.ts
@@ -855,7 +855,12 @@ export function createSchedulesService(
       }
       const claimed = allocation.claimed;
       if ('conflict' in claimed) {
-        return { conflict: claimed.conflict };
+        // withCapacitySlot consumes this internal collision sentinel by retrying the
+        // next free slot. Normalize defensively at the public boundary as well so a
+        // custom/test allocator can never leak an implementation-only conflict.
+        return {
+          conflict: claimed.conflict === 'slot-taken' ? 'capacity' : claimed.conflict,
+        };
       }
       return { capacitySlot: claimed.capacitySlot };
     });