Fix tests

packages/engine/src/__tests__/reliability-interactions/verification-spawn-supervision.real-git.test.ts

@@ -101,7 +101,7 @@ async function spawnParent(scenario: Scenario): Promise<{ parent: ReturnType<typ
 describe("reliability interactions: FN-5189 verification spawn supervision", () => {
   const spawnedParents = new Set<ReturnType<typeof spawn>>();
 
-  afterEach(() => {
+  afterEach(async () => {
     for (const parent of spawnedParents) {
       if (parent.exitCode === null && parent.signalCode === null) {
         try {
@@ -109,6 +109,13 @@ describe("reliability interactions: FN-5189 verification spawn supervision", ()
         } catch {
           // ignore cleanup failures
         }
+        // Wait for the parent to fully exit so the subprocess guard
+        // does not flag it as "left running" under concurrent load.
+        try {
+          await once(parent, "exit");
+        } catch {
+          // Already exited
+        }
       }
     }
     spawnedParents.clear();