diff --git a/packages/ptc-runtime/ptc-runtime-node/src/persistent.ts b/packages/ptc-runtime/ptc-runtime-node/src/persistent.ts
index f15a2f2da1..83ac9c083b 100644
--- a/packages/ptc-runtime/ptc-runtime-node/src/persistent.ts
+++ b/packages/ptc-runtime/ptc-runtime-node/src/persistent.ts
@@ -330,7 +330,9 @@ export class InMemoryExecution {
   async release(owner: object): Promise<void> {
     const kernel = this.owners.get(owner)
     if (!kernel) return
-    this.owners.delete(owner)
-    try { await kernel.dispose() } finally { this.kernels.delete(kernel) }
+    try { await kernel.dispose() } finally {
+      if (this.owners.get(owner) === kernel) this.owners.delete(owner)
+      this.kernels.delete(kernel)
+    }
   }
 }
diff --git a/packages/ptc-runtime/ptc-runtime-node/tests/persistent-host.spec.ts b/packages/ptc-runtime/ptc-runtime-node/tests/persistent-host.spec.ts
index a7212b035f..3f35b8e77e 100644
--- a/packages/ptc-runtime/ptc-runtime-node/tests/persistent-host.spec.ts
+++ b/packages/ptc-runtime/ptc-runtime-node/tests/persistent-host.spec.ts
@@ -375,6 +375,7 @@ it.each(['owner release', 'provider unload'])('keeps idle-crash cleanup tracked
     closing = (action === 'owner release' ? h.runtime.release(request.stateOwner!) : h.fiber.dispose()).then(() => { disposed = true })
     await setImmediate()
     expect(disposed).toBe(false)
+    if (action === 'owner release') await expect(h.runtime.run(h.runtime.resolve(request))).rejects.toThrow('concurrent runs')
     stopped.resolve(true)
     await closing
     expect(disposed).toBe(true)
@@ -411,3 +412,20 @@ it('reports a release failure once and removes the failed environment from provi
     expect(h.waitForExit).toHaveBeenCalledOnce()
   } finally { reported.mockRestore() }
 })
+
+it('reserves the owner while parse-output overflow releases its environment', async () => {
+  const h = await setup({ maxOutputBytes: 32 })
+  const cleanup = Promise.withResolvers<true>()
+  const stopped = Promise.withResolvers<boolean>()
+  h.onBoot(() => { h.emit(frame({ type: 'done' })) })
+  await h.start()
+  h.waitForExit.mockImplementation(async () => { cleanup.resolve(true); return stopped.promise })
+  const pending = h.runtime.run(h.runtime.resolve({ ...request, program: 'return 1' }))
+  try {
+    await cleanup.promise
+    await expect(h.runtime.run(h.runtime.resolve(request))).rejects.toThrow('concurrent runs')
+    expect(h.spawn).toHaveBeenCalledOnce()
+    stopped.resolve(true)
+    expect((await pending).error?.kind).toBe('output-limit')
+  } finally { stopped.resolve(true); await pending }
+})