diff --git a/server/src/modules/computers/adapters/boat.ts b/server/src/modules/computers/adapters/boat.ts
index c6a34faaf2..f74f9eb67a 100644
--- a/server/src/modules/computers/adapters/boat.ts
+++ b/server/src/modules/computers/adapters/boat.ts
@@ -196,7 +196,7 @@ export function boatBackend(
     return value;
   }
   const processProgram = String.raw`
-import os,sys,json,fcntl,subprocess
+import os,sys,json,fcntl,subprocess,shutil
 p=json.load(sys.stdin);base='/home/user/.paperclip-owners';os.makedirs(base,exist_ok=True)
 owner=p['owner'];oid=owner['id'];root=os.path.join(base,oid);os.makedirs(root,exist_ok=True)
 with open(os.path.join(root,'lock'),'a') as lock:
@@ -215,6 +215,12 @@ with open(os.path.join(root,'lock'),'a') as lock:
   subprocess.run(['systemctl','--user','stop',slice,unit],capture_output=True)
   state=subprocess.run(['systemctl','--user','show',slice,'--property=ActiveState','--value'],capture_output=True,text=True).stdout.strip()
   if state not in ('inactive','failed',''):raise RuntimeError('process retirement unconfirmed')
+  # Reap only this retired owner's command spools after its cgroup is stopped.
+  # This covers controller crashes and SSH timeouts that skipped caller cleanup.
+  for entry in os.scandir(root):
+   if entry.name.startswith('command-') and entry.is_dir(follow_symlinks=False):
+    try:shutil.rmtree(entry.path)
+    except FileNotFoundError:pass
   print('{}')
  elif p['action']=='inspect':
   claim=owner.get('process');marker=os.path.join(root,'claim.json');actual=json.load(open(marker)) if os.path.exists(marker) else None
diff --git a/server/src/modules/computers/application/service.test.ts b/server/src/modules/computers/application/service.test.ts
index 80be803a88..5de8a1d598 100644
--- a/server/src/modules/computers/application/service.test.ts
+++ b/server/src/modules/computers/application/service.test.ts
@@ -490,6 +490,14 @@ with open(output,'wb') as out,open(error,'wb') as err:
         cwd: temp,
         stdin: "foreground-input\n",
       });
+      const stdinProbe = await binding.runner.execute({
+        command: "python3",
+        args: ["-c", "import os,sys; assert os.fstat(0).st_nlink > 0, 'stdin backing file was unlinked before child exit'; assert os.fstat(0).st_mode & 0o777 == 0o600; print(sys.stdin.read(),end='')"],
+        cwd: temp,
+        stdin: "persistent-stdin",
+      });
+      expect(stdinProbe.exitCode).toBe(0);
+      expect(stdinProbe.stdout).toBe("persistent-stdin");
       backgroundPid = Number(result.stdout.trim());
       expect(result.exitCode).toBe(7);
       expect(result.stderr).toBe("foreground-input\n");
diff --git a/server/src/modules/computers/application/service.ts b/server/src/modules/computers/application/service.ts
index 947506a1c0..292836dee0 100644
--- a/server/src/modules/computers/application/service.ts
+++ b/server/src/modules/computers/application/service.ts
@@ -209,7 +209,7 @@ export function createComputerService(
             "-c",
             String.raw`
 import os,sys,json,fcntl,subprocess,time,tempfile,shutil
-p=json.load(sys.stdin);root='/home/user/.paperclip-owners/'+p['owner'];os.makedirs(root,exist_ok=True)
+p=json.load(sys.stdin);os.umask(0o077);root='/home/user/.paperclip-owners/'+p['owner'];os.makedirs(root,exist_ok=True)
 # A receipt reports foreground completion independently from cgroup lifetime.
 # ExitType=cgroup keeps nohup/setsid descendants owned until owner retirement.
 supervisor="""
@@ -220,7 +220,8 @@ os.unlink(payload)
 i=p['input']
 try:
  with open(p['stdin'],'rb') as source:
-  os.unlink(p['stdin'])
+  # Boat's persistent filesystem invalidates unlinked stdin descriptors.
+  # Keep the private backing file until the command's normal finally cleanup.
   child=subprocess.Popen([i['command']]+i.get('args',[]),stdin=source)
   code=child.wait()
 except Exception as error: