fix hbb_common

On headless login the desktop manager opens a PAM session, which makes
pam_systemd register a logind session and put the spawned Xorg + window
manager and their children (e.g. pipewire) in a "session-<id>.scope"
cgroup. Teardown only killed the Xorg and wm pids, so the rest of the
session kept running, holding the logind session in "closing" and leaking
runtime sockets and X display numbers on every reconnect.

Capture the session scope cgroup from a child pid and, on teardown, kill the
remaining processes in it and any descendant cgroups (cgroup.procs is not
recursive, and a desktop may move pipewire and apps into child scopes),
excluding our own service process and anything tracked in CHILD_PROCESS
together with its descendants. The connection manager is a sudo child, so the
tracked pid is the wrapper while the real --cm-no-ui worker may be a descendant
(sudo with use_pty runs it under a monitor); both can share the scope when
their PAM stack does not re-home them.

Xorg is killed with SIGKILL, so it also leaves its "/tmp/.X<n>-lock" and
"/tmp/.X11-unix/X<n>" behind; get_avail_display() treats either file as the
display being in use, so the number is never reused and climbs until the
range is exhausted. Remove those files for the session's display on
teardown, as a clean Xorg exit would.

Closes #15183

Signed-off-by: TBX3D <88289044+TBX3D@users.noreply.github.com>

src/lang/ar.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "إعادة تعيين اختيار إدخال لوحة المفاتيح"),
         ("remember-wayland-keyboard-choice-tip", "لا تسأل مرة أخرى لهذا الكمبيوتر البعيد"),
         ("Why this happens", "سبب حدوث ذلك"),
+        ("Switch display", "تبديل الشاشة"),
+        ("Show monitor switch button on the main toolbar", "إظهار زر تبديل الشاشة على شريط الأدوات الرئيسي"),
+        ("Show on the minimized toolbar", "الإظهار على شريط الأدوات المُصغّر"),
     ].iter().cloned().collect();
 }

src/lang/be.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Скінуць выбар уводу з клавіятуры"),
         ("remember-wayland-keyboard-choice-tip", "Не пытацца зноў для гэтага аддаленага кампутара"),
         ("Why this happens", "Чаму гэта адбываецца"),
+        ("Switch display", "Пераключыць дысплэй"),
+        ("Show monitor switch button on the main toolbar", "Паказваць кнопку пераключэння манітора на галоўнай панэлі інструментаў"),
+        ("Show on the minimized toolbar", "Паказваць на згорнутай панэлі інструментаў"),
     ].iter().cloned().collect();
 }

src/lang/bg.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Нулиране на избора за въвеждане от клавиатура"),
         ("remember-wayland-keyboard-choice-tip", "Не питай отново за този отдалечен компютър"),
         ("Why this happens", "Защо се случва това"),
+        ("Switch display", "Превключване на дисплея"),
+        ("Show monitor switch button on the main toolbar", "Показване на бутона за превключване на монитора в главната лента с инструменти"),
+        ("Show on the minimized toolbar", "Показване в минимизираната лента с инструменти"),
     ].iter().cloned().collect();
 }

src/lang/ca.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Restableix l'opció d'entrada de teclat"),
         ("remember-wayland-keyboard-choice-tip", "No tornis a preguntar-ho per a aquest equip remot"),
         ("Why this happens", "Per què passa això"),
+        ("Switch display", "Canvia de pantalla"),
+        ("Show monitor switch button on the main toolbar", "Mostra el botó de canvi de monitor a la barra d’eines principal"),
+        ("Show on the minimized toolbar", "Mostra a la barra d’eines minimitzada"),
     ].iter().cloned().collect();
 }

src/lang/cn.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "重置键盘输入选择"),
         ("remember-wayland-keyboard-choice-tip", "以后对这台远程电脑不再询问"),
         ("Why this happens", "了解原因"),
+        ("Switch display", "切换显示器"),
+        ("Show monitor switch button on the main toolbar", "在主工具栏上显示显示器切换按钮"),
+        ("Show on the minimized toolbar", "在最小化工具栏上显示"),
     ].iter().cloned().collect();
 }

src/lang/cs.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Resetovat volbu vstupu z klávesnice"),
         ("remember-wayland-keyboard-choice-tip", "Pro tento vzdálený počítač se již neptat"),
         ("Why this happens", "Proč k tomu dochází"),
+        ("Switch display", "Přepnout obrazovku"),
+        ("Show monitor switch button on the main toolbar", "Zobrazit tlačítko přepnutí monitoru na hlavním panelu nástrojů"),
+        ("Show on the minimized toolbar", "Zobrazit na minimalizovaném panelu nástrojů"),
     ].iter().cloned().collect();
 }

src/lang/da.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Nulstil valg for tastaturinput"),
         ("remember-wayland-keyboard-choice-tip", "Spørg ikke igen for denne fjerncomputer"),
         ("Why this happens", "Hvorfor dette sker"),
+        ("Switch display", "Skift skærm"),
+        ("Show monitor switch button on the main toolbar", "Vis knap til skærmskift på hovedværktøjslinjen"),
+        ("Show on the minimized toolbar", "Vis på den minimerede værktøjslinje"),
     ].iter().cloned().collect();
 }

src/lang/de.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Auswahl der Tastatureingabe zurücksetzen"),
         ("remember-wayland-keyboard-choice-tip", "Für diesen entfernten Computer nicht erneut fragen"),
         ("Why this happens", "Warum dies passiert"),
+        ("Switch display", "Anzeige wechseln"),
+        ("Show monitor switch button on the main toolbar", "Schaltfläche zum Monitorwechsel in der Haupt-Symbolleiste anzeigen"),
+        ("Show on the minimized toolbar", "In der minimierten Symbolleiste anzeigen"),
     ].iter().cloned().collect();
 }

src/lang/el.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Επαναφορά επιλογής εισαγωγής από πληκτρολόγιο"),
         ("remember-wayland-keyboard-choice-tip", "Να μην ερωτηθώ ξανά για αυτόν τον απομακρυσμένο υπολογιστή"),
         ("Why this happens", "Γιατί συμβαίνει αυτό"),
+        ("Switch display", "Εναλλαγή οθόνης"),
+        ("Show monitor switch button on the main toolbar", "Εμφάνιση κουμπιού εναλλαγής οθόνης στην κύρια γραμμή εργαλείων"),
+        ("Show on the minimized toolbar", "Εμφάνιση στην ελαχιστοποιημένη γραμμή εργαλείων"),
     ].iter().cloned().collect();
 }

src/lang/eo.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Restarigi la elekton de klavara enigo"),
         ("remember-wayland-keyboard-choice-tip", "Ne demandi denove por ĉi tiu fora komputilo"),
         ("Why this happens", "Kial ĉi tio okazas"),
+        ("Switch display", "Ŝalti ekranon"),
+        ("Show monitor switch button on the main toolbar", "Montri ekran-ŝaltan butonon en la ĉefa ilobreto"),
+        ("Show on the minimized toolbar", "Montri en la minimumigita ilobreto"),
     ].iter().cloned().collect();
 }

src/lang/es.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Restablecer la opción de entrada del teclado"),
         ("remember-wayland-keyboard-choice-tip", "No volver a preguntar para este equipo remoto"),
         ("Why this happens", "Por qué ocurre esto"),
+        ("Switch display", "Cambiar de pantalla"),
+        ("Show monitor switch button on the main toolbar", "Mostrar el botón de cambio de monitor en la barra de herramientas principal"),
+        ("Show on the minimized toolbar", "Mostrar en la barra de herramientas minimizada"),
     ].iter().cloned().collect();
 }

src/lang/et.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Lähtesta klaviatuurisisestuse valik"),
         ("remember-wayland-keyboard-choice-tip", "Ära küsi selle kaugarvuti puhul uuesti"),
         ("Why this happens", "Miks see juhtub"),
+        ("Switch display", "Vaheta kuva"),
+        ("Show monitor switch button on the main toolbar", "Näita monitori vahetamise nuppu peamisel tööriistaribal"),
+        ("Show on the minimized toolbar", "Näita minimeeritud tööriistaribal"),
     ].iter().cloned().collect();
 }

src/lang/eu.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Berrezarri teklatuko sarreraren aukera"),
         ("remember-wayland-keyboard-choice-tip", "Ez galdetu berriro urruneko ordenagailu honetarako"),
         ("Why this happens", "Zergatik gertatzen den hau"),
+        ("Switch display", "Aldatu pantaila"),
+        ("Show monitor switch button on the main toolbar", "Erakutsi monitorea aldatzeko botoia tresna-barra nagusian"),
+        ("Show on the minimized toolbar", "Erakutsi minimizatutako tresna-barran"),
     ].iter().cloned().collect();
 }

src/lang/fa.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "بازنشانی انتخاب ورودی صفحه کلید"),
         ("remember-wayland-keyboard-choice-tip", "برای این رایانه از راه دور دوباره نپرس"),
         ("Why this happens", "چرا این اتفاق می‌افتد"),
+        ("Switch display", "تعویض نمایشگر"),
+        ("Show monitor switch button on the main toolbar", "نمایش دکمه تعویض نمایشگر در نوار ابزار اصلی"),
+        ("Show on the minimized toolbar", "نمایش در نوار ابزار کوچک‌شده"),
     ].iter().cloned().collect();
 }

src/lang/fi.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Nollaa näppäimistösyötteen valinta"),
         ("remember-wayland-keyboard-choice-tip", "Älä kysy uudelleen tältä etätietokoneelta"),
         ("Why this happens", "Miksi näin tapahtuu"),
+        ("Switch display", "Vaihda näyttöä"),
+        ("Show monitor switch button on the main toolbar", "Näytä näytön vaihtopainike päätyökalurivillä"),
+        ("Show on the minimized toolbar", "Näytä pienennetyssä työkalurivissä"),
     ].iter().cloned().collect();
 }

src/lang/fr.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Réinitialiser le choix de la saisie au clavier"),
         ("remember-wayland-keyboard-choice-tip", "Ne plus demander pour cet appareil distant"),
         ("Why this happens", "Pourquoi cela se produit"),
+        ("Switch display", "Changer d’écran"),
+        ("Show monitor switch button on the main toolbar", "Afficher le bouton de changement d’écran dans la barre d’outils principale"),
+        ("Show on the minimized toolbar", "Afficher dans la barre d’outils réduite"),
     ].iter().cloned().collect();
 }

src/lang/ge.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "კლავიატურის შეყვანის არჩევანის ჩამოყრა"),
         ("remember-wayland-keyboard-choice-tip", "აღარ მკითხო ამ დისტანციური კომპიუტერისთვის"),
         ("Why this happens", "რატომ ხდება ეს"),
+        ("Switch display", "ეკრანის გადართვა"),
+        ("Show monitor switch button on the main toolbar", "მონიტორის გადართვის ღილაკის ჩვენება მთავარ ხელსაწყოთა ზოლზე"),
+        ("Show on the minimized toolbar", "ჩვენება ჩაკეცილ ხელსაწყოთა ზოლზე"),
     ].iter().cloned().collect();
 }

src/lang/gu.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "કીબોર્ડ ઇનપુટ પસંદગી રિસેટ કરો"),
         ("remember-wayland-keyboard-choice-tip", "આ રિમોટ કમ્પ્યુટર માટે ફરીથી પૂછશો નહીં"),
         ("Why this happens", "આવું શા માટે થાય છે"),
+        ("Switch display", "ડિસ્પ્લે બદલો"),
+        ("Show monitor switch button on the main toolbar", "મુખ્ય ટૂલબાર પર મોનિટર સ્વિચ બટન બતાવો"),
+        ("Show on the minimized toolbar", "ન્યૂનતમ કરેલા ટૂલબાર પર બતાવો"),
     ].iter().cloned().collect();
 }

src/lang/he.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "אפס את בחירת קלט המקלדת"),
         ("remember-wayland-keyboard-choice-tip", "אל תשאל שוב עבור מחשב מרוחק זה"),
         ("Why this happens", "מדוע זה קורה"),
+        ("Switch display", "החלפת צג"),
+        ("Show monitor switch button on the main toolbar", "הצגת לחצן החלפת צג בסרגל הכלים הראשי"),
+        ("Show on the minimized toolbar", "הצגה בסרגל הכלים הממוזער"),
     ].iter().cloned().collect();
 }

src/lang/hi.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "कीबोर्ड इनपुट चयन रीसेट करें"),
         ("remember-wayland-keyboard-choice-tip", "इस रिमोट कंप्यूटर के लिए दोबारा न पूछें"),
         ("Why this happens", "ऐसा क्यों होता है"),
+        ("Switch display", "डिस्प्ले बदलें"),
+        ("Show monitor switch button on the main toolbar", "मुख्य टूलबार पर मॉनिटर स्विच बटन दिखाएं"),
+        ("Show on the minimized toolbar", "न्यूनतम किए गए टूलबार पर दिखाएं"),
     ].iter().cloned().collect();
 }

src/lang/hr.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Poništi izbor unosa tipkovnicom"),
         ("remember-wayland-keyboard-choice-tip", "Ne pitaj ponovno za ovo udaljeno računalo"),
         ("Why this happens", "Zašto se ovo događa"),
+        ("Switch display", "Promijeni zaslon"),
+        ("Show monitor switch button on the main toolbar", "Prikaži gumb za prebacivanje monitora na glavnoj alatnoj traci"),
+        ("Show on the minimized toolbar", "Prikaži na minimiziranoj alatnoj traci"),
     ].iter().cloned().collect();
 }

src/lang/hu.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Billentyűzetbevitel választásának visszaállítása"),
         ("remember-wayland-keyboard-choice-tip", "Ne kérdezze meg újra ennél a távoli számítógépnél"),
         ("Why this happens", "Miért történik ez"),
+        ("Switch display", "Kijelző váltása"),
+        ("Show monitor switch button on the main toolbar", "Monitorváltó gomb megjelenítése a fő eszköztáron"),
+        ("Show on the minimized toolbar", "Megjelenítés a kis méretű eszköztáron"),
     ].iter().cloned().collect();
 }

src/lang/id.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Setel ulang pilihan masukan keyboard"),
         ("remember-wayland-keyboard-choice-tip", "Jangan tanya lagi untuk komputer jarak jauh ini"),
         ("Why this happens", "Mengapa ini terjadi"),
+        ("Switch display", "Ganti tampilan"),
+        ("Show monitor switch button on the main toolbar", "Tampilkan tombol pengalih monitor di bilah alat utama"),
+        ("Show on the minimized toolbar", "Tampilkan di bilah alat yang diperkecil"),
     ].iter().cloned().collect();
 }

src/lang/it.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Ripristina scelta input da tastiera"),
         ("remember-wayland-keyboard-choice-tip", "Non chiedere più per questo computer remoto"),
         ("Why this happens", "Perché accade questo"),
+        ("Switch display", "Cambia schermo"),
+        ("Show monitor switch button on the main toolbar", "Mostra il pulsante di cambio monitor nella barra degli strumenti principale"),
+        ("Show on the minimized toolbar", "Mostra nella barra degli strumenti ridotta a icona"),
     ].iter().cloned().collect();
 }

src/lang/ja.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "キーボード入力の選択をリセット"),
         ("remember-wayland-keyboard-choice-tip", "このリモートコンピューターでは今後確認しない"),
         ("Why this happens", "この問題が起こる理由"),
+        ("Switch display", "ディスプレイを切り替え"),
+        ("Show monitor switch button on the main toolbar", "メインツールバーにモニター切り替えボタンを表示"),
+        ("Show on the minimized toolbar", "最小化したツールバーに表示"),
     ].iter().cloned().collect();
 }

src/lang/ko.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "키보드 입력 선택 초기화"),
         ("remember-wayland-keyboard-choice-tip", "이 원격 컴퓨터에 대해 다시 묻지 않기"),
         ("Why this happens", "이런 현상이 발생하는 이유"),
+        ("Switch display", "디스플레이 전환"),
+        ("Show monitor switch button on the main toolbar", "기본 도구 모음에 모니터 전환 버튼 표시"),
+        ("Show on the minimized toolbar", "최소화된 도구 모음에 표시"),
     ].iter().cloned().collect();
 }

src/lang/kz.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Пернетақта еңгізу таңдауын қалпына келтіру"),
         ("remember-wayland-keyboard-choice-tip", "Осы қашықтағы компьютер үшін қайта сұрамау"),
         ("Why this happens", "Бұл неге болады"),
+        ("Switch display", "Дисплейді ауыстыру"),
+        ("Show monitor switch button on the main toolbar", "Негізгі құралдар тақтасында мониторды ауыстыру түймесін көрсету"),
+        ("Show on the minimized toolbar", "Кішірейтілген құралдар тақтасында көрсету"),
     ].iter().cloned().collect();
 }

src/lang/lt.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Atstatyti klaviatūros įvesties pasirinkimą"),
         ("remember-wayland-keyboard-choice-tip", "Daugiau neklausti dėl šio nuotolinio kompiuterio"),
         ("Why this happens", "Kodėl taip nutinka"),
+        ("Switch display", "Perjungti ekraną"),
+        ("Show monitor switch button on the main toolbar", "Rodyti monitoriaus perjungimo mygtuką pagrindinėje įrankių juostoje"),
+        ("Show on the minimized toolbar", "Rodyti sumažintoje įrankių juostoje"),
     ].iter().cloned().collect();
 }

src/lang/lv.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Atiestatīt tastatūras ievades izvēli"),
         ("remember-wayland-keyboard-choice-tip", "Vairs nejautāt par šo attālo datoru"),
         ("Why this happens", "Kāpēc tas notiek"),
+        ("Switch display", "Pārslēgt displeju"),
+        ("Show monitor switch button on the main toolbar", "Rādīt monitora pārslēgšanas pogu galvenajā rīkjoslā"),
+        ("Show on the minimized toolbar", "Rādīt minimizētajā rīkjoslā"),
     ].iter().cloned().collect();
 }

src/lang/ml.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "കീബോർഡ് ഇൻപുട്ട് തിരഞ്ഞെടുപ്പ് റീസെറ്റ് ചെയ്യുക"),
         ("remember-wayland-keyboard-choice-tip", "ഈ റിമോട്ട് കമ്പ്യൂട്ടറിനായി ഇനി ചോദിക്കരുത്"),
         ("Why this happens", "ഇത് എന്തുകൊണ്ട് സംഭവിക്കുന്നു"),
+        ("Switch display", "ഡിസ്പ്ലേ മാറ്റുക"),
+        ("Show monitor switch button on the main toolbar", "പ്രധാന ടൂൾബാറിൽ മോണിറ്റർ സ്വിച്ച് ബട്ടൺ കാണിക്കുക"),
+        ("Show on the minimized toolbar", "ചെറുതാക്കിയ ടൂൾബാറിൽ കാണിക്കുക"),
     ].iter().cloned().collect();
 }

src/lang/nb.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Tilbakestill valg for tastaturinndata"),
         ("remember-wayland-keyboard-choice-tip", "Ikke spør igjen for denne eksterne datamaskinen"),
         ("Why this happens", "Hvorfor dette skjer"),
+        ("Switch display", "Bytt skjerm"),
+        ("Show monitor switch button on the main toolbar", "Vis knapp for skjermbytte på hovedverktøylinjen"),
+        ("Show on the minimized toolbar", "Vis på den minimerte verktøylinjen"),
     ].iter().cloned().collect();
 }

src/lang/nl.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Keuze voor toetsenbordinvoer opnieuw instellen"),
         ("remember-wayland-keyboard-choice-tip", "Niet meer vragen voor deze externe computer"),
         ("Why this happens", "Waarom dit gebeurt"),
+        ("Switch display", "Beeldscherm wisselen"),
+        ("Show monitor switch button on the main toolbar", "Knop voor monitorwisseling weergeven op de hoofdwerkbalk"),
+        ("Show on the minimized toolbar", "Weergeven op de geminimaliseerde werkbalk"),
     ].iter().cloned().collect();
 }

src/lang/pl.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Zresetuj wybór dotyczący wprowadzania z klawiatury"),
         ("remember-wayland-keyboard-choice-tip", "Nie pytaj ponownie dla tego zdalnego komputera"),
         ("Why this happens", "Dlaczego tak się dzieje"),
+        ("Switch display", "Przełącz ekran"),
+        ("Show monitor switch button on the main toolbar", "Pokaż przycisk przełączania monitora na głównym pasku narzędzi"),
+        ("Show on the minimized toolbar", "Pokaż na zminimalizowanym pasku narzędzi"),
     ].iter().cloned().collect();
 }

src/lang/pt_PT.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Repor escolha de entrada de teclado"),
         ("remember-wayland-keyboard-choice-tip", "Não voltar a perguntar para este computador remoto"),
         ("Why this happens", "Porque é que isto acontece"),
+        ("Switch display", "Trocar de ecrã"),
+        ("Show monitor switch button on the main toolbar", "Mostrar o botão de troca de monitor na barra de ferramentas principal"),
+        ("Show on the minimized toolbar", "Mostrar na barra de ferramentas minimizada"),
     ].iter().cloned().collect();
 }

src/lang/ptbr.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Redefinir escolha de entrada do teclado"),
         ("remember-wayland-keyboard-choice-tip", "Não perguntar novamente para este computador remoto"),
         ("Why this happens", "Por que isso acontece"),
+        ("Switch display", "Trocar de tela"),
+        ("Show monitor switch button on the main toolbar", "Mostrar o botão de troca de monitor na barra de ferramentas principal"),
+        ("Show on the minimized toolbar", "Mostrar na barra de ferramentas minimizada"),
     ].iter().cloned().collect();
 }

src/lang/ro.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Resetează alegerea pentru introducerea de la tastatură"),
         ("remember-wayland-keyboard-choice-tip", "Nu mai întreba pentru acest computer la distanță"),
         ("Why this happens", "De ce se întâmplă acest lucru"),
+        ("Switch display", "Comută afișajul"),
+        ("Show monitor switch button on the main toolbar", "Afișează butonul de comutare a monitorului în bara de instrumente principală"),
+        ("Show on the minimized toolbar", "Afișează în bara de instrumente minimizată"),
     ].iter().cloned().collect();
 }

src/lang/ru.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Сбросить выбор для ввода с клавиатуры"),
         ("remember-wayland-keyboard-choice-tip", "Больше не спрашивать для этого удалённого компьютера"),
         ("Why this happens", "Почему это происходит"),
+        ("Switch display", "Переключить дисплей"),
+        ("Show monitor switch button on the main toolbar", "Показывать кнопку переключения монитора на главной панели инструментов"),
+        ("Show on the minimized toolbar", "Показывать на свёрнутой панели инструментов"),
     ].iter().cloned().collect();
 }

src/lang/sc.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Reseta s'isseberada de s'insertada cun su tecladu"),
         ("remember-wayland-keyboard-choice-tip", "No torres a preguntare pro custu elaboradore remotu"),
         ("Why this happens", "Pro ite custu càpitat"),
+        ("Switch display", "Càmbia ischermu"),
+        ("Show monitor switch button on the main toolbar", "Mustra su butone de càmbiu de monitor in sa barra de aina printzipale"),
+        ("Show on the minimized toolbar", "Mustra in sa barra de aina minimizada"),
     ].iter().cloned().collect();
 }

src/lang/sk.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Obnoviť voľbu vstupu z klávesnice"),
         ("remember-wayland-keyboard-choice-tip", "Nepýtať sa znova pre tento vzdialený počítač"),
         ("Why this happens", "Prečo sa to deje"),
+        ("Switch display", "Prepnúť obrazovku"),
+        ("Show monitor switch button on the main toolbar", "Zobraziť tlačidlo prepnutia monitora na hlavnom paneli nástrojov"),
+        ("Show on the minimized toolbar", "Zobraziť na minimalizovanom paneli nástrojov"),
     ].iter().cloned().collect();
 }

src/lang/sl.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Ponastavi izbiro vnosa s tipkovnice"),
         ("remember-wayland-keyboard-choice-tip", "Za ta oddaljeni računalnik ne vprašaj več"),
         ("Why this happens", "Zakaj se to dogaja"),
+        ("Switch display", "Preklopi zaslon"),
+        ("Show monitor switch button on the main toolbar", "Pokaži gumb za preklop monitorja v glavni orodni vrstici"),
+        ("Show on the minimized toolbar", "Pokaži v pomanjšani orodni vrstici"),
     ].iter().cloned().collect();
 }

src/lang/sq.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Rivendos zgjedhjen e hyrjes nga tastiera"),
         ("remember-wayland-keyboard-choice-tip", "Mos pyet më për këtë kompjuter në distancë"),
         ("Why this happens", "Pse ndodh kjo"),
+        ("Switch display", "Ndërro ekranin"),
+        ("Show monitor switch button on the main toolbar", "Shfaq butonin e ndërrimit të monitorit te shiriti kryesor i veglave"),
+        ("Show on the minimized toolbar", "Shfaq te shiriti i minimizuar i veglave"),
     ].iter().cloned().collect();
 }

src/lang/sr.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Resetuj izbor unosa sa tastature"),
         ("remember-wayland-keyboard-choice-tip", "Ne pitaj ponovo za ovaj udaljeni računar"),
         ("Why this happens", "Zašto se ovo dešava"),
+        ("Switch display", "Промени екран"),
+        ("Show monitor switch button on the main toolbar", "Прикажи дугме за пребацивање монитора на главној траци са алаткама"),
+        ("Show on the minimized toolbar", "Прикажи на умањеној траци са алаткама"),
     ].iter().cloned().collect();
 }

src/lang/sv.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Återställ val av tangentbordsinmatning"),
         ("remember-wayland-keyboard-choice-tip", "Fråga inte igen för den här fjärrdatorn"),
         ("Why this happens", "Varför detta händer"),
+        ("Switch display", "Växla skärm"),
+        ("Show monitor switch button on the main toolbar", "Visa knapp för skärmväxling i huvudverktygsfältet"),
+        ("Show on the minimized toolbar", "Visa i det minimerade verktygsfältet"),
     ].iter().cloned().collect();
 }

src/lang/ta.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "விசைப்பலகை உள்ளீட்டுத் தேர்வை மீட்டமை"),
         ("remember-wayland-keyboard-choice-tip", "இந்தத் தொலை கணினிக்கு மீண்டும் கேட்க வேண்டாம்"),
         ("Why this happens", "இது ஏன் நிகழ்கிறது"),
+        ("Switch display", "திரையை மாற்று"),
+        ("Show monitor switch button on the main toolbar", "முதன்மை கருவிப்பட்டையில் திரை மாற்று பொத்தானைக் காட்டு"),
+        ("Show on the minimized toolbar", "சிறிதாக்கப்பட்ட கருவிப்பட்டையில் காட்டு"),
     ].iter().cloned().collect();
 }

src/lang/template.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", ""),
         ("remember-wayland-keyboard-choice-tip", ""),
         ("Why this happens", ""),
+        ("Switch display", ""),
+        ("Show monitor switch button on the main toolbar", ""),
+        ("Show on the minimized toolbar", ""),
     ].iter().cloned().collect();
 }

src/lang/th.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "รีเซ็ตตัวเลือกการป้อนข้อมูลจากคีย์บอร์ด"),
         ("remember-wayland-keyboard-choice-tip", "ไม่ต้องถามอีกสำหรับคอมพิวเตอร์ปลายทางนี้"),
         ("Why this happens", "เหตุใดจึงเกิดขึ้น"),
+        ("Switch display", "สลับจอแสดงผล"),
+        ("Show monitor switch button on the main toolbar", "แสดงปุ่มสลับจอภาพบนแถบเครื่องมือหลัก"),
+        ("Show on the minimized toolbar", "แสดงบนแถบเครื่องมือที่ย่อเล็กสุด"),
     ].iter().cloned().collect();
 }

src/lang/tr.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Klavye girişi seçimini sıfırla"),
         ("remember-wayland-keyboard-choice-tip", "Bu uzak bilgisayar için bir daha sorma"),
         ("Why this happens", "Bunun nedeni"),
+        ("Switch display", "Ekranı değiştir"),
+        ("Show monitor switch button on the main toolbar", "Ana araç çubuğunda monitör değiştirme düğmesini göster"),
+        ("Show on the minimized toolbar", "Simge durumuna küçültülmüş araç çubuğunda göster"),
     ].iter().cloned().collect();
 }

src/lang/tw.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "重設鍵盤輸入選擇"),
         ("remember-wayland-keyboard-choice-tip", "不要再為此遠端電腦詢問"),
         ("Why this happens", "發生原因"),
+        ("Switch display", "切換螢幕"),
+        ("Show monitor switch button on the main toolbar", "在主工具列上顯示螢幕切換按鈕"),
+        ("Show on the minimized toolbar", "在最小化工具列上顯示"),
     ].iter().cloned().collect();
 }

src/lang/uk.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Скинути вибір щодо введення з клавіатури"),
         ("remember-wayland-keyboard-choice-tip", "Більше не запитувати для цього віддаленого комп'ютера"),
         ("Why this happens", "Чому це відбувається"),
+        ("Switch display", "Перемкнути дисплей"),
+        ("Show monitor switch button on the main toolbar", "Показувати кнопку перемикання монітора на головній панелі інструментів"),
+        ("Show on the minimized toolbar", "Показувати на згорнутій панелі інструментів"),
     ].iter().cloned().collect();
 }

src/lang/vi.rs

@@ -758,5 +758,8 @@ pub static ref T: std::collections::HashMap<&'static str, &'static str> =
         ("wayland-keyboard-input-reset-choice-tip", "Đặt lại lựa chọn nhập bàn phím"),
         ("remember-wayland-keyboard-choice-tip", "Không hỏi lại cho máy tính từ xa này"),
         ("Why this happens", "Tại sao điều này xảy ra"),
+        ("Switch display", "Chuyển màn hình"),
+        ("Show monitor switch button on the main toolbar", "Hiển thị nút chuyển đổi màn hình trên thanh công cụ chính"),
+        ("Show on the minimized toolbar", "Hiển thị trên thanh công cụ thu nhỏ"),
     ].iter().cloned().collect();
 }

src/platform/linux_desktop_manager.rs

@@ -462,10 +462,14 @@ impl DesktopManager {
         let (child_xorg, child_wm) = Self::start_x11(uid, gid, username, display_num, &envs)?;
         is_child_running.store(true, Ordering::SeqCst);
 
+        // capture the logind session scope (from a live child) for teardown, see
+        // reap_session_scope.
+        let scope_dir = Self::session_scope_dir(child_xorg.id());
+
         log::info!("Start xorg and wm done, notify and wait xtop x11");
         allow_err!(tx_res.send("".to_owned()));
 
-        Self::wait_stop_x11(child_xorg, child_wm);
+        Self::wait_stop_x11(child_xorg, child_wm, scope_dir, display_num);
         log::info!("Wait x11 stop done");
         Ok(())
     }
@@ -665,7 +669,222 @@ impl DesktopManager {
         }
     }
 
-    fn try_wait_stop_x11(child_xorg: &mut Child, child_wm: &mut Child) -> bool {
+    // resolve the "session-<id>.scope" directory pam_systemd put the x session in, read
+    // from a live child pid. cgroup v2 mounts every cgroup under /sys/fs/cgroup, v1/hybrid
+    // keeps the scope under the systemd controller mount; pick by the controller field and
+    // confirm the cgroup is real. empty if there is no such scope (e.g. no logind).
+    fn session_scope_dir(pid: u32) -> String {
+        let path = format!("/proc/{}/cgroup", pid);
+        let content = match std::fs::read_to_string(&path) {
+            Ok(c) => c,
+            Err(e) => {
+                log::warn!("Failed to read {} to find session scope: {}", path, e);
+                return "".to_owned();
+            }
+        };
+        for line in content.lines() {
+            // "<hierarchy>:<controllers>:<path>"; v2 unified is "0::<path>", the v1
+            // systemd hierarchy is "<n>:name=systemd:<path>".
+            let mut fields = line.splitn(3, ':');
+            let (controllers, cgroup) = match (fields.next(), fields.next(), fields.next()) {
+                (Some(_), Some(c), Some(p)) => (c, p),
+                _ => continue,
+            };
+            let scope = match Self::session_scope(cgroup) {
+                Some(s) => s,
+                None => continue,
+            };
+            let mount = if controllers.is_empty() {
+                "/sys/fs/cgroup"
+            } else if controllers.split(',').any(|c| c == "name=systemd") {
+                "/sys/fs/cgroup/systemd"
+            } else {
+                continue;
+            };
+            let dir = format!("{}{}", mount, scope);
+            if Path::new(&format!("{}/cgroup.procs", dir)).exists() {
+                return dir;
+            }
+        }
+        "".to_owned()
+    }
+
+    // the "/.../session-<id>.scope" prefix of a cgroup path, dropping any nested child
+    // cgroup below it so a descendant scope does not get mistaken for the session.
+    fn session_scope(cgroup: &str) -> Option<String> {
+        let mut scope = String::new();
+        for comp in cgroup.split('/').filter(|c| !c.is_empty()) {
+            scope.push('/');
+            scope.push_str(comp);
+            if comp.starts_with("session-") && comp.ends_with(".scope") {
+                return Some(scope);
+            }
+        }
+        None
+    }
+
+    // on teardown reap the whole session scope subtree, not just the xorg + wm pids:
+    // the per-session pipewire and other desktop children otherwise outlive them and
+    // hold the logind session in "closing", leaking sockets + displays on reconnect
+    // (rustdesk/rustdesk#15183). SIGTERM first so pipewire unlinks its sockets, then
+    // SIGKILL stragglers; skip our own pid (pam put the service in the scope too).
+    fn reap_session_scope(scope_dir: &str) {
+        if scope_dir.is_empty() {
+            return;
+        }
+        let me = std::process::id();
+        // spare the --server's own children and any descendants of them sharing this scope
+        // (see pid_is_spared); only the desktop session's leftovers are reaped.
+        let spared: Vec<u32> = crate::server::CHILD_PROCESS
+            .lock()
+            .unwrap()
+            .iter()
+            .map(|c| c.id())
+            .collect();
+        for sig in [hbb_common::libc::SIGTERM, hbb_common::libc::SIGKILL] {
+            let mut pids = Vec::new();
+            Self::collect_scope_pids(Path::new(scope_dir), &mut pids);
+            let mut any = false;
+            for pid in pids {
+                if pid == me || Self::pid_is_spared(pid, &spared, me) {
+                    continue;
+                }
+                any = true;
+                log::info!("Reaping leftover session process {} (signal {})", pid, sig);
+                unsafe {
+                    if hbb_common::libc::kill(pid as hbb_common::libc::pid_t, sig) != 0 {
+                        let err = std::io::Error::last_os_error();
+                        // ESRCH = it already exited (or did between snapshot and now).
+                        if err.raw_os_error() != Some(hbb_common::libc::ESRCH) {
+                            log::warn!("Failed to signal session process {}: {}", pid, err);
+                        }
+                    }
+                }
+            }
+            if !any {
+                break;
+            }
+            if sig == hbb_common::libc::SIGTERM {
+                std::thread::sleep(Duration::from_millis(300));
+            }
+        }
+    }
+
+    // a tracked --server child (the sudo wrapper run_as_user spawns) or any descendant of
+    // one: with use_pty sudo runs --cm-no-ui under a monitor with its own pid, so walk the
+    // parent chain (stopping at the --server) to spare the worker, not just the wrapper.
+    fn pid_is_spared(pid: u32, spared: &[u32], me: u32) -> bool {
+        let mut cur = pid;
+        for _ in 0..32 {
+            if spared.contains(&cur) {
+                return true;
+            }
+            if cur <= 1 || cur == me {
+                return false;
+            }
+            match Self::parent_pid(cur) {
+                Some(ppid) => cur = ppid,
+                None => return false,
+            }
+        }
+        false
+    }
+
+    fn parent_pid(pid: u32) -> Option<u32> {
+        // /proc/<pid>/stat is "pid (comm) state ppid ..."; comm can contain spaces and ')',
+        // so read the fields after the last ')'.
+        let stat = std::fs::read_to_string(format!("/proc/{}/stat", pid)).ok()?;
+        stat.rsplit_once(')')?
+            .1
+            .split_whitespace()
+            .nth(1)?
+            .parse()
+            .ok()
+    }
+
+    // collect every pid in the cgroup subtree rooted at dir. "cgroup.procs" lists only
+    // the procs directly in a cgroup, so recurse into child cgroup directories to catch
+    // processes the desktop session moved into descendant scopes.
+    fn collect_scope_pids(dir: &Path, out: &mut Vec<u32>) {
+        let procs = dir.join("cgroup.procs");
+        match std::fs::read_to_string(&procs) {
+            Ok(content) => {
+                out.extend(content.lines().filter_map(|l| l.trim().parse::<u32>().ok()));
+            }
+            Err(e) if e.kind() != std::io::ErrorKind::NotFound => {
+                log::warn!("Failed to read {}: {}", procs.display(), e);
+            }
+            Err(_) => {}
+        }
+        let entries = match std::fs::read_dir(dir) {
+            Ok(e) => e,
+            Err(e) if e.kind() != std::io::ErrorKind::NotFound => {
+                log::warn!("Failed to list cgroup dir {}: {}", dir.display(), e);
+                return;
+            }
+            Err(_) => return,
+        };
+        for entry in entries {
+            let entry = match entry {
+                Ok(entry) => entry,
+                Err(e) => {
+                    log::warn!("Failed to read entry under {}: {}", dir.display(), e);
+                    continue;
+                }
+            };
+            match entry.file_type() {
+                Ok(t) if t.is_dir() => Self::collect_scope_pids(&entry.path(), out),
+                Ok(_) => {}
+                Err(e) if e.kind() != std::io::ErrorKind::NotFound => {
+                    log::warn!("Failed to stat {}: {}", entry.path().display(), e);
+                }
+                Err(_) => {}
+            }
+        }
+    }
+
+    // a SIGKILL'd Xorg (how wait_x11_children_exit ends it) leaves "/tmp/.X<n>-lock" and
+    // "/tmp/.X11-unix/X<n>" behind, and get_avail_display() treats either file as "display
+    // in use", so the number is never reused and climbs until none are free
+    // (rustdesk/rustdesk#15183). a clean exit would remove them; do the same on teardown,
+    // but skip it if a live process still holds the lock: another server could have taken
+    // the number in the gap, and removing its files would break that display.
+    fn cleanup_x_display_files(display_num: u32) {
+        let lock = format!("/tmp/.X{}-lock", display_num);
+        if let Ok(content) = std::fs::read_to_string(&lock) {
+            if let Ok(pid) = content.trim().parse::<i32>() {
+                if Self::pid_alive(pid) {
+                    log::info!("X display {} still held by pid {}, leaving its files", display_num, pid);
+                    return;
+                }
+            }
+        }
+        for path in [lock, format!("/tmp/.X11-unix/X{}", display_num)] {
+            if let Err(e) = std::fs::remove_file(&path) {
+                if e.kind() != std::io::ErrorKind::NotFound {
+                    log::warn!("Failed to remove stale X file {}: {}", path, e);
+                }
+            }
+        }
+    }
+
+    // signal-0 probe: the pid exists if kill succeeds or fails with EPERM (alive but not
+    // ours); only ESRCH means it is gone.
+    fn pid_alive(pid: i32) -> bool {
+        unsafe {
+            if hbb_common::libc::kill(pid as hbb_common::libc::pid_t, 0) == 0 {
+                return true;
+            }
+        }
+        std::io::Error::last_os_error().raw_os_error() == Some(hbb_common::libc::EPERM)
+    }
+
+    fn try_wait_stop_x11(
+        child_xorg: &mut Child,
+        child_wm: &mut Child,
+        scope_dir: &str,
+        display_num: u32,
+    ) -> bool {
         let mut desktop_manager = DESKTOP_MANAGER.lock().unwrap();
         let mut exited = true;
         if let Some(desktop_manager) = &mut (*desktop_manager) {
@@ -677,6 +896,8 @@ impl DesktopManager {
             if exited {
                 log::debug!("Wait x11 children exiting");
                 Self::wait_x11_children_exit(child_xorg, child_wm);
+                Self::reap_session_scope(scope_dir);
+                Self::cleanup_x_display_files(display_num);
                 desktop_manager
                     .is_child_running
                     .store(false, Ordering::SeqCst);
@@ -686,9 +907,14 @@ impl DesktopManager {
         exited
     }
 
-    fn wait_stop_x11(mut child_xorg: Child, mut child_wm: Child) {
+    fn wait_stop_x11(
+        mut child_xorg: Child,
+        mut child_wm: Child,
+        scope_dir: String,
+        display_num: u32,
+    ) {
         loop {
-            if Self::try_wait_stop_x11(&mut child_xorg, &mut child_wm) {
+            if Self::try_wait_stop_x11(&mut child_xorg, &mut child_wm, &scope_dir, display_num) {
                 break;
             }
             std::thread::sleep(Duration::from_millis(super::SERVICE_INTERVAL));
@@ -806,3 +1032,54 @@ fn pam_get_service_name() -> String {
         "gdm".to_owned()
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn session_scope_truncates_at_first_scope() {
+        assert_eq!(
+            DesktopManager::session_scope("/user.slice/user-1000.slice/session-3.scope").as_deref(),
+            Some("/user.slice/user-1000.slice/session-3.scope")
+        );
+        // a nested child scope must not be mistaken for the session
+        assert_eq!(
+            DesktopManager::session_scope(
+                "/user.slice/user-1000.slice/session-3.scope/app-foo.scope"
+            )
+            .as_deref(),
+            Some("/user.slice/user-1000.slice/session-3.scope")
+        );
+        assert_eq!(
+            DesktopManager::session_scope(
+                "/user.slice/user-1000.slice/user@1000.service/app.slice/x.service"
+            ),
+            None
+        );
+        assert_eq!(DesktopManager::session_scope("/"), None);
+    }
+
+    #[test]
+    fn collect_scope_pids_walks_descendant_cgroups() {
+        // regression for #15183: pids in descendant cgroups must be collected too
+        let base = std::env::temp_dir().join(format!("rustdesk-cgtest-{}", std::process::id()));
+        let _ = std::fs::remove_dir_all(&base);
+        let scope = base.join("session-3.scope");
+        let child = scope.join("app-foo.scope");
+        let nested = child.join("deeper.scope");
+        std::fs::create_dir_all(&nested).unwrap();
+        std::fs::create_dir_all(scope.join("empty.scope")).unwrap();
+        std::fs::write(scope.join("cgroup.procs"), "100\n101\n").unwrap();
+        std::fs::write(scope.join("cgroup.controllers"), "memory pids\n").unwrap();
+        std::fs::write(child.join("cgroup.procs"), "200\n").unwrap();
+        std::fs::write(nested.join("cgroup.procs"), "300\n").unwrap();
+
+        let mut pids = Vec::new();
+        DesktopManager::collect_scope_pids(&scope, &mut pids);
+        pids.sort();
+        let _ = std::fs::remove_dir_all(&base);
+
+        assert_eq!(pids, vec![100, 101, 200, 300]);
+    }
+}