diff --git a/tests/tools/test_bot_desktop_install.py b/tests/tools/test_bot_desktop_install.py
index 820f92d16c..afef3220eb 100644
--- a/tests/tools/test_bot_desktop_install.py
+++ b/tests/tools/test_bot_desktop_install.py
@@ -126,6 +126,9 @@ def test_passwordless_sudo_runs_the_install_without_asking_for_a_password(monkey
         def wait(self, timeout=None):
             return 0
 
+        def poll(self):
+            return 0
+
     monkeypatch.setattr(install.subprocess, "Popen", _Proc)
     monkeypatch.setattr(install.os, "killpg", lambda *a: None)
     lines: list[str] = []
@@ -204,3 +207,41 @@ def test_no_sudo_binary_returns_the_host_command_instead_of_a_password_card(monk
                                     on_line=lines.append)
     assert code == install.NO_SUDO
     assert any("apt-get install" in line for line in lines), lines
+
+
+def test_timeout_finishes_the_group_when_only_the_leader_dies_on_term(monkeypatch):
+    """TERM ends the leader shell at once, but a descendant in the same group that ignores TERM used to be
+    left alive holding the dpkg lock: the kill helper returned as soon as the leader was reaped. Cleanup is
+    done only when the whole process group is gone."""
+    import subprocess
+    import time
+
+    monkeypatch.setattr(install, "_sudo_nopasswd", lambda: True)
+    monkeypatch.setattr(install, "_TERM_GRACE_SECONDS", 0.3, raising=False)
+    real_popen = subprocess.Popen
+
+    def popen(argv, **kw):
+        if argv[:1] != ["sudo"]:
+            return real_popen(argv, **kw)
+        return real_popen(["sh", "-c", "sh -c 'trap \"\" TERM; echo child $$; sleep 30' & wait"], **kw)
+
+    monkeypatch.setattr(install.subprocess, "Popen", popen)
+    lines: list[str] = []
+    install.install_packages(ask_password=lambda: "", on_line=lines.append, timeout_seconds=0.5)
+    child = next(int(line.split()[1]) for line in lines if line.startswith("child "))
+    deadline = time.monotonic() + 2.0
+    while time.monotonic() < deadline and _alive(child):
+        time.sleep(0.05)
+    try:
+        assert not _alive(child), "the TERM-ignoring descendant survived the timeout cleanup"
+    finally:
+        subprocess.run(["kill", "-9", str(child)], check=False)
+
+
+def _alive(pid: int) -> bool:
+    import os
+    try:
+        os.kill(pid, 0)
+    except ProcessLookupError:
+        return False
+    return True
diff --git a/tools/bot_desktop/install.py b/tools/bot_desktop/install.py
index 1f66d9ce6b..58765c1c97 100644
--- a/tools/bot_desktop/install.py
+++ b/tools/bot_desktop/install.py
@@ -129,6 +129,8 @@ def _run(cmd: str, *, ask_password: Callable[[], str], on_line: Callable[[str],
         return proc.returncode if proc.returncode is not None else -9
     finally:
         proc.stdout.close()  # type: ignore[union-attr]
+        if proc.poll() is None:  # the drain raised (a failing on_line sink): the slot is released, so no orphan
+            _kill_group(proc)
 
 
 _TERM_GRACE_SECONDS = 5.0
@@ -166,9 +168,24 @@ def _kill_group(proc: subprocess.Popen) -> None:
     apt/dnf running as root with the dpkg lock while the slot is released, so the whole group goes: TERM
     first so dpkg can finish its transaction, KILL after the grace. Best effort — as non-root neither
     signal reaches a root-owned child, which is why the caller never waits on EOF."""
+    def _group_gone() -> bool:
+        try:
+            os.killpg(proc.pid, 0)  # windows-footgun: ok — Linux-only (is_supported_host)
+        except ProcessLookupError:
+            return True
+        except PermissionError:
+            return False  # a root-owned child is still there
+        return False
+
     for sig, grace in ((signal.SIGTERM, _TERM_GRACE_SECONDS), (signal.SIGKILL, 1.0)):  # windows-footgun: ok — Linux-only (is_supported_host)
         with contextlib.suppress(ProcessLookupError, PermissionError):
             os.killpg(proc.pid, sig)  # windows-footgun: ok — Linux-only (is_supported_host)
         with contextlib.suppress(subprocess.TimeoutExpired):
             proc.wait(timeout=grace)
+        # The leader (sudo / the package manager) going away is not the end: wait for the whole group so a
+        # TERM-ignoring descendant gets the KILL round instead of surviving with the dpkg lock.
+        deadline = time.monotonic() + grace
+        while time.monotonic() < deadline and not _group_gone():
+            time.sleep(0.05)
+        if _group_gone():
             return
diff --git a/tools/bot_desktop/runtime.py b/tools/bot_desktop/runtime.py
index 1360eb7205..fadeef6479 100644
--- a/tools/bot_desktop/runtime.py
+++ b/tools/bot_desktop/runtime.py
@@ -231,10 +231,23 @@ def _kill_group_then_wait(pgid: Optional[int], pid: int, grace: float = 2.0) ->
                 os.killpg(pgid, sig)  # windows-footgun: ok — Linux-only runtime (is_supported_host gates start/stop)
             else:
                 os.kill(pid, sig)
+    def _anything_left() -> bool:
+        # The leader dying first is the common case (bash exits on TERM, Xvnc traps it); the group is
+        # done only when killpg(0) finds nobody, else a TERM-ignoring descendant keeps the display.
+        if pgid is None:
+            return _pid_alive(pid)
+        try:
+            os.killpg(pgid, 0)  # windows-footgun: ok — Linux-only runtime (is_supported_host gates start/stop)
+        except ProcessLookupError:
+            return False
+        except PermissionError:
+            return True
+        return True
+
     _signal(signal.SIGTERM)
     deadline = time.monotonic() + grace
     while time.monotonic() < deadline:
-        if not _pid_alive(pid):
+        if not _anything_left():
             return
         time.sleep(0.05)
     _signal(signal.SIGKILL)  # windows-footgun: ok — Linux-only runtime (is_supported_host gates start/stop)