Dont enable the sysext in the live session.

mkosi.extra/usr/bin/set-up-systemd-extension

@@ -33,7 +33,7 @@ else
     sudo chattr +i "${SYSEXT_LOCATION}/extension-release.kde"
 
     # Turn it on!
-    sudo systemd-sysext merge
+    sudo systemd-sysext refresh || sudo systemd-sysext merge
 
     echo "Finished setting up extension! When you put files in ${SYSEXT_BASE_LOCATION} and run 'sudo systemd-sysext refresh', they will appear in /usr/. See https://community.kde.org/KDE_Linux/Add_or_override_content_in_/usr for more information."
 fi

mkosi.extra/usr/lib/systemd/system-preset/50-kde-linux.preset

@@ -47,6 +47,7 @@ enable kde-linux-powertop.service
 enable kde-linux-volatile-var-lib-flatpak.service
 enable kde-linux-sysupdated.socket
 enable plasma-setup-live-system.service
+enable sysext-trigger.service
 
 # KMSCON
 enable kmsconvt@

mkosi.extra/usr/lib/systemd/system/sysext-trigger.service

@@ -0,0 +1,32 @@
+# SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
+# SPDX-FileCopyrightText: 2026 Hadi Chokr <hadichokr@icloud.com>
+
+[Unit]
+Description=Prepare sysext trigger and routing (installed system only)
+DefaultDependencies=no
+After=local-fs.target
+Before=systemd-sysext.service
+ConditionPathExists=!/live/
+ConditionKernelCommandLine=!kde-linux.live=1
+
+[Service]
+Type=oneshot
+
+# --- Ensure base dirs exist ---
+ExecStart=/usr/bin/mkdir -p /var/lib/extensions
+ExecStart=/usr/bin/mkdir -p /var/lib/extensions.mutable/usr
+ExecStart=/usr/bin/mkdir -p /var/lib/extensions.mutable/.systemd-usr-workdir
+
+# --- Ensure correct permissions ---
+ExecStart=/usr/bin/chmod 0755 /var/lib/extensions.mutable
+ExecStart=/usr/bin/chmod 0755 /var/lib/extensions.mutable/usr
+ExecStart=/usr/bin/chmod 0700 /var/lib/extensions.mutable/.systemd-usr-workdir
+
+# --- Route /usr/local → /opt/local ---
+ExecStart=/usr/bin/ln -sfn /opt/local /var/lib/extensions.mutable/usr/local
+
+# --- Trigger sysext normally ---
+ExecStart=/usr/bin/touch /var/lib/extensions/auto-enable
+
+[Install]
+WantedBy=sysinit.target

mkosi.extra/usr/lib/tmpfiles.d/sysext-trigger.conf

@@ -1,6 +0,0 @@
-# SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
-# SPDX-FileCopyrightText: 2026 Hadi Chokr <hadichokr@icloud.com>
-
-# Will trigger the systemd-sysext.service Condition to merge Extensions
-# TODO: Remove when https://github.com/systemd/systemd/issues/40827 is fixed
-f /etc/extensions/enable-sysext 0644 root root -

mkosi.extra/usr/lib/tmpfiles.d/usr-local.conf

@@ -19,10 +19,3 @@ d /opt/local/src           0755 root root -
 d /opt/local/etc/xdg       0755 root root -
 d /opt/local/lib/pkgconfig 0755 root root -
 d /opt/local/share/pkgconfig 0755 root root -
-
-# sysext-routing
-d /var/lib/extensions.mutable 0755 root root -
-d /var/lib/extensions.mutable/usr 0755 root root -
-
-# Route /usr/local → /opt/local
-L /var/lib/extensions.mutable/usr/local - - - - /opt/local