yarn: fix impermiance home directory

system/impermanence.nix

@@ -21,12 +21,15 @@
       "/etc/ssh/ssh_host_rsa_key.pub"
       "/etc/machine-id"
     ];
+  };
 
-    users.${username} = {
-      directories = [
-        "."
-      ];
-    };
+  # Bind mount entire home directory from persistent storage
+  # (impermanence doesn't support "." so we do this directly)
+  fileSystems."/home/${username}" = {
+    device = "/persistent/home/${username}";
+    fsType = "none";
+    options = [ "bind" ];
+    neededForBoot = true;
   };
 
   systemd.tmpfiles.rules = [

system/system-yarn.nix

@@ -75,6 +75,71 @@
       "steam-run"
     ];
 
+  # Override jovian-stubs to disable steamos-update kernel check
+  # This prevents Steam from requesting reboots for "system updates"
+  # Steam client updates will still work normally
+  nixpkgs.overlays = [
+    (final: prev: {
+      jovian-stubs = prev.stdenv.mkDerivation {
+        name = "jovian-stubs-no-update";
+        dontUnpack = true;
+        installPhase = ''
+          mkdir -p $out/bin
+
+          # steamos-update: always report "no update available" (exit 7)
+          # This disables the kernel mismatch check that triggers reboot prompts
+          cat > $out/bin/steamos-update << 'STUB'
+          #!/bin/sh
+          >&2 echo "[JOVIAN] $0: stub called with: $* (system updates disabled)"
+          exit 7
+          STUB
+
+          # steamos-reboot: reboot the system
+          cat > $out/bin/steamos-reboot << 'STUB'
+          #!/bin/sh
+          >&2 echo "[JOVIAN] $0: stub called with: $*"
+          systemctl reboot
+          STUB
+
+          # steamos-select-branch: no-op stub
+          cat > $out/bin/steamos-select-branch << 'STUB'
+          #!/bin/sh
+          >&2 echo "[JOVIAN] $0: stub called with: $*"
+          exit 0
+          STUB
+
+          # steamos-factory-reset-config: no-op stub
+          cat > $out/bin/steamos-factory-reset-config << 'STUB'
+          #!/bin/sh
+          >&2 echo "[JOVIAN] $0: stub called with: $*"
+          exit 0
+          STUB
+
+          # steamos-firmware-update: no-op stub
+          cat > $out/bin/steamos-firmware-update << 'STUB'
+          #!/bin/sh
+          >&2 echo "[JOVIAN] $0: stub called with: $*"
+          exit 0
+          STUB
+
+          # pkexec: pass through to real pkexec
+          cat > $out/bin/pkexec << 'STUB'
+          #!/bin/sh
+          exec /run/wrappers/bin/pkexec "$@"
+          STUB
+
+          # sudo: pass through to doas
+          cat > $out/bin/sudo << 'STUB'
+          #!/bin/sh
+          exec /run/wrappers/bin/doas "$@"
+          STUB
+
+          chmod 755 $out/bin/*
+        '';
+      };
+    })
+  ];
+
   jovian = {
     devices.steamdeck.enable = false;
     steam = {