restart podman when refresh

nixos/linux.nix

@@ -18,6 +18,8 @@
   nixPkgs = specialArgs.nixPkgs;
   ourRustVersion = pkgs.rust-bin.selectLatestNightlyWith (toolchain: toolchain.complete);
 
+  vncContext = builtins.path { path = ./vnc-desktop; name = "vnc-desktop-context"; };
+
   ourRustPlatform = nixPkgs.makeRustPlatform {
     rustc = ourRustVersion;
     cargo = ourRustVersion;
@@ -115,8 +117,8 @@ in {
   systemd.services.arion-riverside.environment.DOCKER_HOST = "unix:///run/podman/podman.sock";
 
   # Build the VNC desktop image locally from the Dockerfile — no registry push/pull needed.
-  # Nix copies the build context into the store; the hash changes when Dockerfile or
-  # start.sh change, triggering a rebuild on the next nixos-rebuild switch.
+  # vncContext is a Nix store path that changes whenever any file under vnc-desktop/ changes,
+  # which causes build-vnc-image to re-run and podman-vnc-desktop to restart on nixos-rebuild.
   systemd.services.build-vnc-image = {
     description = "Build VNC desktop container image from Dockerfile";
     wantedBy = [ "podman-vnc-desktop.service" ];
@@ -126,9 +128,7 @@ in {
       RemainAfterExit = true;
       ExecStart = pkgs.writeShellScript "build-vnc-image" ''
         STAMP=/var/lib/build-vnc-image/context-hash
-        EXPECTED="${builtins.hashString "sha256"
-          (builtins.readFile ./vnc-desktop/Dockerfile +
-           builtins.readFile ./vnc-desktop/start.sh)}"
+        EXPECTED="${vncContext}"
         if [ -f "$STAMP" ] && [ "$(cat "$STAMP")" = "$EXPECTED" ]; then
           echo "VNC image is up to date, skipping build"
           exit 0
@@ -136,13 +136,15 @@ in {
         echo "Building VNC desktop image..."
         ${pkgs.podman}/bin/podman build \
           -t forge.quinefoundation.com/ironmagma/vnc-desktop:latest \
-          ${./vnc-desktop}
+          ${vncContext}
         mkdir -p "$(dirname "$STAMP")"
         echo "$EXPECTED" > "$STAMP"
       '';
     };
   };
 
+  systemd.services.podman-vnc-desktop.restartTriggers = [ "${vncContext}" ];
+
   services.gitea-actions-runner.instances."ubuntu" = {
     enable = true;
     name = "ubuntu";