fix(nix): restore desktop integration (#37197)

Co-authored-by: Test User <test@test.com>

nix/desktop.nix

@@ -8,6 +8,8 @@
   makeWrapper,
   writableTmpDirAsHomeHook,
   autoPatchelfHook,
+  copyDesktopItems,
+  makeDesktopItem,
   opencode,
 }:
 let
@@ -27,9 +29,12 @@ stdenv.mkDerivation (finalAttrs: {
     nodejs
     makeWrapper
     writableTmpDirAsHomeHook
-  ] ++ lib.optionals stdenv.hostPlatform.isLinux [
+  ]
+  ++ lib.optionals stdenv.hostPlatform.isLinux [
     autoPatchelfHook
-  ] ++ lib.optionals stdenv.hostPlatform.isDarwin [
+    copyDesktopItems
+  ]
+  ++ lib.optionals stdenv.hostPlatform.isDarwin [
     # Ad-hoc sign the .app: --config.mac.identity=null below skips signing.
     darwin.autoSignDarwinBinariesHook
   ];
@@ -38,6 +43,16 @@ stdenv.mkDerivation (finalAttrs: {
     (lib.getLib stdenv.cc.cc)
   ];
 
+  desktopItems = lib.optional stdenv.hostPlatform.isLinux (makeDesktopItem {
+    name = "ai.opencode.desktop";
+    desktopName = "OpenCode";
+    exec = "opencode-desktop %U";
+    icon = "ai.opencode.desktop";
+    # Electron 41 derives X11 WM_CLASS from app.name.
+    startupWMClass = "OpenCode";
+    categories = [ "Development" ];
+  });
+
   env = opencode.env // {
     ELECTRON_SKIP_BINARY_DOWNLOAD = "1";
   };
@@ -83,8 +98,7 @@ stdenv.mkDerivation (finalAttrs: {
     runHook postBuild
   '';
 
-  installPhase =
-    ''
+  installPhase = ''
     runHook preInstall
   ''
   + lib.optionalString stdenv.hostPlatform.isDarwin ''
@@ -95,6 +109,18 @@ stdenv.mkDerivation (finalAttrs: {
   + lib.optionalString stdenv.hostPlatform.isLinux ''
     mkdir -p $out/opt/opencode-desktop
     cp -r dist/linux*-unpacked/{resources,LICENSE*} $out/opt/opencode-desktop
+    install -Dm644 resources/icons/32x32.png \
+      "$out/share/icons/hicolor/32x32/apps/ai.opencode.desktop.png"
+    install -Dm644 resources/icons/64x64.png \
+      "$out/share/icons/hicolor/64x64/apps/ai.opencode.desktop.png"
+    install -Dm644 resources/icons/128x128.png \
+      "$out/share/icons/hicolor/128x128/apps/ai.opencode.desktop.png"
+    install -Dm644 resources/icons/128x128@2x.png \
+      "$out/share/icons/hicolor/256x256/apps/ai.opencode.desktop.png"
+    install -Dm644 resources/icons/icon.png \
+      "$out/share/icons/hicolor/512x512/apps/ai.opencode.desktop.png"
+    install -Dm644 resources/ai.opencode.desktop.metainfo.xml \
+      "$out/share/metainfo/ai.opencode.desktop.metainfo.xml"
     makeWrapper ${lib.getExe electron} $out/bin/opencode-desktop \
      --inherit-argv0 \
      --set ELECTRON_FORCE_IS_PACKAGED 1 \