feat(t3_code): add T3 Code AppImage launcher and desktop entry

users/richie/home/gui/default.nix

@@ -7,6 +7,7 @@
     ./firefox
     ./kitty.nix
     ./llm_tools.nix
+    ./t3_code
     ./vscode
   ];
 

users/richie/home/gui/t3_code/default.nix

@@ -0,0 +1,36 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+let
+  t3-code = pkgs.writeShellApplication {
+    name = "t3-code";
+    runtimeInputs = with pkgs; [
+      coreutils
+      kdePackages.kdialog
+    ];
+    text = builtins.readFile ./launch.sh;
+  };
+in
+{
+  home = {
+    # AppImages are runnable from a shell as well
+    sessionPath = [ "${config.home.homeDirectory}/app_images" ];
+    packages = [ t3-code ];
+  };
+
+  # KDE builds its menu from desktop entries, not from PATH
+  xdg.desktopEntries.t3-code = {
+    name = "T3 Code";
+    genericName = "Code Editor";
+    comment = "Newest T3 Code AppImage in ~/app_images";
+    exec = "${lib.getExe t3-code} %U";
+    icon = "${./icon.png}";
+    terminal = false;
+    categories = [ "Development" ];
+    startupNotify = true;
+    settings.StartupWMClass = "t3code";
+  };
+}

users/richie/home/gui/t3_code/launch.sh

@@ -0,0 +1,25 @@
+# Launch the newest T3 Code AppImage in the app image directory.
+#
+# The nightly builds carry the version in the file name, so the file to run is
+# resolved at launch time rather than baked into the desktop entry.
+# No shebang: this is wrapped by writeShellApplication, which supplies one.
+
+dir="${T3_CODE_DIR:-$HOME/app_images}"
+
+shopt -s nullglob
+images=("$dir"/T3-Code-*.AppImage)
+
+if [ "${#images[@]}" -eq 0 ]; then
+  msg="No T3 Code AppImage found in $dir"
+  echo "$msg" >&2
+  # launched from KDE there is no terminal to read, so say it on screen too
+  kdialog --error "$msg" || true
+  exit 1
+fi
+
+img="$(printf '%s\n' "${images[@]}" | sort -V | tail -n1)"
+[ -x "$img" ] || chmod +x "$img"
+
+# --no-sandbox matches the AppImage's own desktop entry; binfmt hands the
+# AppImage off to appimage-run.
+exec "$img" --no-sandbox "$@"