zoom: switch to Wayland & support webrtc screen sharing

i set this XDG_SESSION_TYPE=wayland system-wide because it's also needed for EVERY screensharing client. sad

hosts/common/programs/sway/default.nix

@@ -319,6 +319,13 @@ in
     # docs: <https://discourse.ubuntu.com/t/environment-variables-for-wayland-hackers/12750>
     # N.B.: gtk apps support absolute paths for this; webkit apps (e.g. geary) support only relative paths (relative to $XDG_RUNTIME_DIR)
     env.WAYLAND_DISPLAY = "wl/wayland-1";
+    # XXX(2025-07-31): XDG_SESSION_TYPE=wayland is ingested by a number of libraries/application frameworks
+    # - Qt reads this to decide X11 (default) v.s. Wayland (alternatively, set QT_QPA_PLATFORM=wayland).
+    # - webrtc screen sharing *requires* this to be set else it can only share X11 windows. <https://github.com/emersion/xdg-desktop-portal-wlr/wiki/Screencast-Compatibility>
+    #   - affects Firefox, Zoom, maybe others?
+    # - Komikku crashes without this set.
+    # - xdg-desktop-portal-gnome requires this to be set??
+    env.XDG_SESSION_TYPE = "wayland";
 
     # services.private-storage.dependencyOf = [ "sway" ];  #< HACK: prevent unl0kr and sway from fighting over the tty
     services.sway = {

hosts/common/programs/zoom-us.nix

@@ -1,11 +1,35 @@
+# FIRST TIME SETUP:
+# - in ~/.config/zoom/zoomus.conf: toggle `xwayland=true` -> `xwayland=false`
+#
+# tips for configuring zoom:
+# - <https://wiki.archlinux.org/title/Zoom_Meetings>
+# - <https://www.reddit.com/r/archlinux/comments/19ecsv5/comment/ktot9hf/>
+# webrtc screen sharing:
+# - <https://github.com/emersion/xdg-desktop-portal-wlr/wiki/Screencast-Compatibility>
+# - <https://wiki.archlinux.org/title/PipeWire#WebRTC_screen_sharing>
+# - <https://mozilla.github.io/webrtc-landing/gum_test.html>
 { pkgs, ... }:
 {
   sane.programs.zoom-us = {
-    packageUnwrapped = pkgs.zoom-us.override {
+    packageUnwrapped = (pkgs.zoom-us.override {
       xdgDesktopPortalSupport = true;  #< what does this do? who knows!
       # gnomeXdgDesktopPortalSupport = true;
       # wlrXdgDesktopPortalSupport = true;
-    };
+    });
+    # .overrideAttrs (upstream: {
+    #   # force wayland. even w/ x11 removed from the sandbox, it still manages to connect! probably it does it via the network.
+    #   # so explicitly set QT_QPA_PLATFORM=wayland, and as a precaution, unset `DISPLAY`
+    #   # XXX(2025-07-31): QT_QPA_PLATFORM=wayland is NOT needed if XDG_SESSION_TYPE=wayland is set instead.
+    #   #   XDG_SESSION_TYPE=wayland is *also* required for pipewire screen sharing to work.
+    #   #   setting anything here is no longer required, as i set XDG_SESSION_TYPE at the sway layer.
+    #   nativeBuildInputs = (upstream.nativeBuildInputs or []) ++ [
+    #     pkgs.makeShellWrapper
+    #   ];
+    #   buildCommand = upstream.buildCommand + ''
+    #     wrapProgram $out/bin/zoom \
+    #       --run 'if [[ -n "''${WAYLAND_DISPLAY:-}" ]]; then export QT_QPA_PLATFORM=wayland; unset DISPLAY; fi'
+    #   '';
+    # });
     sandbox.net = "clearnet";
     sandbox.whitelistAudio = true;
     sandbox.whitelistAvDev = true;  #< XXX(2025-05-29): it doesn't use pipewire for mic/video
@@ -16,7 +40,7 @@
       "ScreenCast"  # not sure if used
     ];
     sandbox.whitelistWayland = true;
-    sandbox.whitelistX = true;  # XXX(2025-05-29): required; TODO: try setting QP_... env vars to get native wayland?
+    # sandbox.whitelistX = true;  # XXX(2025-05-29): required; TODO: try setting QP_... env vars to get native wayland?
     sandbox.tmpDir = ".cache/.zoom";  #< tmpdir needs to be shared between instances, for the singleton socket to work (also, it needs to exist)
     mime.associations."x-scheme-handler/zoommtg" = "Zoom.desktop";  #< for when you click on a meeting link
     # TODO: .config/Unknown Organization/zoom.conf
@@ -24,6 +48,7 @@
       ".cache/zoom"  # 8MB qmlcache + 400MB app data (assets Zoom downloads at runtime instead of shipping the package) via the ~/.zoom -> .cache/zoom
       ".config/zoom"
     ];
+
     # coerce Zoom into using XDG dirs:
     fs.".zoom".symlink.target = ".cache/zoom";
     fs.".config/zoom.conf".symlink.target = "zoom/zoom.conf";