Default the x11 headless desktop to GNOME (Openbox still opt-in)

Bare Openbox rendered only a blank slate root — usable but not the
desktop wanted. Make the X11/NVENC capture path render a full GNOME
session by default, with Openbox available via HEADLESS_DESKTOP=openbox
for minimal/low-power hosts.

- files/headless-desktop-gnome.service: full Ubuntu GNOME session forced
  onto the X11 path (XDG_SESSION_TYPE=x11, no dbus-run-session so it
  shares the systemd user bus). Renamed the Openbox unit to
  headless-desktop-openbox.service.
- lib/headless.sh: HEADLESS_DESKTOP (default gnome) selects the unit
  template + the packages to install (gnome-session/gnome-shell vs
  openbox/xsetroot).
- install.sh: step message + usage document HEADLESS_DESKTOP.
- status.sh: the :0 desktop check now reports which desktop is running
  (reads _NET_WM_NAME off the supporting-wm-check window, e.g.
  "GNOME Shell").
- docs: TROUBLESHOOTING §13 + FOLLOWUPS P3 updated for the GNOME default
  and the openbox toggle.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/FOLLOWUPS.md

@@ -249,9 +249,12 @@ TROUBLESHOOTING.md §13.
 
 **Done so far**: the *desktop* piece of the x11 backend is now reproducible.
 `install.sh` detects `capture = x11` (via `capture_backend_is_x11`) and installs
-+ enables `files/headless-desktop.service` (Openbox on `:0`) so the headless
-Xorg has a window manager to render — without it, capture is a black screen.
-`status.sh` gained a matching check (FAIL if no WM on `:0`). Still outstanding:
++ enables `headless-desktop.service` so the headless Xorg has a desktop to
+render — without it, capture is a black screen. Desktop is selectable via
+`HEADLESS_DESKTOP`: `gnome` (default — full Ubuntu GNOME session, X11 path) or
+`openbox` (lightweight bare WM); each ships as its own unit template
+(`files/headless-desktop-{gnome,openbox}.service`). `status.sh` gained a matching
+check (FAIL if no desktop on `:0`, and reports which one). Still outstanding:
 the `--backend x11|wlr` flag/auto-detect, the `config.sh` x11 conf variant, and
 shipping the `xorg-headless.service` + `xorg-headless.conf` templates.
 

docs/TROUBLESHOOTING.md

@@ -490,12 +490,19 @@ DISPLAY=:0 xlsclients                              # only 'sunshine' = no WM/des
 DISPLAY=:0 xprop -root _NET_SUPPORTING_WM_CHECK    # 'not found' = no window manager
 ```
 
-Fix: run a window manager on `:0`. The installer ships a `headless-desktop.service`
-(Openbox) for exactly this and enables it whenever it detects `capture = x11`:
+Fix: run a desktop on `:0`. The installer ships a `headless-desktop.service`
+for exactly this and enables it whenever it detects `capture = x11`. It defaults
+to a full **GNOME** session (`gnome-session --session=ubuntu`, forced to the X11
+path); set `HEADLESS_DESKTOP=openbox` for a lightweight bare WM instead (lower
+overhead, but no panel/launcher — right-click menu only). The unit forces
+`XDG_SESSION_TYPE=x11` and does **not** wrap GNOME in `dbus-run-session` — GNOME
+must share the systemd *user* bus the service already inherits.
 
 ```bash
 systemctl --user enable --now headless-desktop.service
 DISPLAY=:0 xprop -root _NET_SUPPORTING_WM_CHECK    # now reports a 'window id'
+# read the running desktop's name off that window:
+DISPLAY=:0 xprop -id <id> _NET_WM_NAME             # e.g. "GNOME Shell"
 ```
 
 `status.sh` checks for this directly: with `capture = x11` it now FAILs if no

files/headless-desktop-gnome.service

@@ -0,0 +1,30 @@
+[Unit]
+Description=GNOME session on the headless Xorg (gives Sunshine something to capture)
+# Without a desktop running on :0, Sunshine's x11 capture grabs an empty black
+# X root window — pairing, NVENC, and input all work but the client sees only
+# black. This runs a full GNOME session on :0 so the stream shows a real
+# desktop. Only relevant to the X11/NVENC capture backend (capture = x11); the
+# wlr backend's compositor renders for itself.
+Requires=xorg-headless.service
+After=xorg-headless.service
+PartOf=graphical-session.target
+
+[Service]
+Type=simple
+# Force the X11 session path (not Wayland) onto the existing headless Xorg.
+# No dbus-run-session wrapper: GNOME integrates with the systemd *user* bus,
+# which this service already inherits — a fresh bus would break that.
+Environment=DISPLAY=:0
+Environment=XDG_SESSION_TYPE=x11
+Environment=XDG_CURRENT_DESKTOP=ubuntu:GNOME
+Environment=GNOME_SHELL_SESSION_MODE=ubuntu
+# Wait for the X server to accept connections before launching the session.
+ExecStartPre=/bin/sh -c 'for i in $(seq 1 20); do xset -display :0 -q >/dev/null 2>&1 && exit 0; sleep 0.5; done; exit 1'
+ExecStart=/usr/bin/gnome-session --session=ubuntu
+Restart=on-failure
+RestartSec=2s
+
+[Install]
+# Lingering user manager reaches default.target without a graphical login,
+# matching the headless-boot drop-in pattern used for Sunshine.
+WantedBy=default.target

install.sh

@@ -59,6 +59,9 @@ Environment overrides:
   HEADLESS_HOSTS     Comma-separated hostnames that default to headless mode.
                      Unset by default; anything not listed defaults to mirror.
                      Override per-invocation with --headless or --mirror.
+  HEADLESS_DESKTOP   Desktop to render on the headless Xorg :0 for the X11/NVENC
+                     capture path (capture = x11): 'gnome' (default) or 'openbox'
+                     (lightweight, for minimal hosts). Ignored on wlr/kms.
 EOF
 }
 
@@ -194,7 +197,7 @@ main() {
     # (this backend is hand-configured; see FOLLOWUPS.md P3). Harmless no-op on
     # the wlr/kms backends, whose capture source renders for itself.
     if capture_backend_is_x11; then
-      step "Installing headless desktop (Openbox on :0 for the X11 capture path)"
+      step "Installing headless desktop (${HEADLESS_DESKTOP:-gnome} on :0 for the X11 capture path)"
       install_headless_desktop
     fi
     # NOTE: the headless prestart drop-in needs the sunshine unit to already

lib/headless.sh

@@ -48,30 +48,52 @@ capture_backend_is_x11() {
 
 HEADLESS_DESKTOP_UNIT="headless-desktop.service"
 
-# Pull the lightweight WM (Openbox) we drive on :0, plus xsetroot for the
-# solid-background touch. Idempotent — pkg_install skips what's present.
+# Which desktop to render on the headless Xorg :0. Default is a full GNOME
+# session (the familiar Ubuntu desktop). Set HEADLESS_DESKTOP=openbox for a
+# lightweight bare WM instead — lower overhead, better for a truly minimal or
+# low-power host, but no panel/launcher out of the box (right-click menu only).
+: "${HEADLESS_DESKTOP:=gnome}"
+
+# Install the packages the chosen desktop needs. Idempotent — pkg_install
+# skips what's already present.
 ensure_headless_desktop_packages() {
+  case "$HEADLESS_DESKTOP" in
+    gnome)
+      case "$DISTRO" in
+        debian) pkg_install gnome-session gnome-shell ubuntu-session ;;
+        arch)   pkg_install gnome-shell gnome-session ;;
+      esac
+      ;;
+    openbox)
       command -v openbox-session >/dev/null 2>&1 || pkg_install openbox
+      # xsetroot paints a solid root so the bare desktop is visibly non-black.
       if ! command -v xsetroot >/dev/null 2>&1; then
         case "$DISTRO" in
           debian) pkg_install x11-xserver-utils ;;
           arch)   pkg_install xorg-xsetroot ;;
         esac
       fi
+      ;;
+    *)
+      err "Unknown HEADLESS_DESKTOP='$HEADLESS_DESKTOP' (expected: gnome | openbox)"
+      return 1
+      ;;
+  esac
 }
 
-# Install + enable the Openbox session that renders onto the headless Xorg
-# display (:0), so the X11/NVENC capture path has something to show instead of
-# a black root window. Idempotent: safe to re-run. Bound to xorg-headless.service
+# Install + enable a desktop session that renders onto the headless Xorg
+# display (:0), so the X11/NVENC capture path shows a real desktop instead of a
+# black root window. Picks the GNOME or Openbox unit template per
+# $HEADLESS_DESKTOP. Idempotent: safe to re-run. Bound to xorg-headless.service
 # and to default.target (the lingering-user manager reaches it without a login).
 install_headless_desktop() {
-  local src="$SCRIPT_DIR/files/headless-desktop.service"
+  local src="$SCRIPT_DIR/files/headless-desktop-${HEADLESS_DESKTOP}.service"
   if [[ ! -f "$src" ]]; then
-    err "Desktop unit source missing: $src"
+    err "Desktop unit source missing: $src (HEADLESS_DESKTOP=$HEADLESS_DESKTOP)"
     return 1
   fi
 
-  ensure_headless_desktop_packages
+  ensure_headless_desktop_packages || return 1
 
   local unit_dir="$HOME/.config/systemd/user"
   mkdir -p "$unit_dir"
@@ -82,7 +104,7 @@ install_headless_desktop() {
   # headless box with no session yet, fall back to enable-only so it comes up
   # on next boot via default.target.
   if systemctl --user enable --now "$HEADLESS_DESKTOP_UNIT" >/dev/null 2>&1; then
-    ok "Enabled $HEADLESS_DESKTOP_UNIT (Openbox session on :0)"
+    ok "Enabled $HEADLESS_DESKTOP_UNIT ($HEADLESS_DESKTOP session on :0)"
   else
     systemctl --user enable "$HEADLESS_DESKTOP_UNIT" >/dev/null 2>&1 || true
     warn "Installed $HEADLESS_DESKTOP_UNIT but couldn't start it now — it will start on next login/boot."

status.sh

@@ -186,15 +186,19 @@ case "${CAP:-}" in
     # yet have no WM/desktop drawing anything — Sunshine then captures an empty
     # black root window (pairing/NVENC/input all work; client sees only black).
     if command -v xprop >/dev/null 2>&1; then
-      wm_check=$( (if [[ $EUID -eq 0 && "$SUSER" != "$(id -un)" ]]; then sudo -u "$SUSER" DISPLAY=:0 xprop -root _NET_SUPPORTING_WM_CHECK; else DISPLAY=:0 xprop -root _NET_SUPPORTING_WM_CHECK; fi) 2>/dev/null)
-      if grep -q 'window id' <<<"$wm_check"; then
-        pass "a window manager is running on :0 (something to capture)"
+      _xp(){ if [[ $EUID -eq 0 && "$SUSER" != "$(id -un)" ]]; then sudo -u "$SUSER" DISPLAY=:0 xprop "$@"; else DISPLAY=:0 xprop "$@"; fi; }
+      wm_win=$(_xp -root _NET_SUPPORTING_WM_CHECK 2>/dev/null | grep -o '0x[0-9a-f]*' | head -1)
+      if [[ -n $wm_win ]]; then
+        # Read the WM's advertised name (e.g. "GNOME Shell", "Openbox") so the
+        # report says which desktop is actually rendering, not just that one is.
+        wm_name=$(_xp -id "$wm_win" _NET_WM_NAME 2>/dev/null | sed -n 's/.*= "\(.*\)"/\1/p')
+        pass "a desktop is running on :0${wm_name:+ (${wm_name})} — something to capture"
       else
         fail "no window manager on :0 — capture will be a black screen" \
-             "Start a desktop on the headless Xorg: 'systemctl --user enable --now headless-desktop.service' (install.sh installs it for the x11 backend). See TROUBLESHOOTING.md §13."
+             "Start a desktop on the headless Xorg: 'systemctl --user enable --now headless-desktop.service' (install.sh installs it for the x11 backend; HEADLESS_DESKTOP=gnome|openbox). See TROUBLESHOOTING.md §13."
       fi
     else
-      note "xprop not installed — skipping window-manager-on-:0 check (install x11-utils to enable it)"
+      note "xprop not installed — skipping desktop-on-:0 check (install x11-utils to enable it)"
     fi
     # wlr env leaking into an x11 unit (stale sway drop-in — TROUBLESHOOTING §13)
     if [[ -n $UNIT ]]; then