fix: stop gamescope respawning a mangoapp that keeps dying at start

tools/mangoapp/mangoapp

@@ -5,4 +5,17 @@
 # WAYLAND_DISPLAY as Wayland-only, and unset, libwayland falls back to wayland-0 - DroidDeck's own
 # compositor, which shares XDG_RUNTIME_DIR - so both fail; x11 makes GLFW use gamescope's X server.
 export XDG_SESSION_TYPE=x11
+# gamescope's reaper restarts mangoapp the moment it exits, with no backoff. One that dies at start
+# (a stale session preload without the System V queue, a driver it crashes on) was started about
+# once a second for the whole session, each start a full exec under proot - the Steam menu itself
+# lagged. More than 5 starts in 60 s leaves the overlay off: this waits instead of exiting, so the
+# reaper has nothing to restart until the session ends.
+starts=/tmp/droiddeck-mangoapp-starts
+now=$(date +%s)
+recent=$(awk -v now="$now" '$1 > now - 60' "$starts" 2>/dev/null)
+printf '%s\n%s\n' "$recent" "$now" | sed '/^$/d' > "$starts"
+if [ "$(wc -l < "$starts")" -gt 5 ]; then
+  echo "mangoapp: started $(wc -l < "$starts") times in 60 s; the performance overlay stays off for this session" >&2
+  exec sleep infinity
+fi
 LD_LIBRARY_PATH=/usr/local/lib/mangoapp${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH} exec /usr/local/lib/mangoapp/mangoapp "$@"