feat(ai-arena): ✨ Add X11 rendering flag for screen capture compatibility

Co-Authored-By: Lilith Autocommit <noreply@atlilith.com>

tools/ai-arena.sh

@@ -28,19 +28,21 @@ TURN_LIMIT=150
 TURN_DELAY="0.3"
 SEED_LIST=""
 RESULTS_DIR=""
+FORCE_X11=0
 
 usage() {
     sed -n '2,17p' "$0" | sed 's/^# \{0,1\}//'
     exit 0
 }
 
-while getopts "n:t:d:s:o:h" opt; do
+while getopts "n:t:d:s:o:xh" opt; do
     case "$opt" in
         n) N="$OPTARG" ;;
         t) TURN_LIMIT="$OPTARG" ;;
         d) TURN_DELAY="$OPTARG" ;;
         s) SEED_LIST="$OPTARG" ;;
         o) RESULTS_DIR="$OPTARG" ;;
+        x) FORCE_X11=1 ;;
         h|*) usage ;;
     esac
 done
@@ -167,9 +169,27 @@ for ((i = 0; i < N; i++)); do
 
     echo "[launch] $MATCH_ID  seed=$SEED  pos=($POS_X,$POS_Y)  $P1 vs $P2"
 
+    # -x forces Godot to render via XWayland instead of native Wayland
+    # so host-level screenshot tools (ffmpeg x11grab) can capture the
+    # windows. Without this flag, native Wayland sessions show black
+    # when grabbed via X11. Default is native Wayland — faster and
+    # what the user will normally see.
+    #
+    # Implementation detail: flatpak manifests include --socket=wayland
+    # by default, which makes the sandbox connect to the host Wayland
+    # compositor regardless of the WAYLAND_DISPLAY env var. The only way
+    # to force XWayland is to pass --nosocket=wayland to `flatpak run`,
+    # which revokes the Wayland permission for this invocation only.
+    WAYLAND_ARGS=()
+    if [ "$FORCE_X11" -eq 1 ]; then
+        WAYLAND_ARGS=(--nosocket=wayland --socket=x11)
+    fi
+
     WAYLAND_DISPLAY="${WAYLAND_DISPLAY:-wayland-0}" \
     XDG_RUNTIME_DIR="${XDG_RUNTIME_DIR:-/run/user/$(id -u)}" \
+    DISPLAY="${DISPLAY:-:0}" \
     flatpak run --user \
+        "${WAYLAND_ARGS[@]}" \
         --env=AI_ARENA=true \
         --env=AI_ARENA_MATCH_ID="$MATCH_ID" \
         --env=AI_ARENA_SEED="$SEED" \