Actually enforce the iris shield instead of only rendering it

The shield's closed/open state only ever controlled the iris block's
appearance (bedrock vs water) - the teleport listener never checked
it, only whether the gate was open+outgoing. A solid bedrock block
stops normal walking, but nothing stopped a player who ended up
standing there anyway (flight, elytra, a vehicle) from still getting
teleported, which is what was reported: iris visibly closed, travel
still worked.

findOutgoingGateAt() now skips any gate whose iris is closed, and
both teleportPlayer()/teleportEntity() also refuse the trip if the
DESTINATION's shield is closed, matching a real iris blocking
whatever hits it from either side. Same check added to the
cross-server delivery path in CrossServerBridge for the race where
the shield closes between the proxy request and the player landing.

README.md

@@ -84,11 +84,16 @@ material, unsealed interior, too far from the sign, etc.
 - The **iris shield** is a separate, physical thing from the wormhole connection.
   **Right-click a button placed directly below the sign** to toggle it. Closed means
   closed - `gate.iris-shield-material` (default bedrock), solid, blocking everything -
-  whether or not the gate is even connected right now. With the shield open, the
+  whether or not the gate is even connected right now, and travel is refused even if
-  interior just reflects the connection state: `gate.iris-idle-material` (default air)
+  something manages to occupy that space anyway (flight, an elytra, a vehicle - not
-  if idle, or the event horizon if actively dialed. Closing needs nothing extra;
+  just relying on block collision). It blocks in both directions: a closed shield on
-  if the gate has a pin set (`/sg pin <code>`), opening a closed shield prompts you
+  the gate you're dialing *from* stops you from ever stepping in, and a closed shield
-  to type the code in chat within `gate.pin-timeout-seconds` before it'll open.
+  on the *destination* refuses the trip too, matching a real iris stopping anything
+  that hits it from either side. With the shield open, the interior just reflects the
+  connection state: `gate.iris-idle-material` (default air) if idle, or the event
+  horizon if actively dialed. Closing needs nothing extra; if the gate has a pin set
+  (`/sg pin <code>`), opening a closed shield prompts you to type the code in chat
+  within `gate.pin-timeout-seconds` before it'll open.
 
 ## Multi-world
 

stargate-paper/src/main/java/dev/skywalker3200/stargate/paper/listener/GateTeleportListener.java

@@ -85,6 +85,7 @@ public class GateTeleportListener implements Listener {
         List<RuntimeGate> gates = gateManager.all();
         for (RuntimeGate rg : gates) {
             if (!rg.isOpen() || !rg.isOutgoing() || rg.getStructure() == null || rg.getConnectedTo() == null) continue;
+            if (rg.getGate().isIrisClosed()) continue; // shield blocks travel even on a connected gate
             for (Block iris : rg.getStructure().getIris()) {
                 if (iris.getX() == standing.getX() && iris.getY() == standing.getY() && iris.getZ() == standing.getZ()
                         && iris.getWorld().equals(standing.getWorld())) {
@@ -98,6 +99,11 @@ public class GateTeleportListener implements Listener {
     private void teleportPlayer(Player player, RuntimeGate entered) {
         RuntimeGate dest = entered.getConnectedTo();
         if (dest == null) return;
+        if (dest.getGate().isIrisClosed()) {
+            player.sendMessage(net.kyori.adventure.text.Component.text(
+                    "The iris on the other end is closed.", net.kyori.adventure.text.format.NamedTextColor.RED));
+            return;
+        }
 
         Location loc = player.getLocation();
         Vector direction = loc.getDirection();
@@ -121,6 +127,7 @@ public class GateTeleportListener implements Listener {
     private void teleportEntity(Entity entity, RuntimeGate entered) {
         RuntimeGate dest = entered.getConnectedTo();
         if (dest == null) return;
+        if (dest.getGate().isIrisClosed()) return; // shield blocks arrival too
         if (!dest.getGate().getServerId().equals(plugin.getServerId())) return; // no cross-server carry for non-players
 
         Location loc = entity.getLocation();

stargate-paper/src/main/java/dev/skywalker3200/stargate/paper/network/CrossServerBridge.java

@@ -79,6 +79,14 @@ public class CrossServerBridge implements PluginMessageListener {
             Bukkit.getScheduler().runTask(plugin, () -> {
                 Player p = Bukkit.getPlayer(playerId);
                 if (p == null) return;
+                if (rg.getGate().isIrisClosed()) {
+                    // the shield closed between the request and arrival - can't send them back
+                    // through the proxy, so just leave them at this server's default spawn
+                    p.sendMessage(net.kyori.adventure.text.Component.text(
+                            "The iris on the other end closed before you arrived.",
+                            net.kyori.adventure.text.format.NamedTextColor.RED));
+                    return;
+                }
                 double yawRad = Math.toRadians(yaw);
                 Vector direction = new Vector(-Math.sin(yawRad), 0, Math.cos(yawRad));
                 Location landing = gateManager.computeSafeLanding(rg, direction, yaw, pitch);