feat: Folia support

src/main/kotlin/net/hareworks/permits_lib/bukkit/AttachmentSynchronizer.kt

@@ -25,7 +25,7 @@ class AttachmentSynchronizer(
         permissible: Permissible,
         patch: AttachmentPatch,
     ) {
-        ThreadChecks.ensurePrimaryThread("AttachmentSynchronizer.applyPatch")
+        ThreadChecks.ensureRegionThread("AttachmentSynchronizer.applyPatch", permissible)
         if (patch.changes.isEmpty()) return
         val handle = ensureHandle(permissible)
         patch.changes.forEach { (id, value) ->
@@ -58,7 +58,7 @@ class AttachmentSynchronizer(
     }
 
     fun clear(permissible: Permissible) {
-        ThreadChecks.ensurePrimaryThread("AttachmentSynchronizer.clear")
+        ThreadChecks.ensureRegionThread("AttachmentSynchronizer.clear", permissible)
         handles.remove(permissible)?.attachment?.remove()
     }
 

src/main/kotlin/net/hareworks/permits_lib/util/ThreadChecks.kt

@@ -1,11 +1,30 @@
 package net.hareworks.permits_lib.util
 
 import org.bukkit.Bukkit
+import org.bukkit.entity.Player
+import org.bukkit.permissions.Permissible
 
 internal object ThreadChecks {
+    /**
+     * For Bukkit-global operations (e.g. PluginManager permission registration).
+     * In Folia there is no single primary thread; callers should ensure they run
+     * on the global region scheduler (e.g. during onEnable / onDisable).
+     */
     fun ensurePrimaryThread(action: String) {
-        check(Bukkit.isPrimaryThread()) {
-            "$action must be invoked from the primary server thread."
+        // no-op for global ops: Folia has no single primary thread.
+        // PluginManager operations are safe when called from onEnable/onDisable
+        // or from the global region scheduler.
+    }
+
+    /**
+     * For player-bound operations (e.g. PermissionAttachment mutation).
+     * Verifies that the current thread owns the region for the given [permissible].
+     * Non-player permissibles are skipped since they have no region owner.
+     */
+    fun ensureRegionThread(action: String, permissible: Permissible) {
+        val player = permissible as? Player ?: return
+        check(Bukkit.isOwnedByCurrentRegion(player)) {
+            "Action '$action' must be called on the owning region thread for ${player.name}"
         }
     }
 }