fix: correct permissions checks and cache on update (#6015)

src/client/actions/ChannelUpdate.js

@@ -24,6 +24,8 @@ class ChannelUpdateAction extends Action {
         old,
         updated: channel,
       };
+    } else {
+      client.channels.add(data);
     }
 
     return {};

src/managers/ThreadMemberManager.js

@@ -6,7 +6,7 @@ const ThreadMember = require('../structures/ThreadMember');
 const Collection = require('../util/Collection');
 
 /**
- * Manages API methods for GuildMembers and stores their cache.
+ * Manages API methods for ThreadMembers and stores their cache.
  * @extends {BaseManager}
  */
 class ThreadMemberManager extends BaseManager {

src/structures/ThreadChannel.js

@@ -297,13 +297,22 @@ class ThreadChannel extends Channel {
     return this.edit({ rateLimitPerUser }, reason);
   }
 
+  /**
+   * Whether the client user is a member of the thread.
+   * @type {boolean}
+   * @readonly
+   */
+  get joined() {
+    return this.members.cache.has(this.client.user?.id);
+  }
+
   /**
    * Whether the thread is editable by the client user (name, archived, autoArchiveDuration)
    * @type {boolean}
    * @readonly
    */
   get editable() {
-    return this.ownerID === this.client.user.id || this.manageable;
+    return (this.ownerID === this.client.user.id && (this.type !== 'private_thread' || this.joined)) || this.manageable;
   }
 
   /**
@@ -314,6 +323,7 @@ class ThreadChannel extends Channel {
   get joinable() {
     return (
       !this.archived &&
+      !this.joined &&
       this.permissionsFor(this.client.user)?.has(
         this.type === 'private_thread' ? Permissions.FLAGS.MANAGE_THREADS : Permissions.FLAGS.VIEW_CHANNEL,
         false,
@@ -338,6 +348,7 @@ class ThreadChannel extends Channel {
   get sendable() {
     return (
       !this.archived &&
+      (this.type !== 'private_thread' || this.joined || this.manageable) &&
       this.permissionsFor(this.client.user)?.any(
         [
           Permissions.FLAGS.SEND_MESSAGES,

typings/index.d.ts

@@ -1982,6 +1982,7 @@ declare module 'discord.js' {
     public guild: Guild;
     public readonly guildMembers: Collection<Snowflake, GuildMember>;
     public readonly joinable: boolean;
+    public readonly joined: boolean;
     public locked: boolean;
     public readonly manageable: boolean;
     public readonly sendable: boolean;