Init

src/Discord.Net.Core/Entities/Channels/ITextChannel.cs

@@ -35,6 +35,17 @@ namespace Discord
         /// </returns>
         int SlowModeInterval { get; }
 
+        /// <summary>
+        ///     Gets the default auto-archive duration for client-created threads in this channel.
+        /// </summary>
+        /// <remarks>
+        ///     The value of this property does not affect API thread creation, it will not respect this value.
+        /// </remarks>
+        /// <returns>
+        ///     The default auto-archive duration for thread creation in this channel.
+        /// </returns>
+        ThreadArchiveDuration DefaultArchiveDuration { get; }
+
         /// <summary>
         ///     Bulk-deletes multiple messages.
         /// </summary>

src/Discord.Net.Rest/API/Common/Channel.cs

@@ -66,5 +66,8 @@ namespace Discord.API
 
         [JsonProperty("member_count")]
         public Optional<int> MemberCount { get; set; }
+
+        [JsonProperty("default_auto_archive_duration")]
+        public Optional<ThreadArchiveDuration> AutoArchiveDuration { get; set; }
     }
 }

src/Discord.Net.Rest/Entities/Channels/RestTextChannel.cs

@@ -21,11 +21,12 @@ namespace Discord.Rest
         public virtual int SlowModeInterval { get; private set; }
         /// <inheritdoc />
         public ulong? CategoryId { get; private set; }
-
         /// <inheritdoc />
         public string Mention => MentionUtils.MentionChannel(Id);
         /// <inheritdoc />
         public bool IsNsfw { get; private set; }
+        /// <inheritdoc />
+        public ThreadArchiveDuration DefaultArchiveDuration { get; private set; }
 
         internal RestTextChannel(BaseDiscordClient discord, IGuild guild, ulong id)
             : base(discord, guild, id)
@@ -46,6 +47,12 @@ namespace Discord.Rest
             if (model.SlowMode.IsSpecified)
                 SlowModeInterval = model.SlowMode.Value;
             IsNsfw = model.Nsfw.GetValueOrDefault();
+
+            if (model.AutoArchiveDuration.IsSpecified)
+                DefaultArchiveDuration = model.AutoArchiveDuration.Value;
+            else
+                DefaultArchiveDuration = ThreadArchiveDuration.OneDay;
+            // basic value at channel creation. Shouldn't be called since guild text channels always have this property
         }
 
         /// <inheritdoc />

src/Discord.Net.WebSocket/Entities/Channels/SocketTextChannel.cs

@@ -40,7 +40,8 @@ namespace Discord.WebSocket
         private bool _nsfw;
         /// <inheritdoc />
         public bool IsNsfw => _nsfw;
-
+        /// <inheritdoc />
+        public ThreadArchiveDuration DefaultArchiveDuration { get; private set; }
         /// <inheritdoc />
         public string Mention => MentionUtils.MentionChannel(Id);
         /// <inheritdoc />
@@ -76,6 +77,11 @@ namespace Discord.WebSocket
             Topic = model.Topic.GetValueOrDefault();
             SlowModeInterval = model.SlowMode.GetValueOrDefault(); // some guilds haven't been patched to include this yet?
             _nsfw = model.Nsfw.GetValueOrDefault();
+            if (model.AutoArchiveDuration.IsSpecified)
+                DefaultArchiveDuration = model.AutoArchiveDuration.Value;
+            else
+                DefaultArchiveDuration = ThreadArchiveDuration.OneDay;
+            // basic value at channel creation. Shouldn't be called since guild text channels always have this property
         }
 
         /// <inheritdoc />

test/Discord.Net.Tests.Unit/MockedEntities/MockedTextChannel.cs

@@ -10,6 +10,8 @@ namespace Discord
     {
         public bool IsNsfw => throw new NotImplementedException();
 
+        public ThreadArchiveDuration DefaultArchiveDuration => throw new NotImplementedException();
+
         public string Topic => throw new NotImplementedException();
 
         public int SlowModeInterval => throw new NotImplementedException();