Handle SEND_MESSAGES_IN_THREADS in required_permissions calculations

src/dispatch/permissions/application.rs

@@ -1,8 +1,18 @@
 //! Application command permissions calculation
-use crate::serenity_prelude as serenity;
+use crate::{serenity::Permissions, serenity_prelude as serenity};
 
 use super::PermissionsInfo;
 
+/// Checks if a ChannelType is equal to a known thread type.
+fn is_thread(kind: serenity::ChannelType) -> bool {
+    matches!(
+        kind,
+        serenity::ChannelType::NewsThread
+            | serenity::ChannelType::PrivateThread
+            | serenity::ChannelType::PublicThread
+    )
+}
+
 /// Gets the permissions of the ctx author and the bot.
 pub(super) fn get_author_and_bot_permissions(
     interaction: &serenity::CommandInteraction,
@@ -11,10 +21,22 @@ pub(super) fn get_author_and_bot_permissions(
     let author_member = interaction.member.as_ref().expect(err);
 
     let err = "should always be some as inside interaction";
-    let author_permissions = author_member.permissions.expect(err);
+    let mut author_permissions = author_member.permissions.expect(err);
 
     let err = "should always be some according to discord docs";
-    let bot_permissions = interaction.app_permissions.expect(err);
+    let mut bot_permissions = interaction.app_permissions.expect(err);
+
+    let channel = interaction.channel.as_ref();
+    if channel.is_some_and(|c| is_thread(c.kind)) {
+        author_permissions.set(
+            Permissions::SEND_MESSAGES,
+            author_permissions.send_messages_in_threads(),
+        );
+        bot_permissions.set(
+            Permissions::SEND_MESSAGES,
+            bot_permissions.send_messages_in_threads(),
+        );
+    }
 
     PermissionsInfo {
         author_permissions: Some(author_permissions),

src/dispatch/permissions/prefix/cache.rs

@@ -51,7 +51,14 @@ fn get_bot_permissions(
         let parent_channel_id = thread.parent_id.expect(err);
 
         let parent_channel = guild.channels.get(&parent_channel_id)?;
-        Some(guild.user_permissions_in(parent_channel, bot_member))
+        let mut parent_permissions = guild.user_permissions_in(parent_channel, bot_member);
+
+        parent_permissions.set(
+            serenity::Permissions::SEND_MESSAGES,
+            parent_permissions.send_messages_in_threads(),
+        );
+
+        Some(parent_permissions)
     } else {
         // The message was either:
         // - Sent in a guild with broken caching

src/structs/command.rs

@@ -80,15 +80,21 @@ pub struct Command<U, E> {
     ///
     /// Set to [`serenity::Permissions::empty()`] by default
     pub default_member_permissions: serenity::Permissions,
-    /// Permissions which users must have to invoke this command. This is checked internally and
-    /// works for both prefix commands and slash commands.
+    /// Permissions which users must have to invoke this command.
+    ///
+    /// This is checked internally and works for both prefix commands and slash commands.
+    ///
+    /// This also handles the case a message is sent in a thread, in which `SEND_MESSAGES` is set to `SEND_MESSAGES_IN_THREADS`.
     ///
     /// Set to [`serenity::Permissions::empty()`] by default
     pub required_permissions: serenity::Permissions,
-    /// Permissions without which command execution will fail. You can set this to fail early and
-    /// give a descriptive error message in case the
+    /// Permissions without which command execution will fail.
+    ///
+    /// You can set this to fail early and give a descriptive error message in case the
     /// bot hasn't been assigned the minimum permissions by the guild admin.
     ///
+    /// This also handles the case a message is sent in a thread, in which `SEND_MESSAGES` is set to `SEND_MESSAGES_IN_THREADS`.
+    ///
     /// Set to [`serenity::Permissions::empty()`] by default
     pub required_bot_permissions: serenity::Permissions,
     /// If true, only users from the [owners list](crate::FrameworkOptions::owners) may use this