feat(slack): add thread_replies channel option (#3930)

Add a thread_replies option to Slack channel config (default true). When false, replies go to channel root instead of the originating thread.

Closes #3888

src/channels/mod.rs

@@ -3380,6 +3380,7 @@ fn collect_configured_channels(
                     Vec::new(),
                     sl.allowed_users.clone(),
                 )
+                .with_thread_replies(sl.thread_replies.unwrap_or(true))
                 .with_group_reply_policy(sl.mention_only, Vec::new())
                 .with_workspace_dir(config.workspace_dir.clone()),
             ),

src/channels/slack.rs

@@ -25,6 +25,7 @@ pub struct SlackChannel {
     channel_id: Option<String>,
     channel_ids: Vec<String>,
     allowed_users: Vec<String>,
+    thread_replies: bool,
     mention_only: bool,
     group_reply_allowed_sender_ids: Vec<String>,
     user_display_name_cache: Mutex<HashMap<String, CachedSlackDisplayName>>,
@@ -75,6 +76,7 @@ impl SlackChannel {
             channel_id,
             channel_ids,
             allowed_users,
+            thread_replies: true,
             mention_only: false,
             group_reply_allowed_sender_ids: Vec::new(),
             user_display_name_cache: Mutex::new(HashMap::new()),
@@ -94,6 +96,12 @@ impl SlackChannel {
         self
     }
 
+    /// Configure whether outbound replies stay in the originating Slack thread.
+    pub fn with_thread_replies(mut self, thread_replies: bool) -> Self {
+        self.thread_replies = thread_replies;
+        self
+    }
+
     /// Configure workspace directory used for persisting inbound Slack attachments.
     pub fn with_workspace_dir(mut self, dir: PathBuf) -> Self {
         self.workspace_dir = Some(dir);
@@ -122,6 +130,14 @@ impl SlackChannel {
             .any(|entry| entry == "*" || entry == user_id)
     }
 
+    fn outbound_thread_ts<'a>(&self, message: &'a SendMessage) -> Option<&'a str> {
+        if self.thread_replies {
+            message.thread_ts.as_deref()
+        } else {
+            None
+        }
+    }
+
     /// Get the bot's own user ID so we can ignore our own messages
     async fn get_bot_user_id(&self) -> Option<String> {
         let resp: serde_json::Value = self
@@ -2149,7 +2165,7 @@ impl Channel for SlackChannel {
             "text": message.content
         });
 
-        if let Some(ref ts) = message.thread_ts {
+        if let Some(ts) = self.outbound_thread_ts(message) {
             body["thread_ts"] = serde_json::json!(ts);
         }
 
@@ -2484,10 +2500,30 @@ mod tests {
     #[test]
     fn slack_group_reply_policy_defaults_to_all_messages() {
         let ch = SlackChannel::new("xoxb-fake".into(), None, None, vec![], vec!["*".into()]);
+        assert!(ch.thread_replies);
         assert!(!ch.mention_only);
         assert!(ch.group_reply_allowed_sender_ids.is_empty());
     }
 
+    #[test]
+    fn with_thread_replies_sets_flag() {
+        let ch = SlackChannel::new("xoxb-fake".into(), None, None, vec![], vec![])
+            .with_thread_replies(false);
+        assert!(!ch.thread_replies);
+    }
+
+    #[test]
+    fn outbound_thread_ts_respects_thread_replies_setting() {
+        let msg = SendMessage::new("hello", "C123").in_thread(Some("1741234567.100001".into()));
+
+        let threaded = SlackChannel::new("xoxb-fake".into(), None, None, vec![], vec![]);
+        assert_eq!(threaded.outbound_thread_ts(&msg), Some("1741234567.100001"));
+
+        let channel_root = SlackChannel::new("xoxb-fake".into(), None, None, vec![], vec![])
+            .with_thread_replies(false);
+        assert_eq!(channel_root.outbound_thread_ts(&msg), None);
+    }
+
     #[test]
     fn with_workspace_dir_sets_field() {
         let ch = SlackChannel::new("xoxb-fake".into(), None, None, vec![], vec![])

src/config/schema.rs

@@ -4640,6 +4640,10 @@ pub struct SlackConfig {
     /// cancels the in-flight request and starts a fresh response with preserved history.
     #[serde(default)]
     pub interrupt_on_new_message: bool,
+    /// When true (default), replies stay in the originating Slack thread.
+    /// When false, replies go to the channel root instead.
+    #[serde(default)]
+    pub thread_replies: Option<bool>,
     /// When true, only respond to messages that @-mention the bot in groups.
     /// Direct messages remain allowed.
     #[serde(default)]
@@ -9383,6 +9387,7 @@ allowed_users = ["@ops:matrix.org"]
         let parsed: SlackConfig = serde_json::from_str(json).unwrap();
         assert!(parsed.allowed_users.is_empty());
         assert!(!parsed.interrupt_on_new_message);
+        assert_eq!(parsed.thread_replies, None);
         assert!(!parsed.mention_only);
     }
 
@@ -9392,6 +9397,7 @@ allowed_users = ["@ops:matrix.org"]
         let parsed: SlackConfig = serde_json::from_str(json).unwrap();
         assert_eq!(parsed.allowed_users, vec!["U111"]);
         assert!(!parsed.interrupt_on_new_message);
+        assert_eq!(parsed.thread_replies, None);
         assert!(!parsed.mention_only);
     }
 
@@ -9401,6 +9407,7 @@ allowed_users = ["@ops:matrix.org"]
         let parsed: SlackConfig = serde_json::from_str(json).unwrap();
         assert!(parsed.mention_only);
         assert!(!parsed.interrupt_on_new_message);
+        assert_eq!(parsed.thread_replies, None);
     }
 
     #[test]
@@ -9408,6 +9415,16 @@ allowed_users = ["@ops:matrix.org"]
         let json = r#"{"bot_token":"xoxb-tok","interrupt_on_new_message":true}"#;
         let parsed: SlackConfig = serde_json::from_str(json).unwrap();
         assert!(parsed.interrupt_on_new_message);
+        assert_eq!(parsed.thread_replies, None);
+        assert!(!parsed.mention_only);
+    }
+
+    #[test]
+    async fn slack_config_deserializes_thread_replies() {
+        let json = r#"{"bot_token":"xoxb-tok","thread_replies":false}"#;
+        let parsed: SlackConfig = serde_json::from_str(json).unwrap();
+        assert_eq!(parsed.thread_replies, Some(false));
+        assert!(!parsed.interrupt_on_new_message);
         assert!(!parsed.mention_only);
     }
 
@@ -9431,6 +9448,7 @@ channel_id = "C123"
         let parsed: SlackConfig = toml::from_str(toml_str).unwrap();
         assert!(parsed.allowed_users.is_empty());
         assert!(!parsed.interrupt_on_new_message);
+        assert_eq!(parsed.thread_replies, None);
         assert!(!parsed.mention_only);
         assert_eq!(parsed.channel_id.as_deref(), Some("C123"));
     }

src/onboard/wizard.rs

@@ -3975,6 +3975,7 @@ fn setup_channels() -> Result<ChannelsConfig> {
                     },
                     allowed_users,
                     interrupt_on_new_message: false,
+                    thread_replies: None,
                     mention_only: false,
                 });
             }