3 files changed, 16 insertions, 0 deletions
diff --git a/bridge/slack/handlers.go b/bridge/slack/handlers.go
index e013b830..5cfcc42b 100644
--- a/bridge/slack/handlers.go
+++ b/bridge/slack/handlers.go
@@ -192,6 +192,9 @@ func (b *Bslack) handleMessageEvent(ev *slack.MessageEvent) (*config.Message, er
 			// This is probably a webhook we couldn't resolve.
 			return nil, fmt.Errorf("message handling resulted in an empty bot message (probably an incoming webhook we couldn't resolve): %#v", ev)
 		}
+		if ev.SubMessage != nil {
+			return nil, fmt.Errorf("message handling resulted in an empty message: %#v with submessage %#v", ev, ev.SubMessage)
+		}
 		return nil, fmt.Errorf("message handling resulted in an empty message: %#v", ev)
 	}
 	return rmsg, nil
diff --git a/bridge/slack/helpers.go b/bridge/slack/helpers.go
index 9959d4fa..4d191c0d 100644
--- a/bridge/slack/helpers.go
+++ b/bridge/slack/helpers.go
@@ -254,6 +254,13 @@ func (b *Bslack) populateReceivedMessage(ev *slack.MessageEvent) (*config.Messag
 		}
 	}
 
+	// For edits, only submessage has thread ts.
+	// Ensures edits to threaded messages maintain their prefix hint on the
+	// unthreaded end.
+	if ev.SubMessage != nil {
+		rmsg.ParentID = ev.SubMessage.ThreadTimestamp
+	}
+
 	if err = b.populateMessageWithUserInfo(ev, rmsg); err != nil {
 		return nil, err
 	}
diff --git a/bridge/slack/slack.go b/bridge/slack/slack.go
index 001b1268..1685c4fc 100644
--- a/bridge/slack/slack.go
+++ b/bridge/slack/slack.go
@@ -293,6 +293,12 @@ func (b *Bslack) sendRTM(msg config.Message) (string, error) {
 		return "", err
 	}
 
+	// Handle prefix hint for unthreaded messages.
+	if msg.ParentID == "msg-parent-not-found" {
+		msg.ParentID = ""
+		msg.Text = fmt.Sprintf("[thread]: %s", msg.Text)
+	}
+
 	// Handle message deletions.
 	if handled, err = b.deleteMessage(&msg, channelInfo); handled {
 		return msg.ID, err