ai: slack ignore some threaded messages

Author: snormore

tools/dz-ai/internal/slack/processor.go

@@ -126,6 +126,30 @@ func effortModeLabel(isBrainMode bool) string {
 	return "normal"
 }
 
+// startsWithNonBotMention checks if the message text starts with a user mention that is not the bot
+func startsWithNonBotMention(text, botUserID string) bool {
+	if botUserID == "" {
+		return false
+	}
+	text = strings.TrimSpace(text)
+	if !strings.HasPrefix(text, "<@") {
+		return false
+	}
+	// Extract user ID from mention pattern <@USERID> or <@USERID|username>
+	endIdx := strings.Index(text, ">")
+	if endIdx == -1 {
+		return false
+	}
+	mentionPart := text[2:endIdx] // Skip "<@"
+	// Check if it has username part (format: USERID|username)
+	pipeIdx := strings.Index(mentionPart, "|")
+	if pipeIdx != -1 {
+		mentionPart = mentionPart[:pipeIdx]
+	}
+	// Check if this mention is NOT the bot
+	return mentionPart != botUserID
+}
+
 // ProcessMessage processes a single Slack message
 func (p *Processor) ProcessMessage(
 	ctx context.Context,
@@ -147,6 +171,32 @@ func (p *Processor) ProcessMessage(
 		"is_channel", isChannel,
 	)
 
+	// Skip processing if in a thread and message starts with another user being mentioned
+	if ev.ThreadTimeStamp != "" && startsWithNonBotMention(ev.Text, p.slackClient.BotUserID()) {
+		p.log.Info("skipping message in thread that starts with non-bot mention",
+			"channel", ev.Channel,
+			"user", ev.User,
+			"message_ts", ev.TimeStamp,
+			"thread_ts", ev.ThreadTimeStamp,
+			"text_preview", TruncateString(ev.Text, 100),
+		)
+		MessagesIgnoredTotal.WithLabelValues("thread_non_bot_mention").Inc()
+		return
+	}
+
+	// Skip processing if message contains :mute: emoji
+	if strings.Contains(ev.Text, ":mute:") {
+		p.log.Info("skipping message with :mute: emoji",
+			"channel", ev.Channel,
+			"user", ev.User,
+			"message_ts", ev.TimeStamp,
+			"thread_ts", ev.ThreadTimeStamp,
+			"text_preview", TruncateString(ev.Text, 100),
+		)
+		MessagesIgnoredTotal.WithLabelValues("mute_emoji").Inc()
+		return
+	}
+
 	txt := strings.TrimSpace(ev.Text)
 
 	// Remove bot mention from text for cleaner processing