diff --git a/telegram/bot.py b/telegram/bot.py
index b51c537..7299baf 100644
--- a/telegram/bot.py
+++ b/telegram/bot.py
@@ -430,18 +430,29 @@ async def handle_message(update: Update, context: ContextTypes.DEFAULT_TYPE):
     if len(text) < MIN_MESSAGE_LENGTH:
         return
 
-    # Conversation window: track history silently, don't auto-respond
-    # (Ganymede: window = context, not trigger. Reply-to is the only follow-up trigger.)
+    # Conversation window behavior depends on chat type (Rio: DMs vs groups)
+    # DMs: auto-respond (always 1-on-1, no false positives)
+    # Groups: silent context only (reply-to is the only follow-up trigger)
     user = msg.from_user
+    is_dm = msg.chat.type == "private"
+
     if user:
         key = (msg.chat_id, user.id)
         if key in unanswered_count:
             unanswered_count[key] += 1
-            # Record message in conversation history for context (silent — no response)
-            history = conversation_history.setdefault(key, [])
-            history.append({"user": text[:500], "bot": ""})
-            if len(history) > MAX_HISTORY:
-                history.pop(0)
+
+            if is_dm and unanswered_count[key] < CONVERSATION_WINDOW:
+                # DM: auto-respond — conversation window fires
+                logger.info("DM conversation window: @%s msg %d/%d",
+                            user.username or "?", unanswered_count[key], CONVERSATION_WINDOW)
+                await handle_tagged(update, context)
+                return
+            else:
+                # Group: silent context tracking only
+                history = conversation_history.setdefault(key, [])
+                history.append({"user": text[:500], "bot": ""})
+                if len(history) > MAX_HISTORY:
+                    history.pop(0)
             # Expire window after CONVERSATION_WINDOW unanswered messages
             if unanswered_count[key] >= CONVERSATION_WINDOW:
                 del unanswered_count[key]