feat: reply-to-agent detection in Gateway → SOWA Priority 3

When a user replies to an agent's message in Telegram groups,
it is now treated as a direct mention (SOWA FULL response).

Implementation:
- Detect reply_to_message.from.is_bot in Gateway webhook handler
- Verify bot_id matches this agent's token (multi-agent safe)
- Pass is_reply_to_agent=True to detect_explicit_request() and
  analyze_message() (SOWA v2.2)
- Add is_reply_to_agent to Router metadata for analytics

SOWA already had Priority 3 logic for reply_to_agent → FULL,
it was just never wired up (had TODO placeholders with False).

Edge cases handled:
- Only triggers when reply is to THIS agent's bot (not other bots)
- Reply to forwarded messages: won't trigger (from.is_bot would be
  the original sender, not the bot)
- Works alongside existing DM, mention, and training group rules

Co-authored-by: Cursor <cursoragent@cursor.com>

gateway-bot/http_api.py

@@ -1347,6 +1347,23 @@ async def handle_telegram_webhook(
     if not telegram_token:
         raise HTTPException(status_code=500, detail=f"Telegram token not configured for {agent_config.name}")
     
+    # === REPLY-TO-AGENT DETECTION ===
+    # If user replies to a bot message → treat as direct mention (SOWA Priority 3)
+    is_reply_to_agent = False
+    reply_to_message = update.message.get("reply_to_message")
+    if reply_to_message:
+        reply_from = reply_to_message.get("from", {})
+        if reply_from.get("is_bot"):
+            # Verify it's THIS agent's bot (bot_id = first part of token)
+            bot_id = telegram_token.split(":")[0] if telegram_token else None
+            reply_from_id = str(reply_from.get("id", ""))
+            if bot_id and reply_from_id == bot_id:
+                is_reply_to_agent = True
+                logger.info(
+                    f"↩️ {agent_config.name}: Reply-to-agent detected "
+                    f"(user {username} replied to bot msg {reply_to_message.get('message_id', '?')})"
+                )
+
         text = update.message.get("text", "")
 
         # Simple brand commands (Ukrainian)
@@ -2014,7 +2031,7 @@ async def handle_telegram_webhook(
     has_explicit_request = detect_explicit_request(
         text=text,
         is_dm=is_private_chat,
-        is_reply_to_agent=False,  # TODO: detect from Telegram reply_to_message
+        is_reply_to_agent=is_reply_to_agent,
         mentioned_agents=mentioned_agents,
         thread_has_agent_participation=False,  # REQUIRED, fail-closed default
     )
@@ -2033,7 +2050,7 @@ async def handle_telegram_webhook(
         is_private_chat=is_private_chat,
         payload_explicit_request=has_explicit_request,
         payload_has_link=has_link,
-        is_reply_to_agent=False,  # TODO: detect from Telegram reply_to_message
+        is_reply_to_agent=is_reply_to_agent,
         thread_has_agent_participation=False,  # TODO: track per thread
     )
     respond_decision = sowa_decision.should_respond
@@ -2161,6 +2178,7 @@ async def handle_telegram_webhook(
             "sender_is_bot": is_sender_bot,
             "mentioned_bots": mentioned_bots,
             "requires_complex_reasoning": needs_complex_reasoning,
+            "is_reply_to_agent": is_reply_to_agent,
         },
         "context": {
             "agent_name": agent_config.name,