feat: modo diff para /watch — notifica solo si hay novedades reales

src/bot/bot.py

@@ -73,7 +73,8 @@ async def send_chunked(message: Message, text: str, parse_mode=None):
 
 async def run_scheduled_research(bot, chat_id: int, topic: str,
                                   session_id: int, db: ResearchDB,
-                                  progress_message=None):
+                                  progress_message=None,
+                                  silent_completion: bool = False):
     if progress_message is not None:
         reporter = ProgressReporter(progress_message)
     else:
@@ -106,9 +107,14 @@ async def run_scheduled_research(bot, chat_id: int, topic: str,
 
             await processor.process_session(session_id, topic, proc_progress)
             chunk_count = await db.get_chunks_count(session_id)
-            await reporter.done(
-                f"✅ Listo — `{scraped}` fuentes · `{chunk_count}` chunks · usa /generate <tipo>"
-            )
+            if silent_completion:
+                await reporter.done(
+                    f"🔍 Investigación completada — analizando novedades…"
+                )
+            else:
+                await reporter.done(
+                    f"✅ Listo — `{scraped}` fuentes · `{chunk_count}` chunks · usa /generate <tipo>"
+                )
         else:
             await reporter.done(
                 f"⚠️ Ollama no disponible — `{scraped}` fuentes scraped.\n"
@@ -726,11 +732,41 @@ async def _scheduler_loop(app: Application):
                 _active_sessions[chat_id] = session_id
                 await db.update_watch_run(watch["id"])
 
-                async def _task(c=chat_id, t=topic, s=session_id):
+                async def _task(c=chat_id, t=topic, s=session_id, w_id=watch["id"]):
                     inner_db_conn = await get_db()
                     inner_db = ResearchDB(inner_db_conn)
                     try:
-                        await run_scheduled_research(app.bot, c, t, s, inner_db)
+                        await run_scheduled_research(app.bot, c, t, s, inner_db,
+                                                     silent_completion=True)
+
+                        prev_session = await inner_db.get_previous_session(c, t, s)
+                        new_urls = await inner_db.get_session_urls(s)
+                        old_urls = await inner_db.get_session_urls(prev_session["id"]) \
+                                   if prev_session else set()
+                        new_chunks = await inner_db.get_top_chunks(s, limit=30)
+
+                        try:
+                            from src.generator.generator import generate_diff_summary
+                            summary = await generate_diff_summary(
+                                t, new_urls, old_urls, new_chunks, s, inner_db
+                            )
+                        except Exception as e:
+                            logger.warning("Diff summary failed", error=str(e))
+                            summary = (
+                                f"📊 *Actualización disponible — {t}*\n\n"
+                                f"Usa /generate report para ver el análisis completo."
+                            )
+
+                        if summary:
+                            await app.bot.send_message(
+                                c, summary, parse_mode=ParseMode.MARKDOWN
+                            )
+                        else:
+                            await app.bot.send_message(
+                                c,
+                                f"🔄 *{t}* — sin novedades significativas esta vez.",
+                                parse_mode=ParseMode.MARKDOWN
+                            )
                     finally:
                         await inner_db_conn.close()