fix: normalize required channel checks

backend/bot/handlers/user/start.py

@@ -24,6 +24,10 @@ from bot.services.referral_service import ReferralService
 from bot.services.subscription_service import SubscriptionService
 from bot.services.telegram_notifications import TELEGRAM_NOTIFICATIONS_ENABLED
 from bot.utils.callback_answer import safe_answer_callback
+from bot.utils.channel_subscription import (
+    is_required_channel_access_error,
+    normalize_required_channel_id,
+)
 from bot.utils.install_links import (
     append_install_share_link_text,
     ensure_user_install_guide_links,
@@ -215,7 +219,7 @@ async def ensure_required_channel_subscription(
     Verify that the user is a member of the required channel (if configured).
     Returns True when access can proceed, False when user must subscribe first.
     """
-    required_channel_id = settings.REQUIRED_CHANNEL_ID
+    required_channel_id = normalize_required_channel_id(settings.REQUIRED_CHANNEL_ID)
     if not required_channel_id:
         return True
 
@@ -279,6 +283,29 @@ async def ensure_required_channel_subscription(
         if status_value in allowed_statuses:
             is_member = True
     except TelegramBadRequest as bad_request:
+        if is_required_channel_access_error(bad_request):
+            logging.error(
+                "Required channel check failed due to channel access/configuration error "
+                "(configured=%s, normalized=%s): %s",
+                settings.REQUIRED_CHANNEL_ID,
+                required_channel_id,
+                bad_request,
+            )
+            error_text = translate("channel_subscription_check_failed")
+            if isinstance(event, types.CallbackQuery):
+                try:
+                    await event.answer(error_text, show_alert=True)
+                except Exception:
+                    pass
+                if message_obj:
+                    try:
+                        await message_obj.answer(error_text)
+                    except Exception:
+                        pass
+            else:
+                await event.answer(error_text)
+            return False
+
         logging.info(
             "Required channel check: user %s not subscribed (details: %s)",
             user_id,

backend/bot/middlewares/channel_subscription.py

@@ -11,6 +11,7 @@ from sqlalchemy.ext.asyncio import AsyncSession
 
 from bot.keyboards.inline.user_keyboards import get_channel_subscription_keyboard
 from bot.middlewares.i18n import JsonI18n
+from bot.utils.channel_subscription import normalize_required_channel_id
 from config.settings import Settings
 from db.dal import user_dal
 
@@ -32,7 +33,7 @@ class ChannelSubscriptionMiddleware(BaseMiddleware):
         event: Update,
         data: Dict[str, Any],
     ) -> Any:
-        required_channel_id = self.settings.REQUIRED_CHANNEL_ID
+        required_channel_id = normalize_required_channel_id(self.settings.REQUIRED_CHANNEL_ID)
         if not required_channel_id:
             return await handler(event, data)
 

backend/bot/utils/channel_subscription.py

@@ -0,0 +1,40 @@
+from typing import Optional
+
+
+def normalize_required_channel_id(value: object) -> Optional[int]:
+    if value is None:
+        return None
+
+    raw = str(value).strip()
+    if not raw:
+        return None
+
+    try:
+        channel_id = int(raw)
+    except (TypeError, ValueError):
+        return None
+
+    if channel_id == 0:
+        return None
+
+    if channel_id > 0:
+        return int(f"-100{channel_id}")
+
+    raw_abs = str(abs(channel_id))
+    if raw.startswith("-100"):
+        return channel_id
+    if abs(channel_id) < 1_000_000_000:
+        return channel_id
+    return -int(f"100{raw_abs}")
+
+
+def is_required_channel_access_error(error: BaseException) -> bool:
+    message = str(error).lower()
+    configuration_markers = (
+        "chat not found",
+        "bot is not a member",
+        "not enough rights",
+        "have no rights",
+        "kicked",
+    )
+    return any(marker in message for marker in configuration_markers)

backend/config/settings.py

@@ -1018,6 +1018,7 @@ class Settings(BaseSettings):
         "LOG_SUPPORT_THREAD_ID",
         "BACKUP_CHAT_ID",
         "BACKUP_THREAD_ID",
+        "REQUIRED_CHANNEL_ID",
         mode="before",
     )
     @classmethod