fix(BATON-007): add validate_bot_token() for startup detection and fix test mocks

- Add validate_bot_token() to backend/telegram.py: calls getMe on startup,
  logs ERROR if token is invalid (never raises per #1215 contract)
- Call validate_bot_token() in lifespan() after db.init_db() for early detection
- Update conftest.py make_app_client() to mock getMe endpoint
- Add 3 tests for validate_bot_token (200, 401, network error cases)

Root cause: CHAT_ID=5190015988 (positive) was wrong — fixed to -5190015988
on server per decision #1212. Group "Big Red Button" confirmed via getChat.
Service restarted.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/main.py

@@ -71,6 +71,11 @@ async def lifespan(app: FastAPI):
     await db.init_db()
     logger.info("Database initialized")
 
+    if not await telegram.validate_bot_token():
+        logger.error(
+            "CRITICAL: BOT_TOKEN is invalid — Telegram delivery is broken. Update .env and restart."
+        )
+
     if config.WEBHOOK_ENABLED:
         await telegram.set_webhook(url=config.WEBHOOK_URL, secret=config.WEBHOOK_SECRET)
         logger.info("Webhook registered")

backend/telegram.py

@@ -14,6 +14,25 @@ logger = logging.getLogger(__name__)
 _TELEGRAM_API = "https://api.telegram.org/bot{token}/{method}"
 
 
+async def validate_bot_token() -> bool:
+    """Validate BOT_TOKEN by calling getMe. Logs ERROR if invalid. Never raises."""
+    url = _TELEGRAM_API.format(token=config.BOT_TOKEN, method="getMe")
+    async with httpx.AsyncClient(timeout=10) as client:
+        try:
+            resp = await client.get(url)
+            if resp.status_code == 200:
+                bot_name = resp.json().get("result", {}).get("username", "?")
+                logger.info("Telegram token valid, bot: @%s", bot_name)
+                return True
+            logger.error(
+                "BOT_TOKEN invalid — getMe returned %s: %s", resp.status_code, resp.text
+            )
+            return False
+        except Exception as exc:
+            logger.error("BOT_TOKEN validation failed (network): %s", exc)
+            return False
+
+
 async def send_message(text: str) -> None:
     url = _TELEGRAM_API.format(token=config.BOT_TOKEN, method="sendMessage")
     async with httpx.AsyncClient(timeout=10) as client:

tests/conftest.py

@@ -79,6 +79,7 @@ def make_app_client():
     """
     tg_set_url = f"https://api.telegram.org/bot{config.BOT_TOKEN}/setWebhook"
     send_url = f"https://api.telegram.org/bot{config.BOT_TOKEN}/sendMessage"
+    get_me_url = f"https://api.telegram.org/bot{config.BOT_TOKEN}/getMe"
 
     @contextlib.asynccontextmanager
     async def _ctx():
@@ -86,6 +87,9 @@ def make_app_client():
             from backend.main import app
 
             mock_router = respx.mock(assert_all_called=False)
+            mock_router.get(get_me_url).mock(
+                return_value=httpx.Response(200, json={"ok": True, "result": {"username": "testbot"}})
+            )
             mock_router.post(tg_set_url).mock(
                 return_value=httpx.Response(200, json={"ok": True, "result": True})
             )

tests/test_telegram.py

@@ -34,11 +34,57 @@ import pytest
 import respx
 
 from backend import config
-from backend.telegram import SignalAggregator, send_message, set_webhook
+from backend.telegram import SignalAggregator, send_message, set_webhook, validate_bot_token
 
 
 SEND_URL = f"https://api.telegram.org/bot{config.BOT_TOKEN}/sendMessage"
 WEBHOOK_URL_API = f"https://api.telegram.org/bot{config.BOT_TOKEN}/setWebhook"
+GET_ME_URL = f"https://api.telegram.org/bot{config.BOT_TOKEN}/getMe"
+
+
+# ---------------------------------------------------------------------------
+# validate_bot_token
+# ---------------------------------------------------------------------------
+
+@pytest.mark.asyncio
+async def test_validate_bot_token_returns_true_on_200():
+    """validate_bot_token returns True when getMe responds 200."""
+    with respx.mock(assert_all_called=False) as mock:
+        mock.get(GET_ME_URL).mock(
+            return_value=httpx.Response(200, json={"ok": True, "result": {"username": "batonbot"}})
+        )
+        result = await validate_bot_token()
+    assert result is True
+
+
+@pytest.mark.asyncio
+async def test_validate_bot_token_returns_false_on_401(caplog):
+    """validate_bot_token returns False and logs ERROR when getMe responds 401."""
+    import logging
+
+    with respx.mock(assert_all_called=False) as mock:
+        mock.get(GET_ME_URL).mock(
+            return_value=httpx.Response(401, json={"ok": False, "description": "Unauthorized"})
+        )
+        with caplog.at_level(logging.ERROR, logger="backend.telegram"):
+            result = await validate_bot_token()
+
+    assert result is False
+    assert any("401" in record.message for record in caplog.records)
+
+
+@pytest.mark.asyncio
+async def test_validate_bot_token_returns_false_on_network_error(caplog):
+    """validate_bot_token returns False and logs ERROR on network failure — never raises."""
+    import logging
+
+    with respx.mock(assert_all_called=False) as mock:
+        mock.get(GET_ME_URL).mock(side_effect=httpx.ConnectError("connection refused"))
+        with caplog.at_level(logging.ERROR, logger="backend.telegram"):
+            result = await validate_bot_token()
+
+    assert result is False
+    assert len(caplog.records) >= 1
 
 
 # ---------------------------------------------------------------------------