Add credential logging at provider creation.

Shows which API key is being used for each provider.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

providers/registry.py

@@ -226,7 +226,21 @@ class ProviderRegistry:
         return provider_id in self._providers
 
     def get(self, provider_id: str, settings: Settings) -> BaseProvider:
+        from loguru import logger
+
         if provider_id not in self._providers:
+            # Log what credentials are being used
+            from config.provider_catalog import PROVIDER_CATALOG
+
+            desc = PROVIDER_CATALOG.get(provider_id)
+            if desc and desc.credential_attr:
+                cred_value = getattr(settings, desc.credential_attr, "")
+                logger.info(
+                    "Creating provider '{}' with credential '{}' = '{}'",
+                    provider_id,
+                    desc.credential_attr,
+                    cred_value[:10] + "..." if cred_value else "EMPTY",
+                )
             self._providers[provider_id] = create_provider(provider_id, settings)
         return self._providers[provider_id]