fix: custom provider must only accept a model if it's declared explicitly. Upon model rejection (in auto mode) the list of available models is returned up-front to help with selection.

providers/custom.py

@@ -6,7 +6,7 @@ from typing import Optional
 
 from .openai_compatible import OpenAICompatibleProvider
 from .openrouter_registry import OpenRouterModelRegistry
-from .shared import ModelCapabilities, ModelResponse, ProviderType, TemperatureConstraint
+from .shared import ModelCapabilities, ModelResponse, ProviderType
 
 
 class CustomProvider(OpenAICompatibleProvider):
@@ -91,51 +91,22 @@ class CustomProvider(OpenAICompatibleProvider):
         canonical_name: str,
         requested_name: Optional[str] = None,
     ) -> Optional[ModelCapabilities]:
-        """Return custom capabilities from the registry or generic defaults."""
+        """Return capabilities for models explicitly marked as custom."""
 
         builtin = super()._lookup_capabilities(canonical_name, requested_name)
         if builtin is not None:
             return builtin
 
-        capabilities = self._registry.get_capabilities(canonical_name)
-        if capabilities:
-            config = self._registry.resolve(canonical_name)
-            if config and getattr(config, "is_custom", False):
-                capabilities.provider = ProviderType.CUSTOM
-                return capabilities
-            # Non-custom models should fall through so OpenRouter handles them
-            return None
+        registry_entry = self._registry.resolve(canonical_name)
+        if registry_entry and getattr(registry_entry, "is_custom", False):
+            registry_entry.provider = ProviderType.CUSTOM
+            return registry_entry
 
         logging.debug(
-            f"Using generic capabilities for '{canonical_name}' via Custom API. "
-            "Consider adding to custom_models.json for specific capabilities."
+            "Custom provider cannot resolve model '%s'; ensure it is declared with 'is_custom': true in custom_models.json",
+            canonical_name,
         )
-
-        supports_temperature, temperature_constraint, temperature_reason = TemperatureConstraint.resolve_settings(
-            canonical_name
-        )
-
-        logging.warning(
-            f"Model '{canonical_name}' not found in custom_models.json. Using generic capabilities with inferred settings. "
-            f"Temperature support: {supports_temperature} ({temperature_reason}). "
-            "For better accuracy, add this model to your custom_models.json configuration."
-        )
-
-        generic = ModelCapabilities(
-            provider=ProviderType.CUSTOM,
-            model_name=canonical_name,
-            friendly_name=f"{self.FRIENDLY_NAME} ({canonical_name})",
-            context_window=32_768,
-            max_output_tokens=32_768,
-            supports_extended_thinking=False,
-            supports_system_prompts=True,
-            supports_streaming=True,
-            supports_function_calling=False,
-            supports_temperature=supports_temperature,
-            temperature_constraint=temperature_constraint,
-        )
-        generic._is_generic = True
-        return generic
+        return None
 
     def get_provider_type(self) -> ProviderType:
         """Identify this provider for restriction and logging logic."""
@@ -146,49 +117,6 @@ class CustomProvider(OpenAICompatibleProvider):
     # Validation
     # ------------------------------------------------------------------
 
-    def validate_model_name(self, model_name: str) -> bool:
-        """Validate if the model name is allowed.
-
-        For custom endpoints, only accept models that are explicitly intended for
-        local/custom usage. This provider should NOT handle OpenRouter or cloud models.
-
-        Args:
-            model_name: Model name to validate
-
-        Returns:
-            True if model is intended for custom/local endpoint
-        """
-        if super().validate_model_name(model_name):
-            return True
-
-        config = self._registry.resolve(model_name)
-        if config and not getattr(config, "is_custom", False):
-            return False
-
-        clean_model_name = model_name
-        if ":" in model_name:
-            clean_model_name = model_name.split(":", 1)[0]
-            logging.debug(f"Stripped version tag from '{model_name}' -> '{clean_model_name}'")
-
-            if super().validate_model_name(clean_model_name):
-                return True
-
-            config = self._registry.resolve(clean_model_name)
-            if config and not getattr(config, "is_custom", False):
-                return False
-
-        lowered = clean_model_name.lower()
-        if any(indicator in lowered for indicator in ["local", "ollama", "vllm", "lmstudio"]):
-            logging.debug(f"Model '{clean_model_name}' validated via local indicators")
-            return True
-
-        if "/" not in clean_model_name:
-            logging.debug(f"Model '{clean_model_name}' validated as potential local model (no vendor prefix)")
-            return True
-
-        logging.debug(f"Model '{model_name}' rejected by custom provider (appears to be cloud model)")
-        return False
-
     # ------------------------------------------------------------------
     # Request execution
     # ------------------------------------------------------------------