feat(models): support array format for simplified model definitions

Enhance flexibility for defining models loaded via environment variables (e.g., `PROVIDER_MODELS`).

- Allow simple array configuration, converting the list of names into internal model definitions using the name as the key and ID.
- Improve `get_model_id` logic to fall back to the model name if the explicit `id` field is not present in the definition dictionary.
- Update docstrings to clearly document both the simple array and advanced dictionary formats.

src/rotator_library/model_definitions.py

@@ -12,7 +12,18 @@ if not lib_logger.handlers:
 class ModelDefinitions:
     """
     Simple model definitions loader from environment variables.
-    Format: PROVIDER_MODELS={"model1": {"id": "id1"}, "model2": {"id": "id2", "options": {"reasoning_effort": "high"}}}
+
+    Supports two formats:
+    1. Array format (simple): PROVIDER_MODELS=["model-1", "model-2", "model-3"]
+       - Each model name is used as both name and ID
+    2. Dict format (advanced): PROVIDER_MODELS={"model-name": {"id": "model-id", "options": {...}}}
+       - The 'id' field is optional - if not provided, the model name (key) is used as the ID
+
+    Examples:
+    - IFLOW_MODELS='["glm-4.6", "qwen3-max"]' - simple array format
+    - IFLOW_MODELS='{"glm-4.6": {}}' - dict format, uses "glm-4.6" as both name and ID
+    - IFLOW_MODELS='{"custom-name": {"id": "actual-id"}}' - dict format with custom ID
+    - IFLOW_MODELS='{"model": {"id": "id", "options": {"temperature": 0.7}}}' - with options
     """
 
     def __init__(self, config_path: Optional[str] = None):
@@ -28,11 +39,25 @@ class ModelDefinitions:
                 provider_name = env_var[:-7].lower()  # Remove "_MODELS" (7 characters)
                 try:
                     models_json = json.loads(env_value)
+
+                    # Handle dict format: {"model-name": {"id": "...", "options": {...}}}
                     if isinstance(models_json, dict):
                         self.definitions[provider_name] = models_json
                         lib_logger.info(
                             f"Loaded {len(models_json)} models for provider: {provider_name}"
                         )
+                    # Handle array format: ["model-1", "model-2", "model-3"]
+                    elif isinstance(models_json, list):
+                        # Convert array to dict format with empty definitions
+                        models_dict = {model_name: {} for model_name in models_json if isinstance(model_name, str)}
+                        self.definitions[provider_name] = models_dict
+                        lib_logger.info(
+                            f"Loaded {len(models_dict)} models for provider: {provider_name} (array format)"
+                        )
+                    else:
+                        lib_logger.warning(
+                            f"{env_var} must be a JSON object or array, got {type(models_json).__name__}"
+                        )
                 except (json.JSONDecodeError, TypeError) as e:
                     lib_logger.warning(f"Invalid JSON in {env_var}: {e}")
 
@@ -53,9 +78,12 @@ class ModelDefinitions:
         return model_def.get("options", {}) if model_def else {}
 
     def get_model_id(self, provider_name: str, model_name: str) -> Optional[str]:
-        """Get model ID for a specific model."""
+        """Get model ID for a specific model. Falls back to model_name if 'id' is not specified."""
         model_def = self.get_model_definition(provider_name, model_name)
-        return model_def.get("id") if model_def else None
+        if not model_def:
+            return None
+        # Use 'id' if provided, otherwise use the model_name as the ID
+        return model_def.get("id", model_name)
 
     def get_all_provider_models(self, provider_name: str) -> list:
         """Get all model names with provider prefix."""