fix: refine environment variable override logic in config

- Updated the environment variable handling in get_specs to ensure overrides only occur if parameters are not specified in defaults or YAML files.
- Improved logging to reflect the changes made by environment variable overrides.

Author: andrewm4894

anomstack/config.py

@@ -49,12 +49,15 @@ def process_yaml_file(yaml_file: str):
                 return
 
             # Apply global environment variable overrides
+            # Only override if the parameter is NOT specified in either defaults or specific YAML file
             for env_var in env_vars:
                 if env_var in os.environ:
                     param_key = env_var.replace("ANOMSTACK_", "").lower()
-                    yaml_value = metric_specs.get(param_key) or defaults.get(param_key)
-                    merged_specs[param_key] = os.getenv(env_var)
-                    logger.info(f"ENV OVERRIDE: {env_var} replaces {param_key} (was: {yaml_value}, now: {merged_specs[param_key]})")
+                    # Only override if the parameter is NOT specified in either defaults or specific YAML file
+                    if param_key not in metric_specs and param_key not in defaults:
+                        yaml_value = merged_specs.get(param_key)
+                        merged_specs[param_key] = os.getenv(env_var)
+                        logger.info(f"ENV OVERRIDE: {env_var} replaces {param_key} (was: {yaml_value}, now: {merged_specs[param_key]})")
 
             # Apply metric batch-specific environment variable overrides
             # Pattern: ANOMSTACK__<METRIC_BATCH>__<PARAM>