[bghira]

Saving a WebUI config with Auto-detect or Model Default selected can write empty strings for prediction_type, validation_noise_scheduler and distillation_method. Launching then emits flags such as --prediction_type=, which argparse rejects.

Omit blank CLI values when a select offers a null choice and no explicit empty-string choice, allowing the parser to apply the model default. Preserve valid selections, intentionally empty negative prompts, and explicit empty resume choices. Existing saved configs work without manual editing.

Regression coverage includes prefixed/unprefixed keys, null/blank/whitespace values, explicit overrides, and repeated MOSS form normalization, save, JSON reload and real argparse parsing.

Validation: 85 configuration and training-service tests passed with Python 3.13:

.venv/bin/python -m unittest -v -f tests.test_allow_empty_fields tests.test_config_templates tests.test_parser_type_override tests.test_text_json_field tests.test_training_service tests.test_loader_boolean_handling tests.test_config_store_flatten