Function missing_required_fields 

pub fn missing_required_fields(
    schema: &TypeDefinition,
    supplied: &IndexMap<String, String>,
) -> Vec<MissingRequiredField>

Return one MissingRequiredField per required metadata field that the caller did not supply and the schema does not auto-fill. A field is “auto-filled” when it carries default_value, init_timestamp, or auto_timestamp — the engine writes a non-trivial value without caller input. Optional fields and supplied fields are skipped.

Caller-side intent: the warning fires when the entity would land in a stuck state (placeholder today’s-date / empty string) that the agent did not opt into. Surfaced from the create path so dry-run and real-write preview the same set of warnings.