Function effective_policy 

pub fn effective_policy(user: &Value, fragments: &[Value]) -> Value

Compose the effective policy: defaults < packs < user, per-key wholesale on the defaults.outbound / defaults.llm tables, target tables untouched. Returns a NEW value; the input is never borrowed mutably. Idempotent on the embedded Level 0 policy. Byte-identical (as sorted JSON) to Python apply_pack_defaults and Node applyPackDefaults over the same inputs.