Function freeze 

pub fn freeze(
    clock_stamp: &LayeredValue<ClockStampGranularity>,
    clock_zones: &LayeredValue<Vec<ClockZone>>,
    effort: &LayeredValue<Effort>,
    sandbox: &LayeredValue<SandboxLimits>,
    mcp: &LayeredValue<Vec<McpServer>>,
    second_threshold: &LayeredValue<SecondThreshold>,
) -> FrozenConfig

Resolves the ladder into the Run-start snapshot. Absence everywhere falls back to the policy default; the zones ladder overrides as a whole list (a building that writes zones replaces the city list).