Function cmd_context_compress_json 

pub fn cmd_context_compress_json(
    root: &Path,
    goal: &str,
    cmd: Option<String>,
    budget: Option<usize>,
) -> Result<String>

scc context compress <goal> [--cmd <cmd>] [--budget N] [--json]

The pack builder already applies the structural compression ladder (dedup, component collapse, evidence compression, priority-preserving truncation). --cmd additionally pipes the markdown through an external summarizer; its output is treated as UNTRUSTED inference and labeled.