Function charter_with_withheld_families 

fn charter_with_withheld_families(
    charter: &str,
    families: &BTreeSet<McpFamily>,
) -> String

The worker’s prompt charter: the stored text plus one line per withheld MCP family. The row keeps the RAW charter - these lines are composed per spawn from the current selection, so they can neither duplicate across re-spawns nor outlive a revision.