Function heal_due 

fn heal_due(
    msg: &Message,
    boot_evaluated: &mut bool,
    server_names: &[String],
) -> bool

Whether the frame just received should fire the boot-tool heal. Pure so the frame gate, the latch, and the predicate are testable without a client. Only the boot system/init frame can fire it - the latch advances on the first init frame seen either way - so a mid-session init that lacks the tools (a user toggled the server off) is never “healed” back on. The heal’s OUTCOME is not checked here: init is emitted per user message, so a “next frame” may never come or may land inside the heal window; the re-add response itself carries the outcome (see readd_sdk_mcp_servers).

Detection depends on the boot init frame reaching this loop: Client::spawn swallows any pre-initialize init into its cached init data, and today the CLI emits init only after a user message, so the boot frame always lands here - if that seam changes, the predicate silently never runs.