Function run_daemon_with_boot_guard 

pub async fn run_daemon_with_boot_guard<D: DaemonDispatch>(
    dispatcher: D,
    boot_guard: Option<File>,
) -> Result<()>

Run the daemon using a startup lock acquired by the caller before building dispatcher, so a second process racing to boot (e.g. two kkernel mcp --daemon spawns before either has bound its socket) cannot run migrations/FTS DDL concurrently against the same database file. boot_guard is only None on non-unix targets, where there is no advisory boot lock to hold in the first place; every unix daemon-mode caller passes Some.

The guard is held across cleanup → bind → pid-write, then dropped. The caller must not still be holding a different handle to the same lock file when this function is entered — see the “Deadlock note” on the _startup_lock binding below for why that would self-deadlock on flock.