# Builtin and external command routing (K1266–K1270)

The dispatcher receives already parsed shell words. Exact names `cd`, `exit`
and `help` select builtins. Builtin argument counts are validated. Every other
nonempty command name is an external route; prefixes such as `helpful` do not
select a builtin. An empty or whitespace command name is rejected.

The dispatcher makes a decision only. It does not execute external programs,
change directories or terminate a process. Those effects require separate
EL0 integration and product evidence.