StaticcardinalStaticdirectionGrid offset triple for a direction (canonical or alias).
Returns undefined for non-cardinals.
StaticinvertReturn the cardinal inverse of a direction.
Returns undefined for non-cardinals (semantic labels like 'office' or
vessel-synthesized 'out' have no structural inverse; arrival messages
degrade to "Alice arrives." for those cases).
StaticisIs direction (or its alias) one of the 10 canonical cardinals?
StaticnormalizeNormalize a direction string (or alias) to its canonical long-form name.
Returns undefined when the input doesn't name a cardinal direction —
callers should treat that as "not a direction, try it as a vessel keyword
/ semantic label" (see GoController).
List of canonical cardinal directions (useful for tests / iteration).