luxd serves chain APIs under one segment from constants.ChainAliasPrefix
(constants v1.6.4, node v1.36.181):
/v1/bc/<alias>/... -> /v1/chain/<alias>/...
/ext/bc/<alias>/... -> /v1/chain/<alias>/...
Observations keep their original addresses: a dated note or a recorded status
code is a fact about when it was written, not an instruction to follow.