Module-level read of the host build flavor — true for an unpackaged dev
host, false for a packaged one, null before the first theme frame
carried the flag (or under an older host). Convenience for apps that call
connectToHost() fire-and-forget without keeping the handle; listen for the
ispo:theme DOM event to re-read once the bootstrap frame lands.
Module-level read of the host build flavor —
truefor an unpackaged dev host,falsefor a packaged one,nullbefore the first theme frame carried the flag (or under an older host). Convenience for apps that callconnectToHost()fire-and-forget without keeping the handle; listen for theispo:themeDOM event to re-read once the bootstrap frame lands.