get_secret returned os.environ on a scoped miss whenever multiplex was
off, but non-multiplex hosts serve foreign homes too (dashboard/desktop
backend, per-profile cron, MCP owner scopes, kanban spawn-env builds),
where os.environ is the launch profile's. Bound scopes now carry the
home they were built for; serves_routed_profile detects a foreign scope
even when the binder deliberately skips the HERMES_HOME override, and
the miss returns the caller's default. Every production binder stamps
its home; own-home scopes keep the deliberate env overlay.
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