_auth_env fell through to os.environ on a scoped miss, so one profile
could inherit another profile's allowlists and allow-all flags.
bot_relay.waiter_command put connection_id into python -c source. A
quote in the id broke the waiter. A crafted id could run extra Python
in the sender gateway.
Exercises representative migrated sites per cluster: scoped value wins,
scoped miss no-borrow under multiplex, and unscoped-multiplex behavior per
pattern (in-turn get_secret vs Slack-pattern startup fallback).
Adolanium