The adapter's __init__ and send_weixin_direct read WEIXIN_ACCOUNT_ID/
TOKEN/BASE_URL/CDN_BASE_URL via bare get_secret, which raises
UnscopedSecretError when the DEFAULT profile's adapter constructs or
sends unscoped under multiplexing (corrects the direction of #66073 /
#68854, which tried to solve this by borrowing os.environ on every
read — a cross-profile leak).
Add a module-level _wx_secret helper following the established Slack
SLACK_APP_TOKEN pattern (#59739) and WhatsApp's _get_wsecret: a SCOPED
miss returns the default (the scope is authoritative — no environ
borrow), while an UNSCOPED read under multiplex falls back to
os.environ, which is the default profile's own value.
Regression tests cover both directions: scoped construction reads the
scope's value and a scoped miss yields empty (no borrow); unscoped
construction falls back to os.environ instead of raising.
Teknium
f7efe3d766