WEIXIN_DM_POLICY/ALLOWED_USERS/GROUP_ALLOWED_USERS, YUANBAO's equivalents,
WECOM_DM_POLICY/ALLOWED_USERS/GROUP_POLICY, and the startup guard's
GATEWAY_ALLOW_ALL_USERS check still read raw os.getenv at adapter
construction time. Under gateway.multiplex_profiles that reads the process
env instead of the per-profile secret scope, so a secondary profile either
silently drops every DM (its own env-only allowlist is invisible) or
inherits the default profile's allow-all/allowlist config.
Route these reads through the existing scoped helpers (_wx_secret,
_get_scoped_secret, gateway.authz_mixin._platform_gate_env, and
gateway.config._getenv) already used for the adjacent credential reads in
the same adapters.
Fixes#93522.
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.
chelsealong