fix(gateway): revert Weixin get_secret() calls that crash in multiplex mode

[WenhuaXia]

Problem

Commit 6160a80 replaced os.getenv() with get_secret() for Weixin credential resolution. However, WeixinAdapter.__init__() and send_weixin_direct() are called outside any secret_scope context. When multiplex_profiles: true is enabled, get_secret() raises UnscopedSecretError, preventing the platform adapter from initializing and blocking the entire gateway startup sequence.

Reproduction:

1. Set multiplex_profiles: true in config.yaml
2. Configure weixin platform with credentials in .env
3. Start gateway → crashes with UnscopedSecretError: get_secret('WEIXIN_CDN_BASE_URL') called with no profile secret scope active

Fix

Revert to os.getenv() which is the correct fallback for credential resolution outside a scoped context. The config.yaml → env bridge in gateway/config.py already loads WEIXIN_* values into the PlatformConfig object (token/account_id), so os.getenv() serves only as the final fallback for extra config keys.

Files Changed

• gateway/platforms/weixin.py: Reverted 4 get_secret() calls to os.getenv() in both WeixinAdapter.__init__() and send_weixin_direct()

Verification

• Gateway starts successfully with multiplex_profiles: true
• All Weixin credentials resolved correctly via env bridge
• Weixin platform connects and processes inbound messages

[teknium1]

Thanks for isolating the primary-adapter startup failure; the current main path does reproduce it.

Problems

• gateway/run.py:8453 constructs primary adapters without _profile_runtime_scope, while secondary construction is scoped at gateway/run.py:10412-10413; this is the missing lifecycle boundary.
• The replacement at gateway/platforms/weixin.py:1190-1195 and :2328-2331 bypasses the fail-closed secret contract. agent/secret_scope.py:166-173 explicitly rejects unscoped reads in multiplex mode because os.environ can expose another profile's credential. Commit 6160a80253 moved these exact Weixin fallbacks to get_secret() for that reason.

Suggested changes

• Scope primary adapter creation in GatewayRunner under the default profile when multiplexing is enabled, including the relevant reconnect path, and retain get_secret() in Weixin.
• Add a regression test for primary Weixin construction using the default profile's isolated secret scope. Related bug(gateway): primary Weixin adapter startup lacks multiplex secret scope #70652 describes this scope-preserving approach.

This is an automated hermes-sweeper review.

[teknium1]

Closing in favor of the merged correction (#76663), same grounds as the sibling #66073: the unscoped-construction crash was real, but reverting to raw environ reads re-opens the cross-profile token leak for secondary profiles. Main now applies the Slack-pattern wx_secret helper to all WEIXIN* reads — including send_weixin_direct (:2316-2319), which your PR correctly identified as also affected; that finding carried into the fix. Thanks @WenhuaXia.