fix(gateway): read API_SERVER_* through profile secret scope in multiplex mode

[Bartok9]

x

[tonydwb]

Code Review Summary

Verdict: Approved

Clean fix for API_SERVER_* credential scope in multiplex mode. Under multiplexing, the default profile's .env is loaded into global os.environ at import time, so raw os.getenv("API_SERVER_KEY") would find the DEFAULT profile's key while resolving a SECONDARY profile (#52307).

The fix introduces _scoped_env() that reads through get_secret() (which honors the active profile scope) with a safe fallback to os.environ for single-profile deployments. The 3 test cases cover: secondary profile without key (should not enable), secondary profile with key (should enable), single profile (legacy behavior).

Looks Good

• Well-scoped: 27 additions to gateway/config.py, 50 lines of tests
• Safe fallback to os.environ when no scope is active
• 3 test cases covering the key scenarios
• Clear documentation of the root cause in comments

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Reviewed by Hermes Agent

[Bartok9]

Thanks for the review! The os.environ fallback keeps single-profile deployments on the legacy path, so this should be safe to land. Ready to merge whenever convenient.

[Bartok9]

Plate-clear 2026-07-11: Branch was massively stale vs main. Current main already routes env reads via scoped _getenv_str; PR rewritten to add TestApiServerEnvIsScoped regression tests for #52307 multiplex isolation. Source rewrite of _scoped_env is no longer needed.

[teknium1]

Thanks for preserving the regression intent after rebasing the work.

Automated hermes-sweeper review found this guarantee is already implemented on current main:

• 0f154e780e71c74f8a1cdccb25c97a6abd8e5a57 introduced scoped gateway configuration environment reads.
• gateway/config.py:174-194 resolves environment values from the active profile secret scope, without falling back to process environment while scoped.
• gateway/config.py:1755-1780 applies that helper to every API_SERVER_* value.
• tests/gateway/test_config.py:1260-1295 already proves that a secondary scoped profile does not inherit default-profile API-server enablement.

The PR's July 11 note correctly identifies that the source fix is already on main; its remaining tests duplicate the implemented and covered behavior.