fix(gateway): read multiplex_profiles from nested gateway section

[davidgut1982]

What does this PR do?

Fixes a config-loading bug where gateway.multiplex_profiles: true written under the nested gateway: section of config.yaml was silently ignored, so the gateway loaded with multiplex_profiles=False.

This is the form written by hermes config set gateway.multiplex_profiles true, so the documented CLI path to enable profile multiplexing did not actually take effect when set that way.

Related Issue

Fixes #

Type of Change

• 🐛 Bug fix (non-breaking change that fixes an issue)

Root cause

gateway/config.py — load_gateway_config() (around the multiplex_profiles block, ~line 851):

load_gateway_config() builds gw_data from the top-level keys of config.yaml and then calls GatewayConfig.from_dict(gw_data). from_dict() does honor the nested gateway.multiplex_profiles fallback — but only against the dict it is handed. Since load_gateway_config() only copied the top-level multiplex_profiles key into gw_data, the nested value never reached from_dict(), and the flag defaulted to False.

The sibling max_concurrent_sessions already had a nested-gateway: fallback in this same block; multiplex_profiles was missing the equivalent.

Changes Made

• gateway/config.py: in load_gateway_config(), read gateway.multiplex_profiles into gw_data when the top-level key is absent, mirroring the existing nested fallback for max_concurrent_sessions.
• tests/gateway/test_config.py: add TestLoadGatewayConfig::test_multiplex_profiles_from_nested_gateway_section — writes a config.yaml with gateway.multiplex_profiles: true, calls load_gateway_config(), and asserts cfg.multiplex_profiles is True.

How to Test

1. Check out this branch, then run:
   pytest tests/gateway/test_config.py::TestLoadGatewayConfig::test_multiplex_profiles_from_nested_gateway_section -v
2. Without the config.py change the test FAILS (assert False is True — multiplex_profiles=False); with it the test PASSES.
3. Full file is green: pytest tests/gateway/test_config.py -q → 70 passed.

Existing coverage gap: tests/gateway/test_multiplex_phase0.py only exercises GatewayConfig.from_dict, never load_gateway_config() with a YAML file — which is exactly where this bug lived.

Checklist

Code

• My commit messages follow Conventional Commits (fix(gateway):)
• My PR contains only changes related to this fix
• I've added tests for my changes
• Tested on Ubuntu (Linux), Python 3.13

🤖 Generated with Claude Code

[tonydwb]

Code Review Summary

Verdict: Approved

Targeted fix: load_gateway_config() now reads multiplex_profiles from the nested gateway: section (the form written by hermes config set gateway.multiplex_profiles true), not just the top-level key.

Looks Good

• Clean fix: adds a check for multiplex_profiles in the gateway_section dict
• Test verifies the nested form is correctly loaded
• 2 files changed, well-scoped
• The comment update explains why the nested form matters

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Reviewed by Hermes Agent

[teknium1]

Thanks for the focused fix. This is an automated hermes-sweeper review; the change has already been salvaged onto current main with contributor authorship preserved.

• Current main implements the nested gateway.multiplex_profiles fallback in gateway/config.py:1058-1060.
• The requested YAML-loader regression test is present at tests/gateway/test_config.py:455.
• Commit d3602e630874b5633841d0ad21b95496ca35a317 has the same stable patch-id as this PR and is contained in release tag v2026.7.7.
• The related salvage PR fix(gateway): honor nested gateway.multiplex_profiles in load_gateway_config (#51372 salvage) #59320 is closed.