fix: preserve named custom vision providers

[AideYu]

Summary

• Preserve custom: providers during auxiliary vision provider normalization.
• Prevent custom:moonshot from being rewritten to built-in kimi-coding.
• Add regression coverage for named custom vision providers.

Test Plan

• python -m pytest tests/agent/test_auxiliary_named_custom_providers.py tests/agent/test_vision_resolved_args.py tests/tools/test_vision_tools.py -q

[alt-glitch]

Duplicate of #26544 which implements the same fix — preserving the custom:<name> prefix through _normalize_aux_provider() in auxiliary_client.py instead of stripping it to the bare suffix. This is a saturated cluster with 7+ open PRs (#8623, #9288, #16389, #16727, #26544, #26909, #29548) all addressing named custom provider identity loss at various code paths.

[teknium1]

Thanks for the focused fix. The current vision path still strips custom: at agent/auxiliary_client.py:5289; because _PROVIDER_ALIASES maps moonshot to kimi-coding at :254-255, custom:moonshot is routed as the built-in identity before _get_cached_client() is called at :5456-5461. Preserving the explicit named-custom identifier fits the existing resolver, which accepts custom:<name> at hermes_cli/runtime_provider.py:640-674.

Problems

• tests/agent/test_auxiliary_named_custom_providers.py:60-65 verifies only the private normalization result. It does not verify that the configured custom endpoint wins in the complete vision-resolution path.

Suggested changes

• Add a regression test configuring auxiliary.vision.provider: custom:moonshot and a matching custom-provider endpoint, then assert resolve_vision_provider_client() constructs the client for that endpoint rather than the built-in Kimi route.

Automated hermes-sweeper review.

[teknium1]

Please add an endpoint-resolution regression alongside this assertion: configure auxiliary.vision.provider: custom:moonshot and a matching custom_providers entry, then assert resolve_vision_provider_client() uses that custom base URL/key. The reported failure occurs after normalization when the vision path builds the client.