hermes - 💡(How to fix) Fix [Bug]: v0.13.0 provider plugin systems do not fully integrate with runtime resolution and /model picker [1 pull requests]

Summary

The new plugins/model-providers/ plugin architecture (#20324) for custom endpoints has two gaps that prevent it from replacing custom_providers in v0.13.0.

Issue 1 - Empty model list in /model picker

After dropping a plugins/model-providers/<name>/ directory and calling register_provider with a ProviderProfile that sets fallback_models, the provider appears in /model with the correct name (source=canonical), but the model list is empty (total_models=0).

Root cause: list_authenticated_providers Section 2b uses curated.get(_cp.slug, []) which pulls from _PROVIDER_MODELS and OPENROUTER_MODELS. Provider plugins cannot populate these curated lists through the current register_provider() API. The fallback_models field on ProviderProfile is not consulted for populating the model picker.

Issue 2 - Runtime resolution fails

The gateway and auxiliary tasks report Unknown provider '<name>' when the plugin provider is used in config (e.g. provider: ds2api).

Root cause: resolve_runtime_provider in hermes_cli/runtime_provider.py relies on auth.py's PROVIDER_REGISTRY which is populated via ProviderConfig entries. The new plugin registration path (providers/__init__.py register_provider()) does not feed into PROVIDER_REGISTRY, so runtime resolution never sees plugin-defined providers.

Expected behavior

1. The /model picker should show models from the plugin's fallback_models field (or the /models endpoint) when no _PROVIDER_MODELS entry exists.
2. resolve_runtime_provider should resolve plugin providers using the ProviderProfile data (base_url, api_key, api_mode) registered via providers/__init__.py.

Reproduction

1. Create ~/.hermes/plugins/model-providers/ds2api/__init__.py with a valid ProviderProfile calling register_provider.
2. Set model.provider: ds2api in config.yaml.
3. Restart gateway, open hermes CLI, and run /model.
4. Observe empty model list for the provider.
5. Send a message to trigger an auxiliary task (compression, title) → gateway logs show Unknown provider.

Environment

• Hermes Agent v0.13.0 (2026.5.7)
• OS: Linux (WSL2 on Windows 11)
• Local OpenAI-compatible custom endpoint (DeepSeek-V4 via DS2API)