Three issues caused the gateway to display 'openrouter' instead of
'Custom endpoint' when users configured a custom OAI-compatible endpoint:
1. hermes setup: custom endpoint path saved OPENAI_BASE_URL and
OPENAI_API_KEY to .env but never wrote model.provider to config.yaml.
All other providers (Codex, z.ai, Kimi, etc.) call
_update_config_for_provider() which sets this — custom was the only
path that skipped it. Now writes model.provider='custom' and
model.base_url to config.yaml.
2. hermes model: custom endpoint set model.provider='auto' in config.yaml.
The CLI display had a hack to detect OPENAI_BASE_URL and override to
'custom', but the gateway didn't. Now sets model.provider='custom'
directly.
3. gateway /model and /provider commands: defaulted to 'openrouter' and
read config.yaml — which had no provider set. Added OPENAI_BASE_URL
detection fallback (same pattern the CLI uses) as a defensive catch
for existing users who set up before this fix.