## What changed
- Route turn-cost queries for non-OpenAI providers through the configured
provider endpoint and authentication, while retaining the existing OpenAI
API-key path and excluding Amazon Bedrock.
- Observe turns only when their model provider matches the worker's provider.
- Retry custom-provider authentication failures during periodic availability
probes and ensure client authentication takes precedence over provider
headers.
## Testing
- Add coverage for provider matching, custom-provider authentication retries,
ChatGPT-auth rejection, and header precedence.
GitOrigin-RevId: 04a7b28e8e3e18a510ae6fface5193af40d114c0