xfyun engine busy response not retried #31812

Description

When using xfyun (讯飞云) as the provider, if the API returns an engine busy response during temporary overload, OpenCode does not retry the request. This causes requests to fail unnecessarily.

The error message contains "engine busy" which is a transient error similar to "rate limit" or "too many requests" that are already handled. The fix adds "engine busy" to the retryable error patterns.

Plugins

None

OpenCode version

1.17.3

Steps to reproduce

1. Configure xfyun as the provider
2. Send a request when xfyun's engine is temporarily busy
3. The request fails with "engine busy" and is not retried

Screenshot and/or share link

N/A

Operating System

Linux

Terminal

N/A