[Bug] Anthropic API Error: Internal Server Error (500)

**Bug Description**
Keep getting error 500 on Opus, but Fable works fine.

**Environment Info**
- Platform: linux
- Terminal: gnome-terminal
- Version: 2.1.234
- Feedback ID: 3f6d4027-38c1-424b-a664-3f9e0f263220

**Errors**
```json
[{"error":"Error: 500 {\"type\":\"error\",\"error\":{\"type\":\"api_error\",\"message\":\"Internal server error\"},\"request_id\":\"req_011Ce9AWJm8Eudi89M4mHxLi\"}\n at generate (/$bunfs/root/cli:39:39579)\n at makeRequest (/$bunfs/root/cli:90:8063)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-08-17T23:10:22.332Z"},{"error":"Error: 500 {\"type\":\"error\",\"error\":{\"type\":\"api_error\",\"message\":\"Internal server error\"},\"request_id\":\"req_011Ce9AbrLorwBHkReEaD7M9\"}\n at generate (/$bunfs/root/cli:39:39579)\n at makeRequest (/$bunfs/root/cli:90:8063)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-08-17T23:11:37.708Z"},{"error":"Error: 500 {\"type\":\"error\",\"error\":{\"type\":\"api_error\",\"message\":\"Internal server error\"},\"request_id\":\"req_011Ce9AiRDejV7eWAhxpmUJm\"}\n at generate (/$bunfs/root/cli:39:39579)\n at makeRequest (/$bunfs/root/cli:90:8063)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-08-17T23:13:06.642Z"}]
```

Start by reproducing the Opus request on Linux with version 2.1.234, comparing it with the working Fable path. Use the supplied feedback ID and Anthropic request IDs to trace the repeated 500 responses; done means identifying the cause or documenting that the failure is upstream and outside the CLI.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.