Custom API configuration with DeepSeek v3 model causes error in autocomplete feature

[grassfish1122]

Before submitting your bug report

• [x] I believe this is a bug. I'll try to join the Continue Discord for questions
• [x] I'm not able to find an open issue that reports the same bug
• [x] I've seen the troubleshooting guide on the Continue Docs

Relevant environment info

- OS:
- Continue version:
- IDE version:
- Model:
- config:
  
name: Local Assistant
version: 1.0.0
schema: v1
models:
  - name: DeepSeek-V3-250324
    provider: deepseek
    apiKey: xxx
    apiBase: https://ark.cn-beijing.volces.com/api/v3
    model: ep-20250326174349-z9bgg
    roles:
      - chat
      - edit
      - apply
      - summarize
      - autocomplete
context:
  - provider: code
  - provider: docs
  - provider: diff
  - provider: terminal
  - provider: problems
  - provider: folder
  - provider: codebase
  
  OR link to assistant in Continue hub:

Description

When using a custom API configuration with the DeepSeek v3 model, while standard chat functionality works successfully, an error prompt appears when attempting to use the autocomplete feature.

To reproduce

Log output

{"error":{"message":"Authentication Fails (no such user)","type":"authentication_error","param":null,"code":"invalid_request_error"}}