Can´t use DeepSeek API

[raffaeler]

Describe the bug

When I run the following command:

export COPILOT_PROVIDER_BASE_URL="https://api.deepseek.com" \
export COPILOT_PROVIDER_API_KEY="...." \
export COPILOT_PROVIDER_TYPE="openai" \
export COPILOT_MODEL="deepseek-v4-pro" \
copilot

When I make a question to the copilot, I get this answer back:

● Request failed (transient_bad_request). Retrying...
● Request failed (transient_bad_request). Retrying...
✗ 400 The `reasoning_content` in the thinking mode must be passed back to the API. 

I confirm that the DeepSeek API needs the entire reasoning_content field to be returned back to the API every time. In my own code I had the same problem and could rapidly fix the issue by sending back the the entire conversation.

Affected version

No response

Steps to reproduce the behavior

I run the following command:

export COPILOT_PROVIDER_BASE_URL="https://api.deepseek.com" \
export COPILOT_PROVIDER_API_KEY="...." \
export COPILOT_PROVIDER_TYPE="openai" \
export COPILOT_MODEL="deepseek-v4-pro" \
copilot

Ensure to have a valid api key for the DeepSeek endpoint

Expected behavior

I expect the request to be fulfilled.

Additional context

No response

[raffaeler]

I created this Proxy as a workaround for this bug:
https://github.com/raffaeler/mindthegap

If you like it, please give it a star.

[abchatra]

SxS team evaluating DeepSeek is also hitting the same issue https://github.com/github/cli-side-by-side-launcher

[Aquaakuma]

Using DeepSeek's Anthropic-compatible API can resolve this issue, but it may still be triggered under certain circumstances. For example, during a long conversation, if you run commands like copilot CLI or /plugins to check some information, then wait for a while before continuing the conversation, the issue might occur. Additionally, the DeepSeek API included in the OpenCode Go subscription plan also has usability problems, as it uses an OpenAI-compatible API.

[raffaeler]

@Aquaakuma I tried but unfortunately it does not resolve.
I could fully resolve using my own proxy (see my comment above) which also has the bonus to show the thinking tokens.

I would expect the Copilot CLI to give a better user experience in adding, editing and switching providers/models. At the moment I am using a tool called cpm.

[Aquaakuma]

@Aquaakuma I tried but unfortunately it does not resolve. I could fully resolve using my own proxy (see my comment above) which also has the bonus to show the thinking tokens.

I would expect the Copilot CLI to give a better user experience in adding, editing and switching providers/models. At the moment I am using a tool called cpm.

If you are using the DeepSeek Official API, you can try this method: [接入 GitHub Copilot CLI]（https://api-docs.deepseek.com/zh-cn/quick_start/agent_integrations/copilot_cli）. but it may still be triggered in some times.