BYOK Copilot CLI not working anymore with Deepseek
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- Dominant language
- Shell
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Description
Describe the bug
BYOK is not working in Copilot CLI anymore. GPT5.4 is selected and an error is coming: 400 Failed to deserialize the JSON body into the target type: tools[4].type: unknownvariant custom, expected function at line 1 column 47113
export COPILOT_PROVIDER_BASE_URL=https://api.deepseek.com
export COPILOT_MODEL=deepseek-flash
export COPILOT_MODEL=deepseek-v4-pro
export COPILOT_PROVIDER_API_KEY=....
copilot
Affected version
No response
Steps to reproduce the behavior
No response
Expected behavior
No response
Additional context
No response
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by running the copilot entry point with the listed BYOK environment variables and reproduce the request against https://api.deepseek.com. Compare the generated tool payload with DeepSeek's accepted format; done means the selected DeepSeek model works without the custom tool deserialization error.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- shell
- Domain
- api, cli
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Active
- Clarity
- Needs clarification
- Newbie friendliness
- 38/100