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BYOK Copilot CLI not working anymore with Deepseek

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#4,840 0 comments 1 reaction 0 assignees View on GitHub

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
38/100
Issue type
Bug
Clarity
Needs clarification
Activity status
Active
Tech stack
shell
Domain
api, cli

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.

Description

triage
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

Dominant language
Shell
Stars
11.2k
Forks
1.9k
Avg merge
14h 16m
Merged PRs (30d)
6

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