Cline already supports the OpenAI Compatible Provider. DeepSeek API is also compatible with OpenAI SDK-style calls, so connecting deepseek-v4-pro to Cline is not complicated: choose OpenAI Compatible, then fill in DeepSeek’s Base URL, API Key, and model name.

The steps below cover both the VS Code extension UI and Cline CLI.

Prepare a DeepSeek API Key

First, create an API Key on the DeepSeek platform.

You need three values:

DeepSeek’s official documentation states that the V4 series uses the existing OpenAI-compatible interface. Keep base_url as https://api.deepseek.com, and set model to deepseek-v4-pro or deepseek-v4-flash when calling it.

Configure It in the Cline Extension

If you use the Cline extension in VS Code, configure it this way:

1. Open Cline from the VS Code sidebar.
2. Go to Cline settings or model configuration.
3. Select OpenAI Compatible as the provider.
4. Enter your DeepSeek API Key.
5. Set Base URL to:

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https://api.deepseek.com

6. Set Model ID to:

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deepseek-v4-pro

7. Save the configuration and run a simple test in Cline.

Start with a low-risk read-only task:

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Please read the current project directory structure and summarize what type of project this is. Do not modify any files.

If Cline can read and answer normally, the model connection is working.

Configure It in Cline CLI

If you use Cline CLI, run cline provider configure openai-compatible to enter interactive configuration.

Example:

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cline provider configure openai-compatible

Fill in:

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API Key: sk-...
Base URL: https://api.deepseek.com
Model ID: deepseek-v4-pro

After configuration, test it with a read-only task:

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cline "Summarize this repository structure without changing files."

If you want to lower cost first, you can temporarily change Model ID to:

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deepseek-v4-flash

Then switch back to deepseek-v4-pro for complex planning, fact checking, multi-tool collaboration, or high-risk code changes.

Recommended Model Split

DeepSeek V4 Pro and Flash are better used with a clear split.

For Agent tools like Cline, cost mainly comes from long context, repeated file reads, plan generation, and multi-round tool calls. If the task is light, use Flash for volume; if the task needs stronger judgment, switch to Pro.

How to Set Context Length

DeepSeek V4 Pro and Flash both support long context. If Cline requires a manual context window value, you can understand it according to the 1M context listed on DeepSeek’s official model page.

In practice, do not put every file into context at the beginning. Cline reads files according to the task, and a better workflow is usually:

• first ask it to inspect the directory structure;
• then ask it to locate relevant files;
• finally let it modify only the target files.

This saves tokens and keeps the task boundary clearer.

Common Issues

1. Model Not Found

First check that Model ID is exactly:

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deepseek-v4-pro

Do not write DeepSeek V4 Pro, deepseek-v4, or another display name.

2. 401 or Authentication Failed

Check the API Key:

• whether it was copied completely;
• whether it contains extra spaces;
• whether it was entered into the provider configuration Cline is currently using;
• whether the DeepSeek account has available balance.

3. Connection Failed

Check the Base URL:

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https://api.deepseek.com

Do not append /v1/chat/completions at the end. Cline’s OpenAI Compatible Provider will construct compatible interface requests itself.

4. Cline Calls Are Too Expensive

You can switch routine tasks to deepseek-v4-flash and use deepseek-v4-pro only for complex tasks.

Also, make the task description as clear as possible:

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Only modify files related to the login page. Do not refactor unrelated modules. First provide a plan, and modify code only after confirmation.

Agent tasks are most expensive when boundaries are unclear. The clearer the boundary, the fewer files it reads, the fewer tool calls it makes, and the more controllable the cost becomes.

5. Error: reasoning_content must be passed back

If you see an error like this:

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{
  "message": "400 The `reasoning_content` in the thinking mode must be passed back to the API.",
  "code": "invalid_request_error",
  "modelId": "deepseek-v4-pro"
}

This is usually not a Key, quota, or Base URL problem. It means DeepSeek V4 Pro’s thinking mode and the current client’s multi-round tool-call history are not aligned.

DeepSeek’s official documentation states:

• thinking mode is enabled by default;
• thinking mode returns reasoning_content;
• if a tool call happens in one round, subsequent requests must pass back the reasoning_content from that assistant message;
• if the client does not pass it back correctly, the API returns 400.

When Cline connects through the OpenAI Compatible Provider, this error may appear in the second round or after tool calls if the current version does not fully preserve and return DeepSeek’s reasoning_content.

Try this order:

1. Upgrade Cline to the latest version;
2. confirm you are using OpenAI Compatible, not the normal OpenAI provider;
3. if Cline supports a custom request body, try disabling thinking mode:

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{
  "thinking": {
    "type": "disabled"
  }
}

4. if Cline does not support extra body parameters, temporarily use another model or a compatible proxy service;
5. switch back to deepseek-v4-pro after Cline supports passing back DeepSeek V4 reasoning_content.

Note that disabling thinking mode may reduce complex reasoning ability, but it can work around client compatibility issues where reasoning_content is not passed back.

Copyable Configuration

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Provider: OpenAI Compatible
API Key: sk-your DeepSeek API Key
Base URL: https://api.deepseek.com
Model ID: deepseek-v4-pro

For low-cost mode:

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Provider: OpenAI Compatible
API Key: sk-your DeepSeek API Key
Base URL: https://api.deepseek.com
Model ID: deepseek-v4-flash

Summary

There are only three key steps to calling DeepSeek V4 Pro in Cline:

1. choose OpenAI Compatible as the provider;
2. set Base URL to https://api.deepseek.com;
3. set Model ID to deepseek-v4-pro.

After configuration, test with a read-only task before giving it real code changes. If you often run Agent tasks, split Flash and Pro: Flash handles high-frequency lightweight work, while Pro handles complex judgment and fallback tasks.

References:

• Cline Docs: OpenAI Compatible Provider
• Cline Docs: Provider Configuration
• DeepSeek API Docs: News
• DeepSeek API Docs: Models & Pricing