DeepSeek Adds GitHub Copilot CLI BYOK Documentation

What we verified on June 16, 2026

• DeepSeek now has an official GitHub Copilot CLI integration page in its agent-integration docs.
• That page explicitly tells users to use anthropic as the provider type when wiring GitHub Copilot CLI to DeepSeek via BYOK.
• The same page warns that the openai provider path triggers a 400 error because Copilot CLI's OpenAI integration does not echo reasoning_content back on later requests, while the Anthropic Messages route avoids that failure mode.
• DeepSeek's documented environment contract is concrete: COPILOT_PROVIDER_BASE_URL=https://api.deepseek.com/anthropic, a DeepSeek API key, and COPILOT_MODEL=deepseek-v4-pro, with deepseek-v4-flash also listed as an available model.
• The same page adds explicit token-limit guidance for custom DeepSeek model wiring inside Copilot CLI: 840000 prompt tokens and 128000 output tokens.
• DeepSeek also documents an optional offline mode that blocks GitHub API calls while prompts still go to api.deepseek.com.

Sources

• DeepSeek English homepage
• DeepSeek official GitHub Copilot CLI integration guide
• DeepSeek official GitHub Copilot integration guide
• DeepSeek official status page
• DeepSeek official X account surface