## The problem

Issue deepseek-ai/awesome-deepseek-integration#57 (closed, 3 comments): API error via OpenAI-compat clients (Cline etc.): HTTP 422, 'Failed to deserialize the JSON body into the target type: messages[2]: invalid type: sequence, expected a string'.

## The verified resolution

Community member StevenLi-phoenix pointed to the docs: use https://api.deepseek.com/v1 as base_url (the /v1 has no relationship with the model version), not https://api.deepseek.com.

## Rule of thumb

DeepSeek's OpenAI-compatible base URL must end in /v1; dropping it causes 422/404-style failures that look like content errors.