Is DeepSeek's API About to Break Your Code? Model Name Deprecation Hits July 24

TL;DR

I've been tracking this story since it broke, and the implications for anyone building with AI are bigger than most people realize.

DeepSeek API deepseek-chat 2026724 deepseek-chat deepseek-reasoner API deepseek-v4-pro reasoning deepseek-v4-flash chat

What's Changing?

DeepSeek API legacy , , deepseek-chat deepseek-reasoner, , 2026724 15:59 UTC API

What You Need to Change

response = client.chat.completions.create(
 model="deepseek-chat",
 messages=[{"role": "user", "content": "Hello"}]
)

response = client.chat.completions.create(
 model="deepseek-reasoner",
 messages=[{"role": "user", "content": "Solve this math problem"}]
)

response = client.chat.completions.create(
 model="deepseek-v4-flash",
 messages=[{"role": "user", "content": "Hello"}]
)

response = client.chat.completions.create(
 model="deepseek-v4-pro",
 messages=[{"role": "user", "content": "Solve this math problem"}]
)

DeepSeek Anthropic Messages API Claude DeepSeek

import anthropic
client = anthropic.Anthropic(
 base_url="https://api.deepseek.com/anthropic",
 api_key="your-deepseek-api-key"
)

1. OpenAI SDK DeepSeek , model

2. LangChain / LlamaIndex , model name

3. OpenRouter , provider

4. ****grep -r "deepseek-chat\|deepseek-reasoner" .

5. **** deepseek-chat → deepseek-v4-flash``deepseek-reasoner → deepseek-v4-pro

6. ****V4 Pro reasoner V4 Flash reasoning

, , breaking change with a hard deadline 7 24 5