Future-Proof Your Production Apps by Updating Legacy Model IDs
Update your model IDs now to avoid breaking changes in July.
Transition your API calls from 'deepseek-chat' and 'deepseek-reasoner' to the specific 'deepseek-v4-flash' or 'deepseek-v4-pro' identifiers before the July 2026 sunset date.
The Scenario
You are maintaining a production application that uses legacy DeepSeek model names and you need to ensure it doesn't break in July 2026.
Before & after
Users relied on generic legacy names like 'deepseek-chat', which may become unpredictable as models are deprecated or upgraded, potentially breaking production systems after the 3-month grace period. This could lead to hours of emergency debugging.
Update your model parameter to 'deepseek-v4-flash' to maintain current 'chat' or 'reasoner' functionality while ensuring future stability. This takes about 5 minutes.
The Prompt
Scan my configuration file for all instances of 'deepseek-chat' and 'deepseek-reasoner' and provide a patch to update them to 'deepseek-v4-flash' to ensure compatibility before the July 2026 deprecation. [PASTE_CONFIG_CODE]
The legacy names 'deepseek-chat' and 'deepseek-reasoner' are being deprecated on July 24, 2026. Currently, 'chat' maps to non-thinking mode and 'reasoner' maps to thinking mode of the V4-Flash model.
Source
Change Log | DeepSeek API Docs"The two legacy API model names, deepseek-chat and deepseek-reasoner, will be discontinued in three months (2026-07-24)."