DeepSeek is MIT-'open' — then swapped the model behind its API overnight.DeepSeek 是 MIT『开放』的——然后它一夜之间换掉了自己 API 背后的模型。

Open weights don't make the hosted endpoint stable — your old evals now describe a dead checkpoint.

What 'open' protects, what it doesn't, and the one line to add to your config

OUR READ

MIT weights mean you can leave; they don't mean the hosted service you call is stable or yours. Call the API and you depend on a version the vendor can change without notice.

WHAT HAPPENED (Oct 17)

• DeepSeek repointed the deepseek-flash endpoint to the new V4.1-Flash-1017 checkpoint — same name, same price, no changelog.
• Every eval you ran last week now describes a checkpoint that no longer serves traffic.
• The cheap agent setup leans on a hosted Search/Fetch API: free through Oct 31, then $0.75 per 1,000 calls.
• The real exit — self-hosting — means running about 510 GB of weights.

WHY IT MATTERS

Open weights widen what you can run; the hosted endpoint, where most run it, is owned by the vendor — version and price. 'Open' protects your right to leave, not the stability of what you use today.

A model you can download is still a dependency if you call it by a name the vendor can repoint.

Second-order: dependence quietly accumulates behind the 'open' label, so leaving costs more later.

BEST CASE AGAINST US

Unlike a closed model, MIT is a genuine exit: pin the 1017 checkpoint, self-host, or use a neutral host. For teams with that infrastructure, the dependency is opt-in and reversible.

DO THIS WEEK

In production? Stop calling the floating alias: pin the 1017 checkpoint, log the version, and budget the Oct 31 Search/Fetch fees.

We'd revise if DeepSeek ships versioned, pinnable model ids with changelogs by default, or affordable third-party hosting of the exact checkpoint becomes widely available, by Mar 31, 2027.