Deprecation and versioning

Pin the model id, watch the retirement calendar, and treat a version bump as a change that needs its own evals.

Part of the Cheap and fast track on lAItest.

The model you shipped on has a retirement date. It was published before you shipped.

Pin the version, always

Vendors ship dated model ids for a reason. Cohere's Command A+ carries its release month inside its own name. A pinned id gives you behaviour that stops changing underneath you and a date you can plan a migration against. An unpinned alias gives you a model that can be swapped while you sleep, and a bug report you cannot reproduce.

A common misconception

Commonly believed: Auto-upgrading to the newest version of a model is the safe default.

Actually: A version bump is a model swap. The newer model may be tuned differently, may have a smaller context window than the one it replaces, and may be the one the vendor stopped recommending for your workload. A swap also throws away your prompt cache, because caches belong to a single model id. Re-run the evals, then move.

Prices have versions too

Introductory pricing expires on a published date with no change to the model at all. A standard rate can sit meaningfully above the launch-week rate that your finance model quoted. Read a pricing page for expiry dates and footnotes, not only for the numbers in the table, and check whether the row you copied was a promotion.

Dates you can actually check

Try it

Open the index and read the release dates. The newest row is rarely the most expensive one. This step is an interactive widget; open the lesson to use it.

In one sentence

Pin the id, watch the retirement calendar, and treat every version bump as a change that has to earn its way through your evals.