DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.
You get fewer pointless "model changed" notices when the switch isn't meaningful.
What's wrong with this entry?
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What
When the model changes mid-session, the notice shown to you is now suppressed unless the switch is actually meaningful, comparing the new model's alias and family, and any stepped-down variant of it, against both the previous model and the conversation's model.
Details
Switches within the same family no longer produce a breadcrumb.
Always on.
Evidence
conversationModel
Strings lifted out of the shipped bundle, so the claim above can be checked against them.