You'll notice
When a tool description or prompt section changes mid-conversation, Claude is now sent a diff saying the newer version is in effect.
A new sent-prefix ledger, tracked per conversation, compares each outgoing request against what was previously committed to detect a model switch, a declared boundary, or a violation. When a tool description, input_schema, or system-prompt section has changed since it was first sent, it synthesizes a diff block for the model prefaced with: "The following changed since it was first sent in this conversation. The earlier text above stays as sent; where they differ, the current version below is the one in effect."