Migration Diary: Port the Tool Contract Before a Free Server Inherits Paid Endpoints

You should port the tool contract before you repoint a coding workflow at free model access. Leftover paid endpoints, unbounded retries, and vendor tool names survive cancellation and keep steering the next run. A portable contract plus a leftover scan gives you a cutover you can rehearse on a laptop. Free server capacity does not repair a tool schema that still calls the old paid host. This migration diary treats the move as an operations problem, not as a contest between model brands. This is not a ledger of past tool calls, and it is not a snapshot of the public API your service already exposes. You keep review rules that are yours, and you drop bindings that only exist because a vendor SDK hid the endpoint. It is a proposal you should execute in a scratch directory, not a claim that any particular quota will hold. Name the leftovers before you choose a host A paid coding agent usually stores three things that never appear in the chat transcript you export. The first is