Agree what a milestone delivers and how it will be checked before implementation starts. A fixed price is meaningful only with a defined scope, exclusions and a way to handle new information.
Make acceptance observable For each important workflow, describe the starting state, user role, expected result and failure behavior. “Users can download invoices” still leaves questions about company access, the invoice source and unavailable files. Resolve the important ones in the scope.
At review, compare the delivered version with the agreed checks. Keep actual defects, new requests and unresolved questions separate. Record the evidence, responsible person and next action.
When the scope changes Describe the proposed change and its effect on delivery, cost, tests and dependencies. Agree the update before treating it as part of the milestone. A weekly engagement also needs priorities; changing direction uses capacity even when there is no fixed feature list.
Wavect's published terms explain acceptance, exclusions and change requests. The specific offer governs your engagement. If you need to understand a contractual deadline or dispute, review that agreement with a qualified adviser rather than relying on chat.
For a concrete example of the format, inspect the illustrative milestone evidence pack. It is an English example document, not a customer result or an additional contractual promise.
Before signing: ask, “Which version will we review, against which checks, and who decides what happens to an open item?”