Negotiation and signature used to be different files. One tool for the markup, another for the signature, and a download in between that could drop a change.
You can mark up a contract with tracked changes. Insertions and deletions stay visible as changes, so the other party can see what moved. Comments sit on the draft for the questions that are not themselves an edit. A history of the draft records what happened across the review.
That same document can then be signed. The contract that was negotiated is the contract that goes out for signature. There is no second upload of a "final" file that might not match the last turn.
The review has a place for the changes, a place for the conversation, and a record of the draft. Signing is the next step on that document, not a new document.
