Scope and acceptance
Tie each milestone to testable functions, define exclusions, and document how changes are assessed.
Ownership and accounts
Define ownership of code, designs, and data, plus control of store, hosting, domain, and provider accounts.
Support and security
Document warranty, response expectations, backups, updates, incident handling, and sensitive-data responsibilities.
Make delivery testable
Turn broad descriptions into acceptance scenarios: what the user does, the expected result, and the device or environment. Tie payments to clear milestones and define who signs off and how much review time each stage gets.
What happens after launch?
Distinguish a defect in agreed scope from a new feature request. Specify hosting, backups, security updates, incident response, and handover if the delivery team changes.