Ask what is handed over.
Your agreement should identify the project code, data, domain and documentation, with the payment stage at which ownership transfers. Existing proprietary tools and third-party components can have separate licences. Ask where the repository sits and what another developer would need.
List the accounts and services.
Hosting, email delivery, maps, payment processing and other APIs may have their own charges. Establish who holds each account, who pays the provider and what happens if usage grows. The relevant costs belong in the proposal.
Agree the care the system needs.
Updates, backups, monitoring and recovery checks are jobs somebody must own. Agree the scope, access, response arrangements and cost. A completed build does not automatically include unlimited changes or continuing cover.
Keep the exit practical.
Discuss exports, handover notes, account access and the treatment of private data before launch. If another supplier takes over, the agreed responsibilities and dependencies should be understandable without reconstructing the project.