Define the product before you define the team
Start with users, business outcomes, system boundaries, integrations, security requirements and what the next release must accomplish. A vendor cannot estimate responsibly from a sentence such as “build an app like X.”
Separate product decisions from implementation decisions. The buyer should own priorities and acceptance. The engineering team can recommend architecture, libraries and deployment patterns, but those decisions should be documented so they can be reviewed later.
Ask who will actually write the code
Sales presentations often show a company’s strongest people. Interview the lead engineer, not only the account manager. Ask what similar systems they have personally built, how they handle pull requests, testing, deployment and incident response, and how much of their time is allocated to your project.
Keep repositories and environments under buyer control
Use repositories that the business can access from day one. Protect the main branch, require review for significant changes and keep environment secrets outside source code. Development and production accounts should be separate wherever practical.
Build in vertical slices
A useful milestone is something a user can see or an integration can prove, not “50% complete.” For a booking product, one milestone might accept an origin and destination, calculate a route, return a rate and store a test reservation. That is easier to review than a large unseen block of backend work.
Code quality is a delivery requirement
Specify automated tests where they matter, linting or formatting rules, dependency management, logging, error handling and documentation. Ask for a short architecture note and deployment instructions. A project is not complete if only the original developer knows how to run it.
Plan handoff before the first sprint
Ownership should include source code, configuration, database schema, deployment scripts, design files and documentation created for the project. Define what happens to access and retained copies when the engagement ends.
Plan application support after launch
New features are only part of the lifecycle. Define who monitors production, handles defects, applies dependency updates and responds when an integration changes. Support should have response expectations and clear ownership of emergency access.
Keep architecture decisions visible
Ask senior developers to record important tradeoffs in short architecture decision records. This helps future internal or external teams understand why the system was built a certain way instead of reverse-engineering every choice.