Source code is necessary for handover, but it is not enough. The next team needs to know how the system runs, which services it depends on, and what to check when it fails.
Document the first hour
Start with a short README that gets a developer from a fresh machine to a running application. Name the required versions, environment variables, setup commands, and a small set of tests. Keep secrets out of the document; explain where authorized staff obtain them. If setup requires tribal knowledge, do the handover with someone who has never run the project locally.
Document the operating path
List deploy steps, rollback steps, monitoring dashboards, backups, and who receives alerts. Record external services, domain ownership, payment or email providers, and renewal dates. A diagram is useful when it answers a question; it should never be the only place the information lives.
Explain decisions that are easy to undo badly
Short architecture notes can say why the system uses a particular queue, why customer records live in one database, or why a feature is behind a flag. Include known limits and unfinished work. That honesty saves the next team from rediscovering a problem that the first team already understood.
Finally, make sure the client controls the repository, hosting accounts, and data exports. A handover is complete when the product can move forward without the original team on the call.
