A handover document should help a new person understand what the project does and how to verify it. Record the public routes, source-of-truth files, environment assumptions, deployment steps, known issues, and decisions that should not be changed casually.
Keep secrets out of the document. Instead, describe where controlled access is managed and what a maintainer should confirm before making a change. A short accurate guide is more useful than a large archive nobody can navigate.
Before development or a major change, turn this idea into a clear operating agreement: define the people who use the process, the records that must remain trustworthy, the approval boundaries, and the result the business will review. A small pilot with real examples can reveal missing rules earlier than a large build and make later support, handover, and integration safer.