do we want every coding agent writing everything from scratch for every project?

or would reusability/modularity across projects and teams be beneficial?

The human desire for interoperability would prevent writing everything from scratch, but to the extent that is reasonably possible, yes. We would already do that now if humans weren't a limiting factor. But coding agents, as I know the term, is about removing humans from the equation of writing code. I did ask if there is another interpretation for "coding agent" being used.

Of course, distinct projects is a human construct that computers don't care about. As coding agents evolve (if they do), it isn't likely that the idea of projects will persist long-term.