python.analysis.diagnosticMode

[InSyncWithFoo]

This setting has two possible values: workspace and openFilesOnly. I get it that this changes the number of diagnostics reported in one publishDiagnostic notification, but is that all? Are there other differences that would make one more or less preferable?

In other words, what are their intended usages?

[erictraut]

The workspace setting typically requires more computation (significantly more in some cases) because any modification to one file will cause pyright to reanalyze any dependent files. If you are modifying a file that many other files in your project depend upon, this could cause hundreds or thousands of files to be reanalyzed after a single keystroke.

That said, I personally prefer to use workspace in most cases because I want to understand the impact of any changes I make in my code. If I don't introduce any new typing violations anywhere within the workspace, there's a good chance that I haven't introduced any new bugs when making a change.

Some developers prefer to use pre-commit hooks to run a type checker once prior to committing a set of changes. In that case, it may be preferable to use openFilesOnly.