does prefect-cli support dynamic passing of vars for one-off flow runs? Sometimes our usecase requires adhoc execution with custom parameters (sometimes running a whole pipeline is not time efficient or necessary, like if a smaller date range needs to be backfilled etc.).

Of course,

Parameters

are a first class feature

The Prefect CLI

run

command allows you to add parameters

okay I just want to clarify the docs real quick:

Yes to takes precedence. Do you mean you want to supply both a file and a string and have the string override the file?

Oh my bad! I didn't mean to imply I was trying to use both at once, I just wanted to clarify the snippet in the doc you linked about how one overwrites the other

These supplied parameters override the ones in the Python file, if that’s what you meant. Yep!