I'd default to transparency - but that means also being up front about risks. It's very nice to be able to say you have a partnership that is being discussed -

I'd default to transparency - but that means also being up front about risks. It's very nice to be able to say you have a partnership that is being discussed - it's less nice to "pump them up" on a partnership that's not a sure thing. So if you disclose (and I think most times founders should) - disclose responsibly. That means - don't bullshit them about how real the partnership is. If it's "Just in the discussion phase" (or frankly, anything other than a signed deal) make sure they know it's not a sure thing. "We're working on a partnership with ____. We think it can provide some great opportunities, but it's not a done deal. We're still trying to figure out the details, and there's a chance it may not happen - but right now it's being discussed".