That is also not enough. An agent could build an application that functions, but you also need to have a well-designed underlying architecture if you want the application to be extensible and maintainable - something the original dreamer may not even be capable of - so perhaps a shared extended dream share with a Sr. architect is also needed. Oh wait .. I guess we're back to square 1 again? lol
And even that would not be enough.
In reality, it would have to put the user to sleep and go through various dream scenarios to have the user's brain really build an internal model that is not there in the first place. No brain interface can help find what is not there.
We usually need interactions with reality to build the internal model of what we actually want step by step, especially for things we have not done before.
Even for info that is there, that's also a limit to fantasy or sci-fi brain scanning. The knowledge is not stored like in a RAM chip, even when it is there. You would have to simulate the brain to actually go through the relevant experiences to extract the information. Predicting the actual dynamic behavior of the brain would require some super-super sub-molecular level scan and then correctly simulating that, since what the neurons will actually do depends on much more than the basic wiring. Aaaaand you may get a different result depending on time of day, how well they slept, mood and when and what the person ate and what news they recently read, etc. :)