Great product with lot of interesting features, congratulations!
There is one thought: in my life, ideas are never separated from context. Mostly, ideas appears as part of long discussion. Almost all of these discussions are in comments on Google Docs.
Actually, ideas (IMHO) do not belong to external authors. They are always summary of discussions, spin-off phrases, which are based on context.
So, it might be interesting to get not only ideas–project link, but context–ideas workflow.
Not sure it concerns your product vision, thought.