In response to a solicitation in an area of my expertise, I approached a known expert in a different field; I had thought of a way to apply that field to solve the problem. He liked my idea and set up a meeting with him and his postdocs; over time, we went through several rounds of written communication, proposal outlines, research plans, and revisions amongst us.
Midway through, I learned more about the solicitation and concluded that it wasn't a good match; we discussed this, decided not to apply, but that the plan was good and that we should look for other sources of funding. As we did this, we continued to do some revisions together.
A while later, he sent me an email that he found a good source of funding, that he has a good relationship with the source and doesn't really need a partner for it, and that he is going to apply without me. I was quite upset, but, seeing that he was telling me and not asking me, and that I had no way to stop him, said "okay, makes sense, please send me a copy of the proposal and keep me informed."
In truth, his proposal was advanced far beyond what I had last worked on. But, the core idea was mine; and I have the records to attest to that, not to mention that his postdocs could verify that as well.
Assuming he gets the grant, I have no desire to get a share of the funds. At this point, he can do the rest of the work without me. He really is an expert and manages a very large, very prominent research program with lots of high profile funding. And rightfully so - he produces results.
What I would like is coauthorship. After all, the entire approach is my idea. I thought of using his area of expertise to solve a very high profile problem of growing importance in my field, and described to him in detail why all the indigenous methods to my field are failing, and why an approach drawing on his expertise could succeed.
What is the right way to handle this? I won't be satisfied with an acknowledgement at the end; I'd like to be one of the authors. I'm happy helping with the research further though I'm not sure he feels he needs me.
And, moreover, is this type of behavior acceptable? Do I have any leverage here? Do I need it?
To clarify, while I certainly didn't do the research yet, it was more than just giving him an idea. I sent an outline, discussed the plan, and spent hours revising and iterating on their research plan. I'll be equally clear that the final proposal was very high quality, and went far beyond what I had worked on.
From the responses, it seems this falls into a grey area. So let me revise my question: Given that he's probably going forward with this, what's the best way to approach him and ask to be a coauthor? I'd be happy being involved with the research itself, but I'm not sure he wants that. He'd probably be best off career-wise keeping it to him and his students (and, mind you, this is a researcher who puts a lot of effort on career advancement - he's an equally talented businessperson, albeit in academic research, as scholar).