... And then a few months later the decision-makers apparently had that same idea independently, and did not acknowledge me or any of the work that I'd already done on it under the aegis of the Outreach Program.

Which reminds me of many pieces of home-brew wisdom I received as a child "respect and credit is often the price of success". Another I value, which may not be relevant to your case was, "choose carefully whose opinions you make yourself a prisoner of".

My grandmother never lived to know the internet - but I find her advice transfers to the medium.

SFITCS