Nice! I hope this will lead to many more-useful-and-lovely links 
So the Discourse OneBox theoretically supports Open Graph, buuut... if I’m reading the code right (ha!), I think right now the Open Graph metadata created by headR is going to run afoul of Jeff Atwood’s beliefs about the absolute importance of the og:description tag
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I don’t know if Discourse is an important enough venue for you to want to support its opinionated OG dialect?