Why are these things never simple celebrations? MUC -> CDG -> JFK -> XXX. GUC applied to CDG -> JFK clears several months ago (the agent was more surprised than me). Yay!
MUC -> CDG goes mechanical. Eventually at CDG 'transfer desk' takes almost 2 hours to find another flight (CDG -> ATL -> XXX), but I'm back to standby for an upgrade (is that how things work? I thought I had a confirmed delta 1 seat?).
Get to the gate a few minutes before closing and the agent (actually very helpful and efficient, with a phone that seemed to go to some all-knowing and very efficient center) says its back-of-the-bus for me (but also checks on Air France to JFK, which had availability but is now too late... why didn't the transfer desk do this?). Some back-and-forth, and then it's closing time and 'take the seat or take your chances tomorrow', so I take the seat. And it's 1D, a favorite. Where did that come from?
And then one miscellaneous piece that I might have misunderstood. I thought the gate agent was saying that actually the certificate had been open for the MUC -> CDG flight, and for that reason I was considered a 'gate upgrade' to D1 on CDG -> JFK. I guess it's plausible that the certificate had been applied to the TATL and then shorter leg (can I use a GUC on Air France?), but actually there were available / open business seats on MUC -> CDG so even if the certificate were being applied, the agents weren't actually paying any attention to it.
But at the end of the day, a nice flight across the pond, especially the departing storms on arrival in ATL.