Hey, thanks for the report, and extra thanks for the deep dive. Isolating the OSC 52 path and comparing the bytes really helps.
This is a known bug on our side. When copying non ASCII text like CJK through the terminal, it ends up as double encoded mojibake. This doesn’t happen in VS Code. I’ve filed an internal report that the OSC 52 path is affected too, not just normal selection. I can’t share a fix timeline yet.
Your workaround using set-clipboard off plus copy-pipe with pbcopy is a good temporary fix for local tmux. For remote SSH, where OSC 52 is the main bridge to the clipboard, we don’t have a workaround yet.
If there’s an update on the fix, I’ll reply in the thread.