Claude Code hasn't updated yet it seems, but I was able to test it using `claude --model claude-opus-4-7` Or `/model claude-opus-4-7` from an existing session edit: `/model claude-opus-4-7[1m]` to select the 1m context window version
My statusline showed _Opus 4_, but it did indeed accept this line.
I did change it to `/model claude-opus-4-7[1m]`, because it would pick the non-1M context model instead.