The LANG variable is unset in src/javascript-node/.devcontainer/Dockerfile which causes UTF-8 rendering issues in tmux and other locale-aware tools.
If you run tmux display-message -p "#{client_utf8}" from within a tmux session (tmux new-session) you'll see it returns 0. If you try to paste a Unicode character (like a Braille figure ⣾, for example), you'll see it does not render in a tmux window.
I use dev containers for my dev workflow, and today I tried to experiment with using tmux within my self-hosted dev container (using mcr.microsoft.com/devcontainers/javascript-node:24 image), but noticed that characters did not render correctly when running Claude Code CLI from within a tmux session.
I have updated my own dev container setup to include a step to set LANG=en_US.UTF-8, but I believe this would be better fixed at the image level via:
Another GitHub user filed an issue for this problem on the nodejs/docker-node project, but it looks like it would be a breaking change: nodejs/docker-node#1839
The
LANGvariable is unset insrc/javascript-node/.devcontainer/Dockerfilewhich causes UTF-8 rendering issues in tmux and other locale-aware tools.If you run
tmux display-message -p "#{client_utf8}"from within a tmux session (tmux new-session) you'll see it returns0. If you try to paste a Unicode character (like a Braille figure ⣾, for example), you'll see it does not render in atmuxwindow.I use dev containers for my dev workflow, and today I tried to experiment with using tmux within my self-hosted dev container (using
mcr.microsoft.com/devcontainers/javascript-node:24image), but noticed that characters did not render correctly when running Claude Code CLI from within a tmux session.I have updated my own dev container setup to include a step to set
LANG=en_US.UTF-8, but I believe this would be better fixed at the image level via:Another GitHub user filed an issue for this problem on the nodejs/docker-node project, but it looks like it would be a breaking change: nodejs/docker-node#1839