https://blog.margrop.net/en/tag/utf-8/ Recent content in Utf-8 on Margrop Blog Hugo -- gohugo.io en-US Tue, 28 Apr 2026 18:40:00 +0800 https://blog.margrop.net/en/post/tmux-opencode-chinese-underscore-fix/ Tue, 28 Apr 2026 18:40:00 +0800 https://blog.margrop.net/en/post/tmux-opencode-chinese-underscore-fix/ <blockquote> <p><strong>Short version</strong></p> <p>This was not an opencode Chinese rendering bug, and it was not a broken terminal font. The tmux client had been detected as not supporting UTF-8. The decisive evidence was <code>tmux display-message -p 'client_utf8=#{client_utf8}'</code>, which returned <code>client_utf8=0</code>. In that state, tmux replaces non-ASCII output with underscores, so every Chinese character inside the opencode TUI appeared as <code>_</code>.</p> </blockquote> <p>This post documents a small but very typical terminal debugging session. On the same Mac, running <code>opencode</code> directly displayed Chinese text correctly. But after starting a tmux session first and then running <code>opencode</code>, all Chinese text became underscores.</p> <p>This kind of problem is easy to misdiagnose. The first instinct is often to blame the font, the terminal emulator, the opencode version, a color theme, Nerd Font configuration, Unicode width handling, or a bug in the TUI framework. In this case, however, the key question was much narrower: <strong>does the current tmux client believe it can write UTF-8 back to the outer terminal?</strong></p> <p>To avoid exposing private environment details, all examples below are generalized. They do not include real hostnames, private addresses, session names, credentials, usernames, or project paths. The only things preserved are the technical facts needed to understand the failure and the fix.</p>