TUI renders box-drawing glyphs as mojibake under ConPTY hosts on Windows (console codepage never set) #1524

Environment

• Windows 11 x64 (build 26300), observed 2026-11-15
• zcode CLI 0.17.1 — affects both the desktop-bundled CLI and standalone dists
• Terminal: a ConPTY-based terminal multiplexer (herdr-core 0.1.21) whose console output codepage is the default OEM codepage

Repro

Launch the interactive TUI under a ConPTY host whose console output codepage is the default OEM codepage. All box-drawing glyphs — panel borders, spinner frames — render as mojibake (e.g. the ╭─ Yolo ─╮ header comes out as ð▒ð-style sequences); plain ASCII text is unaffected. The same mojibake appears in plain classic console windows running with codepage 437/850.

Root cause

The TUI (Node/Ink) writes UTF-8 bytes to stdout but never calls SetConsoleOutputCP(65001) (or the equivalent) on win32. libuv writes the raw UTF-8 bytes to the ConPTY pipe, and the host decodes them with the console's OEM codepage, producing mojibake. Other agent CLIs on the same machine (Rust- and Go-based TUIs) set the console codepage themselves and render correctly in the same host.

Suggested fix

On win32 at TUI startup, set the console output codepage to UTF-8 (a single SetConsoleOutputCP(65001) call), or configure the output encoding accordingly.

Workaround

Running chcp 65001 before launching the CLI fully fixes rendering.