Claude/Code/Q/Why does piping claude --help to bat break keyboard scrolling while mise --help works fine?

• Why does piping claude --help to bat break keyboard scrolling while mise --help works fine?

  • AI Answer

    • AI/Response
    • Short answer: yes, this is a Claude/Code-specific bug, not a bat misconfiguration. Claude/Code enables an enhanced keyboard-input protocol (the kitty keyboard protocol / xterm's modifyOtherKeys, aka XTMODKEYS) on the terminal and doesn't always restore it afterward. The piped --help text itself carries no escape bytes — the terminal is left in this altered input mode from Claude Code's own terminal setup, so it mangles what less (bat's underlying pager) reads back from the keyboard.
    • Why j stops working and ctrl+j scrolls with blank lines:
      • While the enhanced mode is enabled, ordinary keys like j are no longer sent to the terminal as the plain byte j — they arrive as multi-byte CSI u escape sequences instead.
      • less doesn't recognize that sequence as its "scroll down" command, so it falls back to treating the bytes as literal input on its colon-style command line — matching the :jjjjjjj... shown at the bottom of the screen.
      • ctrl+j (linefeed, 0x0A) partially survives this re-encoding, so it does trigger a scroll, but the surrounding altered escape sequences are what produce the extra blank lines.
      • mise --help | bat works because mise never touches these terminal keyboard modes, so the terminal stays in normal input state.
    • Documented in the wild: anthropics/claude-code#38761 ("Terminal left in enhanced keyboard mode after exit — Ctrl-C/Ctrl-D broken") describes exactly this mechanism for Ghostty + tmux and was fixed in Claude Code v2.1.86, but the underlying protocol-restoration problem has recurred since: #62423 (legacy XTMODKEYS still sent even when the terminal advertises the kitty protocol) and #69063 (extra blank lines while scrolling tmux scrollback, same Ghostty + tmux setup) are both still open.
    • Workaround: run printf '\e[<u\e[=0u\e[>0m' (or reset) to force the terminal back to normal keyboard mode after the glitch appears. As a standing fix, a Stop hook in ~/.claude/settings.json that runs that printf on every Claude Code exit prevents the leak from persisting into the next command.
    • Related: Claude/Code/Q/Why can't I scroll up in tmux copy mode when Claude Code is in TUI mode? is a different symptom (alternate screen buffer) from the same general family of Claude Code terminal-mode side effects.