Every harness runs shell commands. What differs underneath?

Present but not verified. 24 more harnesses register a shell tool that has not been read from source: Claude Code Bash, Claude Code BashOutput, Codex exec_command, Codex unified_exec, Codex write_stdin, dsh bash-persistent, dsh bash, dsh pwsh, dsh terminal_open/read/send, Grok Build bash, Grok Build monitor, Hermes process, Hermes terminal, Kimi Code bash, MiMo Code bash-interactive, MiMo Code bash, OpenClaw exec, OpenClaw process, OpenClaw terminal, opencode bash, OpenHands terminal, pi bash, Qwen Code run_shell_command, ZCode Bash. They are left out of the table below rather than shown as empty rows — a blank cell would claim the behaviour is absent, which is a different thing from not having checked.