Drop the TUI `/cancel` slash command
Drop the TUI `/cancel` slash command
The TUI exposed two identical ways to cancel a running turn: the `Esc` (and `Ctrl+C`) keybinding and a `/cancel` slash command. Both called `agent.cancel('cancelled from terminal')` with the same reason; when idle, `/cancel` only printed a "The agent is already idle." notice while the keybindings stayed silent. The running status line already advertises the keybinding (`Enter sends steering, Esc cancels`), and cancel
English
Problem
The TUI exposed two identical ways to cancel a running turn: the Esc (and Ctrl+C) keybinding and a /cancel slash command. Both called agent.cancel('cancelled from terminal') with the same reason; when idle, /cancel only printed a "The agent is already idle." notice while the keybindings stayed silent. The running status line already advertises the keybinding (Enter sends steering, Esc cancels), and cancelling by keystroke needs no editor submission, so the slash command was a second, less discoverable path to the same effect — surface area with no behavior of its own.
Decision
/cancel is removed. Cancelling a running turn is a keybinding-only affordance (Esc, or Ctrl+C while running), which the status-line hint and the /help shortcut list already document. The baseCommands autocomplete entry, the /help command line, the case '/cancel' branch in the editor submit handler, and the "already idle" notice it owned are gone; every other slash command (/help, /clear, /reasoning, /tools, /redraw, /reload, /resume, /exit, /skill:<name>) is unchanged. Typing /cancel now falls through to the generic Unknown command: warning like any other unrecognized slash input.
Alternatives considered
Keep /cancel as a discoverability alias — rejected: the running status line and /help both name Esc, so a typed alias adds a maintained code path and a per-idle-state notice for an action a single keystroke already performs more directly. No consumer needed the editor-submission route to cancellation.
Testing
packages/ui/tui/tests/tui.spec.ts asserts agent.cancelled contains 'cancelled from terminal', driven by the Esc/Ctrl+C keystrokes in that turn — the sole cancel affordance. The errors-and-help and disposed-terminal snapshots pin the /help line without /cancel; per-file coverage on packages/ui/tui/src stays at 100%.
Consequences
There is no way to cancel a turn by editor submission; cancellation is keybinding-only. This is a net removal of a redundant path and its idle-state notice, matching the single-primitive shape the rest of the stop surface already follows (public stop surface). Restoring a typed cancel would return with the autocomplete entry, the submit-handler branch, and its own test.
中文
Problem
TUI 提供了两条完全相同的取消运行中轮次的方式：Esc（以及 Ctrl+C）键位绑定，和一条 /cancel 斜杠命令。两者都以相同的原因调用 agent.cancel('cancelled from terminal')；空闲时 /cancel 只打印一条 "The agent is already idle." 通知，而键位绑定保持静默。运行状态行本就标示了该键位绑定（Enter sends steering, Esc cancels），且按键取消无需提交编辑器，因此这条斜杠命令只是通往同一效果的第二条、且更难被发现的路径——一块本身不含任何行为的界面。
Decision
/cancel 已移除。取消运行中的轮次是一项仅由键位绑定提供的能力（Esc，或运行中的 Ctrl+C），状态行提示与 /help 快捷键清单已对其作出说明。baseCommands 自动补全条目、/help 命令行、编辑器提交处理函数中的 case '/cancel' 分支，以及它拥有的 "already idle" 通知都已删去；其余每一条斜杠命令（/help、/clear、/reasoning、/tools、/redraw、/reload、/resume、/exit、/skill:<name>）保持不变。键入 /cancel 会像任何其他无法识别的斜杠输入一样，落入通用的 Unknown command: 警告。
Alternatives considered
保留 /cancel 作为便于发现的别名。 否决：运行状态行与 /help 都已标示 Esc，因此一个键入式别名会为一项单个按键已能更直接完成的操作，增加一条需维护的代码路径和一条逐空闲状态的通知。没有任何消费方需要经由编辑器提交来触发取消。
Testing
packages/ui/tui/tests/tui.spec.ts 断言 agent.cancelled 包含 'cancelled from terminal'，由该轮次中的 Esc/Ctrl+C 按键驱动——这是唯一的取消能力。errors-and-help 与 disposed-terminal 快照固定了不含 /cancel 的 /help 行；packages/ui/tui/src 的逐文件覆盖率维持在 100%。
Consequences
无法再经由编辑器提交取消一个轮次；取消仅由键位绑定提供。这是对一条冗余路径及其空闲状态通知的净移除，与其余停止能力已遵循的单一原语形态一致（public stop surface）。若要恢复键入式取消，需连同自动补全条目、提交处理函数分支及其专属测试一并回归。