arc is built into the radian binary. It keeps plans and tasks as files in your repository, runs each task as its own headless radian worker, and merges only what passes a fixed gate. arc is a program, not a model, and you stay the one who confirms and merges. arc 内置在 radian 这个二进制里。它把计划和任务存成你仓库里的文件，每个任务交给一个独立的无头 radian worker，只合并通过固定门禁的结果。arc 是一个程序，不是模型；确认和合并仍然由你来做。
$ radian arcPart of radian, open source under MIT or Apache-2.0.属于 radian，开源，MIT 或 Apache-2.0 协议。
Every step leaves a file or a journal you can read afterwards.每一步都留下一个可以事后翻看的文件或日志。
01 · leadA lead writes the plan and its tasks through arc's MCP server. It cannot confirm, start or merge anything.lead 通过 arc 的 MCP 服务器写计划和任务。它不能确认、启动或合并任何东西。02 · confirmYou confirm the plan. At auto off you start each task yourself; at run arc starts a task once the tasks it waits for are merged.你确认计划。auto 为 off 时每个任务由你启动；为 run 时，arc 在任务所等的任务合并之后自己启动它。03 · workersEach task runs as a separate radian exec process in its own worktree, on its own branch, and pushes the result.每个任务是一个独立的 radian exec 进程，有自己的 worktree 和分支，做完把结果推上去。04 · gateThe gate checks the pushed commit. A failed stage sends the task back for rework.门禁检查推上来的提交。某个阶段失败，任务就退回去返工。05 · mergeradian arc merge takes your approval and pushes to the remote main. If the branch moved after the gate, the approval is void and the task is verified again.radian arc merge 取你的批准，再推到远端 main。门禁之后分支又动过的话，批准作废，任务重新验证。arc schedules by fixed rules. No step waits on a model's judgement.arc 按固定的规则调度，没有哪一步要等模型来判断。
autoPer plan: off (you start and merge each task), run (arc starts tasks and runs the gate, then waits for you), or merge (arc also merges when every required stage passed).每个计划一个级别：off（启动和合并都由你）、run（arc 启动任务、跑门禁，然后等你）、merge（所有必需阶段都过了，arc 也替你合并）。owner-onlyConfirm, start, merge, reject, priority and auto are yours, in the TUI or on the CLI. The lead's MCP server has no tool for them.确认、启动、合并、驳回、优先级和 auto 都是你的，在 TUI 里或命令行上做。lead 的 MCP 服务器里没有对应的工具。verdictsA verdict is written once and never changed. An approval binds to one commit.结论只写一次，之后不再改动。批准绑定在一个提交上。budgetsEvery task and plan records its cost, and each can carry a cost and wall-time budget.每个任务和计划都记录花费，也都可以设花费和耗时的预算。the TUIPlans, a board that groups open tasks by who acts next (todo, doing, verifying, needs you), each task's conversation, brief, diff and attempts, and the merge page.计划列表，按“下一步由谁来做”分组的看板（待办、进行中、验证中、需要你处理），每个任务的对话、简报、diff 和尝试记录，以及合并页。arc comes with radian. Run these in the repository you want it to work on.arc 随 radian 一起装好。在你要让它干活的仓库里运行下面三条。
$ radian arc init$ claude mcp add arc -- radian arc mcp$ radian arcinit lays out .radian/arc/ and checks four things: the credential, the origin remote, a dry-run push of the main branch, and the sandbox. Each failure is a warning.init 建好 .radian/arc/ 目录，并检查四件事：凭据、origin 远端、对 main 分支的一次试推送，以及沙箱。哪一项失败就给一行警告。origin remote you can push the main branch to.arc 需要一个 git 工作区，并且有一个你能往 main 分支推送的 origin 远端。.radian/arc/config.toml.门禁要跑的命令写在 .radian/arc/config.toml 里。