docs(ci): explain why the review-pr sweep needs a whole-workspace quarantine

[CanReader]

What this PR does

Rewrites the comment above the quarantine fallback in the review-pr job's
Clean stale .qwen before checkout step. Comment only, zero executable lines
change.

Why it's needed

I opened this against #10392 by mistake. The sweep that issue asks for is
already on main: #10214 (commit 379bef96) added it to this workflow along
with the cleanIdx < checkoutIdx pin in
scripts/tests/review-worktree-cleanup-workflow.test.js, even though its
description said it was scoped to ci.yml. Nothing here changes behaviour, so
the Fixes link is gone and #10392 should be closed against #10214 instead.

What's left is still worth keeping on its own. The old comment stated the
fallback but not the reason it exists:

# If a foreign-owned directory cannot move to a different parent,
# quarantine the runner-owned workspace and recreate the checkout
# root. Warm contents are lost only on this unrecoverable path.

Reading that, the fallback looks redundant, since the mv right above it
already targets a writable parent. The missing piece is that renaming a
directory across parents also needs write permission on the directory being
moved, because the kernel has to update its .. entry. For a root-owned
.qwen.root-orig the runner does not have that, and the preceding
chmod -R u+w cannot grant it either, so the individual mv fails with
EACCES even though the workspace parent is perfectly writable. That is the
case the whole-workspace quarantine exists to catch, and it was not obvious
from the code.

Reviewer Test Plan

How to verify

Read the diff. It touches # lines only. The comment-stripped run: body is
byte-identical to main:

git numstat main..HEAD -> 6 3 .github/workflows/qwen-code-pr-review.yml

Evidence (Before & After)

N/A (comment-only change)

Tested on

OS	Status
🍏 macOS	N/A
🪟 Windows	N/A
🐧 Linux	✅

Risk & Scope

• Main risk or tradeoff: None. No executable line changes.
• Not validated / out of scope: The sweep's runtime behaviour, unchanged here and covered by the existing structural test.
• Breaking changes / migration notes: None

Linked Issues

None. The actual fix for #10392 shipped in #10214.

中文说明

仅改写 review-pr 任务中 Clean stale .qwen before checkout 步骤里 quarantine
兜底逻辑上方的注释，无任何可执行行变化。

本 PR 最初错误地关联了 #10392。该 issue 要求的清理逻辑其实已经在 main 上
（#10214，commit 379bef96），因此已移除 Fixes 关联，#10392 应改为指向
#10214 关闭。

保留注释改写的理由：旧注释只说明了兜底行为，没有说明它为何存在。关键点在于，
跨父目录重命名目录还需要对被移动目录本身有写权限（内核需更新其 .. 项）。
对 root 所有的 .qwen.root-orig，runner 不具备该权限，前面的 chmod -R u+w
也无法赋予，因此即使工作区父目录可写，单独的 mv 仍会以 EACCES 失败。这正是
整体工作区 quarantine 所要处理的场景，而这一点从代码中并不显而易见。

[qwen-code-ci-bot]

✅ Qwen Triage finished — view run. See the stage comments in this thread for the result.

✅ Qwen Triage 已完成 —— 查看运行。结果见本线程中的各阶段评论。

[qwen-code-ci-bot]

@CanReader thanks for the PR — but the gap it describes is already fixed on main, and the diff doesn't match the description.

• The fix already landed. #10214 (merged today 10:33 UTC as commit 379bef96) added exactly this sweep to the review-pr job: the Clean stale .qwen before checkout step running the chmod → rm → sudo rm → quarantine loop over both .qwen and .qwen.root-orig, placed before Checkout base branch — plus the structural test pin asserting cleanIdx < checkoutIdx in scripts/tests/review-worktree-cleanup-workflow.test.js. #10214's description said its diff was scoped to the three ci.yml copies, but the merged PR also modified qwen-code-pr-review.yml (+47 lines). Everything #10392 asks for is already on the default branch; the issue is simply still open.
• The actual diff here is comment-only. The entire change is a 3-line → 6-line rewording of the quarantine-fallback comment inside the sweep (+6/−3, zero functional change). The sweep and the test the description references are not added by this PR — they are already in the base.
• Why request changes: merging as-is would auto-close #10392 via a PR that doesn't contain the fix, misattributing the history. Two reasonable paths forward:
  • Close this PR; a maintainer can then close #10392 pointing at #10214, since the fix is already live.
  • If you think the comment rewording is worth keeping on its own merits, re-purpose this PR with an accurate title/description and drop the Fixes #10392 link.

中文说明

@CanReader 感谢提交 —— 但这个 PR 描述的缺口已经在 main 上修复了，而且 diff 与描述不符。

• 修复已经合入。 #10214（今天 10:33 UTC 合入，commit 379bef96）已经把这个清理逻辑加进了 review-pr 任务：Clean stale .qwen before checkout 步骤，对 .qwen 和 .qwen.root-orig 两个名字执行 chmod → rm → sudo rm → quarantine 循环，位于 Checkout base branch 之前 —— 同时还在 scripts/tests/review-worktree-cleanup-workflow.test.js 中加了断言 cleanIdx < checkoutIdx 的结构测试。虽然 #10214 的描述说它只改了三份 ci.yml，但合入的版本实际也修改了 qwen-code-pr-review.yml（+47 行）。#10392 要求的内容已经全部在默认分支上，issue 只是还没被关闭。
• 这里的实际 diff 只是注释改写。 全部改动是把 sweep 中 quarantine 兜底路径的 3 行注释改写成 6 行（+6/−3，零功能变化）。描述中提到的 sweep 和结构测试都不是这个 PR 加的 —— 它们已经在 base 里了。
• 为什么 request changes： 按现状合入会通过一个不包含修复的 PR 自动关闭 #10392，造成历史归属错误。两个合理的处理方式：
  • 关闭本 PR，由维护者指向 #10214 关闭 #10392（修复已生效）。
  • 如果你认为这个注释改写本身值得保留，请把 PR 改成准确的标题/描述，并去掉 Fixes #10392 关联。

— Qwen Code · qwen3.8-max

[qwen-code-ci-bot]

Not explored to full depth (tool budget reached): "agent 6b": none — no check was cut short by the tool ceiling..

Not linted (tool limitation, not a blocker): the executable-script lint — .github/workflows/qwen-code-pr-review.yml: actionlint embedded-shell source mapping is not yet supported — not linted.

中文说明

未探索到全部深度（达到工具调用预算）："agent 6b"：none — no check was cut short by the tool ceiling.。

未检查（工具限制，非阻断）：the executable-script lint — .github/workflows/qwen-code-pr-review.yml: actionlint embedded-shell source mapping is not yet supported — not linted。

— qwen3.8-max via Qwen Code /review (v0.22.3)

[github-actions]

Please do not rebase or force-push to an active PR as it invalidates existing review comments. Note for future reference, the bots always squash all changes into a single commit automatically as part of the integration.

中文

请勿对活跃的 PR 执行 rebase 或 force-push，因为这会使已有的评审评论失效。另外，供日后参考：作为集成流程的一部分，机器人始终会自动将所有改动压缩（squash）为单个提交。

[qwen-code-ci-bot]

Partially reviewed — gaps disclosed.

Not reviewed: reverse audit — stopped before round 1 by the review time budget.

Not linted (tool limitation, not a blocker): the executable-script lint — .github/workflows/qwen-code-pr-review.yml: actionlint embedded-shell source mapping is not yet supported — not linted.

中文说明

仅完成部分审查，审查缺口已披露。

未审查：反向审计——评审时间预算不足，未能开始第 1 轮。

未检查（工具限制，非阻断）：the executable-script lint — .github/workflows/qwen-code-pr-review.yml: actionlint embedded-shell source mapping is not yet supported — not linted。

— qwen3.8-max via Qwen Code /review (v0.22.3)