fix(ci): 两个标签写入 job 不再并发、也不再被标签事件重复触发 (#5649) (#5683)

`Check PR Size` 与 `Auto Label` 都用**整集 PUT**(`PUT /issues/{n}/labels`)
写标签,不是新增 POST。源码实测(非文档推断):

- `codelytv/pr-size-labeler@v1.10.4` `src/github.sh:68-91`:GET 读 PR 标签,
  grep 掉自己那套 size 家族,追加新 size 标签,然后 `curl -X PUT`。
- `actions/labeler@v7.0.0` `src/labeler.ts:56,111-133` + `src/api/set-labels.ts`:
  run 开始时快照 `preexistingLabels`,并入 config 命中项,回读一次实时标签,
  再 `client.rest.issues.setLabels` —— 就是 PUT。

两者都没有把写入改成新增的输入项;`sync-labels` 也不是那个开关 —— 它只管
「config 自己拥有的标签在 glob 不再命中时是否删掉」(`labeler.ts:81-83`),
缺省已是 false。本 PR 仍把它显式写出,只为防升级漂移,不是本缺陷的修复。

整集 PUT 只在「别人的写入落在读→PUT 窗口内」时才有破坏性,所以本文件能修的是
**重叠**:

1. 两个写入方不再并发(`auto-label` needs `pr-size`)。原先由同一事件同时拉起、
   窗口完全重合:PR #5650 run 31051251795(`opened`)里 `Add size label`
   22:03:47->22:03:49、`Label based on changed files` 22:03:47->22:03:49,
   labeler 的 PUT 在 22:03:49 发出 `unlabeled size/s` —— 抹掉的是它不管的标签。
2. 两个写入方不再被 `labeled`/`unlabeled` 触发。它们唯一的输入是 diff,标签事件
   改不了 diff,这种 run 只能把同一个集合再 PUT 一遍 —— 零新信息,多一次互抹
   机会。同 PR run 31051273625(由标签事件拉起):`Auto Label` 重算后没写,
   `Check PR Size` 在 22:04:22 又 PUT 了一次。两个事件类型保留在 `on:` 里,
   因为 `changeset-check` 确实需要(#5580)。

未被本 PR 关闭、并写进文件注释而非留给下一个读者踩:**工作流之外**的写入方
(`gh pr create` 后几秒挂标签的 agent 或人,正好落在这两个 job 运行期间)
仍可能落进 PUT 窗口被抹 —— #5533 的 `skip-changeset` 豁免只活一秒就是这样丢的
(15:46:44 挂上,15:46:45 被 labeler 的 `{size/m, tests}` PUT 抹掉)。关掉这半
需要写入本身变成新增语义,不是排序问题,任何本文件的配置都替代不了。

`changeset-check` 的实时读与计数逻辑(#5580/#5625)、`allow-major`(#5620)一字未动。

Co-authored-by: Claude <noreply@anthropic.com>

Author: os-zhuang

.github/workflows/pr-automation.yml

@@ -5,8 +5,59 @@ on:
     types: [opened, synchronize, reopened, labeled, unlabeled]
 
 jobs:
+  # ===========================================================================
+  # Both label-writing jobs below write this PR's label set with a WHOLE-SET PUT
+  # (`PUT /issues/{n}/labels`), never an additive POST. Read out of the pinned
+  # sources rather than inferred from the docs (#5649):
+  #
+  #   * codelytv/pr-size-labeler@v1.10.4 -- src/github.sh:68-91
+  #     (`github::add_label_to_pr`): GETs the PR, greps its OWN size family out
+  #     of the result, appends the new size label, then
+  #     `curl -X PUT .../issues/$pr_number/labels` with the whole set.
+  #   * actions/labeler@v7.0.0 -- src/labeler.ts:56,111-133 plus
+  #     src/api/set-labels.ts: snapshots `preexistingLabels` at run start,
+  #     unions in the config matches, re-reads the live label list once, then
+  #     calls `client.rest.issues.setLabels` -- which IS the PUT.
+  #
+  # Neither action exposes an input that makes its write additive, and
+  # `sync-labels` is NOT that input: it only decides whether a label the CONFIG
+  # owns is dropped once its globs stop matching (labeler.ts:81-83). It is
+  # pinned explicitly below for upgrade-drift protection only. It does not, and
+  # cannot, stop the clobbering described here.
+  #
+  # A whole-set PUT only destroys someone else's label when that label lands
+  # inside the window between the writer's read and its PUT. What this file can
+  # therefore fix is the OVERLAP, and two changes below do exactly that:
+  #
+  #   1. The two writers no longer run concurrently -- `auto-label` needs
+  #      `pr-size`. They used to be started by the same event and overlapped
+  #      exactly. Live specimen, PR #5650 run 31051251795 (the `opened` run):
+  #      `Add size label` ran 22:03:47->22:03:49 and
+  #      `Label based on changed files` ran 22:03:47->22:03:49, and the
+  #      labeler's PUT emitted `unlabeled size/s` at 22:03:49 -- one second
+  #      after the size job added it, for a label the labeler does not manage.
+  #   2. Neither writer runs on `labeled`/`unlabeled` any more. Their only input
+  #      is the diff, which a label event cannot change, so such a run could
+  #      only ever re-PUT the same set -- one more chance to erase a concurrent
+  #      writer in exchange for no new information. Same PR, run 31051273625
+  #      (started by a label event): `Auto Label` recomputed and wrote nothing,
+  #      `Check PR Size` re-PUT at 22:04:22. The two event types stay in `on:`
+  #      because `changeset-check` genuinely needs them (#5580).
+  #
+  # NOT closed by either change, and deliberately recorded rather than implied:
+  # a writer OUTSIDE this workflow -- an agent or a human labelling the PR
+  # seconds after `gh pr create`, i.e. exactly while these jobs run -- can still
+  # land inside a PUT window and be erased. That is how #5533 lost its
+  # `skip-changeset` exemption for one second (15:46:44 applied, 15:46:45 erased
+  # by the labeler's PUT of `{size/m, tests}`). Closing that half needs the
+  # writes themselves to become additive, not merely better ordered; it is the
+  # open half of #5649 and no configuration here can stand in for it.
+  # ===========================================================================
   pr-size:
     name: Check PR Size
+    # A `labeled`/`unlabeled` event cannot change this job's input (the diff),
+    # so running it there buys nothing and costs one whole-set PUT. See above.
+    if: github.event.action != 'labeled' && github.event.action != 'unlabeled'
     runs-on: ubuntu-latest
     permissions:
       pull-requests: write
@@ -31,6 +82,19 @@ jobs:
 
   auto-label:
     name: Auto Label
+    # ORDERING ONLY, not a dependency: this job wants `pr-size`'s PUT to be
+    # already done, so that the label set this one reads includes the size
+    # label and its own PUT carries it forward. `!cancelled()` is written out
+    # because GitHub would otherwise wrap this `if:` in an implicit `success()`
+    # -- a failed or skipped size job must not silently stop path labelling.
+    # (Same reasoning the check-workflow-status-functions gate exists to make
+    # explicit; that gate scans only `needs.*.outputs.*` reads, so this one is
+    # out of its scope and has to state its intent by hand.)
+    needs: pr-size
+    if: >-
+      !cancelled()
+      && github.event.action != 'labeled'
+      && github.event.action != 'unlabeled'
     runs-on: ubuntu-latest
     permissions:
       contents: read
@@ -45,6 +109,14 @@ jobs:
         with:
           repo-token: ${{ secrets.GITHUB_TOKEN }}
           configuration-path: .github/labeler.yml
+          # Pinned at the value it already defaults to (action.yml), because a
+          # default is not a decision: an upgrade may move it, and `true` would
+          # make this step REMOVE a label of its own config whenever the globs
+          # stop matching -- on a `synchronize` that reverts a docs file, for
+          # instance. Pinning it is upgrade-drift protection and nothing more:
+          # `sync-labels` never governed foreign labels, so it is NOT the fix
+          # for the clobbering documented at the top of this file (#5649).
+          sync-labels: false
 
   changeset-check:
     name: Check Changeset