@@ -87,7 +87,7 @@
 - 这种 PR 停在 draft,正文写精确的预期红清单:逐条失败测试名 + 报错签名。
 - 正文同写解除条件:点名所依赖的那张 PR 合入。
 - 每个 CI-failure 事件与清单比对:签名匹配静默跳过,新签名才是真问题。
-- 依赖合入后:最后一轮同步 → 红清零 → 转 ready → 入队。
+- 依赖合入后:末轮同步走中继 `pr_update_branch`(`rest-channel.md`)→ 红清零 → 转 ready → 入队。
 
 ## D. 串行接力:多个已实现 PR 全碰生成物时,一次只放行一个
 
 
@@ -86,7 +86,7 @@
 - 摘标签与翻 ready 是状态写,同 head 重起标签敏感检查 ⇒ ③ 在入队前末次状态写之后读。
 - 检查全部完成的 PR 挂 auto-merge 即入队,本仓 28–60 秒 ⇒ 挂载与落地之间无窗口。
 - `mergeable_state` 未落定时挂上的是经典 auto-merge、不入队,落定后再挂才入队。
-- `behind` 的 PR 照常入队:落后于 main 不是入队否决,⛔ 不为它先跑 update-branch。
+- `behind` 的 PR 照常入队:落后于 main 不是入队否决,⛔ 不为它先发 `pr_update_branch`。
 - `check_suite.completed` 会命名过期 head,check-run 也只属最后一次 push ⇒ 用前先重读当前 head。
 - 落地相邻的写侧一则:GitHub 标签描述上限 100 字符,超长写回 422,133 字的原文即不可存。
 
 
@@ -46,8 +46,8 @@
 - ✓ 该 `PATCH` 带 `state` 关卡/重开,`state_reason` 交付 `completed`、撤单 `not_planned`,走裸 REST。
 - 请求体走文件(`-d @file`)或引号定界 heredoc(`<<'EOF'`),⛔ 永不内联双引号串。
 - ✓ 请求复审 `POST .../pulls/{n}/requested_reviewers` · 开 PR `POST .../pulls` 带 `draft=true`。
-- ✓ `origin/main` 合进 PR head:`PUT .../pulls/{n}/update-branch`,PM 席位、零文件写、真合并提交。
-- `expected_head_sha` 须完整 40 字符 SHA(短 SHA 回 422);base 未动回 422 = 无事可做,不是失败。
+- ✓ `origin/main` 合进 PR head:中继 op `pr_update_branch`(`pull` + 40 位 `expected_head_sha`),真合并提交。
+- ⛔ 裸 `PUT .../pulls/{n}/update-branch` 落个人账号;短 SHA 派发前即拒;base 未动 422 = op 报 no-op。
 - ✓ 落地经中继 `node scripts/pm/fleet-write/dispatch.mjs --repo O/N --actions-file F`;`--via dispatch` 同载。
 - ⛔ 裸 `PATCH /pulls/{n}` 带 `{"draft": false}` 回 200 零改;状态码不作数,`GET /pulls/{n}` 才作数。
 - 线程自己建:`POST .../pulls/{n}/comments` 带 `commit_id`·`path`·`line`,回读看 `review_threads`。
@@ -71,7 +71,7 @@
 
 - `merged_by` 是入队者,⛔ 不是绕队证据:队列合并归属给入队的账户,对队列与直合零分辨力。
 - 判据 ①:直接合并 `PUT .../pulls/{n}/merge` 在强制队列 ruleset 下回 405。
-- ②:PR 上的 `added_to_merge_queue` timeline 事件。③:对已入队 PR 调 update-branch 回不能更新。
+- ②:PR 上的 `added_to_merge_queue` timeline 事件。③:对已入队 PR 发 `pr_update_branch` 回不能更新。
 - ①② 的拼写与边界住 `platform-readings.md` 队列段,本条只归拢判据。
 - 队列 required 集按 job 与 check-run 名匹配,workflow 名从不作为 check context 出现,搜也搜不到。
 - 改任一 job 名或 test 分片矩阵的形状,必须同一笔更新队列 required 集,否则队列静默挂起。
 
@@ -202,7 +202,12 @@
  *     its default 6. Neither is ever a fall-back to direct — no outcome of an
  *     accepted dispatch is (the no-run conformance below) — and neither is 0.
  *   - a stroke carrying no body (labels, assignees, state, a transfer, the
- *     GraphQL ops) reads nothing back and its outcome is unchanged.
+ *     GraphQL ops) reads nothing back and its outcome is unchanged;
+ *   - `pr_update_branch` carries no body and is confirmed INSIDE the run — the
+ *     executor polls the pull's head off `expected_head_sha`, or measures a
+ *     422 as a no-op, before it calls the action landed — so a `success` run
+ *     IS that confirmation; the seat reads the new head with one
+ *     `GET /repos/{repo}/pulls/{n}` after, and this file reads nothing back.
  *
  * ## The no-run conformance — every sender, one answer
  *
@@ -1132,7 +1137,7 @@ const SELF_TEST_BATTERIES = Object.freeze({
   'the dispatch: one paced POST to the board repo with event_type and client_payload; 204 is acceptance, anything else a refusal': 7,
   'the run-poller: the run named after the request id, its completion, its conclusion': 6,
   'the ceilings: no run in the start window, no completion in the ceiling — UNCONFIRMED, never retried': 7,
-  'the read-back targets: every op the table lets carry a body — derived, each with a locator — and no other op is read back': 6,
+  'the read-back targets: every op the table lets carry a body — derived, each with a locator — and no other op is read back': 7,
   "the verdict: post-stamped's own classifier, imported — declared normalisations land, a split, lost or truncated byte is NOT STORED at its first differing byte, an unreadable body is unverified, the PR-create footer forgiven on pr_create alone": 13,
   "the round trip: the card's 41,699 bytes with a multi-byte character across every 16 KiB boundary of every stream, byte for byte through pack, the wire, the runner's env text, the validator and the executor; a per-chunk decode is NOT STORED": 8,
   'the read-back end to end: after a success run each body at its locator — a corrupted read-back exits 4 through the CLI, an unreadable or unfound one 6, a body-less stroke reads nothing, never a retry': 17,
@@ -1526,6 +1531,7 @@ export async function selfTest() {
       const mixed = { repo: 'objectstack-ai/objectstack', actions: [{ op: 'labels_add', issue: 1, labels: ['a'] }, { op: 'issue_patch', issue: 2, state: 'closed' }, { op: 'issue_patch', issue: 3, body: 'B' }, { op: 'pr_create', title: 'T', head: 'h', base: 'main' }, { op: 'pr_create', title: 'T', head: 'h2', base: 'main', body: 'P' }] };
       t('only an action that SENT a body is a target, numbered as the stroke numbers it', readBackTargets(mixed).map((x) => [x.action, x.op]), [[3, 'issue_patch'], [5, 'pr_create']]);
       t('…carrying the keys its locator needs', [readBackTargets(mixed)[0].issue, readBackTargets(mixed)[1].head, readBackTargets(mixed)[1].sent], [3, 'h2', 'P']);
+      t("pr_update_branch carries no body — not in BODY_OPS, no locator, no target: its confirmation is the executor's, inside the run", [BODY_OPS.includes('pr_update_branch'), 'pr_update_branch' in READ_BACK_LOCATORS, readBackTargets({ repo: 'objectstack-ai/objectstack', actions: [{ op: 'pr_update_branch', pull: 1, expected_head_sha: '1'.repeat(40) }] })], [false, false, []]);
       let fetched = 0;
       const none = await readBackStroke({ repo: 'objectstack-ai/objectstack', actions: [{ op: 'labels_add', issue: 1, labels: ['a'] }] }, { dispatchedAt: T0 }, {
         judge: JUDGE,