docs(skills): page-builder guide drops the retired page:header breadcrumb and names placedActions (#30115)

domain:skills#1 · huangyiirene · session_01J8VVAnMUWA9rufXzFaEh4J

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Fixes #30031

Clause-②: no
Metadata-protocol: none

The maintainer waived the model-tier mandate for `skills/**` while that
tier had no quota; this PR was developed below it.

## 维护者速读

- 改了什么:`skills/objectui/guides/page-builder.md` L100-101 的 `page:header`
标题行键表删掉已退役的 `breadcrumb`,并加上已上线的 `placedActions: true`,现为 (`title`,
`subtitle`, `actions` or `placedActions: true`)。
- 为什么改:`PageHeaderProps.breadcrumb` 自 spec 17 起是 `retiredKey`
墓碑(ADR-0087 D2),props lint 拒绝手写的 `breadcrumb`;#30097 合入后 header 渲染器已读取
`placedActions`。
- 风险与回滚:一个文件改一行,token 3410/3411,不动上限、不付账;发布 `@objectstack/skills`
patch;回滚即 revert。
- 先看:page-builder.md L101。
- 需要你做的:无;席位处理 ready 与合并队列。

## What changes

- `skills/objectui/guides/page-builder.md` L101: `` `breadcrumb`, `` is
removed from the `page:header` title-row list, and `placedActions: true`
is named as the alternative to `actions`. The sentence now reads "a
title row (`title`, `subtitle`, `actions` or `placedActions: true`) that
takes no `children`". The rest of the file is byte-identical to `main`.
- `.changeset/30031-page-builder-header-breadcrumb.md`:
`'@objectstack/skills': patch` with `Clause-②: no` and
`Metadata-protocol: none`, its prose naming `page-builder.md` only. No
`skip-changeset` label: a `skills/**` diff ships in
`@objectstack/skills` (pr-automation.yml route 1).

An earlier head of this PR also changed the `page:header` row in
`skills/objectstack-ui/rules/pages.md` L46, which said `placedActions:
true` was "not drawn yet". PR #30127 (#29951) landed that fix on `main`
("(all placed, read live)"). The merge of `main` into this branch took
`main`'s line as is, so `pages.md` is no longer in this PR's diff.

Read off `main` at `9a53fc9f` (merged into the branch, no rebase):

- `PageHeaderProps` in `packages/spec/src/ui/component.zod.ts`:
`breadcrumb` and `showStar` are `retiredKey` tombstones. Live keys:
`title`, `subtitle`, `actions`, `placedActions`, `recordChrome`,
`showCopyId`, `maxVisible`, `mobileMaxVisible`, `aria`.
- **`placedActions` is live.** #30097 (#29951) dropped the `[PLANNED —
not yet rendered]` marker from its describe, which now reads "Draw every
action of the page's object whose `locations` include `record_header` or
`record_more`, read live from the object's metadata, in place of an
authored `actions` list … Refused as `true` beside an authored `actions`
list: keep one." The `page:header` renderer in
`ui/packages/components/src/renderers/layout/containers.tsx` reads
`placedActions` and draws the placed header actions. The `.refine` on
`PageHeaderProps` refuses `placedActions: true` beside an authored
`actions` list, so the guide spells the two as alternatives ("or"). The
first head of this PR (`d93cef6e`) left `placedActions` out because the
describe at its base still carried the PLANNED marker; that reason no
longer holds on `main`.
- `recordChrome`, `showCopyId` and `maxVisible` shape the record chip
and the overflow menu, not what the title row holds, so the guide's
sentence does not name them.
- Sweep of `skills/objectui/**`: L101 was the only `breadcrumb`.
`showStar` appears nowhere.

**Token ratchet.** `page-builder.md`: 13628 → 13639 bytes, 3410 tokens
(ceiling 3411, headroom 1). No ceiling row moves, nothing was
re-wrapped, and no payment is owed.

## Why

The guide taught a key the props lint refuses, so a page authored from
it would fail validation, and it did not name `placedActions` after
#30097 made the header draw it.

## Verification

Head `16145621`: on top of `0f1ccaec`, a merge of `origin/main` at
`9a53fc9f` (`31fbfb98`, `pages.md` resolved to `main`'s line) and one
commit scoping the changeset prose.

<details><summary>Local gates on 1614562: 44 derived, 44 run with exit
0, 0 NOT MEASURED (`dispatch-gates --ran`)</summary>

- `node scripts/pm/dispatch-gates.mjs --commands --repo
objectstack-ai/objectstack` derived 44 commands for the two changed
files. All ran after `pnpm install --frozen-lockfile` and a full `pnpm
build` on the merged tree (exit 0), each under a 900 s timeout with its
exit code captured before any pipe.
- All 44 exited 0, among them `check-skills-token-ratchet.mjs`,
`check:skill-examples`, `check:skill-identifier-liveness`,
`check:skill-frame-sync`, `check:doc-authoring`, `check:dts-closure`,
`check:dual-build-cjs-loads` and `check-comment-mask-corpus.mjs`.
- `--ran` printed: `44 derived famil(ies) accounted for — 44 run, 0
NOT-MEASURED (a DERIVED zero — all 44 recorded an exit code and none of
them is 3)`.
- `node scripts/check-commit-card-trailers.mjs --range
origin/main..HEAD`: exit 0 (5 commits) before the push.

</details>

## Human Minimum

- [x] 1. Schemas start as Zod; `packages/spec` holds no runtime logic.
(Not touched.)
- [x] 2. Every name I added uses the casing for its kind. (No names
added.)
- [x] 3. No formatter ran.
- [x] 4. One issue, one branch off an up-to-date `main`, one pull
request.
- [x] 5. A change that publishes carries a changeset, and both
declaration lines are filled in here and in the changeset.
- [x] 6. `packages/spec` touched: its generated artifacts are
regenerated and committed. (Not touched.)
- [x] 7. No hand edits to `content/docs/references/`,
`packages/*/CHANGELOG.md` or `content/docs/releases/`.
- [x] 8. Title, body and comments are in English. (The 维护者速读 section is
Chinese, per the lane template.)
- [x] The *Before Submitting* list in CONTRIBUTING.md is done.

---
_Generated by [Claude
Code](https://claude.ai/code/session_01J8VVAjSbVpQUeFNuTTm3me)_

---------

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

Author: objectstack-fleet[bot]

.changeset/30031-page-builder-header-breadcrumb.md

@@ -0,0 +1,10 @@
+---
+'@objectstack/skills': patch
+---
+
+docs(skills): the `page:header` title row drops the retired `breadcrumb` and names the live `placedActions: true`
+
+Clause-②: no
+Metadata-protocol: none
+
+- `skills/objectui/guides/page-builder.md`: the `page:header` sentence named `breadcrumb` among the title row's keys. `PageHeaderProps.breadcrumb` is a `retiredKey` tombstone since @objectstack/spec 17 (ADR-0087 D2), and the props lint refuses an authored one. The row now lists `title`, `subtitle`, `actions` or `placedActions: true`; the last two are refused together.

skills/objectui/guides/page-builder.md

@@ -98,7 +98,7 @@ its own (`page:section` spaces its children with `space-y-4`; `page:footer`
 draws a separator above a justified, muted row; `page:sidebar` is a
 `w-full md:w-80 shrink-0` column, fixed at 20rem from `md` up), and
 `page:header` renders the page's `header`, a title row (`title`, `subtitle`,
-`breadcrumb`, `actions`) that takes no `children`. The bare HTML sectioning
+`actions` or `placedActions: true`) that takes no `children`. The bare HTML sectioning
 tags (`section`, `header`, `nav`, …) are not curated blocks; they belong to
 `kind:'html'` pages.