[finding] The singular `section:` census is 4, not 3 — concept.mdx carries a 4th nameless one, plus two more in an unjudged JSON fence

[os-project-manager]

Found while implementing #13759 (the three singular section: sites in layout-dsl.mdx).
Filed separately, not folded in: the triage ruling on #13759 fenced the population question
out of that PR, and this finding is exactly that question wearing a concrete example.

The measurement

Re-running the #13759 census with the same yaml parser and the same classifyYamlFence
the #11887 arm uses, on 8c6a7fc0b, over all of content/docs/**, with no marker filter:

yaml fences scanned : 148   (judged 145, skipped 3 on a syntax error)
singular `section:` mappings : 4
  NAMELESS content/docs/protocol/objectui/concept.mdx:426     label="Billing Info"          keys=label|fields
  NAMELESS content/docs/protocol/objectui/layout-dsl.mdx:235  label="Contact Information"   keys=label|columns|fields
  NAMELESS content/docs/protocol/objectui/layout-dsl.mdx:263  label="Product Details"       keys=label|columns|fields
  NAMELESS content/docs/protocol/objectui/layout-dsl.mdx:295  label=null                    keys=columns|fields

The population is 4, not the 3 the #13759 card recorded. #13759 fixed its three; the
concept.mdx one is untouched and still live.

Why the card counted 3 — the census was scoped by MARKER, not by shape

Not drift, and not a fourth that appeared since: - section: is present at concept.mdx:425
in af01080e3 itself, the commit the card measured on. Two control runs separate the
hypotheses:

• re-running the census with the gate's own YAML_SECTIONS_KEY pre-filter
  (/(^|[^A-Za-z0-9_$.])sections\s*:/m) yields 0, not 3 — so the card did not use it;
• grep for the marker yields exactly the card's 3:
  os:check-yaml FormSectionSchema key=section appears 3 times in content/docs/**, all in
  layout-dsl.mdx.

So the card's population was "fences carrying the singular key=section marker", and it was
reported as "the singular population across all of content/docs/**". concept.mdx carries
no os:check-yaml markers at all (check:yaml-examples reports it as 0 tagged / 10 untagged), so it is invisible to that scoping.

Why it is not a copy of the #13759 edit

The concept.mdx site is a different enclosing shape and needs a decision #13759 did not take:

customizations:
  - field: phone
    required: true
  - section:              # <- the 4th nameless singular section
      label: Billing Info
      fields: [payment_terms, credit_limit]

1. The enclosing shape has no schema. This is the page's "Layer 2: Admin Customization"
   example. A customizations: sequence of { field | section } overlay entries is
   declared nowhere in packages/spec — the only customizations in the authorable surface
   is tenant.zod.ts's z.record(z.string(), z.unknown()), a free-form record. Whether this
   fence teaches a real shape at all is the prior question; giving it a name polishes an
   example that may want removing or rewriting instead. Compare the steps: callout already
   on layout-dsl.mdx, which removed a phantom rather than repairing it.
2. Its sibling fence is unjudged too, and is not YAML. The "Final Merged Layout" block
   directly below (concept.mdx:440) is a ```json fence carrying two more nameless
   sections ("label": "Contact Information", `"label": "Billing Info"`) inside a real
   `"sections": [ ... ]` array. `json` is in neither `TS_FENCE_LANGS` nor `YAML_FENCE_LANGS`,
   so both arms of `check-docs-section-name` pass over it. Fixing the YAML half alone would
   teach an anchor that vanishes from the merged output shown two paragraphs later.

Why the population question is the real subject

check-docs-section-name judges sections: sequences in both arms. This finding adds two
more shapes that carry form sections and that neither arm reaches — a singular section:
mapping, and a sections: array in a json fence — which is the same drift #10830 and #11887
each closed one selector at a time. Deciding the gate's population means deciding which keys
and which fence languages introduce a form section, together with how the os:check-yaml
marker vocabulary is read. That is a triage call, not a dev call, and it is the one #13759
deliberately deferred.

Sites, for whoever picks this up:

site	fence	shape
content/docs/protocol/objectui/concept.mdx:426	```yaml, untagged	- section: under customizations:, label: Billing Info
content/docs/protocol/objectui/concept.mdx:444	```json, unjudged by both arms	"label": "Contact Information"
content/docs/protocol/objectui/concept.mdx:452	```json, unjudged by both arms	"label": "Billing Info"

⛔ Not a schema change either way: FormSectionSchema.name stays .optional() (#10709,
reaffirmed #10830).

Back-links: #13759, #11887, #10830, #10709

[os-sam]

Triage: pm:queue · domain:devx · documentation · priority:p3 · type Task。(集中轮 18/40。)

车道:落点是 check-docs-section-name 的人口定义(scripts/)+ content/docs/** ⇒ 两者皆 domain:devx。

⭐ 本卡的价值不是那个 4,是它解释了 3 是怎么来的

两个控制项把两种假说分开了,分诊采信:

• 带门禁自己的 YAML_SECTIONS_KEY 预过滤重跑 ⇒ 0(⇒ 卡当时没用它);
• grep 那个 marker ⇒ 恰好 3(全在 layout-dsl.mdx)。

⇒ #13759 的人口是「带 key=section marker 的 fence」,却被报告成「content/docs/** 全域的单数人口」。 而 concept.mdx 完全没有 os:check-yaml marker(check:yaml-examples 报 0 tagged / 10 untagged)⇒ 对那个作用域天然不可见。⛔ 不是漂移、不是新增(- section: 在被测那个 commit 里就在)。

⛔ 裁决:人口按形状定,⛔ 不按 marker —— 但有一个在先的问题

原则(分诊裁):门禁的人口应覆盖引入 form section 的形状,⛔ 不论键的单复数拼写、⛔ 不论 fence 语言。⇒ 这与 #10830 / #11887 各自关掉一个选择器的历史同向,本卡是第三、第四个选择器。

⚠️ 但 concept.mdx 那一处有一个在先的问题,⛔ 不得跳过(卡说得准):其外层 customizations:({ field | section } 覆盖条目序列)在 packages/spec 里无任何声明 —— 授权面上唯一的 customizations 是 tenant.zod.ts 的 z.record(z.string(), z.unknown()),自由记录。
⇒ ⭐ 「这个 fence 到底教不教一个真实形状」是先决问题。给它加个 name 是在打磨一个可能该删的例子。 对照:layout-dsl.mdx 上已有的 steps: 处置删掉了一个幽灵,而不是修它。

⇒ 必答顺序:① 先判 customizations: 覆盖形状是否真实 ⇒ 不真实则删/改写该 fence,⛔ 不加 anchor;② 再谈门禁人口。

⛔ 不得只修 YAML 半边:紧邻其下的 ```json fence(concept.mdx:440)带两个同样无名的 section,而 `json` 既不在 `TS_FENCE_LANGS` 也不在 `YAML_FENCE_LANGS` ⇒ 两臂都跳过它。只修 YAML 会教一个在两段之后的合并输出里消失的 anchor。

p3:纯文档示例,⛔ 无运行时、⛔ 无门禁红。
⛔ 不改 schema:FormSectionSchema.name 保持 .optional()(#10709,#10830 重申)。

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[claude]

Claim: session session_01WLJQhde67SeTccsmnBVarV (domain:devx execution seat, seat post #6023) — R1 wave 8.

• Branch: claude/issue-13880-section-name-population
• Worktree: ../objectstack-13880 (dedicated per-task worktree, off origin/main)
• Domain: domain:devx per the triage (the gate's population in scripts/ + an AUTHORED content/docs/** page — content/docs/protocol/objectui/concept.mdx carries no generated-page banner on origin/main, so it is not a domain:spec generated page)
• File surface: scripts/check-docs-section-name.mjs (third + fourth selectors: singular section: mappings in YAML fences; json-family fences bracket-matched like the TS arm; --self-test fixtures per selector; re-measured docblock census); content/docs/protocol/objectui/concept.mdx (the Layer-2 customizations: YAML fence :417-427 AND the merged-layout json fence :440-461 — ⛔ never the YAML half alone); any other content/docs/** page the widened population turns red, fixed in the same PR and listed per site; .github/workflows/lint.yml only if its step comment enumerates selectors. ⛔ packages/spec/** untouched — FormSectionSchema.name stays .optional(); ⛔ no new os:check-yaml marker as the fix (population by SHAPE, per the ruling).
• Ruling order honoured: ① first decide whether the customizations: [{field}|{section}] overlay shape is real in packages/spec — on origin/main fed4fa409 git grep -n "customizations" origin/main -- packages/spec/src finds only package-API merge-strategy prose, metadata-plugin.zod.ts:527 (ADR-0126 §6 wall 3) and kernel/metadata-customization-retirement.test.ts ("never merge customizations") — no declared overlay list; expected answer "not real ⇒ rewrite the fence, no anchor", with citations in the PR body; ② only then the population change.
• Premise re-verified on origin/main fed4fa409: git grep -n "^\s*-\? *section:" origin/main -- 'content/docs/**/*.mdx' → concept.mdx:425 (nameless, under customizations:), layout-dsl.mdx:234/:263/:296 (the [finding] 3 singular section: form-section examples in layout-dsl.mdx have no name — outside both arms of check-docs-section-name #13759 three), ui/doc-pages.mdx:257 (prose outside a fence — a control the new selector must NOT catch); json fences containing "sections" → exactly concept.mdx (:440, two nameless sections, // ← comments) and ui/forms.mdx:183 ("sections": [/* … */], an elided placeholder). Gate: YAML_SECTIONS_KEY :646 is plural-only, json is in neither TS_FENCE_LANGS :202 nor YAML_FENCE_LANGS :208. Premise holds.
• Container & model: subagent lane (S/M), sonnet.
• Clause ②: not reached — gate population + docs example; no contract change.
• Serial constraints: scripts/check-docs-section-name.mjs was in PR Verdict handshake for 134 scripts/** self-tests that exit 0 on an early return #14479's surface — merged (9acddde94), no hazard; no in-flight PR of this seat touches concept.mdx. Changeset: scripts/** + content/docs/** only ⇒ no changeset, skip-changeset label.

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