docs(skills): name the pluralLabel exception to "an extension can add but never remove" (#30722)

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_Requested by **Elon** · [project
thread](https://claude.ai/code/project/chan_01WedDzV26nniwxv7jC88B9D?thread=cmsg_01WedDzV26nniwxv7jC88B9DRJUuDG85hCcfSGBtmU6XdK)_

domain:skills#1 · os-elon-musk · session_016WV4cx4foyi3wUWBrRHCmF

Fixes #30466

Clause-②: no
Metadata-protocol: none

## 维护者速读

- 改了什么：`objectstack-data` 技能「对象扩展」一节仍说扩展“只能加、不能删”，但补上唯一的例外：扩展改了 `label`
却没给 `pluralLabel` 时，基础对象的复数名会被清掉（租户自己写的复数除外），要保留就两个一起写。
- 为什么改：PR #30459（#30391）落地后合并规则就是这样，原句对 `pluralLabel` 不再准确；这是那次合同评审的
should-fix 2。
- 风险与回滚：只改技能文档一句话，无代码、无 schema 变化；回滚即 revert。
- 先看：`skills/objectstack-data/SKILL.md` 第 349–350 行；规则出处
`packages/objectql/src/registry.ts` 的 `mergeObjectDefinitions`（第 916 行）。
- 两分钟验证：`node scripts/check-skills-token-ratchet.mjs | grep
"objectstack-data/SKILL.md "`，预期 `6122 / 6123`。
- 需要你做的：ADR-0029 D9.2 第 473 行“has no expression for *removal* at
all”一句是否加修订注，由你定（本 PR 不碰 ADR）。

## What changes

- `skills/objectstack-data/SKILL.md` § Object Extension Model keeps "an
extension can add but never remove" and names the one exception: a new
`label` without `pluralLabel` clears the base plural unless a tenant
authored it, so an author sets both.
- The rule is read off `origin/main`,
`packages/objectql/src/registry.ts` `mergeObjectDefinitions`: `if
(extension.pluralLabel === undefined && extension.label !== merged.label
&& !yields('pluralLabel')) delete merged.pluralLabel;`, inside the
`extension.label !== undefined && !yields('label')` branch. So the
plural survives when the extension repeats the running label, when the
tenant authored the plural (the ADR-0029 D9.2a yield), or when the
tenant authored the label (the label itself yields).
- Token payment, same file: the Lifecycle Hooks pointer line drops its
parenthetical second link to `references/data-hooks.md`. That file is
already linked from the catalog list (L46) and from the backfill
paragraph (L160), so the parenthetical restated a link.
- `.changeset/30466-extension-plurallabel-exception.md`:
`'@objectstack/skills': patch`.

## Tests

Docs-only. No behaviour changes, so no test or ablation applies.

## Acceptance notes

- Out of scope by the order, for the seat to raise for Tier H: ADR-0029
D9.2,
`docs/adr/0029-kernel-object-ownership-and-platform-objects-decomposition.md`
L472–473, "`mergeObjectDefinitions` merges fields additively (...) and
has no expression for *removal* at all." Since PR #30459 it has one, for
`pluralLabel`. No decision moves (the sentence argues about fields in an
overlay); whether it gets an amendment note is the maintainer's.

## Verification

Skills readings (lines and tokens):

- `skills/objectstack-data/SKILL.md`: 464 → 465 lines; 6116 → 6122
tokens (ceiling 6123, headroom 7 → 1). Net +6 after the same-file
deletion, inside the existing headroom. The ceiling row is not touched.
- Whole package, all `SKILL.md`: 4534 → 4535 lines. Bundle total (whole
shipped tree, ratchet reading): 226234 → 226240 tokens.

Gates, head `a069bdb668` (`dispatch-gates --commands`, 44 derived
families, plus `pnpm lint`):

- 40 families exit 0, and `pnpm lint` exit 0. `--ran` reconciliation:
"44 derived famil(ies) accounted for — 40 run, 4 NOT-MEASURED".
- `check:doc-formula-expressions` first exited 3 (prerequisite); after
`turbo run build --filter=@objectstack/formula
--filter=@objectstack/lint` it exits 0.
- NOT MEASURED: `check:dts-closure`, `check:dual-build-cjs-loads`,
`check:lean-entry-closure`, `check:sourcemap-no-sources-content`.
Reason: exit 3, they need a whole-tree build. They read package `dist/`
output, which this docs-only diff does not change; CI measures them.

<details><summary>COMMAND :: exit CODE record</summary>

```text
node scripts/check-adr-0087-registration.mjs --base origin/main :: exit 0
node scripts/check-adr-0087-registration.mjs --self-test :: exit 0
node scripts/check-changeset-no-major.mjs --base origin/main :: exit 0
node scripts/check-closing-keyword-parity.mjs :: exit 0
node scripts/check-closing-keyword-parity.mjs --self-test :: exit 0
node scripts/check-comment-mask-corpus.mjs :: exit 0
node scripts/check-doc-route-spelling.mjs --advisory :: exit 0
node scripts/check-doc-route-spelling.mjs --self-test :: exit 0
node scripts/check-dts-emitted.mjs --self-test :: exit 0
node scripts/check-empty-changeset.mjs --base origin/main :: exit 0
node scripts/check-empty-changeset.mjs --self-test :: exit 0
node scripts/check-skills-token-ratchet.mjs :: exit 0
node scripts/check-skills-token-ratchet.mjs --self-test :: exit 0
node scripts/ci/assert-turbo-remote-cache.mjs --self-test :: exit 0
node scripts/ci/plan-test-core-shards.mjs --self-test :: exit 0
node scripts/ci/prune-turbo-cache.mjs --self-test :: exit 0
node scripts/pm/release-rehearsal-clone.mjs --self-test :: exit 0
node scripts/release-pending-publish.mjs --self-test :: exit 0
pnpm --filter @objectstack/spec run check:skill-docs :: exit 0
pnpm check:agent-test-spelling :: exit 0
pnpm check:changeset-gate-self-tests :: exit 0
pnpm check:ci-filter-parity :: exit 0
pnpm check:closed-ceremony-text :: exit 0
pnpm check:corpus-claim-drift :: exit 0
pnpm check:cross-package-test-inputs :: exit 0
pnpm check:doc-authoring :: exit 0
pnpm check:driver-memory-census :: exit 0
pnpm check:dts-closure :: exit 3
pnpm check:dual-build-cjs-loads :: exit 3
pnpm check:gitlink-declared :: exit 0
pnpm check:lean-entry-closure :: exit 3
pnpm check:merge-driver :: exit 0
pnpm check:nul-bytes :: exit 0
pnpm check:pm-governed-merges :: exit 0
pnpm check:pm-skill-id-lint :: exit 0
pnpm check:published-files :: exit 0
pnpm check:refd-timer-probe :: exit 0
pnpm check:role-word :: exit 0
pnpm check:skill-compatibility :: exit 0
pnpm check:skill-frame-sync :: exit 0
pnpm check:skill-identifier-liveness :: exit 0
pnpm check:sourcemap-no-sources-content :: exit 3
pnpm check:watch-hint-literal :: exit 0
pnpm --filter @objectstack/lint run check:doc-formula-expressions :: exit 0
pnpm lint :: exit 0
```

</details>

---
_Generated by [Claude
Code](https://claude.ai/code/session_016WV4cx4foyi3wUWBrRHCmF)_

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

Author: objectstack-fleet[bot]

.changeset/30466-extension-plurallabel-exception.md

@@ -0,0 +1,10 @@
+---
+'@objectstack/skills': patch
+---
+
+docs(skills): an object extension that renames `label` without `pluralLabel` clears the base plural
+
+Clause-②: no
+Metadata-protocol: none
+
+`objectstack-data` § Object Extension Model still says an extension can add but never remove, and now names the one exception the object fold has: an extension that sets a new `label` and no `pluralLabel` takes the base's `pluralLabel` off the served object unless a tenant authored that plural, so an author who renames an object sets both to keep a plural. An extension that repeats the label it extends removes nothing. The Lifecycle Hooks pointer line drops its second link to `references/data-hooks.md`, which the catalog list and the backfill paragraph already link. No schema, key or behaviour changes.

skills/objectstack-data/SKILL.md

@@ -337,7 +337,7 @@ See [rules/indexing.md](./rules/indexing.md) for composite indexes, unique scope
 refused), the retired `type` / `partial`, and partial / gin / gist indexes at the
 database layer.
 
-→ Moved verbatim to [references/examples-objects.md](./references/examples-objects.md) § Lifecycle Hooks (the hooks reference itself is [references/data-hooks.md](./references/data-hooks.md)).
+→ Moved verbatim to [references/examples-objects.md](./references/examples-objects.md) § Lifecycle Hooks.
 
 ---
 
@@ -346,7 +346,8 @@ database layer.
 To add fields/validations/indexes to an object you do not own, author
 `defineObjectExtension({ extend, fields, fieldPatches, priority })` and register it on
 `defineStack({ objectExtensions: [...] })`. `priority` sets merge order (default
-`200`, range `0–999`); an extension can add but never remove. ⛔ Not the same key
+`200`, range `0–999`); an extension can add but never remove, except that a new
+`label` without `pluralLabel` clears the base plural unless a tenant authored it (set both). ⛔ Not the same key
 as object-level `ownership` (the record-ownership enum
 `'user' | 'business_unit' | 'org' | 'none'`). Schema:
 `node_modules/@objectstack/spec/src/data/object.zod.ts` (`ObjectExtensionSchema`).