diff --git a/.changeset/auth-components-react-spec-symbol-burn-down.md b/.changeset/auth-components-react-spec-symbol-burn-down.md
index fb3eca011..c4b785b8d 100644
--- a/.changeset/auth-components-react-spec-symbol-burn-down.md
+++ b/.changeset/auth-components-react-spec-symbol-burn-down.md
@@ -1,7 +1,7 @@
 ---
-"@object-ui/auth": major
-"@object-ui/components": major
-"@object-ui/react": major
+"@object-ui/auth": minor
+"@object-ui/components": minor
+"@object-ui/react": minor
 ---
 
 Stop declaring 18 `@object-ui/auth` / `@object-ui/components` / `@object-ui/react`
@@ -55,3 +55,8 @@ output type — every `.default()`ed key required — would reject outright.
 
 `@objectstack/spec` moves from `devDependencies` to `dependencies` in
 `@object-ui/components`: its public type surface now references the spec.
+
+Scored `minor`, not `major`, per this repo's fixed-group rule — objectui's major
+tracks `@objectstack`, so breaking changes of our own ship as minor with the
+semantics spelled out above (see AGENTS.md §版本号策略). A `major` here would carry
+all 39 packages of the fixed group to `18.0.0` and off objectstack's 17.x line.
diff --git a/.changeset/data-objectstack-chatbot-list-spec-symbol-burn-down.md b/.changeset/data-objectstack-chatbot-list-spec-symbol-burn-down.md
index b2c6a05e8..d3470e5bc 100644
--- a/.changeset/data-objectstack-chatbot-list-spec-symbol-burn-down.md
+++ b/.changeset/data-objectstack-chatbot-list-spec-symbol-burn-down.md
@@ -1,7 +1,7 @@
 ---
-"@object-ui/data-objectstack": major
-"@object-ui/plugin-chatbot": major
-"@object-ui/plugin-list": major
+"@object-ui/data-objectstack": minor
+"@object-ui/plugin-chatbot": minor
+"@object-ui/plugin-list": minor
 ---
 
 Stop declaring 12 `@object-ui/data-objectstack` / `@object-ui/plugin-chatbot` /
@@ -58,3 +58,8 @@ vendored Vercel AI Elements / Shadcn primitives — upstream's component API, no
 objectui's authored surface — so the guard now skips that directory the same way
 it already skips `components/src/ui/`, with a test that fails if any file there
 stops carrying its vendor banner.
+
+Scored `minor`, not `major`, per this repo's fixed-group rule — objectui's major
+tracks `@objectstack`, so breaking changes of our own ship as minor with the
+semantics spelled out above (see AGENTS.md §版本号策略). A `major` here would carry
+all 39 packages of the fixed group to `18.0.0` and off objectstack's 17.x line.
diff --git a/.changeset/long-tail-spec-symbol-burn-down.md b/.changeset/long-tail-spec-symbol-burn-down.md
index d836b3b21..c8a482e4e 100644
--- a/.changeset/long-tail-spec-symbol-burn-down.md
+++ b/.changeset/long-tail-spec-symbol-burn-down.md
@@ -1,14 +1,14 @@
 ---
-"@object-ui/collaboration": major
-"@object-ui/fields": major
-"@object-ui/layout": major
-"@object-ui/plugin-charts": major
-"@object-ui/plugin-detail": major
-"@object-ui/plugin-form": major
-"@object-ui/plugin-grid": major
-"@object-ui/providers": major
-"@object-ui/runner": major
-"@object-ui/sdui-parser": major
+"@object-ui/collaboration": minor
+"@object-ui/fields": minor
+"@object-ui/layout": minor
+"@object-ui/plugin-charts": minor
+"@object-ui/plugin-detail": minor
+"@object-ui/plugin-form": minor
+"@object-ui/plugin-grid": minor
+"@object-ui/providers": minor
+"@object-ui/runner": minor
+"@object-ui/sdui-parser": minor
 ---
 
 Stop declaring 14 symbols across ten packages under names `@objectstack/spec`
@@ -67,3 +67,8 @@ batch 3, so one concept does not acquire two dialect names one package apart.
 `@objectstack/spec` moves from `devDependencies` to `dependencies` in
 `@object-ui/fields` (it re-exports a runtime function) and `@object-ui/providers`
 (its public `.d.ts` now references the spec).
+
+Scored `minor`, not `major`, per this repo's fixed-group rule — objectui's major
+tracks `@objectstack`, so breaking changes of our own ship as minor with the
+semantics spelled out above (see AGENTS.md §版本号策略). A `major` here would carry
+all 39 packages of the fixed group to `18.0.0` and off objectstack's 17.x line.
diff --git a/.changeset/remove-dead-layout-page-node-renderer.md b/.changeset/remove-dead-layout-page-node-renderer.md
index a75a78806..3976828cc 100644
--- a/.changeset/remove-dead-layout-page-node-renderer.md
+++ b/.changeset/remove-dead-layout-page-node-renderer.md
@@ -1,5 +1,5 @@
 ---
-"@object-ui/layout": major
+"@object-ui/layout": minor
 ---
 
 Remove `PageNodeRenderer`, the dead page-node renderer (objectui#3223, ADR-0049
@@ -33,3 +33,8 @@ Also note: this supersedes the `Page` → `PageNodeRenderer` rename shipped for
 this package in the batch 7 symbol burn-down — the renamed symbol is gone rather
 than renamed again. `PageHeaderProps` → `PageHeaderComponentProps` from that same
 batch is unaffected.
+
+Scored `minor`, not `major`, per this repo's fixed-group rule — objectui's major
+tracks `@objectstack`, so breaking changes of our own ship as minor with the
+semantics spelled out above (see AGENTS.md §版本号策略). A `major` here would carry
+all 39 packages of the fixed group to `18.0.0` and off objectstack's 17.x line.
diff --git a/.github/workflows/changeset-guard.yml b/.github/workflows/changeset-guard.yml
new file mode 100644
index 000000000..d7a0b7055
--- /dev/null
+++ b/.github/workflows/changeset-guard.yml
@@ -0,0 +1,44 @@
+name: Changeset Guard
+
+# Why this is its own workflow instead of a job in `ci.yml`: a changeset is a
+# markdown file under `.changeset/`, and both `ci.yml` and `lint.yml` list
+# `'**/*.md'` AND `.changeset/**` under `paths-ignore`. A PR that adds only a
+# changeset therefore starts no workflow at all — which is exactly the PR this
+# check needs to see. GitHub has no per-job path filter, so the gate lives here,
+# with the inverse trigger: it runs *only* when `.changeset/**` changes.
+#
+# It needs no install and no build — a checkout plus one `node` call, a few
+# seconds — so keep it that way if you add checks to it.
+
+on:
+  pull_request:
+    branches: [main, develop]
+    paths:
+      - '.changeset/**'
+  push:
+    branches: [main]
+    paths:
+      - '.changeset/**'
+
+concurrency:
+  group: changeset-guard-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+permissions:
+  contents: read
+
+jobs:
+  no-major:
+    name: Changeset Bump Policy
+    runs-on: ubuntu-latest
+    timeout-minutes: 5
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v7
+
+      # One `major` in the 39-package `fixed` group publishes all 39 as the next
+      # major, taking objectui off the `@objectstack` major it is pinned to.
+      # See AGENTS.md §版本号策略, and the script's header for the full rationale.
+      - name: Verify no changeset declares a major bump
+        run: node scripts/check-changeset-no-major.mjs
diff --git a/AGENTS.md b/AGENTS.md
index 9b93dd2a1..dafb77100 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -168,6 +168,7 @@ export const SchemaRenderer = ({ schema }: { schema: UIComponent }) => {
 - minor/patch **独立演进**——objectstack 没动时不必跟发;objectui 自己的改动照常用 changeset 推进(从当前 major 起步,如 `11.0.0 → 11.1.0`)。
 - objectstack 跨 major(→12)时,下一次 objectui 发版一并把 major 提到 `12`。
 - 推论:**changeset 里不要声明 `major`** —— fixed 组任一 `major` 都会把全组推上去、脱离 objectstack 的节奏(如 17.x 期间被推到 18)。objectui 自身的破坏性变更也标 `minor`(在正文里写清 breaking 语义即可);唯一例外是跟随 objectstack 跨 major 的那一次同步升级。
+- **这一条现在由 CI 机械强制** —— `scripts/check-changeset-no-major.mjs` 在任一 changeset 声明 `major` 时退出非零,由 `.github/workflows/changeset-guard.yml` 跑(它是唯一以 `.changeset/**` 为**触发**路径的 workflow:`ci.yml`/`lint.yml` 都把 `**/*.md` 和 `.changeset/**` 列进 `paths-ignore`,只加 changeset 的 PR 不会启动任何 workflow),`pnpm test` 里另有一条仓库状态断言兜底。跟随 objectstack 跨 major 的那一次发版设 `OBJECTUI_ALLOW_MAJOR=1` 放行。前情:objectui#3161/#3159/#3160/#3225 四个 changeset 在 17.x 期间标了 `major`(17 个包条目),足以把 39 个包发成 `18.0.0`。
 - 这是约定优先于 semver 纯粹性的取舍(为可维护/好记),因此 objectui 的 major 不代表「它自身 API 的破坏性变更次数」。`@object-ui/site` 与 `@object-ui/example-*` 在 `ignore` 列表,不随组联动。
 
 ### 多 agent 协作纪律(并行修改本仓库,务必遵守)
diff --git a/content/docs/guide/ci-cd-pipeline.md b/content/docs/guide/ci-cd-pipeline.md
index 4138cb11c..0d0d28653 100644
--- a/content/docs/guide/ci-cd-pipeline.md
+++ b/content/docs/guide/ci-cd-pipeline.md
@@ -152,6 +152,22 @@ Uses [Changesets](https://github.com/changesets/changesets) for automated versio
 3. Publishes to npm.
 4. Configures a pnpm-lock.yaml merge driver to prevent lock file conflicts.
 
+### Changeset Guard (`changeset-guard.yml`)
+
+**Trigger:** PR to `main`/`develop`, and push to `main`, **when `.changeset/**` changes** — the
+inverse of every other workflow's filter. `ci.yml` and `lint.yml` both list `'**/*.md'` and
+`.changeset/**` under `paths-ignore`, so a PR that adds only a changeset starts nothing else.
+
+Runs `scripts/check-changeset-no-major.mjs`, which fails if any pending changeset declares a
+`major` bump. Every publishable package is in one `fixed` group (39 packages), so a single
+`major` publishes all of them as the next major — and objectui's major is pinned to the
+`@objectstack` major it is compatible with, not to its own count of breaking changes. Score
+breaking changes of our own as `minor` and describe the break in the changeset body.
+
+The one release that legitimately bumps the major is the one following `@objectstack` across
+its major; it sets `OBJECTUI_ALLOW_MAJOR=1`. `pnpm test` asserts the same repository state, so
+the rule survives this workflow being skipped.
+
 ### Changelog Generation (`changelog.yml`)
 
 **Trigger:** `release` event (when a GitHub Release is published), or manual dispatch.
diff --git a/package.json b/package.json
index a50a337c3..6ebdb3521 100644
--- a/package.json
+++ b/package.json
@@ -51,7 +51,7 @@
     "build:console": "pnpm --filter @object-ui/console build",
     "shadcn:diff": "node scripts/shadcn-sync.js --diff",
     "shadcn:list": "node scripts/shadcn-sync.js --list",
-    "changeset:check": "node scripts/check-changeset-fixed.mjs",
+    "changeset:check": "node scripts/check-changeset-fixed.mjs && node scripts/check-changeset-no-major.mjs",
     "changeset": "changeset",
     "changeset:version": "changeset version",
     "changeset:publish": "changeset publish",
diff --git a/scripts/__tests__/check-changeset-no-major.test.ts b/scripts/__tests__/check-changeset-no-major.test.ts
new file mode 100644
index 000000000..c53e0a72e
--- /dev/null
+++ b/scripts/__tests__/check-changeset-no-major.test.ts
@@ -0,0 +1,128 @@
+import { describe, expect, it } from 'vitest';
+import fs from 'node:fs';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+// @ts-expect-error — plain-JS CI helper, intentionally untyped
+import { findMajorBumps, parseFrontmatterBumps } from '../check-changeset-no-major.mjs';
+
+/**
+ * objectui's major is not a count of its own breaking changes — it is pinned to
+ * the `@objectstack` major so that "same major ⇒ compatible" holds across the
+ * two repos (AGENTS.md §版本号策略). Since every publishable package sits in one
+ * `fixed` group, ONE `major` in ONE changeset publishes all 39 of them as the
+ * next major and breaks that pin.
+ *
+ * Four pending changesets had scored `major` (17 package entries) during the
+ * 17.x line, which would have shipped 39 packages as 18.0.0 against an
+ * `@objectstack` still on 17. The rule was written down and nothing ran it:
+ * `ci.yml` and `lint.yml` both `paths-ignore` `.changeset/**`, so a
+ * changeset-only PR started no workflow at all.
+ *
+ * These tests are the second lock. `.github/workflows/changeset-guard.yml`
+ * catches it on the PR that adds the changeset; the repo-state test below
+ * catches it in `pnpm test` even if that workflow is ever removed or its
+ * trigger stops matching.
+ */
+const repoRoot = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '../..');
+const changesetDir = path.join(repoRoot, '.changeset');
+const workflowDir = path.join(repoRoot, '.github/workflows');
+
+describe('parseFrontmatterBumps', () => {
+  it('reads the package/bump pairs out of the frontmatter block', () => {
+    const source = [
+      '---',
+      '"@object-ui/layout": minor',
+      "'@object-ui/fields': patch",
+      '@object-ui/core: minor',
+      '---',
+      '',
+      'Body text.',
+    ].join('\n');
+
+    expect(parseFrontmatterBumps(source)).toEqual([
+      { pkg: '@object-ui/layout', bump: 'minor', line: 2 },
+      { pkg: '@object-ui/fields', bump: 'patch', line: 3 },
+      { pkg: '@object-ui/core', bump: 'minor', line: 4 },
+    ]);
+  });
+
+  it('stops at the closing `---`, so prose about a bump is not a bump', () => {
+    // Changeset bodies in this repo discuss the major/minor call explicitly —
+    // and a body may hold a fenced YAML example. Neither may register as a
+    // declaration, or the guard would fail on a changeset that is obeying it.
+    const source = [
+      '---',
+      '"@object-ui/layout": minor',
+      '---',
+      '',
+      'Scored `minor`, not `major`, per the fixed-group rule.',
+      '',
+      '```yaml',
+      '"@object-ui/layout": major',
+      '```',
+    ].join('\n');
+
+    expect(parseFrontmatterBumps(source)).toEqual([
+      { pkg: '@object-ui/layout', bump: 'minor', line: 2 },
+    ]);
+    expect(findMajorBumps([{ file: 'x.md', source }])).toEqual([]);
+  });
+
+  it('returns nothing for a file with no frontmatter', () => {
+    expect(parseFrontmatterBumps('# Just a readme\n')).toEqual([]);
+  });
+});
+
+describe('findMajorBumps', () => {
+  it('reports every major entry with a file:line to jump to', () => {
+    const source = ['---', '"@object-ui/auth": major', '"@object-ui/react": minor', '---'].join(
+      '\n'
+    );
+
+    expect(findMajorBumps([{ file: '.changeset/a.md', source }])).toEqual([
+      { file: '.changeset/a.md', pkg: '@object-ui/auth', line: 2 },
+    ]);
+  });
+});
+
+describe('the repository itself', () => {
+  it('has no pending changeset declaring a `major` bump', () => {
+    const changesets = fs
+      .readdirSync(changesetDir)
+      .filter((name) => name.endsWith('.md') && name !== 'README.md')
+      .map((name) => ({
+        file: path.join('.changeset', name),
+        source: fs.readFileSync(path.join(changesetDir, name), 'utf8'),
+      }));
+
+    const offenders = findMajorBumps(changesets) as { file: string; pkg: string; line: number }[];
+
+    expect(
+      offenders.map(({ file, pkg, line }) => `${pkg} at ${file}:${line}`),
+      'A `major` publishes all 39 fixed-group packages as the next major, off the @objectstack ' +
+        'major objectui is pinned to. Score it `minor` and describe the break in the body — ' +
+        'see AGENTS.md §版本号策略.'
+    ).toEqual([]);
+  });
+});
+
+describe('changeset-guard.yml', () => {
+  const guard = fs.readFileSync(path.join(workflowDir, 'changeset-guard.yml'), 'utf8');
+
+  it('runs the guard script', () => {
+    expect(guard).toContain('node scripts/check-changeset-no-major.mjs');
+  });
+
+  it('triggers on `.changeset/**` — the paths every other workflow ignores', () => {
+    // The inverse pin. `ci.yml` cannot host this check: a changeset-only PR
+    // matches its `paths-ignore` twice over (`**/*.md` and `.changeset/**`), so
+    // no job in it would ever run. If that ever stops being true, this test
+    // fails and the separate workflow can be folded back in.
+    expect(guard).toMatch(/paths:\s*\n\s*- '\.changeset\/\*\*'/);
+
+    const ci = fs.readFileSync(path.join(workflowDir, 'ci.yml'), 'utf8');
+    expect(ci).toContain("paths-ignore:");
+    expect(ci).toContain("- '**/*.md'");
+  });
+});
diff --git a/scripts/check-changeset-no-major.mjs b/scripts/check-changeset-no-major.mjs
new file mode 100644
index 000000000..53142e82b
--- /dev/null
+++ b/scripts/check-changeset-no-major.mjs
@@ -0,0 +1,151 @@
+#!/usr/bin/env node
+/**
+ * Fails when a pending changeset declares a `major` bump.
+ *
+ * Why this is a gate and not a review note: every publishable package in this
+ * repo sits in ONE `fixed` group (`.changeset/config.json`, 39 packages), and
+ * changesets applies the highest bump in the group to all of it. So a single
+ * `"@object-ui/layout": major` does not release one package as a major — it
+ * carries the whole family to the next major and off `@objectstack`'s line.
+ *
+ * That matters because objectui's major is not its own count of breaking
+ * changes: it is pinned to the `@objectstack` (spec/client/formula) major, so
+ * that "same major ⇒ compatible" holds across the two repos (AGENTS.md
+ * §版本号策略). objectui's own breaking changes ship as `minor` with the break
+ * spelled out in the changeset body. The major moves exactly once per
+ * objectstack major, deliberately.
+ *
+ * This ran for the first time against four pending changesets scoring `major`
+ * (17 package entries between them) during the 17.x line — enough to publish
+ * 39 packages as 18.0.0 against an `@objectstack` still on 17. The rule was
+ * already written down; nothing executed it, and no workflow even looked at
+ * `.changeset/**` (both `ci.yml` and `lint.yml` list it under `paths-ignore`).
+ *
+ * The one legitimate major is the synchronized bump that follows objectstack
+ * across ITS major. Set `OBJECTUI_ALLOW_MAJOR=1` for that release, and only
+ * then.
+ *
+ * Run:  node scripts/check-changeset-no-major.mjs
+ * Exit: 0 = no `major` declared, 1 = at least one `major` declared
+ */
+
+import { readFileSync, readdirSync } from 'node:fs';
+import { resolve, dirname, join } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const root = resolve(dirname(fileURLToPath(import.meta.url)), '..');
+const changesetDir = resolve(root, '.changeset');
+
+/** `.changeset/README.md` is documentation, not a changeset. */
+const NOT_A_CHANGESET = new Set(['README.md']);
+
+/**
+ * Package/bump pairs from a changeset's YAML frontmatter — the block between
+ * the leading `---` and the next `---`.
+ *
+ * Hand-parsed on purpose: this check runs in CI on a bare checkout with no
+ * `pnpm install` (the job is a checkout plus a `node` invocation), so it may
+ * not import a YAML parser or `@changesets/*`. The frontmatter dialect is
+ * tiny and fully covered here — one `name: bump` per line, name optionally
+ * quoted, `#` comments and blank lines ignored.
+ *
+ * @param {string} source raw file contents
+ * @returns {{ pkg: string, bump: string, line: number }[]}
+ */
+export function parseFrontmatterBumps(source) {
+  const lines = source.split(/\r?\n/);
+  const open = lines.findIndex((line) => line.trim() === '---');
+  if (open === -1) return [];
+
+  const bumps = [];
+  for (let i = open + 1; i < lines.length; i++) {
+    const raw = lines[i];
+    if (raw.trim() === '---') break; // end of frontmatter
+    const text = raw.trim();
+    if (text === '' || text.startsWith('#')) continue;
+
+    const match = text.match(
+      /^(?:"([^"]+)"|'([^']+)'|([^:]+?))\s*:\s*(major|minor|patch)\s*$/
+    );
+    if (!match) continue;
+
+    bumps.push({
+      pkg: match[1] ?? match[2] ?? match[3],
+      bump: match[4],
+      line: i + 1, // 1-based, for a clickable `file:line`
+    });
+  }
+  return bumps;
+}
+
+/**
+ * @param {{ file: string, source: string }[]} changesets
+ * @returns {{ file: string, pkg: string, line: number }[]} every `major` entry
+ */
+export function findMajorBumps(changesets) {
+  return changesets.flatMap(({ file, source }) =>
+    parseFrontmatterBumps(source)
+      .filter(({ bump }) => bump === 'major')
+      .map(({ pkg, line }) => ({ file, pkg, line }))
+  );
+}
+
+/** Reads `.changeset/*.md`, minus the README. */
+function readChangesets(dir) {
+  let entries;
+  try {
+    entries = readdirSync(dir);
+  } catch {
+    return []; // no `.changeset/` — nothing to police
+  }
+  return entries
+    .filter((name) => name.endsWith('.md') && !NOT_A_CHANGESET.has(name))
+    .sort()
+    .map((name) => ({
+      file: join('.changeset', name),
+      source: readFileSync(join(dir, name), 'utf8'),
+    }));
+}
+
+function main() {
+  const offenders = findMajorBumps(readChangesets(changesetDir));
+
+  if (offenders.length === 0) {
+    console.log('✅  No changeset declares a `major` bump.');
+    return 0;
+  }
+
+  if (process.env.OBJECTUI_ALLOW_MAJOR === '1') {
+    console.log(
+      `⚠️   OBJECTUI_ALLOW_MAJOR=1 — allowing ${offenders.length} \`major\` entr${
+        offenders.length === 1 ? 'y' : 'ies'
+      }.`
+    );
+    console.log(
+      '    Only correct when this release follows `@objectstack` across its own major.'
+    );
+    return 0;
+  }
+
+  console.error('❌  A changeset declares a `major` bump:\n');
+  for (const { file, pkg, line } of offenders) {
+    console.error(`    • ${pkg}  (${file}:${line})`);
+  }
+  console.error(`
+Every publishable package is in one \`fixed\` group, so ONE \`major\` publishes
+all of them as the next major — objectui would leave the \`@objectstack\` major
+it is pinned to, and "same major ⇒ compatible" would stop holding.
+
+Fix: score it \`minor\` and describe the break in the changeset body (that is
+the convention, not an oversight — see AGENTS.md §版本号策略).
+
+Following \`@objectstack\` across its own major is the one exception; that
+release sets OBJECTUI_ALLOW_MAJOR=1.
+`);
+  return 1;
+}
+
+// Only run when invoked as a script — the tests import the parser above.
+if (process.argv[1] && resolve(process.argv[1]) === fileURLToPath(import.meta.url)) {
+  process.exit(main());
+}