diff --git a/.changeset/20592-ui-html-page-div-refused.md b/.changeset/20592-ui-html-page-div-refused.md
new file mode 100644
index 00000000000..edf3e9d1b22
--- /dev/null
+++ b/.changeset/20592-ui-html-page-div-refused.md
@@ -0,0 +1,24 @@
+---
+'@objectstack/spec': patch
+---
+
+feat(spec): the protocol-18 migration step records the html-tier `div` refusal as the semantic entry `ui-html-page-div-refused` (#20592)
+
+Clause-②: no
+
+`MIGRATIONS_BY_MAJOR[18].semantic` gains one entry, `ui-html-page-div-refused`.
+It records the narrowing `@objectstack/cli` takes on when its JSX page gate
+reaches the SDUI component manifest that `@objectstack/console` ships: a project
+with no `sdui.manifest.json` of its own has its `kind: 'html'` pages checked
+against that manifest, which does not declare `div`, so `objectstack validate`,
+`compile` and `lint` refuse a `div` there (`jsx-forbidden-tag`,
+`jsx-unknown-component`). The entry prescribes `box` for a plain wrapper, names
+the layout containers to reach for instead only when their layout is wanted, and
+says how to prove the rewrite done.
+
+What moves for a consumer of this package: `MIGRATIONS_BY_MAJOR` carries the
+entry, and `objectstack migrate meta` prints it, because its default range
+already runs to protocol 18, the highest major with a step. Nothing else does.
+The protocol-18 step is not cut yet, so `spec-changes.json` and the protocol
+upgrade guide, which project the steps up to the current protocol major, are
+unchanged, and no schema accepts or refuses anything it did not before.
diff --git a/packages/spec/src/migrations/entries/semantic/18.ui-html-page-div-refused.ts b/packages/spec/src/migrations/entries/semantic/18.ui-html-page-div-refused.ts
new file mode 100644
index 00000000000..63f8b8df74a
--- /dev/null
+++ b/packages/spec/src/migrations/entries/semantic/18.ui-html-page-div-refused.ts
@@ -0,0 +1,56 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+import type { SemanticMigration } from '../../types.js';
+
+// #20592 — the D3 record of the accept-set narrowing the CLI's JSX page gate
+// takes on when its console-manifest fallback becomes reachable (#19922): a
+// project with no `sdui.manifest.json` of its own has its `kind:'html'` pages
+// checked against the manifest `@objectstack/console` ships, which does not
+// declare `div`. The vocabulary is ruling A on #20112 (record 5852014527): an
+// html page may author the intrinsic tags its renderer registers, the published
+// manifest declares that set, and `div` stays deprecated in favour of `box` —
+// the console's own html compile refuses it too since objectui#10808. No D2
+// conversion and no tombstone: the tag sits inside an authored JSX string, which
+// no conversion rewrites and no schema key can tombstone, so this entry is the
+// migration channel beside the changeset's FROM → TO table.
+export const entry: SemanticMigration = {
+  id: 'ui-html-page-div-refused',
+  // No backticks and no pipes in `surface` — build-upgrade-guide.ts renders it
+  // inside a code span.
+  surface:
+    "kind:'html' page source (and its deprecated kind:'jsx' alias) in a project with no "
+    + 'sdui.manifest.json of its own — the div tag, and any other tag or prop the SDUI '
+    + 'component manifest shipped in @objectstack/console does not declare',
+  replacement:
+    '`box` for a plain wrapper — the one drop-in swap: the same element, your `className` '
+    + 'verbatim, the same children, and no layout of its own. Reach for `card`, `flex`, '
+    + '`container`, `stack` or `grid` only where you want their layout. For any other tag or '
+    + 'prop the command names, a component and prop the manifest declares; the file is '
+    + '`dist/sdui.manifest.json` inside `@objectstack/console`.',
+  reason:
+    'An html page\'s source is a JSX string, not a keyed document: `objectstack migrate meta` '
+    + 'rewrites stored metadata by key and cannot rewrite a tag inside authored source, so the '
+    + 'move is by hand, and which wrapper keeps a page\'s layout is the author\'s call. '
+    + '`objectstack validate`, `objectstack compile` (which `dev` and `start` run first) and '
+    + '`objectstack lint` check that source against an SDUI component manifest: the '
+    + '`sdui.manifest.json` in the directory the command runs in, then the copy '
+    + '`@objectstack/console` ships. The second lookup asked for a file the console package '
+    + 'does not export, so it always failed, and a project without its own manifest had its '
+    + 'html pages checked at parse level only — syntax and structure, never which components '
+    + 'and props they use. It now reaches the shipped copy. That manifest declares the html '
+    + 'tier\'s intrinsic tags but not `div`: the maintainer ruled (2026-09-27) that an html page '
+    + 'may author the intrinsic tags its renderer registers and that the published manifest '
+    + 'declares that set, while `div` stays deprecated in favour of `box`, and the console\'s '
+    + 'own html-page compile refuses `div` the same way. A `div` in such a page, which used to '
+    + 'pass unchecked, now fails the command with `jsx-forbidden-tag` and '
+    + '`jsx-unknown-component`. A project that keeps its own `sdui.manifest.json` is checked '
+    + 'against that file, as before.',
+  acceptanceCriteria:
+    '`objectstack validate` reports no `jsx-forbidden-tag`, `jsx-unknown-component` or '
+    + '`jsx-unknown-prop` finding on any `kind:\'html\'` page and prints no '
+    + '`sdui/jsx-parse-level-only` notice — that notice means the component check did not run, '
+    + 'so a clean result beside it proves nothing; `objectstack compile` and `objectstack lint` '
+    + 'agree. No html page source authors `div`, and in the console each rewritten page renders '
+    + 'with no compile error. The platform\'s own reference is the showcase app\'s three html '
+    + 'pages, which author their wrappers as `box` and pass with zero findings.',
+};
diff --git a/packages/spec/src/migrations/registry.ts b/packages/spec/src/migrations/registry.ts
index 8ff375ba697..ac898834c6b 100644
--- a/packages/spec/src/migrations/registry.ts
+++ b/packages/spec/src/migrations/registry.ts
@@ -17147,6 +17147,58 @@ const step18: MigrationStep = {
         + 'authoring-path save (zero such documents were measured to exist); on refusal the '
         + 'author re-gates by record state or moves the gate to an app surface.',
     },
+    // #20592 — the D3 record of the accept-set narrowing the CLI's JSX page gate
+    // takes on when its console-manifest fallback becomes reachable (#19922): a
+    // project with no `sdui.manifest.json` of its own has its `kind:'html'` pages
+    // checked against the manifest `@objectstack/console` ships, which does not
+    // declare `div`. The vocabulary is ruling A on #20112 (record 5852014527): an
+    // html page may author the intrinsic tags its renderer registers, the published
+    // manifest declares that set, and `div` stays deprecated in favour of `box` —
+    // the console's own html compile refuses it too since objectui#10808. No D2
+    // conversion and no tombstone: the tag sits inside an authored JSX string, which
+    // no conversion rewrites and no schema key can tombstone, so this entry is the
+    // migration channel beside the changeset's FROM → TO table.
+    {
+      id: 'ui-html-page-div-refused',
+      // No backticks and no pipes in `surface` — build-upgrade-guide.ts renders it
+      // inside a code span.
+      surface:
+        "kind:'html' page source (and its deprecated kind:'jsx' alias) in a project with no "
+        + 'sdui.manifest.json of its own — the div tag, and any other tag or prop the SDUI '
+        + 'component manifest shipped in @objectstack/console does not declare',
+      replacement:
+        '`box` for a plain wrapper — the one drop-in swap: the same element, your `className` '
+        + 'verbatim, the same children, and no layout of its own. Reach for `card`, `flex`, '
+        + '`container`, `stack` or `grid` only where you want their layout. For any other tag or '
+        + 'prop the command names, a component and prop the manifest declares; the file is '
+        + '`dist/sdui.manifest.json` inside `@objectstack/console`.',
+      reason:
+        'An html page\'s source is a JSX string, not a keyed document: `objectstack migrate meta` '
+        + 'rewrites stored metadata by key and cannot rewrite a tag inside authored source, so the '
+        + 'move is by hand, and which wrapper keeps a page\'s layout is the author\'s call. '
+        + '`objectstack validate`, `objectstack compile` (which `dev` and `start` run first) and '
+        + '`objectstack lint` check that source against an SDUI component manifest: the '
+        + '`sdui.manifest.json` in the directory the command runs in, then the copy '
+        + '`@objectstack/console` ships. The second lookup asked for a file the console package '
+        + 'does not export, so it always failed, and a project without its own manifest had its '
+        + 'html pages checked at parse level only — syntax and structure, never which components '
+        + 'and props they use. It now reaches the shipped copy. That manifest declares the html '
+        + 'tier\'s intrinsic tags but not `div`: the maintainer ruled (2026-09-27) that an html page '
+        + 'may author the intrinsic tags its renderer registers and that the published manifest '
+        + 'declares that set, while `div` stays deprecated in favour of `box`, and the console\'s '
+        + 'own html-page compile refuses `div` the same way. A `div` in such a page, which used to '
+        + 'pass unchecked, now fails the command with `jsx-forbidden-tag` and '
+        + '`jsx-unknown-component`. A project that keeps its own `sdui.manifest.json` is checked '
+        + 'against that file, as before.',
+      acceptanceCriteria:
+        '`objectstack validate` reports no `jsx-forbidden-tag`, `jsx-unknown-component` or '
+        + '`jsx-unknown-prop` finding on any `kind:\'html\'` page and prints no '
+        + '`sdui/jsx-parse-level-only` notice — that notice means the component check did not run, '
+        + 'so a clean result beside it proves nothing; `objectstack compile` and `objectstack lint` '
+        + 'agree. No html page source authors `div`, and in the console each rewritten page renders '
+        + 'with no compile error. The platform\'s own reference is the showcase app\'s three html '
+        + 'pages, which author their wrappers as `box` and pass with zero findings.',
+    },
     // The sibling axis of `ui-list-view-grouping-field-padded-refused` (#17360),
     // which scoped this one out by name. Same defect, same refusal, one difference
     // that changes the author's options: `kanban.groupByField` is REQUIRED, so a