@@ -0,0 +1,53 @@
+---
+'@objectstack/spec': minor
+---
+
+**BREAKING for authored metadata** — a delegated-admin scope's `businessUnit` (`AdminScopeSchema`, reached as `adminScope.businessUnit` on a permission set) must now name a business unit. An empty or whitespace-only value is refused at parse, at the key's own path, with a message naming what a valid anchor is: the `sys_business_unit.name` of the root of the delegated subtree (#19461).
+
+Clause-②: yes
+
+Maintainer ruling A on decision batch #217 item 1, 2026-09-23 「217 同意」.
+
+## What changed, and why
+
+`businessUnit` is the scope's one required key, and every other key of the scope is scoped to it. It was declared as a bare string with no minimum, so `{ businessUnit: '' }` and `{ businessUnit: '   ' }` parsed green: the requirement was satisfied by a value that names no business unit. The delegated-admin gate looks the anchor up by exact name, so a blank anchor resolved to an empty subtree. No escalation was measured; the defect is a declaration that did not enforce what it declared. The likeliest author of a blank anchor is an AI that knew the key was required and did not yet know the unit, and until now the platform answered "accepted".
+
+```
+FROM  AdminScopeSchema.safeParse({ businessUnit: '' })
+      -> { success: true }
+
+TO    AdminScopeSchema.safeParse({ businessUnit: '' })
+      -> { success: false,
+           issues: [{ code: 'custom', path: ['businessUnit'],
+                      message: 'A blank businessUnit is not a delegation boundary: businessUnit is
+                                the sys_business_unit.name (machine name) of the business unit at
+                                the root of the subtree this scope delegates, …' }] }
+```
+
+The refusal is a non-transforming refinement: nothing is trimmed. The metadata save path stores the submitted body as written, so a trimming schema would validate one string and store another. A real name parses byte-identical. The published JSON Schema states the same rule (`minLength: 1` and a non-whitespace `pattern`).
+
+## Migration — FROM → TO
+
+| You wrote | Write instead |
+| --- | --- |
+| `adminScope: { businessUnit: '' }` | `adminScope: { businessUnit: 'north_america' }`, using the machine name of the unit at the root of the subtree |
+| `adminScope: { businessUnit: '   ' }` (or a tab or newline) | the same: the root unit's `sys_business_unit.name` |
+| a blank-anchored scope on a set that should not delegate at all | remove `adminScope` from the permission set |
+
+**The one-line fix: set `businessUnit` to the `sys_business_unit.name` of the business unit at the root of the delegated subtree, or remove `adminScope` if the set should not delegate administration.** This cannot be converted automatically, because a blank names no unit and the intended root cannot be inferred. So this ships as an ADR-0087 D3 structured TODO with **no D2 conversion**.
+
+<!-- adr-0087: registered admin-scope-business-unit-blank-refused -->
+
+## Stored permission sets
+
+- **Stored scopes are not rewritten.** Reads do not re-validate stored rows, so no stored permission set becomes unreadable. A stored blank anchor loads and resolves exactly as before.
+- **The next write refuses it.** A Setup or data-door edit of a permission set whose stored scope has a blank anchor answers `422 INVALID_METADATA` naming `adminScope.businessUnit`, until the anchor is named or the scope removed.
+- **The boot reconciliation backfill reports it.** A legacy `sys_permission_set` record with no metadata definition and a blank anchor is not backfilled. It is reported on every boot through the existing ADR-0094 D4 durability `ERROR`, which names the record and the offending key, until the record is fixed or deleted. Restoring a trashed blank-anchored set brings the record back and reports the missing definition at `ERROR` the same way. No path skips the row.
+- **A clean boot is not a completed sweep.** A definition already stored in `sys_metadata` says nothing until it is written again, so search stored permission sets and the `admin_scope` column for a blank `businessUnit`.
+
+## What does NOT change
+
+- **An absent `businessUnit`** is refused exactly as before, with its own `invalid_type` issue.
+- **A real name with surrounding whitespace** is not judged by this change. It parses and is stored byte-identical.
+- **The other keys of the scope** (`includeSubtree`, `manageAssignments`, `manageBindings`, `authorEnvironmentSets`, `assignablePermissionSets`) are untouched.
+- **The published export surface.** No export is added, removed or renamed, and the `AdminScope` / `AdminScopeParsed` types are unchanged.
@@ -27,7 +27,7 @@ const result = AdminScopeSchema.parse(data);
 
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
-| **businessUnit** | `string` | ✅ | [ADR-0090 D12] Delegation boundary: sys_business_unit.name of the subtree root |
+| **businessUnit** | `string` | ✅ | [ADR-0090 D12] Delegation boundary: sys_business_unit.name of the subtree root. Required and non-blank: an empty or whitespace-only value names no business unit and is refused. |
 | **includeSubtree** | `boolean` | optional (default: `true`) | Cover descendant business units too (default true) |
 | **manageAssignments** | `boolean` | optional (default: `false`) | Manage user↔position assignments within the subtree |
 | **manageBindings** | `boolean` | optional (default: `false`) | Manage position↔permission-set bindings within the subtree |
@@ -178,7 +178,7 @@ const result = AdminScopeSchema.parse(data);
 
 | Property | Type | Required | Description |
 | :--- | :--- | :--- | :--- |
-| **businessUnit** | `string` | ✅ | [ADR-0090 D12] Delegation boundary: sys_business_unit.name of the subtree root |
+| **businessUnit** | `string` | ✅ | [ADR-0090 D12] Delegation boundary: sys_business_unit.name of the subtree root. Required and non-blank: an empty or whitespace-only value names no business unit and is refused. |
 | **includeSubtree** | `boolean` | optional (default: `true`) | Cover descendant business units too (default true) |
 | **manageAssignments** | `boolean` | optional (default: `false`) | Manage user↔position assignments within the subtree |
 | **manageBindings** | `boolean` | optional (default: `false`) | Manage position↔permission-set bindings within the subtree |
 
@@ -0,0 +1,68 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+import type { SemanticMigration } from '../../types.js';
+
+// The delegated-admin scope's one required key, required NON-BLANK. Stored
+// scopes are deliberately not rewritten: the root of a subtree cannot be
+// inferred from a blank, so the stored row is refused on its next write and
+// named by the boot reconciliation's existing durability error instead.
+export const entry: SemanticMigration = {
+  id: 'admin-scope-business-unit-blank-refused',
+  // No backticks in `surface` — build-upgrade-guide.ts renders it inside a
+  // code span already, and a nested backtick would close it.
+  surface:
+    'security.permission.adminScope.businessUnit (AdminScopeSchema, ADR-0090 D12) authored or stored '
+    + 'BLANK: the empty string, or a value that is nothing but whitespace (spaces, a tab, a newline). '
+    + 'The key is the scope\'s only required one and names the root business unit of the delegated '
+    + 'subtree; a blank value satisfied the requirement while naming no unit',
+  replacement:
+    'the sys_business_unit.name (machine name) of the business unit at the root of the subtree the '
+    + 'delegate administers, written out: `businessUnit: \'north_america\'`. If the permission set '
+    + 'should not delegate administration at all, remove `adminScope` from it. ⛔ There is no '
+    + 'replacement that can be DERIVED from what was written: a blank names no unit, so the root the '
+    + 'author meant is not recoverable, and the platform must not pick one.',
+  reason:
+    'Maintainer ruling A on #19461 (decision batch #217 item 1, 2026-09-23 「217 同意」). '
+    + '`AdminScopeSchema` declared `businessUnit` as a bare string with no minimum, so '
+    + '`{ businessUnit: \'\' }` and `{ businessUnit: \'   \' }` parsed green — measured against the '
+    + 'published spec 17.4.0 and re-measured on `main` before the change. This narrows a published '
+    + 'face: every other key of the scope is scoped TO this one, and ADR-0090 D12 declares the scope\'s '
+    + 'WHERE as a business-unit subtree, which a blank does not name. The delegated-admin gate '
+    + 'resolves the anchor by exact name, so a blank anchor resolves to an empty subtree and approves '
+    + 'nothing on the subtree axes — no escalation was measured; the defect is a declaration that '
+    + 'does not enforce what it declares, satisfied most readily by an author (an AI author above '
+    + 'all) that knew the key was required and did not yet know the unit. The refusal is a '
+    + 'NON-TRANSFORMING refinement at the key\'s own path, deliberately not a trim: the metadata save '
+    + 'path persists the submitted body verbatim rather than the parsed value, so a trimming schema '
+    + 'would validate one string and store another that the gate\'s exact lookup cannot resolve. A '
+    + 'real name therefore parses byte-identical. Scope is blankness only: a real name with '
+    + 'surrounding whitespace is not judged by this entry. ⚠️ STORED ROWS ARE NOT REWRITTEN and there '
+    + 'is no D2 conversion (no lossless rewrite exists — the root cannot be inferred, and dropping '
+    + 'the scope would silently change who is a delegate). The read path does not re-validate stored '
+    + 'rows, so no stored permission set becomes unreadable. A stored blank-anchored scope is refused '
+    + 'on its NEXT WRITE instead: a Setup or data-door edit of that permission set answers 422 '
+    + 'INVALID_METADATA naming adminScope.businessUnit, and the boot reconciliation backfill of a '
+    + 'legacy record with no metadata definition reports it through its existing durability ERROR '
+    + '(ADR-0094 D4), whose own prescription is to make the record body spec-valid; restoring a '
+    + 'trashed blank-anchored set brings the record back and reports the missing definition at ERROR '
+    + 'the same way. ⛔ No path skips the row. Ships at once, no grace window and no dual spelling '
+    + '(2026-08-27 maintainer ruling 「短期不考虑渐进」). ADR-0049 / ADR-0087 / ADR-0090.',
+  acceptanceCriteria:
+    'Search every authored and stored permission set for an `adminScope` whose `businessUnit` is '
+    + 'empty or whitespace-only — metadata files, `sys_metadata` permission rows, and the '
+    + '`admin_scope` column of `sys_permission_set` — and write the root unit\'s machine name, or '
+    + 'remove `adminScope` where the set should not delegate. The sweep is mechanical for authored '
+    + 'metadata: `AdminScopeSchema.safeParse` and `PermissionSetSchema.safeParse` answer exactly one '
+    + '`custom` issue at `businessUnit` (or `adminScope.businessUnit` when the set is parsed whole) '
+    + 'naming `sys_business_unit.name` as the valid anchor. For STORED rows the search above is the '
+    + 'catch-all, because reads never refuse: a definition already stored in `sys_metadata` with a '
+    + 'blank anchor loads and resolves exactly as before and says nothing until it is written again. '
+    + 'Two write paths then name it: a re-save of the set (refused 422 at adminScope.businessUnit), '
+    + 'and — for a legacy `sys_permission_set` record with no metadata definition only — the boot '
+    + 'log, where the ADR-0094 D4 backfill\'s first-failure ERROR names the record and carries the '
+    + 'offending key and its summary ERROR counts and names the failed records. ⛔ A clean boot is '
+    + 'therefore NOT a completed sweep. An absent `businessUnit` is refused exactly as before, with its own invalid_type issue. Nothing is '
+    + 'normalised on the way through: an accepted anchor arrives byte-identical to what was written. '
+    + 'The repo and example apps carried zero blank anchors at the time of the change, so no fixture '
+    + 'had to be rewritten.',
+};
@@ -5489,6 +5489,70 @@ const step18: MigrationStep = {
         + 'exportable by nobody, which is the point of the change; confirm that is what you want '
         + 'before granting it back.',
     },
+    // The delegated-admin scope's one required key, required NON-BLANK. Stored
+    // scopes are deliberately not rewritten: the root of a subtree cannot be
+    // inferred from a blank, so the stored row is refused on its next write and
+    // named by the boot reconciliation's existing durability error instead.
+    {
+      id: 'admin-scope-business-unit-blank-refused',
+      // No backticks in `surface` — build-upgrade-guide.ts renders it inside a
+      // code span already, and a nested backtick would close it.
+      surface:
+        'security.permission.adminScope.businessUnit (AdminScopeSchema, ADR-0090 D12) authored or stored '
+        + 'BLANK: the empty string, or a value that is nothing but whitespace (spaces, a tab, a newline). '
+        + 'The key is the scope\'s only required one and names the root business unit of the delegated '
+        + 'subtree; a blank value satisfied the requirement while naming no unit',
+      replacement:
+        'the sys_business_unit.name (machine name) of the business unit at the root of the subtree the '
+        + 'delegate administers, written out: `businessUnit: \'north_america\'`. If the permission set '
+        + 'should not delegate administration at all, remove `adminScope` from it. ⛔ There is no '
+        + 'replacement that can be DERIVED from what was written: a blank names no unit, so the root the '
+        + 'author meant is not recoverable, and the platform must not pick one.',
+      reason:
+        'Maintainer ruling A on #19461 (decision batch #217 item 1, 2026-09-23 「217 同意」). '
+        + '`AdminScopeSchema` declared `businessUnit` as a bare string with no minimum, so '
+        + '`{ businessUnit: \'\' }` and `{ businessUnit: \'   \' }` parsed green — measured against the '
+        + 'published spec 17.4.0 and re-measured on `main` before the change. This narrows a published '
+        + 'face: every other key of the scope is scoped TO this one, and ADR-0090 D12 declares the scope\'s '
+        + 'WHERE as a business-unit subtree, which a blank does not name. The delegated-admin gate '
+        + 'resolves the anchor by exact name, so a blank anchor resolves to an empty subtree and approves '
+        + 'nothing on the subtree axes — no escalation was measured; the defect is a declaration that '
+        + 'does not enforce what it declares, satisfied most readily by an author (an AI author above '
+        + 'all) that knew the key was required and did not yet know the unit. The refusal is a '
+        + 'NON-TRANSFORMING refinement at the key\'s own path, deliberately not a trim: the metadata save '
+        + 'path persists the submitted body verbatim rather than the parsed value, so a trimming schema '
+        + 'would validate one string and store another that the gate\'s exact lookup cannot resolve. A '
+        + 'real name therefore parses byte-identical. Scope is blankness only: a real name with '
+        + 'surrounding whitespace is not judged by this entry. ⚠️ STORED ROWS ARE NOT REWRITTEN and there '
+        + 'is no D2 conversion (no lossless rewrite exists — the root cannot be inferred, and dropping '
+        + 'the scope would silently change who is a delegate). The read path does not re-validate stored '
+        + 'rows, so no stored permission set becomes unreadable. A stored blank-anchored scope is refused '
+        + 'on its NEXT WRITE instead: a Setup or data-door edit of that permission set answers 422 '
+        + 'INVALID_METADATA naming adminScope.businessUnit, and the boot reconciliation backfill of a '
+        + 'legacy record with no metadata definition reports it through its existing durability ERROR '
+        + '(ADR-0094 D4), whose own prescription is to make the record body spec-valid; restoring a '
+        + 'trashed blank-anchored set brings the record back and reports the missing definition at ERROR '
+        + 'the same way. ⛔ No path skips the row. Ships at once, no grace window and no dual spelling '
+        + '(2026-08-27 maintainer ruling 「短期不考虑渐进」). ADR-0049 / ADR-0087 / ADR-0090.',
+      acceptanceCriteria:
+        'Search every authored and stored permission set for an `adminScope` whose `businessUnit` is '
+        + 'empty or whitespace-only — metadata files, `sys_metadata` permission rows, and the '
+        + '`admin_scope` column of `sys_permission_set` — and write the root unit\'s machine name, or '
+        + 'remove `adminScope` where the set should not delegate. The sweep is mechanical for authored '
+        + 'metadata: `AdminScopeSchema.safeParse` and `PermissionSetSchema.safeParse` answer exactly one '
+        + '`custom` issue at `businessUnit` (or `adminScope.businessUnit` when the set is parsed whole) '
+        + 'naming `sys_business_unit.name` as the valid anchor. For STORED rows the search above is the '
+        + 'catch-all, because reads never refuse: a definition already stored in `sys_metadata` with a '
+        + 'blank anchor loads and resolves exactly as before and says nothing until it is written again. '
+        + 'Two write paths then name it: a re-save of the set (refused 422 at adminScope.businessUnit), '
+        + 'and — for a legacy `sys_permission_set` record with no metadata definition only — the boot '
+        + 'log, where the ADR-0094 D4 backfill\'s first-failure ERROR names the record and carries the '
+        + 'offending key and its summary ERROR counts and names the failed records. ⛔ A clean boot is '
+        + 'therefore NOT a completed sweep. An absent `businessUnit` is refused exactly as before, with its own invalid_type issue. Nothing is '
+        + 'normalised on the way through: an accepted anchor arrives byte-identical to what was written. '
+        + 'The repo and example apps carried zero blank anchors at the time of the change, so no fixture '
+        + 'had to be rewritten.',
+    },
     {
       id: 'advanced-plugin-lifecycle-config-retired',
       surface: