@@ -0,0 +1,26 @@
+---
+'@objectstack/plugin-sharing': minor
+'@objectstack/runtime': minor
+---
+
+fix(plugin-sharing,runtime)!: a declared sharing rule is read-only and clonable — no rule, new or renamed, can take its name, and it is switched off through the activation ledger, which revokes its grants at once
+
+Clause-②: no (narrowing)
+
+<!-- adr-0087: not-required (no-migration-prescription) no spec key, export, option or stored metadata shape is added, removed or renamed, so `objectstack migrate meta` has nothing to rewrite; what changes is the accept set of two write doors, whose remedy is another name for the caller's rule plus one activation call -->
+
+**BREAKING** (an accept-set narrowing), shipped as `minor` under the launch-window convention for breaking changes.
+
+ADR-0131 D6 charts declared sharing rules under regime C: a rule a package declares is read-only, it is customised by a clone under another name, and it is switched off through the deployment-level activation ledger (`sys_metadata_activation`), like flows, actions, positions and permission sets. Same-name shadowing is retired.
+
+What is refused now:
+
+- `POST /api/v1/sharing/rules` (and `SharingRuleService.defineRule`) creating a rule under a declared rule's name — FROM `201`, the new row replacing the declared rule in its scope, TO `409 RESOURCE_CONFLICT` naming the declared rule. Fix: create your rule under another name, and switch the declared one off with `POST /api/v1/security/_activation/sharing_rule/<name>` and `{ "enabled": false }`.
+- A `/data` insert of a `sys_sharing_rule` row under a declared rule's name, or an update that renames a row onto one — FROM `201` / `200`, TO `409 RESOURCE_CONFLICT`. Fix: the same.
+
+What is added:
+
+- **The switch.** `POST /api/v1/security/_activation/sharing_rule/:name` writes the declared rule's activation row, behind the same authority as the other activation doors: `manage_metadata`, and the platform operator under a wall, because the row covers every organization. A declared rule switched off is served nowhere. The write revokes every grant that carries the rule's name in the same request, and switching it back on re-derives them. The name must be a declared rule (`404` otherwise; a rule your organization authored keeps its own `active` field), and with no sharing-rule service bound the door answers `503`.
+- **A declaration over a stored row is reported, never made an overlay.** When a package declares a rule whose name a `sys_sharing_rule` row already holds in a scope (a package upgrade, or a copy customised before this release), the row keeps answering as its own rule. The declaration is not served beside it, and that is logged at `error` once per name and scope per process, with the remedy.
+
+Unchanged: rules whose name no declaration holds are created, renamed and switched as before. A stored row that already holds a declared name stays editable as itself. `DELETE /api/v1/sharing/rules/:idOrName` on a declared rule is still `403 PERMISSION_DENIED`, and is now answered the same way when the rule is switched off.
@@ -159,7 +159,7 @@ One of the largest consumers of the flag;
 | 37 | `sys_record_share` reads are **not** self-scoped | Get: tenant-wide share listing without `manage_sharing` | `packages/plugins/plugin-sharing/src/sharing-plugin.ts#buildSharingMiddleware` |
 | 38 | Share-link policy `enabled` check bypassed; system callers re-enter under a system context | Get: link **creation** while the policy is off — resolution is **not** bypassed since #14033 (`publicSharing.enabled` is a standing policy held at every redemption): a link minted this way does not resolve until the block is enabled | `packages/plugins/plugin-sharing/src/share-link-service.ts#createLink`, `#revokeLink`, `#listLinks` |
 | 39 | Sharing-rule provenance stamp skipped | Lose: the row is not marked as an admin customization — seeder / `defineRule` / boot reconcilers are "the package door" | `packages/plugins/plugin-sharing/src/sharing-rule-provenance.ts#bindRuleProvenanceStamp` |
-| 40 | Sharing-rule service write + delete paths return early | Lose: the manage-rules gate on the service surface, and the platform-global-rule delete guard | `packages/plugins/plugin-sharing/src/sharing-rule-service.ts#assertCanManageRules`, `#assertCanDeletePlatformGlobalRule` |
+| 40 | Sharing-rule service write + delete paths return early | Lose: the manage-rules gate on the service surface, the platform-global-rule delete guard, and the declared-name guard on `sys_sharing_rule` writes (a new row or a rename taking a declared rule's name, 409) — `defineRule` makes that check itself before its own system write, and the other system writers are the platform's machinery (the ownership ceremony, migrations) | `packages/plugins/plugin-sharing/src/sharing-rule-service.ts#assertCanManageRules`, `#assertCanDeletePlatformGlobalRule`, `#bindDeclaredRuleNameGuard` |
 
 ### 4. Approvals, attachments, comments, knowledge
 
 
@@ -151,6 +151,13 @@ export interface DeclaredSharingRule {
   recipientId: string;
   accessLevel: ShareAccessLevel;
   active: boolean;
+  /**
+   * The package that ships the declaration (the registry item's `_packageId`),
+   * when it names one — the provenance an activation-ledger row records
+   * (`sys_metadata_activation.package_id`). Absent for a declaration no package
+   * names.
+   */
+  packageId?: string;
 }
 
 /** Why a declaration is not served: the compiler's own refusal, or a shape the runtime has no slot for. */
@@ -217,6 +224,7 @@ export function translateDeclaredSharingRule(
       recipientId: String(r.sharedWith.value),
       accessLevel: (r.accessLevel ?? 'read') as ShareAccessLevel,
       active: r.active !== false,
+      ...(typeof r._packageId === 'string' && r._packageId ? { packageId: r._packageId } : {}),
     },
   };
 }
 
@@ -56,7 +56,7 @@ import {
   type SharingSecurityProbe,
   type SharingTenancyProbe,
 } from './sharing-service.js';
-import { SharingRuleService } from './sharing-rule-service.js';
+import { SharingRuleService, bindDeclaredRuleNameGuard, bindSharingRuleActivationReconcile } from './sharing-rule-service.js';
 import { ShareLinkService } from './share-link-service.js';
 import { registerShareLinkRoutes } from './share-link-routes.js';
 import { bindRuleHooks, unbindAllRuleHooks, bindRuleCriteriaGuard, RULE_REBIND_TRIGGER_PACKAGE } from './rule-hooks.js';
@@ -849,6 +849,14 @@ export class SharingServicePlugin implements Plugin {
             // match-all criteria gate has to sit on the table itself too.
             bindRuleCriteriaGuard(engine, ctx.logger as any);
 
+            // [ADR-0131 D6 regime C] …and so must the refusal of a row, new or
+            // renamed, that takes a declared rule's name: `defineRule` makes it
+            // for its own callers. A declared rule is customised by a clone
+            // under another name plus the declared rule switched off in the
+            // activation ledger, whose writes reconcile its grants at once.
+            bindDeclaredRuleNameGuard(engine, this.ruleService);
+            bindSharingRuleActivationReconcile(engine, this.ruleService);
+
             // [#2909 T1] Stamp `customized` on admin edits of seeded rules so
             // a customized copy keeps answering for its name — the declared
             // rule is not served beside it (ADR-0131 D2), and the ownership