diff --git a/packages/api/src/admin/config.handler.spec.ts b/packages/api/src/admin/config.handler.spec.ts
index 23d595de89..b44ee085ba 100644
--- a/packages/api/src/admin/config.handler.spec.ts
+++ b/packages/api/src/admin/config.handler.spec.ts
@@ -994,7 +994,45 @@ describe('createAdminConfigHandlers', () => {
       await handlers.upsertConfigOverrides(req, res);
 
       expect(res.statusCode).toBe(201);
-      expect(deps.upsertConfig).toHaveBeenCalled();
+      expect(deps.upsertConfig).toHaveBeenCalledWith(
+        'role',
+        'admin',
+        expect.anything(),
+        {},
+        10,
+        undefined,
+        { expectEmpty: true, preservePriority: true },
+      );
+    });
+
+    it('requests atomic priority preservation for ASSIGN_CONFIGS-only empty-overrides upsert', async () => {
+      const findConfigByPrincipal = jest
+        .fn()
+        .mockResolvedValue({ _id: 'c1', priority: 7, overrides: {} });
+      const { handlers, deps } = createHandlers({
+        hasConfigCapability: jest.fn().mockResolvedValue(false),
+        hasCapability: jest.fn().mockResolvedValue(true),
+        findConfigByPrincipal,
+      });
+      const req = mockReq({
+        params: { principalType: 'role', principalId: 'admin' },
+        body: { overrides: {}, priority: 999 },
+      });
+      const res = mockRes();
+
+      await handlers.upsertConfigOverrides(req, res);
+
+      expect(res.statusCode).toBe(201);
+      expect(deps.upsertConfig).toHaveBeenCalledWith(
+        'role',
+        'admin',
+        expect.anything(),
+        {},
+        10,
+        undefined,
+        { expectEmpty: true, preservePriority: true },
+      );
+      expect(findConfigByPrincipal).not.toHaveBeenCalled();
     });
 
     it('rejects non-empty overrides for ASSIGN_CONFIGS-only caller', async () => {
@@ -1113,7 +1151,15 @@ describe('createAdminConfigHandlers', () => {
       await handlers.upsertConfigOverrides(req, res);
 
       expect(res.statusCode).toBe(201);
-      expect(deps.upsertConfig).toHaveBeenCalled();
+      expect(deps.upsertConfig).toHaveBeenCalledWith(
+        'role',
+        'admin',
+        expect.anything(),
+        {},
+        10,
+        undefined,
+        { expectEmpty: true, preservePriority: true },
+      );
     });
 
     it('rejects upsert when parameterized grant targets a different principalType', async () => {
@@ -1245,7 +1291,7 @@ describe('createAdminConfigHandlers', () => {
         expect.anything(),
         expect.anything(),
         undefined,
-        { expectEmpty: true },
+        { expectEmpty: true, preservePriority: true },
       );
     });
 
diff --git a/packages/api/src/admin/config.ts b/packages/api/src/admin/config.ts
index f19c28940b..30d3a4d79c 100644
--- a/packages/api/src/admin/config.ts
+++ b/packages/api/src/admin/config.ts
@@ -79,7 +79,7 @@ export interface AdminConfigDeps {
     overrides: Partial<TCustomConfig>,
     priority: number,
     session?: ClientSession,
-    options?: { expectEmpty?: boolean },
+    options?: { expectEmpty?: boolean; preservePriority?: boolean },
   ) => Promise<IConfig | null>;
   patchConfigFields: (
     principalType: PrincipalType,
@@ -393,14 +393,25 @@ export function createAdminConfigHandlers(deps: AdminConfigDeps): {
         return res.status(403).json({ error: 'Insufficient permissions' });
       }
 
+      if (priority != null && !hasBroadManage) {
+        logger.warn(
+          `[adminConfig] Ignoring caller-supplied priority on assign-only scope lifecycle upsert to ${principalType}/${principalId}: only broad manage:configs may modify document priority`,
+        );
+      }
+
+      const requestedPriority = hasBroadManage ? (priority ?? DEFAULT_PRIORITY) : DEFAULT_PRIORITY;
+      const upsertOptions = hasBroadManage
+        ? { expectEmpty: false }
+        : { expectEmpty: true, preservePriority: true };
+
       const config = await upsertConfig(
         principalType,
         principalId,
         principalModel(principalType),
         filteredOverrides,
-        priority ?? DEFAULT_PRIORITY,
+        requestedPriority,
         undefined,
-        { expectEmpty: !hasBroadManage },
+        upsertOptions,
       );
       if (!config && !hasBroadManage) {
         return res.status(403).json({ error: 'Insufficient permissions' });
diff --git a/packages/data-schemas/src/methods/config.spec.ts b/packages/data-schemas/src/methods/config.spec.ts
index 35cc3cece7..5111a915e6 100644
--- a/packages/data-schemas/src/methods/config.spec.ts
+++ b/packages/data-schemas/src/methods/config.spec.ts
@@ -587,6 +587,39 @@ describe('expectEmpty atomic guard', () => {
     expect(result!.priority).toBe(99);
   });
 
+  it('upsertConfig with preservePriority inserts with the requested priority', async () => {
+    const result = await methods.upsertConfig(
+      PrincipalType.ROLE,
+      'admin',
+      PrincipalModel.ROLE,
+      {},
+      10,
+      undefined,
+      { expectEmpty: true, preservePriority: true },
+    );
+
+    expect(result).toBeTruthy();
+    expect(result!.priority).toBe(10);
+  });
+
+  it('upsertConfig with preservePriority keeps an empty existing doc priority', async () => {
+    await methods.upsertConfig(PrincipalType.ROLE, 'admin', PrincipalModel.ROLE, {}, 5);
+
+    const result = await methods.upsertConfig(
+      PrincipalType.ROLE,
+      'admin',
+      PrincipalModel.ROLE,
+      {},
+      99,
+      undefined,
+      { expectEmpty: true, preservePriority: true },
+    );
+
+    expect(result).toBeTruthy();
+    expect(result!.priority).toBe(5);
+    expect(result!.configVersion).toBe(2);
+  });
+
   it('upsertConfig with expectEmpty returns null when existing doc has non-empty overrides', async () => {
     await methods.upsertConfig(
       PrincipalType.ROLE,
diff --git a/packages/data-schemas/src/methods/config.ts b/packages/data-schemas/src/methods/config.ts
index 62f6c10e96..16f94efd9e 100644
--- a/packages/data-schemas/src/methods/config.ts
+++ b/packages/data-schemas/src/methods/config.ts
@@ -37,7 +37,7 @@ export function createConfigMethods(mongoose: typeof import('mongoose')): {
     overrides: Partial<TCustomConfig>,
     priority: number,
     session?: ClientSession,
-    options?: { expectEmpty?: boolean },
+    options?: { expectEmpty?: boolean; preservePriority?: boolean },
   ) => Promise<IConfig | null>;
   patchConfigFields: (
     principalType: PrincipalType,
@@ -149,7 +149,7 @@ export function createConfigMethods(mongoose: typeof import('mongoose')): {
     overrides: Partial<TCustomConfig>,
     priority: number,
     session?: ClientSession,
-    options?: { expectEmpty?: boolean },
+    options?: { expectEmpty?: boolean; preservePriority?: boolean },
   ): Promise<IConfig | null> {
     const Config = mongoose.models.Config as Model<IConfig>;
 
@@ -168,9 +168,10 @@ export function createConfigMethods(mongoose: typeof import('mongoose')): {
       $set: {
         principalModel,
         overrides,
-        priority,
+        ...(options?.preservePriority ? {} : { priority }),
         isActive: true,
       },
+      ...(options?.preservePriority ? { $setOnInsert: { priority } } : {}),
       $inc: { configVersion: 1 },
     };