diff --git a/backend/__tests__/unit/routes/registry.agent-config-installer-gate.test.js b/backend/__tests__/unit/routes/registry.agent-config-installer-gate.test.js
index 47c3c205fd..adfb1395bf 100644
--- a/backend/__tests__/unit/routes/registry.agent-config-installer-gate.test.js
+++ b/backend/__tests__/unit/routes/registry.agent-config-installer-gate.test.js
@@ -290,6 +290,104 @@ describe('agent config PATCH — installer gate', () => {
     expect(primary.save).not.toHaveBeenCalled();
   });
 
+  it('refuses a name shown on another owned agent card even when its bot label differs', async () => {
+    const primary = installation({ installedBy: MEMBER, displayName: 'Curator' });
+    const other = installation({
+      agentName: 'guide', instanceId: 'u1234567890', podId: 'pod-2',
+      installedBy: MEMBER, displayName: 'uda599d9d45',
+    });
+    setPod();
+    AgentInstallation.findOne.mockResolvedValue(primary);
+    AgentInstallation.find.mockResolvedValueOnce([primary]).mockResolvedValueOnce([primary, other]);
+
+    const res = await request(app)
+      .patch('/api/registry/pods/pod-1/agents/openclaw')
+      .send({ instanceId: 'curator', displayName: ' UDA599D9D45 ' });
+
+    expect(res.status).toBe(409);
+    expect(res.body.code).toBe('agent_display_name_taken');
+    expect(AgentIdentityService.renameAgentDisplayName).not.toHaveBeenCalled();
+    expect(primary.save).not.toHaveBeenCalled();
+    expect(AgentProfile.updateMany).not.toHaveBeenCalled();
+  });
+
+  it('refuses an admin rename that collides with the target installer\'s visible card', async () => {
+    const primary = installation({ installedBy: INSTALLER, displayName: 'Curator' });
+    const other = installation({
+      agentName: 'guide', instanceId: 'another', podId: 'pod-2',
+      installedBy: INSTALLER, displayName: 'Scout',
+    });
+    setCallerRole('admin');
+    setPod();
+    AgentInstallation.findOne.mockResolvedValue(primary);
+    AgentInstallation.find.mockResolvedValueOnce([primary]).mockResolvedValueOnce([primary, other]);
+
+    const res = await request(app)
+      .patch('/api/registry/pods/pod-1/agents/openclaw')
+      .send({ instanceId: 'curator', displayName: 'Scout' });
+
+    expect(res.status).toBe(409);
+    expect(res.body.code).toBe('agent_display_name_taken');
+    expect(AgentInstallation.find).toHaveBeenLastCalledWith({
+      installedBy: { $in: [INSTALLER] }, status: 'active',
+    });
+    expect(primary.displayName).toBe('Curator');
+    expect(primary.save).not.toHaveBeenCalled();
+    expect(AgentIdentityService.renameAgentDisplayName).not.toHaveBeenCalled();
+    expect(AgentProfile.updateMany).not.toHaveBeenCalled();
+  });
+
+  it('checks every affected installer when an admin renames a shared identity', async () => {
+    const primary = installation({ installedBy: INSTALLER, displayName: 'Curator' });
+    const peer = installation({ podId: 'pod-2', installedBy: 'other-installer', displayName: 'Curator' });
+    const other = installation({
+      agentName: 'guide', instanceId: 'another', podId: 'pod-3',
+      installedBy: 'other-installer', displayName: 'Scout',
+    });
+    setCallerRole('admin');
+    setPod();
+    Pod.find.mockReturnValue({ select: jest.fn().mockReturnValue({ lean: jest.fn().mockResolvedValue([
+      { _id: 'pod-1', members: [{ userId: MEMBER }] },
+      { _id: 'pod-2', members: [{ userId: MEMBER }] },
+    ]) }) });
+    AgentInstallation.findOne.mockResolvedValue(primary);
+    AgentInstallation.find.mockResolvedValueOnce([primary, peer]).mockResolvedValueOnce([primary, peer, other]);
+
+    const res = await request(app)
+      .patch('/api/registry/pods/pod-1/agents/openclaw')
+      .send({ instanceId: 'curator', displayName: 'Scout' });
+
+    expect(res.status).toBe(409);
+    expect(res.body.code).toBe('agent_display_name_taken');
+    expect(AgentInstallation.find).toHaveBeenLastCalledWith({
+      installedBy: { $in: [INSTALLER, 'other-installer'] }, status: 'active',
+    });
+    expect(primary.save).not.toHaveBeenCalled();
+    expect(peer.save).not.toHaveBeenCalled();
+    expect(AgentIdentityService.renameAgentDisplayName).not.toHaveBeenCalled();
+    expect(AgentProfile.updateMany).not.toHaveBeenCalled();
+  });
+
+  it('does not treat another pod for the same identity as a name collision', async () => {
+    const primary = installation({ installedBy: MEMBER, displayName: 'Curator' });
+    const sibling = installation({ podId: 'pod-2', installedBy: MEMBER, displayName: 'New name' });
+    setPod();
+    Pod.find.mockReturnValue({ select: jest.fn().mockReturnValue({ lean: jest.fn().mockResolvedValue([
+      { _id: 'pod-1', members: [{ userId: MEMBER }] },
+      { _id: 'pod-2', members: [{ userId: MEMBER }] },
+    ]) }) });
+    AgentInstallation.findOne.mockResolvedValue(primary);
+    AgentInstallation.find.mockResolvedValueOnce([primary, sibling]).mockResolvedValueOnce([primary, sibling]);
+
+    const res = await request(app)
+      .patch('/api/registry/pods/pod-1/agents/openclaw')
+      .send({ instanceId: 'curator', displayName: 'New name' });
+
+    expect(res.status).toBe(200);
+    expect(primary.displayName).toBe('New name');
+    expect(sibling.displayName).toBe('New name');
+  });
+
   it('does not claim a completed rename when the chat mirror is behind', async () => {
     const primary = installation({ installedBy: MEMBER });
     setPod();
diff --git a/backend/routes/registry/agent-config.ts b/backend/routes/registry/agent-config.ts
index 0e55e4f3cc..f9d6ef407b 100644
--- a/backend/routes/registry/agent-config.ts
+++ b/backend/routes/registry/agent-config.ts
@@ -326,6 +326,29 @@ agentConfigRouter.patch('/pods/:podId/agents/:name', auth, async (req: any, res:
       const { status: refusalStatus, ...refusalBody } = writeRefusal;
       return res.status(refusalStatus).json(refusalBody);
     }
+    // An installation can show a different label from its bot User. Guard
+    // every affected installer's active cards, including when an admin edits
+    // someone else's agent, before renaming the shared identity.
+    if (displayName !== undefined) {
+      const requestedName = displayName.trim().toLowerCase();
+      const installerIds = Array.from(new Set(installationsToUpdate
+        .map((entry: any) => entry.installedBy?.toString?.())
+        .filter(Boolean)));
+      const ownerInstallations = await AgentInstallation.find({
+        installedBy: { $in: installerIds }, status: 'active',
+      });
+      const nameTaken = ownerInstallations.some((entry: any) => (
+        !(entry.agentName === name.toLowerCase()
+          && (entry.instanceId || 'default') === normalizedInstanceId)
+        && String(entry.displayName || entry.agentName || '').trim().toLowerCase() === requestedName
+      ));
+      if (nameTaken) {
+        return res.status(409).json({
+          code: 'agent_display_name_taken',
+          error: 'Another agent already uses this name',
+        });
+      }
+    }
     // Decide for every fan-out target before saving any row. A runtime object
     // without runtimeType also removes an existing native declaration here.
     if (config?.runtime !== undefined || status === 'active') {