🛡️ fix: Enforce MULTI_CONVO and agent ACL checks on addedConvo (#12243)

* 🛡️ fix: Enforce MULTI_CONVO and agent ACL checks on addedConvo

addedConvo.agent_id was passed through to loadAddedAgent without any
permission check, enabling an authenticated user to load and execute
another user's private agent via the parallel multi-convo feature.

The middleware now chains a checkAddedConvoAccess gate after the primary
agent check: when req.body.addedConvo is present it verifies the user
has MULTI_CONVO:USE role permission, and when the addedConvo agent_id is
a real (non-ephemeral) agent it runs the same canAccessResource ACL
check used for the primary agent.

* refactor: Harden addedConvo middleware and avoid duplicate agent fetch

- Convert checkAddedConvoAccess to curried factory matching Express
  middleware signature: (requiredPermission) => (req, res, next)
- Call checkPermission directly for the addedConvo agent instead of
  routing through canAccessResource's tempReq pattern; this avoids
  orphaning the resolved agent document and enables caching it on
  req.resolvedAddedAgent for downstream loadAddedAgent
- Update loadAddedAgent to use req.resolvedAddedAgent when available,
  eliminating a duplicate getAgent DB call per chat request
- Validate addedConvo is a plain object and agent_id is a string
  before passing to isEphemeralAgentId (prevents TypeError on object
  injection, returns 400-equivalent early exit instead of 500)
- Fix JSDoc: "VIEW access" → "same permission as primary agent",
  add @param/@returns to helpers, restore @example on factory
- Fix redundant return await in resolveAgentIdFromBody

* test: Add canAccessAgentFromBody spec covering IDOR fix

26 integration tests using MongoMemoryServer with real models, ACL
entries, and PermissionService — no mocks for core logic.

Covered paths:
- Factory validation (requiredPermission type check)
- Primary agent: missing agent_id, ephemeral, non-agents endpoint
- addedConvo absent / invalid shape (string, array, object injection)
- MULTI_CONVO:USE gate: denied, missing role, ADMIN bypass
- Agent resource ACL: no ACL → 403, insufficient bits → 403,
  nonexistent agent → 404, valid ACL → next + cached on req
- End-to-end: both real agents, primary denied short-circuits,
  ephemeral primary + real addedConvo

api/models/loadAddedAgent.js

@@ -48,14 +48,14 @@ const loadAddedAgent = async ({ req, conversation, primaryAgent }) => {
     return null;
   }
 
-  // If there's an agent_id, load the existing agent
   if (conversation.agent_id && !isEphemeralAgentId(conversation.agent_id)) {
-    if (!getAgent) {
-      throw new Error('getAgent not initialized - call setGetAgent first');
+    let agent = req.resolvedAddedAgent;
+    if (!agent) {
+      if (!getAgent) {
+        throw new Error('getAgent not initialized - call setGetAgent first');
+      }
+      agent = await getAgent({ id: conversation.agent_id });
     }
-    const agent = await getAgent({
-      id: conversation.agent_id,
-    });
 
     if (!agent) {
       logger.warn(`[loadAddedAgent] Agent ${conversation.agent_id} not found`);

api/server/middleware/accessResources/canAccessAgentFromBody.js

@@ -1,42 +1,144 @@
 const { logger } = require('@librechat/data-schemas');
 const {
   Constants,
+  Permissions,
   ResourceType,
+  SystemRoles,
+  PermissionTypes,
   isAgentsEndpoint,
   isEphemeralAgentId,
 } = require('librechat-data-provider');
+const { checkPermission } = require('~/server/services/PermissionService');
 const { canAccessResource } = require('./canAccessResource');
+const { getRoleByName } = require('~/models/Role');
 const { getAgent } = require('~/models/Agent');
 
 /**
- * Agent ID resolver function for agent_id from request body
- * Resolves custom agent ID (e.g., "agent_abc123") to MongoDB ObjectId
- * This is used specifically for chat routes where agent_id comes from request body
- *
+ * Resolves custom agent ID (e.g., "agent_abc123") to a MongoDB document.
  * @param {string} agentCustomId - Custom agent ID from request body
- * @returns {Promise<Object|null>} Agent document with _id field, or null if not found
+ * @returns {Promise<Object|null>} Agent document with _id field, or null if ephemeral/not found
  */
 const resolveAgentIdFromBody = async (agentCustomId) => {
-  // Handle ephemeral agents - they don't need permission checks
-  // Real agent IDs always start with "agent_", so anything else is ephemeral
   if (isEphemeralAgentId(agentCustomId)) {
-    return null; // No permission check needed for ephemeral agents
+    return null;
   }
-
-  return await getAgent({ id: agentCustomId });
+  return getAgent({ id: agentCustomId });
 };
 
 /**
- * Middleware factory that creates middleware to check agent access permissions from request body.
- * This middleware is specifically designed for chat routes where the agent_id comes from req.body
- * instead of route parameters.
+ * Creates a `canAccessResource` middleware for the given agent ID
+ * and chains to the provided continuation on success.
+ *
+ * @param {string} agentId - The agent's custom string ID (e.g., "agent_abc123")
+ * @param {number} requiredPermission - Permission bit(s) required
+ * @param {import('express').Request} req
+ * @param {import('express').Response} res - Written on deny; continuation called on allow
+ * @param {Function} continuation - Called when the permission check passes
+ * @returns {Promise<void>}
+ */
+const checkAgentResourceAccess = (agentId, requiredPermission, req, res, continuation) => {
+  const middleware = canAccessResource({
+    resourceType: ResourceType.AGENT,
+    requiredPermission,
+    resourceIdParam: 'agent_id',
+    idResolver: () => resolveAgentIdFromBody(agentId),
+  });
+
+  const tempReq = {
+    ...req,
+    params: { ...req.params, agent_id: agentId },
+  };
+
+  return middleware(tempReq, res, continuation);
+};
+
+/**
+ * Middleware factory that validates MULTI_CONVO:USE role permission and, when
+ * addedConvo.agent_id is a non-ephemeral agent, the same resource-level permission
+ * required for the primary agent (`requiredPermission`). Caches the resolved agent
+ * document on `req.resolvedAddedAgent` to avoid a duplicate DB fetch in `loadAddedAgent`.
+ *
+ * @param {number} requiredPermission - Permission bit(s) to check on the added agent resource
+ * @returns {(req: import('express').Request, res: import('express').Response, next: Function) => Promise<void>}
+ */
+const checkAddedConvoAccess = (requiredPermission) => async (req, res, next) => {
+  const addedConvo = req.body?.addedConvo;
+  if (!addedConvo || typeof addedConvo !== 'object' || Array.isArray(addedConvo)) {
+    return next();
+  }
+
+  try {
+    if (!req.user?.role) {
+      return res.status(403).json({
+        error: 'Forbidden',
+        message: 'Insufficient permissions for multi-conversation',
+      });
+    }
+
+    if (req.user.role !== SystemRoles.ADMIN) {
+      const role = await getRoleByName(req.user.role);
+      const hasMultiConvo = role?.permissions?.[PermissionTypes.MULTI_CONVO]?.[Permissions.USE];
+      if (!hasMultiConvo) {
+        return res.status(403).json({
+          error: 'Forbidden',
+          message: 'Multi-conversation feature is not enabled',
+        });
+      }
+    }
+
+    const addedAgentId = addedConvo.agent_id;
+    if (!addedAgentId || typeof addedAgentId !== 'string' || isEphemeralAgentId(addedAgentId)) {
+      return next();
+    }
+
+    if (req.user.role === SystemRoles.ADMIN) {
+      return next();
+    }
+
+    const agent = await resolveAgentIdFromBody(addedAgentId);
+    if (!agent) {
+      return res.status(404).json({
+        error: 'Not Found',
+        message: `${ResourceType.AGENT} not found`,
+      });
+    }
+
+    const hasPermission = await checkPermission({
+      userId: req.user.id,
+      role: req.user.role,
+      resourceType: ResourceType.AGENT,
+      resourceId: agent._id,
+      requiredPermission,
+    });
+
+    if (!hasPermission) {
+      return res.status(403).json({
+        error: 'Forbidden',
+        message: `Insufficient permissions to access this ${ResourceType.AGENT}`,
+      });
+    }
+
+    req.resolvedAddedAgent = agent;
+    return next();
+  } catch (error) {
+    logger.error('Failed to validate addedConvo access permissions', error);
+    return res.status(500).json({
+      error: 'Internal Server Error',
+      message: 'Failed to validate addedConvo access permissions',
+    });
+  }
+};
+
+/**
+ * Middleware factory that checks agent access permissions from request body.
+ * Validates both the primary agent_id and, when present, addedConvo.agent_id
+ * (which also requires MULTI_CONVO:USE role permission).
  *
  * @param {Object} options - Configuration options
  * @param {number} options.requiredPermission - The permission bit required (1=view, 2=edit, 4=delete, 8=share)
  * @returns {Function} Express middleware function
  *
  * @example
- * // Basic usage for agent chat (requires VIEW permission)
  * router.post('/chat',
  *   canAccessAgentFromBody({ requiredPermission: PermissionBits.VIEW }),
  *   buildEndpointOption,
@@ -46,11 +148,12 @@ const resolveAgentIdFromBody = async (agentCustomId) => {
 const canAccessAgentFromBody = (options) => {
   const { requiredPermission } = options;
 
-  // Validate required options
   if (!requiredPermission || typeof requiredPermission !== 'number') {
     throw new Error('canAccessAgentFromBody: requiredPermission is required and must be a number');
   }
 
+  const addedConvoMiddleware = checkAddedConvoAccess(requiredPermission);
+
   return async (req, res, next) => {
     try {
       const { endpoint, agent_id } = req.body;
@@ -67,28 +170,13 @@ const canAccessAgentFromBody = (options) => {
         });
       }
 
-      // Skip permission checks for ephemeral agents
-      // Real agent IDs always start with "agent_", so anything else is ephemeral
+      const afterPrimaryCheck = () => addedConvoMiddleware(req, res, next);
+
       if (isEphemeralAgentId(agentId)) {
-        return next();
+        return afterPrimaryCheck();
       }
 
-      const agentAccessMiddleware = canAccessResource({
-        resourceType: ResourceType.AGENT,
-        requiredPermission,
-        resourceIdParam: 'agent_id', // This will be ignored since we use custom resolver
-        idResolver: () => resolveAgentIdFromBody(agentId),
-      });
-
-      const tempReq = {
-        ...req,
-        params: {
-          ...req.params,
-          agent_id: agentId,
-        },
-      };
-
-      return agentAccessMiddleware(tempReq, res, next);
+      return checkAgentResourceAccess(agentId, requiredPermission, req, res, afterPrimaryCheck);
     } catch (error) {
       logger.error('Failed to validate agent access permissions', error);
       return res.status(500).json({

api/server/middleware/accessResources/canAccessAgentFromBody.spec.js

@@ -0,0 +1,509 @@
+const mongoose = require('mongoose');
+const {
+  ResourceType,
+  SystemRoles,
+  PrincipalType,
+  PrincipalModel,
+} = require('librechat-data-provider');
+const { MongoMemoryServer } = require('mongodb-memory-server');
+const { canAccessAgentFromBody } = require('./canAccessAgentFromBody');
+const { User, Role, AclEntry } = require('~/db/models');
+const { createAgent } = require('~/models/Agent');
+
+describe('canAccessAgentFromBody middleware', () => {
+  let mongoServer;
+  let req, res, next;
+  let testUser, otherUser;
+
+  beforeAll(async () => {
+    mongoServer = await MongoMemoryServer.create();
+    await mongoose.connect(mongoServer.getUri());
+  });
+
+  afterAll(async () => {
+    await mongoose.disconnect();
+    await mongoServer.stop();
+  });
+
+  beforeEach(async () => {
+    await mongoose.connection.dropDatabase();
+
+    await Role.create({
+      name: 'test-role',
+      permissions: {
+        AGENTS: { USE: true, CREATE: true, SHARE: true },
+        MULTI_CONVO: { USE: true },
+      },
+    });
+
+    await Role.create({
+      name: 'no-multi-convo',
+      permissions: {
+        AGENTS: { USE: true, CREATE: true, SHARE: true },
+        MULTI_CONVO: { USE: false },
+      },
+    });
+
+    await Role.create({
+      name: SystemRoles.ADMIN,
+      permissions: {
+        AGENTS: { USE: true, CREATE: true, SHARE: true },
+        MULTI_CONVO: { USE: true },
+      },
+    });
+
+    testUser = await User.create({
+      email: 'test@example.com',
+      name: 'Test User',
+      username: 'testuser',
+      role: 'test-role',
+    });
+
+    otherUser = await User.create({
+      email: 'other@example.com',
+      name: 'Other User',
+      username: 'otheruser',
+      role: 'test-role',
+    });
+
+    req = {
+      user: { id: testUser._id, role: testUser.role },
+      params: {},
+      body: {
+        endpoint: 'agents',
+        agent_id: 'ephemeral_primary',
+      },
+    };
+    res = {
+      status: jest.fn().mockReturnThis(),
+      json: jest.fn(),
+    };
+    next = jest.fn();
+
+    jest.clearAllMocks();
+  });
+
+  describe('middleware factory', () => {
+    test('throws if requiredPermission is missing', () => {
+      expect(() => canAccessAgentFromBody({})).toThrow(
+        'canAccessAgentFromBody: requiredPermission is required and must be a number',
+      );
+    });
+
+    test('throws if requiredPermission is not a number', () => {
+      expect(() => canAccessAgentFromBody({ requiredPermission: '1' })).toThrow(
+        'canAccessAgentFromBody: requiredPermission is required and must be a number',
+      );
+    });
+
+    test('returns a middleware function', () => {
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      expect(typeof middleware).toBe('function');
+      expect(middleware.length).toBe(3);
+    });
+  });
+
+  describe('primary agent checks', () => {
+    test('returns 400 when agent_id is missing on agents endpoint', async () => {
+      req.body.agent_id = undefined;
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).not.toHaveBeenCalled();
+      expect(res.status).toHaveBeenCalledWith(400);
+    });
+
+    test('proceeds for ephemeral primary agent without addedConvo', async () => {
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).toHaveBeenCalled();
+      expect(res.status).not.toHaveBeenCalled();
+    });
+
+    test('proceeds for non-agents endpoint (ephemeral fallback)', async () => {
+      req.body.endpoint = 'openAI';
+      req.body.agent_id = undefined;
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).toHaveBeenCalled();
+    });
+  });
+
+  describe('addedConvo — absent or invalid shape', () => {
+    test('calls next when addedConvo is absent', async () => {
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).toHaveBeenCalled();
+    });
+
+    test('calls next when addedConvo is a string', async () => {
+      req.body.addedConvo = 'not-an-object';
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).toHaveBeenCalled();
+    });
+
+    test('calls next when addedConvo is an array', async () => {
+      req.body.addedConvo = [{ agent_id: 'agent_something' }];
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).toHaveBeenCalled();
+    });
+  });
+
+  describe('addedConvo — MULTI_CONVO permission gate', () => {
+    test('returns 403 when user lacks MULTI_CONVO:USE', async () => {
+      req.user.role = 'no-multi-convo';
+      req.body.addedConvo = { agent_id: 'agent_x', endpoint: 'agents', model: 'gpt-4' };
+
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).not.toHaveBeenCalled();
+      expect(res.status).toHaveBeenCalledWith(403);
+      expect(res.json).toHaveBeenCalledWith(
+        expect.objectContaining({ message: 'Multi-conversation feature is not enabled' }),
+      );
+    });
+
+    test('returns 403 when user.role is missing', async () => {
+      req.user = { id: testUser._id };
+      req.body.addedConvo = { agent_id: 'agent_x', endpoint: 'agents', model: 'gpt-4' };
+
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).not.toHaveBeenCalled();
+      expect(res.status).toHaveBeenCalledWith(403);
+    });
+
+    test('ADMIN bypasses MULTI_CONVO check', async () => {
+      req.user.role = SystemRoles.ADMIN;
+      req.body.addedConvo = { agent_id: 'ephemeral_x', endpoint: 'agents', model: 'gpt-4' };
+
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).toHaveBeenCalled();
+      expect(res.status).not.toHaveBeenCalled();
+    });
+  });
+
+  describe('addedConvo — agent_id shape validation', () => {
+    test('calls next when agent_id is ephemeral', async () => {
+      req.body.addedConvo = { agent_id: 'ephemeral_xyz', endpoint: 'agents', model: 'gpt-4' };
+
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).toHaveBeenCalled();
+    });
+
+    test('calls next when agent_id is absent', async () => {
+      req.body.addedConvo = { endpoint: 'agents', model: 'gpt-4' };
+
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).toHaveBeenCalled();
+    });
+
+    test('calls next when agent_id is not a string (object injection)', async () => {
+      req.body.addedConvo = { agent_id: { $gt: '' }, endpoint: 'agents', model: 'gpt-4' };
+
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).toHaveBeenCalled();
+    });
+  });
+
+  describe('addedConvo — agent resource ACL (IDOR prevention)', () => {
+    let addedAgent;
+
+    beforeEach(async () => {
+      addedAgent = await createAgent({
+        id: `agent_added_${Date.now()}`,
+        name: 'Private Agent',
+        provider: 'openai',
+        model: 'gpt-4',
+        author: otherUser._id,
+      });
+
+      await AclEntry.create({
+        principalType: PrincipalType.USER,
+        principalId: otherUser._id,
+        principalModel: PrincipalModel.USER,
+        resourceType: ResourceType.AGENT,
+        resourceId: addedAgent._id,
+        permBits: 15,
+        grantedBy: otherUser._id,
+      });
+    });
+
+    test('returns 403 when requester has no ACL for the added agent', async () => {
+      req.body.addedConvo = { agent_id: addedAgent.id, endpoint: 'agents', model: 'gpt-4' };
+
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).not.toHaveBeenCalled();
+      expect(res.status).toHaveBeenCalledWith(403);
+      expect(res.json).toHaveBeenCalledWith(
+        expect.objectContaining({
+          message: 'Insufficient permissions to access this agent',
+        }),
+      );
+    });
+
+    test('returns 404 when added agent does not exist', async () => {
+      req.body.addedConvo = {
+        agent_id: 'agent_nonexistent_999',
+        endpoint: 'agents',
+        model: 'gpt-4',
+      };
+
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).not.toHaveBeenCalled();
+      expect(res.status).toHaveBeenCalledWith(404);
+    });
+
+    test('proceeds when requester has ACL for the added agent', async () => {
+      await AclEntry.create({
+        principalType: PrincipalType.USER,
+        principalId: testUser._id,
+        principalModel: PrincipalModel.USER,
+        resourceType: ResourceType.AGENT,
+        resourceId: addedAgent._id,
+        permBits: 1,
+        grantedBy: otherUser._id,
+      });
+
+      req.body.addedConvo = { agent_id: addedAgent.id, endpoint: 'agents', model: 'gpt-4' };
+
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).toHaveBeenCalled();
+      expect(res.status).not.toHaveBeenCalled();
+    });
+
+    test('denies when ACL permission bits are insufficient', async () => {
+      await AclEntry.create({
+        principalType: PrincipalType.USER,
+        principalId: testUser._id,
+        principalModel: PrincipalModel.USER,
+        resourceType: ResourceType.AGENT,
+        resourceId: addedAgent._id,
+        permBits: 1,
+        grantedBy: otherUser._id,
+      });
+
+      req.body.addedConvo = { agent_id: addedAgent.id, endpoint: 'agents', model: 'gpt-4' };
+
+      const middleware = canAccessAgentFromBody({ requiredPermission: 2 });
+      await middleware(req, res, next);
+
+      expect(next).not.toHaveBeenCalled();
+      expect(res.status).toHaveBeenCalledWith(403);
+    });
+
+    test('caches resolved agent on req.resolvedAddedAgent', async () => {
+      await AclEntry.create({
+        principalType: PrincipalType.USER,
+        principalId: testUser._id,
+        principalModel: PrincipalModel.USER,
+        resourceType: ResourceType.AGENT,
+        resourceId: addedAgent._id,
+        permBits: 1,
+        grantedBy: otherUser._id,
+      });
+
+      req.body.addedConvo = { agent_id: addedAgent.id, endpoint: 'agents', model: 'gpt-4' };
+
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).toHaveBeenCalled();
+      expect(req.resolvedAddedAgent).toBeDefined();
+      expect(req.resolvedAddedAgent._id.toString()).toBe(addedAgent._id.toString());
+    });
+
+    test('ADMIN bypasses agent resource ACL for addedConvo', async () => {
+      req.user.role = SystemRoles.ADMIN;
+      req.body.addedConvo = { agent_id: addedAgent.id, endpoint: 'agents', model: 'gpt-4' };
+
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).toHaveBeenCalled();
+      expect(res.status).not.toHaveBeenCalled();
+      expect(req.resolvedAddedAgent).toBeUndefined();
+    });
+  });
+
+  describe('end-to-end: primary real agent + addedConvo real agent', () => {
+    let primaryAgent, addedAgent;
+
+    beforeEach(async () => {
+      primaryAgent = await createAgent({
+        id: `agent_primary_${Date.now()}`,
+        name: 'Primary Agent',
+        provider: 'openai',
+        model: 'gpt-4',
+        author: testUser._id,
+      });
+
+      await AclEntry.create({
+        principalType: PrincipalType.USER,
+        principalId: testUser._id,
+        principalModel: PrincipalModel.USER,
+        resourceType: ResourceType.AGENT,
+        resourceId: primaryAgent._id,
+        permBits: 15,
+        grantedBy: testUser._id,
+      });
+
+      addedAgent = await createAgent({
+        id: `agent_added_${Date.now()}`,
+        name: 'Added Agent',
+        provider: 'openai',
+        model: 'gpt-4',
+        author: otherUser._id,
+      });
+
+      await AclEntry.create({
+        principalType: PrincipalType.USER,
+        principalId: otherUser._id,
+        principalModel: PrincipalModel.USER,
+        resourceType: ResourceType.AGENT,
+        resourceId: addedAgent._id,
+        permBits: 15,
+        grantedBy: otherUser._id,
+      });
+
+      req.body.agent_id = primaryAgent.id;
+    });
+
+    test('both checks pass when user has ACL for both agents', async () => {
+      await AclEntry.create({
+        principalType: PrincipalType.USER,
+        principalId: testUser._id,
+        principalModel: PrincipalModel.USER,
+        resourceType: ResourceType.AGENT,
+        resourceId: addedAgent._id,
+        permBits: 1,
+        grantedBy: otherUser._id,
+      });
+
+      req.body.addedConvo = { agent_id: addedAgent.id, endpoint: 'agents', model: 'gpt-4' };
+
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).toHaveBeenCalled();
+      expect(res.status).not.toHaveBeenCalled();
+      expect(req.resolvedAddedAgent).toBeDefined();
+    });
+
+    test('primary passes but addedConvo denied → 403', async () => {
+      req.body.addedConvo = { agent_id: addedAgent.id, endpoint: 'agents', model: 'gpt-4' };
+
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).not.toHaveBeenCalled();
+      expect(res.status).toHaveBeenCalledWith(403);
+    });
+
+    test('primary denied → 403 without reaching addedConvo check', async () => {
+      const foreignAgent = await createAgent({
+        id: `agent_foreign_${Date.now()}`,
+        name: 'Foreign Agent',
+        provider: 'openai',
+        model: 'gpt-4',
+        author: otherUser._id,
+      });
+
+      await AclEntry.create({
+        principalType: PrincipalType.USER,
+        principalId: otherUser._id,
+        principalModel: PrincipalModel.USER,
+        resourceType: ResourceType.AGENT,
+        resourceId: foreignAgent._id,
+        permBits: 15,
+        grantedBy: otherUser._id,
+      });
+
+      req.body.agent_id = foreignAgent.id;
+      req.body.addedConvo = { agent_id: addedAgent.id, endpoint: 'agents', model: 'gpt-4' };
+
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).not.toHaveBeenCalled();
+      expect(res.status).toHaveBeenCalledWith(403);
+    });
+  });
+
+  describe('ephemeral primary + real addedConvo agent', () => {
+    let addedAgent;
+
+    beforeEach(async () => {
+      addedAgent = await createAgent({
+        id: `agent_added_${Date.now()}`,
+        name: 'Added Agent',
+        provider: 'openai',
+        model: 'gpt-4',
+        author: otherUser._id,
+      });
+
+      await AclEntry.create({
+        principalType: PrincipalType.USER,
+        principalId: otherUser._id,
+        principalModel: PrincipalModel.USER,
+        resourceType: ResourceType.AGENT,
+        resourceId: addedAgent._id,
+        permBits: 15,
+        grantedBy: otherUser._id,
+      });
+    });
+
+    test('runs full addedConvo ACL check even when primary is ephemeral', async () => {
+      req.body.addedConvo = { agent_id: addedAgent.id, endpoint: 'agents', model: 'gpt-4' };
+
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).not.toHaveBeenCalled();
+      expect(res.status).toHaveBeenCalledWith(403);
+    });
+
+    test('proceeds when user has ACL for added agent (ephemeral primary)', async () => {
+      await AclEntry.create({
+        principalType: PrincipalType.USER,
+        principalId: testUser._id,
+        principalModel: PrincipalModel.USER,
+        resourceType: ResourceType.AGENT,
+        resourceId: addedAgent._id,
+        permBits: 1,
+        grantedBy: otherUser._id,
+      });
+
+      req.body.addedConvo = { agent_id: addedAgent.id, endpoint: 'agents', model: 'gpt-4' };
+
+      const middleware = canAccessAgentFromBody({ requiredPermission: 1 });
+      await middleware(req, res, next);
+
+      expect(next).toHaveBeenCalled();
+      expect(res.status).not.toHaveBeenCalled();
+    });
+  });
+});