fix: enforce Tess session ownership scope (#715)

apps/gateway/src/agent/__tests__/agent-service-ownership.test.ts

@@ -0,0 +1,142 @@
+import { ForbiddenException } from '@nestjs/common';
+import { describe, expect, it, vi } from 'vitest';
+import { AgentService, type AgentSession } from '../agent.service.js';
+import type { ActorTenantScope } from '../../auth/session-scope.js';
+
+const CONVERSATION_ID = '22222222-2222-4222-8222-222222222222';
+const OWNER_SCOPE: ActorTenantScope = { userId: 'owner-user', tenantId: 'owner-tenant' };
+const FOREIGN_SCOPE: ActorTenantScope = { userId: 'foreign-user', tenantId: 'foreign-tenant' };
+
+type AgentServiceInternals = {
+  sessions: Map<string, AgentSession>;
+  creating: Map<string, Promise<AgentSession>>;
+};
+
+function makeService(): AgentService {
+  return new AgentService(
+    {} as never,
+    {} as never,
+    {} as never,
+    { available: false } as never,
+    {} as never,
+    {} as never,
+    {} as never,
+    null,
+    null,
+    { collect: vi.fn().mockResolvedValue(undefined) } as never,
+  );
+}
+
+function internals(service: AgentService): AgentServiceInternals {
+  return service as unknown as AgentServiceInternals;
+}
+
+function makeSession(scope: ActorTenantScope = OWNER_SCOPE): AgentSession {
+  return {
+    id: CONVERSATION_ID,
+    provider: 'test-provider',
+    modelId: 'test-model',
+    piSession: {
+      thinkingLevel: 'off',
+      getAvailableThinkingLevels: vi.fn().mockReturnValue(['off', 'low', 'high']),
+      setThinkingLevel: vi.fn(),
+      abort: vi.fn().mockResolvedValue(undefined),
+      prompt: vi.fn().mockResolvedValue(undefined),
+      dispose: vi.fn(),
+      getSessionStats: vi.fn(),
+      getContextUsage: vi.fn(),
+    } as unknown as AgentSession['piSession'],
+    listeners: new Set(),
+    unsubscribe: vi.fn(),
+    createdAt: Date.now(),
+    promptCount: 0,
+    channels: new Set(),
+    skillPromptAdditions: [],
+    sandboxDir: '/tmp/tess-session-ownership-test',
+    allowedTools: null,
+    userId: scope.userId,
+    tenantId: scope.tenantId,
+    metrics: {
+      tokens: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
+      modelSwitches: 0,
+      messageCount: 0,
+      lastActivityAt: new Date('2026-07-12T00:00:00Z').toISOString(),
+    },
+  };
+}
+
+describe('AgentService owner/tenant scope enforcement', () => {
+  it('allows owner-scoped operations and rejects foreign scopes for seeded sessions', async () => {
+    const service = makeService();
+    const session = makeSession();
+    internals(service).sessions.set(CONVERSATION_ID, session);
+
+    expect(service.getSession(CONVERSATION_ID, OWNER_SCOPE)).toBe(session);
+    expect(service.getSession(CONVERSATION_ID, FOREIGN_SCOPE)).toBeUndefined();
+    expect(service.getSessionInfo(CONVERSATION_ID, FOREIGN_SCOPE)).toBeUndefined();
+    expect(service.listSessions(OWNER_SCOPE)).toHaveLength(1);
+    expect(service.listSessions(FOREIGN_SCOPE)).toEqual([]);
+
+    service.addChannel(CONVERSATION_ID, 'websocket:owner', OWNER_SCOPE);
+    expect(session.channels.has('websocket:owner')).toBe(true);
+    expect(() => service.addChannel(CONVERSATION_ID, 'websocket:foreign', FOREIGN_SCOPE)).toThrow(
+      ForbiddenException,
+    );
+    expect(() => service.removeChannel(CONVERSATION_ID, 'websocket:owner', FOREIGN_SCOPE)).toThrow(
+      ForbiddenException,
+    );
+
+    expect(() =>
+      service.updateSessionModel(CONVERSATION_ID, 'foreign-model', FOREIGN_SCOPE),
+    ).toThrow(ForbiddenException);
+    service.updateSessionModel(CONVERSATION_ID, 'owner-model', OWNER_SCOPE);
+    expect(session.modelId).toBe('owner-model');
+
+    expect(() =>
+      service.applyAgentConfig(CONVERSATION_ID, 'agent-foreign', 'Foreign Agent', FOREIGN_SCOPE),
+    ).toThrow(ForbiddenException);
+    service.applyAgentConfig(CONVERSATION_ID, 'agent-owner', 'Owner Agent', OWNER_SCOPE);
+    expect(session.agentConfigId).toBe('agent-owner');
+
+    expect(() => service.onEvent(CONVERSATION_ID, vi.fn(), FOREIGN_SCOPE)).toThrow(
+      ForbiddenException,
+    );
+    const cleanup = service.onEvent(CONVERSATION_ID, vi.fn(), OWNER_SCOPE);
+    cleanup();
+
+    await expect(
+      service.prompt(CONVERSATION_ID, 'foreign prompt', FOREIGN_SCOPE),
+    ).rejects.toBeInstanceOf(ForbiddenException);
+    await service.prompt(CONVERSATION_ID, 'owner prompt', OWNER_SCOPE);
+    expect(session.piSession.prompt).toHaveBeenCalledWith('owner prompt');
+
+    await expect(service.destroySession(CONVERSATION_ID, FOREIGN_SCOPE)).rejects.toBeInstanceOf(
+      ForbiddenException,
+    );
+    expect(internals(service).sessions.has(CONVERSATION_ID)).toBe(true);
+
+    await service.destroySession(CONVERSATION_ID, OWNER_SCOPE);
+    expect(session.piSession.dispose).toHaveBeenCalled();
+    expect(internals(service).sessions.has(CONVERSATION_ID)).toBe(false);
+  });
+
+  it('checks owner/tenant scope before returning an in-flight session creation', async () => {
+    const service = makeService();
+    const session = makeSession();
+    internals(service).creating.set(CONVERSATION_ID, Promise.resolve(session));
+
+    await expect(
+      service.createSession(CONVERSATION_ID, {
+        userId: FOREIGN_SCOPE.userId,
+        tenantId: FOREIGN_SCOPE.tenantId,
+      }),
+    ).rejects.toBeInstanceOf(ForbiddenException);
+
+    await expect(
+      service.createSession(CONVERSATION_ID, {
+        userId: OWNER_SCOPE.userId,
+        tenantId: OWNER_SCOPE.tenantId,
+      }),
+    ).resolves.toBe(session);
+  });
+});

apps/gateway/src/agent/__tests__/session-ownership.test.ts

@@ -0,0 +1,262 @@
+import { readFileSync } from 'node:fs';
+import { resolve } from 'node:path';
+import { ForbiddenException, NotFoundException } from '@nestjs/common';
+import { describe, expect, it, vi } from 'vitest';
+
+vi.mock('../agent.service.js', () => ({ AgentService: class AgentService {} }));
+vi.mock('../../commands/command-executor.service.js', () => ({
+  CommandExecutorService: class CommandExecutorService {},
+}));
+vi.mock('../routing/routing-engine.service.js', () => ({
+  RoutingEngineService: class RoutingEngineService {},
+}));
+
+import { SessionsController } from '../sessions.controller.js';
+import { ChatController } from '../../chat/chat.controller.js';
+import { ChatGateway } from '../../chat/chat.gateway.js';
+import type { AgentSession } from '../agent.service.js';
+import type { SessionInfoDto } from '../session.dto.js';
+
+const USER_A = { id: 'user-a', tenantId: 'tenant-a' };
+const USER_B = { id: 'user-b', tenantId: 'tenant-b' };
+const CONVERSATION_ID = '11111111-1111-4111-8111-111111111111';
+
+function makeSessionInfo(overrides?: Partial<SessionInfoDto>): SessionInfoDto {
+  return {
+    id: CONVERSATION_ID,
+    provider: 'test-provider',
+    modelId: 'test-model',
+    createdAt: new Date('2026-07-12T00:00:00Z').toISOString(),
+    promptCount: 0,
+    channels: [],
+    durationMs: 0,
+    metrics: {
+      tokens: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
+      modelSwitches: 0,
+      messageCount: 0,
+      lastActivityAt: new Date('2026-07-12T00:00:00Z').toISOString(),
+    },
+    ...overrides,
+  };
+}
+
+function makeAgentSession(owner = USER_A): AgentSession {
+  return {
+    id: CONVERSATION_ID,
+    provider: 'test-provider',
+    modelId: 'test-model',
+    piSession: {
+      thinkingLevel: 'off',
+      getAvailableThinkingLevels: vi.fn().mockReturnValue(['off', 'low', 'high']),
+      setThinkingLevel: vi.fn(),
+      abort: vi.fn().mockResolvedValue(undefined),
+      prompt: vi.fn().mockResolvedValue(undefined),
+      dispose: vi.fn(),
+      getSessionStats: vi.fn(),
+      getContextUsage: vi.fn(),
+    } as unknown as AgentSession['piSession'],
+    listeners: new Set(),
+    unsubscribe: vi.fn(),
+    createdAt: Date.now(),
+    promptCount: 0,
+    channels: new Set(),
+    skillPromptAdditions: [],
+    sandboxDir: '/tmp',
+    allowedTools: null,
+    userId: owner.id,
+    tenantId: owner.tenantId,
+    metrics: {
+      tokens: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
+      modelSwitches: 0,
+      messageCount: 0,
+      lastActivityAt: new Date('2026-07-12T00:00:00Z').toISOString(),
+    },
+  };
+}
+
+function makeScopedAgentService() {
+  const foreign = makeAgentSession(USER_A);
+  return {
+    listSessions: vi.fn((scope?: { userId: string; tenantId?: string }) =>
+      scope?.userId === USER_B.id ? [] : [makeSessionInfo({ id: foreign.id })],
+    ),
+    getSessionInfo: vi.fn((_id: string, scope?: { userId: string; tenantId?: string }) =>
+      scope?.userId === USER_B.id ? undefined : makeSessionInfo({ id: foreign.id }),
+    ),
+    destroySession: vi.fn(),
+    getSession: vi.fn((_id: string, scope?: { userId: string; tenantId?: string }) =>
+      scope?.userId === USER_B.id ? undefined : foreign,
+    ),
+    createSession: vi.fn().mockRejectedValue(new ForbiddenException('Session scope mismatch')),
+    onEvent: vi.fn(() => vi.fn()),
+    addChannel: vi.fn(),
+    removeChannel: vi.fn(),
+    recordMessage: vi.fn(),
+    prompt: vi.fn().mockResolvedValue(undefined),
+  };
+}
+
+describe('TESS-M1-SEC-002 AgentService ownership boundary', () => {
+  it('requires explicit owner+tenant scope on protected session operations', () => {
+    const source = readFileSync(resolve('src/agent/agent.service.ts'), 'utf8');
+
+    expect(source).toContain('getSession(sessionId: string, scope: ActorTenantScope)');
+    expect(source).toContain('listSessions(scope: ActorTenantScope)');
+    expect(source).toContain('getSessionInfo(sessionId: string, scope: ActorTenantScope)');
+    expect(source).toContain(
+      'addChannel(sessionId: string, channel: string, scope: ActorTenantScope)',
+    );
+    expect(source).toContain(
+      'removeChannel(sessionId: string, channel: string, scope: ActorTenantScope)',
+    );
+    expect(source).toContain(
+      'async prompt(sessionId: string, message: string, scope: ActorTenantScope)',
+    );
+    expect(source).toContain('scope: ActorTenantScope,');
+    expect(source).toContain('async destroySession(sessionId: string, scope: ActorTenantScope)');
+    expect(source).not.toContain('scope?: ActorTenantScope');
+  });
+});
+
+describe('TESS-M1-SEC-002 REST session ownership and tenant binding', () => {
+  it('lists only sessions owned by the authenticated owner+tenant scope', () => {
+    const agentService = makeScopedAgentService();
+    const controller = new SessionsController(agentService as never);
+
+    expect(controller.list(USER_B)).toEqual({ sessions: [], total: 0 });
+    expect(agentService.listSessions).toHaveBeenCalledWith({
+      userId: USER_B.id,
+      tenantId: USER_B.tenantId,
+    });
+  });
+
+  it('does not reveal another owner/tenant session by guessed id', () => {
+    const agentService = makeScopedAgentService();
+    const controller = new SessionsController(agentService as never);
+
+    expect(() => controller.findOne(CONVERSATION_ID, USER_B)).toThrow(NotFoundException);
+    expect(agentService.getSessionInfo).toHaveBeenCalledWith(CONVERSATION_ID, {
+      userId: USER_B.id,
+      tenantId: USER_B.tenantId,
+    });
+  });
+
+  it('does not terminate another owner/tenant session by guessed id', async () => {
+    const agentService = makeScopedAgentService();
+    const controller = new SessionsController(agentService as never);
+
+    await expect(controller.destroy(CONVERSATION_ID, USER_B)).rejects.toBeInstanceOf(
+      NotFoundException,
+    );
+    expect(agentService.destroySession).not.toHaveBeenCalled();
+  });
+});
+
+describe('TESS-M1-SEC-002 REST chat send ownership and tenant binding', () => {
+  it('does not send a prompt into another owner/tenant session by guessed conversationId', async () => {
+    const agentService = makeScopedAgentService();
+    const controller = new ChatController(agentService as never);
+
+    await expect(
+      controller.chat({ conversationId: CONVERSATION_ID, content: 'take over' }, USER_B),
+    ).rejects.toMatchObject({ status: 404 });
+
+    expect(agentService.getSession).toHaveBeenCalledWith(CONVERSATION_ID, {
+      userId: USER_B.id,
+      tenantId: USER_B.tenantId,
+    });
+    expect(agentService.prompt).not.toHaveBeenCalled();
+  });
+});
+
+describe('TESS-M1-SEC-002 WebSocket session ownership and tenant binding', () => {
+  function makeGateway(agentService = makeScopedAgentService()) {
+    const brain = {
+      conversations: {
+        findById: vi.fn().mockResolvedValue(undefined),
+        create: vi.fn().mockResolvedValue(undefined),
+        update: vi.fn().mockResolvedValue(undefined),
+        findMessages: vi.fn().mockResolvedValue([]),
+        addMessage: vi.fn().mockResolvedValue(undefined),
+      },
+    };
+    const commandRegistry = { getManifest: vi.fn().mockReturnValue([]) };
+    const commandExecutor = { execute: vi.fn() };
+    const routingEngine = {
+      resolve: vi.fn().mockResolvedValue({ provider: 'test', model: 'test-model' }),
+    };
+    const gateway = new ChatGateway(
+      agentService as never,
+      {} as never,
+      brain as never,
+      commandRegistry as never,
+      commandExecutor as never,
+      routingEngine as never,
+    );
+    return { gateway, agentService };
+  }
+
+  function makeSocket() {
+    return {
+      id: 'socket-b',
+      connected: true,
+      data: { user: USER_B, session: { id: 'auth-session-b', userId: USER_B.id } },
+      emit: vi.fn(),
+      disconnect: vi.fn(),
+    };
+  }
+
+  it('does not attach or send to another owner/tenant session by guessed conversationId', async () => {
+    const { gateway, agentService } = makeGateway();
+    const socket = makeSocket();
+
+    await gateway.handleMessage(socket as never, {
+      conversationId: CONVERSATION_ID,
+      content: 'attach to foreign session',
+    });
+
+    expect(agentService.getSession).toHaveBeenCalledWith(CONVERSATION_ID, {
+      userId: USER_B.id,
+      tenantId: USER_B.tenantId,
+    });
+    expect(agentService.onEvent).not.toHaveBeenCalled();
+    expect(agentService.addChannel).not.toHaveBeenCalled();
+    expect(agentService.prompt).not.toHaveBeenCalled();
+    expect(socket.emit).toHaveBeenCalledWith(
+      'error',
+      expect.objectContaining({ conversationId: CONVERSATION_ID }),
+    );
+  });
+
+  it('does not mutate thinking level on another owner/tenant session', () => {
+    const { gateway, agentService } = makeGateway();
+    const socket = makeSocket();
+
+    gateway.handleSetThinking(socket as never, { conversationId: CONVERSATION_ID, level: 'high' });
+
+    expect(agentService.getSession).toHaveBeenCalledWith(CONVERSATION_ID, {
+      userId: USER_B.id,
+      tenantId: USER_B.tenantId,
+    });
+    expect(socket.emit).toHaveBeenCalledWith(
+      'error',
+      expect.objectContaining({ conversationId: CONVERSATION_ID }),
+    );
+  });
+
+  it('does not terminate another owner/tenant session over WebSocket abort', async () => {
+    const { gateway, agentService } = makeGateway();
+    const socket = makeSocket();
+
+    await gateway.handleAbort(socket as never, { conversationId: CONVERSATION_ID });
+
+    expect(agentService.getSession).toHaveBeenCalledWith(CONVERSATION_ID, {
+      userId: USER_B.id,
+      tenantId: USER_B.tenantId,
+    });
+    expect(socket.emit).toHaveBeenCalledWith(
+      'error',
+      expect.objectContaining({ conversationId: CONVERSATION_ID }),
+    );
+  });
+});

apps/gateway/src/agent/agent.service.ts

@@ -1,4 +1,11 @@
-import { Inject, Injectable, Logger, Optional, type OnModuleDestroy } from '@nestjs/common';
+import {
+  ForbiddenException,
+  Inject,
+  Injectable,
+  Logger,
+  Optional,
+  type OnModuleDestroy,
+} from '@nestjs/common';
 import {
   createAgentSession,
   DefaultResourceLoader,
@@ -28,6 +35,7 @@ import type { SessionInfoDto, SessionMetrics } from './session.dto.js';
 import { SystemOverrideService } from '../preferences/system-override.service.js';
 import { PreferencesService } from '../preferences/preferences.service.js';
 import { SessionGCService } from '../gc/session-gc.service.js';
+import type { ActorTenantScope } from '../auth/session-scope.js';
 
 /** A single message from DB conversation history, used for context injection. */
 export interface ConversationHistoryMessage {
@@ -68,6 +76,8 @@ export interface AgentSessionOptions {
   agentConfigId?: string;
   /** ID of the user who owns this session. Used for preferences and system override lookups. */
   userId?: string;
+  /** Server-derived tenant scope that owns this session. Falls back to userId for solo users. */
+  tenantId?: string;
   /**
    * Prior conversation messages to inject as context when resuming a session.
    * These messages are formatted and prepended to the system prompt so the
@@ -94,6 +104,8 @@ export interface AgentSession {
   allowedTools: string[] | null;
   /** User ID that owns this session, used for preference lookups. */
   userId?: string;
+  /** Server-derived tenant scope that owns this session. Falls back to userId for solo users. */
+  tenantId?: string;
   /** Agent config ID applied to this session, if any (M5-001). */
   agentConfigId?: string;
   /** Human-readable agent name applied to this session, if any (M5-001). */
@@ -174,12 +186,20 @@ export class AgentService implements OnModuleDestroy {
       .filter((t) => t.length > 0);
   }
 
-  async createSession(sessionId: string, options?: AgentSessionOptions): Promise<AgentSession> {
+  async createSession(sessionId: string, options: AgentSessionOptions): Promise<AgentSession> {
+    const scope = this.scopeFromOptions(options);
     const existing = this.sessions.get(sessionId);
-    if (existing) return existing;
+    if (existing) {
+      this.assertSessionScope(existing, scope);
+      return existing;
+    }
 
     const inflight = this.creating.get(sessionId);
-    if (inflight) return inflight;
+    if (inflight) {
+      const session = await inflight;
+      this.assertSessionScope(session, scope);
+      return session;
+    }
 
     const promise = this.doCreateSession(sessionId, options).finally(() => {
       this.creating.delete(sessionId);
@@ -342,6 +362,7 @@ export class AgentService implements OnModuleDestroy {
       sandboxDir,
       allowedTools,
       userId: mergedOptions?.userId,
+      tenantId: this.tenantIdFor(mergedOptions?.userId, mergedOptions?.tenantId),
       agentConfigId: mergedOptions?.agentConfigId,
       agentName: resolvedAgentName,
       metrics: {
@@ -473,38 +494,70 @@ export class AgentService implements OnModuleDestroy {
     return this.providerService.getDefaultModel() ?? null;
   }
 
-  getSession(sessionId: string): AgentSession | undefined {
-    return this.sessions.get(sessionId);
+  getSession(sessionId: string, scope: ActorTenantScope): AgentSession | undefined {
+    const session = this.sessions.get(sessionId);
+    if (!session || !this.sessionMatchesScope(session, scope)) return undefined;
+    return session;
   }
 
-  listSessions(): SessionInfoDto[] {
+  listSessions(scope: ActorTenantScope): SessionInfoDto[] {
     const now = Date.now();
-    return Array.from(this.sessions.values()).map((s) => ({
-      id: s.id,
-      provider: s.provider,
-      modelId: s.modelId,
-      ...(s.agentName ? { agentName: s.agentName } : {}),
-      createdAt: new Date(s.createdAt).toISOString(),
-      promptCount: s.promptCount,
-      channels: Array.from(s.channels),
-      durationMs: now - s.createdAt,
-      metrics: { ...s.metrics },
-    }));
+    return Array.from(this.sessions.values())
+      .filter((s) => this.sessionMatchesScope(s, scope))
+      .map((s) => this.toSessionInfo(s, now));
   }
 
-  getSessionInfo(sessionId: string): SessionInfoDto | undefined {
+  listAllSessionsForSystem(): SessionInfoDto[] {
+    const now = Date.now();
+    return Array.from(this.sessions.values()).map((s) => this.toSessionInfo(s, now));
+  }
+
+  getSessionInfo(sessionId: string, scope: ActorTenantScope): SessionInfoDto | undefined {
     const s = this.sessions.get(sessionId);
-    if (!s) return undefined;
+    if (!s || !this.sessionMatchesScope(s, scope)) return undefined;
+    return this.toSessionInfo(s);
+  }
+
+  private scopeFromOptions(options: AgentSessionOptions): ActorTenantScope {
+    if (!options.userId) {
+      throw new ForbiddenException('Session owner scope is required');
+    }
     return {
-      id: s.id,
-      provider: s.provider,
-      modelId: s.modelId,
-      ...(s.agentName ? { agentName: s.agentName } : {}),
-      createdAt: new Date(s.createdAt).toISOString(),
-      promptCount: s.promptCount,
-      channels: Array.from(s.channels),
-      durationMs: Date.now() - s.createdAt,
-      metrics: { ...s.metrics },
+      userId: options.userId,
+      tenantId: this.tenantIdFor(options.userId, options.tenantId) ?? options.userId,
+    };
+  }
+
+  private tenantIdFor(
+    userId: string | undefined,
+    tenantId: string | undefined,
+  ): string | undefined {
+    return tenantId ?? userId;
+  }
+
+  private sessionMatchesScope(session: AgentSession, scope: ActorTenantScope): boolean {
+    return (
+      session.userId === scope.userId && (session.tenantId ?? session.userId) === scope.tenantId
+    );
+  }
+
+  private assertSessionScope(session: AgentSession, scope: ActorTenantScope): void {
+    if (!this.sessionMatchesScope(session, scope)) {
+      throw new ForbiddenException('Session does not belong to the current owner/tenant scope');
+    }
+  }
+
+  private toSessionInfo(session: AgentSession, now = Date.now()): SessionInfoDto {
+    return {
+      id: session.id,
+      provider: session.provider,
+      modelId: session.modelId,
+      ...(session.agentName ? { agentName: session.agentName } : {}),
+      createdAt: new Date(session.createdAt).toISOString(),
+      promptCount: session.promptCount,
+      channels: Array.from(session.channels),
+      durationMs: now - session.createdAt,
+      metrics: { ...session.metrics },
     };
   }
 
@@ -553,9 +606,10 @@ export class AgentService implements OnModuleDestroy {
    * not reconstructed — the model is used on the next createSession call for
    * the same conversationId when the session is torn down or a new one is created.
    */
-  updateSessionModel(sessionId: string, modelId: string): void {
+  updateSessionModel(sessionId: string, modelId: string, scope: ActorTenantScope): void {
     const session = this.sessions.get(sessionId);
     if (!session) return;
+    this.assertSessionScope(session, scope);
     const prev = session.modelId;
     session.modelId = modelId;
     this.recordModelSwitch(sessionId);
@@ -572,48 +626,51 @@ export class AgentService implements OnModuleDestroy {
     sessionId: string,
     agentConfigId: string,
     agentName: string,
+    scope: ActorTenantScope,
     modelId?: string,
   ): void {
     const session = this.sessions.get(sessionId);
     if (!session) return;
+    this.assertSessionScope(session, scope);
     session.agentConfigId = agentConfigId;
     session.agentName = agentName;
     if (modelId) {
-      this.updateSessionModel(sessionId, modelId);
+      this.updateSessionModel(sessionId, modelId, scope);
     }
     this.logger.log(
       `Session ${sessionId}: agent switched to "${agentName}" (${agentConfigId}) (M5-003)`,
     );
   }
 
-  addChannel(sessionId: string, channel: string): void {
+  addChannel(sessionId: string, channel: string, scope: ActorTenantScope): void {
     const session = this.sessions.get(sessionId);
-    if (session) {
-      session.channels.add(channel);
-    }
+    if (!session) return;
+    this.assertSessionScope(session, scope);
+    session.channels.add(channel);
   }
 
-  removeChannel(sessionId: string, channel: string): void {
+  removeChannel(sessionId: string, channel: string, scope: ActorTenantScope): void {
     const session = this.sessions.get(sessionId);
-    if (session) {
-      session.channels.delete(channel);
-    }
+    if (!session) return;
+    this.assertSessionScope(session, scope);
+    session.channels.delete(channel);
   }
 
-  async prompt(sessionId: string, message: string): Promise<void> {
+  async prompt(sessionId: string, message: string, scope: ActorTenantScope): Promise<void> {
     const session = this.sessions.get(sessionId);
     if (!session) {
       throw new Error(`No agent session found: ${sessionId}`);
     }
+    this.assertSessionScope(session, scope);
     session.promptCount += 1;
 
     // Prepend session-scoped system override if present (renew TTL on each turn)
     let effectiveMessage = message;
     if (this.systemOverride) {
-      const override = await this.systemOverride.get(sessionId);
+      const override = await this.systemOverride.get(sessionId, scope);
       if (override) {
         effectiveMessage = `[System Override]\n${override}\n\n${message}`;
-        await this.systemOverride.renew(sessionId);
+        await this.systemOverride.renew(sessionId, scope);
         this.logger.debug(`Applied system override for session ${sessionId}`);
       }
     }
@@ -629,16 +686,28 @@ export class AgentService implements OnModuleDestroy {
     }
   }
 
-  onEvent(sessionId: string, listener: (event: AgentSessionEvent) => void): () => void {
+  onEvent(
+    sessionId: string,
+    listener: (event: AgentSessionEvent) => void,
+    scope: ActorTenantScope,
+  ): () => void {
     const session = this.sessions.get(sessionId);
     if (!session) {
       throw new Error(`No agent session found: ${sessionId}`);
     }
+    this.assertSessionScope(session, scope);
     session.listeners.add(listener);
     return () => session.listeners.delete(listener);
   }
 
-  async destroySession(sessionId: string): Promise<void> {
+  async destroySession(sessionId: string, scope: ActorTenantScope): Promise<void> {
+    const session = this.sessions.get(sessionId);
+    if (!session) return;
+    this.assertSessionScope(session, scope);
+    await this.destroySessionForSystem(sessionId);
+  }
+
+  private async destroySessionForSystem(sessionId: string): Promise<void> {
     const session = this.sessions.get(sessionId);
     if (!session) return;
     this.logger.log(`Destroying agent session ${sessionId}`);
@@ -667,7 +736,7 @@ export class AgentService implements OnModuleDestroy {
 
   async onModuleDestroy(): Promise<void> {
     this.logger.log('Shutting down all agent sessions');
-    const stops = Array.from(this.sessions.keys()).map((id) => this.destroySession(id));
+    const stops = Array.from(this.sessions.keys()).map((id) => this.destroySessionForSystem(id));
     const results = await Promise.allSettled(stops);
     for (const result of results) {
       if (result.status === 'rejected') {

apps/gateway/src/agent/sessions.controller.ts

@@ -10,6 +10,8 @@ import {
   UseGuards,
 } from '@nestjs/common';
 import { AuthGuard } from '../auth/auth.guard.js';
+import { CurrentUser } from '../auth/current-user.decorator.js';
+import { scopeFromUser, type AuthenticatedUserLike } from '../auth/session-scope.js';
 import { AgentService } from './agent.service.js';
 
 @Controller('api/sessions')
@@ -18,23 +20,24 @@ export class SessionsController {
   constructor(@Inject(AgentService) private readonly agentService: AgentService) {}
 
   @Get()
-  list() {
-    const sessions = this.agentService.listSessions();
+  list(@CurrentUser() user: AuthenticatedUserLike) {
+    const sessions = this.agentService.listSessions(scopeFromUser(user));
     return { sessions, total: sessions.length };
   }
 
   @Get(':id')
-  findOne(@Param('id') id: string) {
-    const info = this.agentService.getSessionInfo(id);
+  findOne(@Param('id') id: string, @CurrentUser() user: AuthenticatedUserLike) {
+    const info = this.agentService.getSessionInfo(id, scopeFromUser(user));
     if (!info) throw new NotFoundException('Session not found');
     return info;
   }
 
   @Delete(':id')
   @HttpCode(HttpStatus.NO_CONTENT)
-  async destroy(@Param('id') id: string) {
-    const info = this.agentService.getSessionInfo(id);
+  async destroy(@Param('id') id: string, @CurrentUser() user: AuthenticatedUserLike) {
+    const scope = scopeFromUser(user);
+    const info = this.agentService.getSessionInfo(id, scope);
     if (!info) throw new NotFoundException('Session not found');
-    await this.agentService.destroySession(id);
+    await this.agentService.destroySession(id, scope);
   }
 }