test(tess): cover approval ingress with server scope

.woodpecker/ci.yml

@@ -7,7 +7,14 @@ variables:
   - &enable_pnpm 'corepack enable'
 
 when:
-  - event: [push, pull_request, manual]
+  # PR + manual CI run on any branch — the pull_request pipeline is the merge gate.
+  # push CI is restricted to protected branches (main) so a feature-branch push no
+  # longer fires a redundant SECOND pipeline alongside its PR pipeline. This ~halves
+  # CI load on the storage-constrained runner with zero loss of gating (branch
+  # protection requires no push/ci status context; main still gets full push CI).
+  - event: [pull_request, manual]
+  - event: push
+    branch: main
 
 # Turbo remote cache (turbo.mosaicstack.dev) is configured via Woodpecker
 # repository-level environment variables (TURBO_API, TURBO_TEAM, TURBO_TOKEN).

apps/gateway/src/admin/admin-health.controller.ts

@@ -20,7 +20,7 @@ export class AdminHealthController {
   async check(): Promise<HealthStatusDto> {
     const [database, cache] = await Promise.all([this.checkDatabase(), this.checkCache()]);
 
-    const sessions = this.agentService.listSessions();
+    const sessions = this.agentService.listAllSessionsForSystem();
     const providers = this.providerService.listProviders();
 
     const allOk = database.status === 'ok' && cache.status === 'ok';

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);
   }
 }

apps/gateway/src/auth/session-scope.ts

@@ -0,0 +1,24 @@
+export interface AuthenticatedUserLike {
+  id: string;
+  tenantId?: string | null;
+  teamId?: string | null;
+  organizationId?: string | null;
+  orgId?: string | null;
+}
+
+export interface ActorTenantScope {
+  userId: string;
+  tenantId: string;
+}
+
+/**
+ * Build the immutable server-derived scope used for Tess session operations.
+ * Current Mosaic auth is user-scoped; future org/team claims can populate one
+ * of the tenant fields without allowing clients to choose another tenant.
+ */
+export function scopeFromUser(user: AuthenticatedUserLike): ActorTenantScope {
+  return {
+    userId: user.id,
+    tenantId: user.tenantId ?? user.teamId ?? user.organizationId ?? user.orgId ?? user.id,
+  };
+}

apps/gateway/src/chat/__tests__/chat-security.test.ts

@@ -12,7 +12,8 @@ describe('Chat controller source hardening', () => {
     const source = readFileSync(resolve('src/chat/chat.controller.ts'), 'utf8');
 
     expect(source).toContain('@UseGuards(AuthGuard)');
-    expect(source).toContain('@CurrentUser() user: { id: string }');
+    expect(source).toContain('@CurrentUser() user: AuthenticatedUserLike');
+    expect(source).toContain('const scope = scopeFromUser(user);');
   });
 });
 

apps/gateway/src/chat/chat.controller.ts

@@ -3,8 +3,10 @@ import {
   Post,
   Body,
   Logger,
+  ForbiddenException,
   HttpException,
   HttpStatus,
+  NotFoundException,
   Inject,
   UseGuards,
 } from '@nestjs/common';
@@ -13,6 +15,7 @@ import { Throttle } from '@nestjs/throttler';
 import { AgentService } from '../agent/agent.service.js';
 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 { v4 as uuid } from 'uuid';
 import { ChatRequestDto } from './chat.dto.js';
 
@@ -32,16 +35,23 @@ export class ChatController {
   @Throttle({ default: { limit: 10, ttl: 60_000 } })
   async chat(
     @Body() body: ChatRequestDto,
-    @CurrentUser() user: { id: string },
+    @CurrentUser() user: AuthenticatedUserLike,
   ): Promise<ChatResponse> {
     const conversationId = body.conversationId ?? uuid();
+    const scope = scopeFromUser(user);
 
     try {
-      let agentSession = this.agentService.getSession(conversationId);
+      let agentSession = this.agentService.getSession(conversationId, scope);
       if (!agentSession) {
-        agentSession = await this.agentService.createSession(conversationId);
+        agentSession = await this.agentService.createSession(conversationId, {
+          userId: scope.userId,
+          tenantId: scope.tenantId,
+        });
       }
     } catch (err) {
+      if (err instanceof ForbiddenException) {
+        throw new NotFoundException('Session not found');
+      }
       this.logger.error(
         `Session creation failed for conversation=${conversationId}`,
         err instanceof Error ? err.stack : String(err),
@@ -60,20 +70,27 @@ export class ChatController {
         reject(new Error('Agent response timed out'));
       }, 120_000);
 
-      const cleanup = this.agentService.onEvent(conversationId, (event: AgentSessionEvent) => {
-        if (event.type === 'message_update' && event.assistantMessageEvent.type === 'text_delta') {
-          responseText += event.assistantMessageEvent.delta;
-        }
-        if (event.type === 'agent_end') {
-          clearTimeout(timer);
-          cleanup();
-          resolve();
-        }
-      });
+      const cleanup = this.agentService.onEvent(
+        conversationId,
+        (event: AgentSessionEvent) => {
+          if (
+            event.type === 'message_update' &&
+            event.assistantMessageEvent.type === 'text_delta'
+          ) {
+            responseText += event.assistantMessageEvent.delta;
+          }
+          if (event.type === 'agent_end') {
+            clearTimeout(timer);
+            cleanup();
+            resolve();
+          }
+        },
+        scope,
+      );
     });
 
     try {
-      await this.agentService.prompt(conversationId, body.content);
+      await this.agentService.prompt(conversationId, body.content, scope);
       await done;
     } catch (err) {
       if (err instanceof HttpException) throw err;

apps/gateway/src/chat/chat.gateway-command-approval.spec.ts

@@ -0,0 +1,74 @@
+import { describe, expect, it, vi } from 'vitest';
+import type { SlashCommandPayload } from '@mosaicstack/types';
+import { ChatGateway } from './chat.gateway.js';
+
+const payload: SlashCommandPayload = {
+  command: 'gc',
+  conversationId: 'conversation-1',
+  approvalId: 'approval-1',
+};
+
+function buildGateway(commandExecutor: {
+  execute: ReturnType<typeof vi.fn>;
+  createApproval: ReturnType<typeof vi.fn>;
+}): ChatGateway {
+  return new ChatGateway(
+    {} as never,
+    {} as never,
+    {} as never,
+    {} as never,
+    commandExecutor as never,
+    {} as never,
+  );
+}
+
+describe('ChatGateway command approval ingress', () => {
+  it('passes the client approval ID through to command execution while deriving the actor server-side', async (): Promise<void> => {
+    const commandExecutor = {
+      execute: vi.fn().mockResolvedValue({ ...payload, success: true }),
+      createApproval: vi.fn(),
+    };
+    const gateway = buildGateway(commandExecutor);
+    const client = { data: { user: { id: 'admin-1' } }, emit: vi.fn() };
+
+    await gateway.handleCommandExecute(client as never, payload);
+
+    expect(commandExecutor.execute).toHaveBeenCalledWith(payload, {
+      userId: 'admin-1',
+      tenantId: 'admin-1',
+    });
+    expect(client.emit).toHaveBeenCalledWith(
+      'command:result',
+      expect.objectContaining({ success: true }),
+    );
+  });
+
+  it('issues a durable approval only for the authenticated actor', async (): Promise<void> => {
+    const commandExecutor = {
+      execute: vi.fn(),
+      createApproval: vi.fn().mockResolvedValue({
+        approvalId: 'approval-1',
+        expiresAt: '2026-07-12T00:05:00.000Z',
+      }),
+    };
+    const gateway = buildGateway(commandExecutor);
+    const client = { data: { user: { id: 'admin-1' } }, emit: vi.fn() };
+
+    await gateway.handleCommandApproval(client as never, {
+      command: 'gc',
+      conversationId: 'conversation-1',
+    });
+
+    expect(commandExecutor.createApproval).toHaveBeenCalledWith(
+      { command: 'gc', conversationId: 'conversation-1' },
+      { userId: 'admin-1', tenantId: 'admin-1' },
+    );
+    expect(client.emit).toHaveBeenCalledWith('command:approval', {
+      command: 'gc',
+      conversationId: 'conversation-1',
+      success: true,
+      approvalId: 'approval-1',
+      expiresAt: '2026-07-12T00:05:00.000Z',
+    });
+  });
+});

apps/gateway/src/chat/chat.gateway.ts

@@ -15,6 +15,7 @@ import type { Auth } from '@mosaicstack/auth';
 import type { Brain } from '@mosaicstack/brain';
 import type {
   SetThinkingPayload,
+  SlashCommandApprovalResultPayload,
   SlashCommandPayload,
   SystemReloadPayload,
   RoutingDecisionInfo,
@@ -22,6 +23,11 @@ import type {
 } from '@mosaicstack/types';
 import { AgentService, type ConversationHistoryMessage } from '../agent/agent.service.js';
 import { AUTH } from '../auth/auth.tokens.js';
+import {
+  scopeFromUser,
+  type ActorTenantScope,
+  type AuthenticatedUserLike,
+} from '../auth/session-scope.js';
 import { BRAIN } from '../brain/brain.tokens.js';
 import { CommandRegistryService } from '../commands/command-registry.service.js';
 import { CommandExecutorService } from '../commands/command-executor.service.js';
@@ -40,6 +46,8 @@ interface ClientSession {
   toolCalls: Array<{ toolCallId: string; toolName: string; args: unknown; isError: boolean }>;
   /** Tool calls in-flight (started but not ended yet). */
   pendingToolCalls: Map<string, { toolName: string; args: unknown }>;
+  /** Server-derived owner/tenant scope for this socket's conversation attachment. */
+  scope: ActorTenantScope;
   /** Last routing decision made for this session (M4-008) */
   lastRoutingDecision?: RoutingDecisionInfo;
 }
@@ -97,25 +105,48 @@ export class ChatGateway implements OnGatewayInit, OnGatewayConnection, OnGatewa
     const session = this.clientSessions.get(client.id);
     if (session) {
       session.cleanup();
-      this.agentService.removeChannel(session.conversationId, `websocket:${client.id}`);
+      this.agentService.removeChannel(
+        session.conversationId,
+        `websocket:${client.id}`,
+        session.scope,
+      );
       this.clientSessions.delete(client.id);
     }
   }
 
+  private getClientScope(client: Socket): ActorTenantScope | null {
+    const user = client.data.user as AuthenticatedUserLike | undefined;
+    if (!user?.id) return null;
+    return scopeFromUser(user);
+  }
+
+  private modelOverrideKey(conversationId: string, scope: ActorTenantScope): string {
+    return `${scope.tenantId}:${scope.userId}:${conversationId}`;
+  }
+
+  private scopesEqual(a: ActorTenantScope, b: ActorTenantScope): boolean {
+    return a.userId === b.userId && a.tenantId === b.tenantId;
+  }
+
   @SubscribeMessage('message')
   async handleMessage(
     @ConnectedSocket() client: Socket,
     @MessageBody() data: ChatSocketMessageDto,
   ): Promise<void> {
     const conversationId = data.conversationId ?? uuid();
-    const userId = (client.data.user as { id: string } | undefined)?.id;
+    const scope = this.getClientScope(client);
+    if (!scope) {
+      client.emit('error', { conversationId, error: 'Authenticated user scope is required.' });
+      return;
+    }
+    const userId = scope.userId;
 
     this.logger.log(`Message from ${client.id} in conversation ${conversationId}`);
 
     // Ensure agent session exists for this conversation
     let sessionRoutingDecision: RoutingDecisionInfo | undefined;
     try {
-      let agentSession = this.agentService.getSession(conversationId);
+      let agentSession = this.agentService.getSession(conversationId, scope);
       if (!agentSession) {
         // When resuming an existing conversation, load prior messages to inject as context (M1-004)
         const conversationHistory = await this.loadConversationHistory(conversationId, userId);
@@ -135,7 +166,7 @@ export class ChatGateway implements OnGatewayInit, OnGatewayConnection, OnGatewa
         let resolvedProvider = data.provider;
         let resolvedModelId = data.modelId;
 
-        const modelOverride = modelOverrides.get(conversationId);
+        const modelOverride = modelOverrides.get(this.modelOverrideKey(conversationId, scope));
         if (modelOverride) {
           // /model override bypasses routing engine (M4-007)
           resolvedModelId = modelOverride;
@@ -172,6 +203,7 @@ export class ChatGateway implements OnGatewayInit, OnGatewayConnection, OnGatewa
           modelId: resolvedModelId,
           agentConfigId: data.agentId,
           userId,
+          tenantId: scope.tenantId,
           conversationHistory: conversationHistory.length > 0 ? conversationHistory : undefined,
         });
 
@@ -232,9 +264,13 @@ export class ChatGateway implements OnGatewayInit, OnGatewayConnection, OnGatewa
     }
 
     // Subscribe to agent events and relay to client
-    const cleanup = this.agentService.onEvent(conversationId, (event: AgentSessionEvent) => {
-      this.relayEvent(client, conversationId, event);
-    });
+    const cleanup = this.agentService.onEvent(
+      conversationId,
+      (event: AgentSessionEvent) => {
+        this.relayEvent(client, conversationId, event);
+      },
+      scope,
+    );
 
     // Preserve routing decision from the existing client session if we didn't get a new one
     const prevClientSession = this.clientSessions.get(client.id);
@@ -246,16 +282,17 @@ export class ChatGateway implements OnGatewayInit, OnGatewayConnection, OnGatewa
       assistantText: '',
       toolCalls: [],
       pendingToolCalls: new Map(),
+      scope,
       lastRoutingDecision: routingDecisionToStore,
     });
 
     // Track channel connection
-    this.agentService.addChannel(conversationId, `websocket:${client.id}`);
+    this.agentService.addChannel(conversationId, `websocket:${client.id}`, scope);
 
     // Send session info so the client knows the model/provider (M4-008: include routing decision)
     // Include agentName when a named agent config is active (M5-001)
     {
-      const agentSession = this.agentService.getSession(conversationId);
+      const agentSession = this.agentService.getSession(conversationId, scope);
       if (agentSession) {
         const piSession = agentSession.piSession;
         client.emit('session:info', {
@@ -275,7 +312,7 @@ export class ChatGateway implements OnGatewayInit, OnGatewayConnection, OnGatewa
 
     // Dispatch to agent
     try {
-      await this.agentService.prompt(conversationId, data.content);
+      await this.agentService.prompt(conversationId, data.content, scope);
     } catch (err) {
       this.logger.error(
         `Agent prompt failed for client=${client.id}, conversation=${conversationId}`,
@@ -293,7 +330,16 @@ export class ChatGateway implements OnGatewayInit, OnGatewayConnection, OnGatewa
     @ConnectedSocket() client: Socket,
     @MessageBody() data: SetThinkingPayload,
   ): void {
-    const session = this.agentService.getSession(data.conversationId);
+    const scope = this.getClientScope(client);
+    if (!scope) {
+      client.emit('error', {
+        conversationId: data.conversationId,
+        error: 'Authenticated user scope is required.',
+      });
+      return;
+    }
+
+    const session = this.agentService.getSession(data.conversationId, scope);
     if (!session) {
       client.emit('error', {
         conversationId: data.conversationId,
@@ -334,7 +380,13 @@ export class ChatGateway implements OnGatewayInit, OnGatewayConnection, OnGatewa
     const conversationId = data.conversationId;
     this.logger.log(`Abort requested by ${client.id} for conversation ${conversationId}`);
 
-    const session = this.agentService.getSession(conversationId);
+    const scope = this.getClientScope(client);
+    if (!scope) {
+      client.emit('error', { conversationId, error: 'Authenticated user scope is required.' });
+      return;
+    }
+
+    const session = this.agentService.getSession(conversationId, scope);
     if (!session) {
       client.emit('error', {
         conversationId,
@@ -363,11 +415,45 @@ export class ChatGateway implements OnGatewayInit, OnGatewayConnection, OnGatewa
     @ConnectedSocket() client: Socket,
     @MessageBody() payload: SlashCommandPayload,
   ): Promise<void> {
-    const userId = (client.data.user as { id: string } | undefined)?.id ?? 'unknown';
-    const result = await this.commandExecutor.execute(payload, userId);
+    const scope = this.getClientScope(client);
+    if (!scope) {
+      client.emit('command:result', {
+        command: payload.command,
+        conversationId: payload.conversationId,
+        success: false,
+        message: 'Authenticated user scope is required.',
+      });
+      return;
+    }
+
+    const result = await this.commandExecutor.execute(payload, scope);
     client.emit('command:result', result);
   }
 
+  @SubscribeMessage('command:approve')
+  async handleCommandApproval(
+    @ConnectedSocket() client: Socket,
+    @MessageBody() payload: SlashCommandPayload,
+  ): Promise<void> {
+    const scope = this.getClientScope(client);
+    const approval = scope ? await this.commandExecutor.createApproval(payload, scope) : null;
+    const result: SlashCommandApprovalResultPayload = approval
+      ? {
+          command: payload.command,
+          conversationId: payload.conversationId,
+          success: true,
+          approvalId: approval.approvalId,
+          expiresAt: approval.expiresAt,
+        }
+      : {
+          command: payload.command,
+          conversationId: payload.conversationId,
+          success: false,
+          message: 'Not authorized to approve this command.',
+        };
+    client.emit('command:approval', result);
+  }
+
   broadcastReload(payload: SystemReloadPayload): void {
     this.server.emit('system:reload', payload);
     this.logger.log('Broadcasted system:reload to all connected clients');
@@ -380,18 +466,23 @@ export class ChatGateway implements OnGatewayInit, OnGatewayConnection, OnGatewa
    * M5-005: Emits session:info to clients subscribed to this conversation when a model is set.
    * M5-007: Records a model switch in session metrics.
    */
-  setModelOverride(conversationId: string, modelName: string | null): void {
+  setModelOverride(
+    conversationId: string,
+    modelName: string | null,
+    scope: ActorTenantScope,
+  ): void {
+    const key = this.modelOverrideKey(conversationId, scope);
     if (modelName) {
-      modelOverrides.set(conversationId, modelName);
+      modelOverrides.set(key, modelName);
       this.logger.log(`Model override set: conversation=${conversationId} model="${modelName}"`);
 
       // M5-002: Update the live session's modelId so session:info reflects the new model immediately
-      this.agentService.updateSessionModel(conversationId, modelName);
+      this.agentService.updateSessionModel(conversationId, modelName, scope);
 
       // M5-005: Broadcast session:info to all clients subscribed to this conversation
-      this.broadcastSessionInfo(conversationId);
+      this.broadcastSessionInfo(conversationId, scope);
     } else {
-      modelOverrides.delete(conversationId);
+      modelOverrides.delete(key);
       this.logger.log(`Model override cleared: conversation=${conversationId}`);
     }
   }
@@ -399,8 +490,8 @@ export class ChatGateway implements OnGatewayInit, OnGatewayConnection, OnGatewa
   /**
    * Return the active model override for a conversation, or undefined if none.
    */
-  getModelOverride(conversationId: string): string | undefined {
-    return modelOverrides.get(conversationId);
+  getModelOverride(conversationId: string, scope: ActorTenantScope): string | undefined {
+    return modelOverrides.get(this.modelOverrideKey(conversationId, scope));
   }
 
   /**
@@ -409,9 +500,10 @@ export class ChatGateway implements OnGatewayInit, OnGatewayConnection, OnGatewa
    */
   broadcastSessionInfo(
     conversationId: string,
+    scope: ActorTenantScope,
     extra?: { agentName?: string; routingDecision?: RoutingDecisionInfo },
   ): void {
-    const agentSession = this.agentService.getSession(conversationId);
+    const agentSession = this.agentService.getSession(conversationId, scope);
     if (!agentSession) return;
 
     const piSession = agentSession.piSession;
@@ -428,7 +520,7 @@ export class ChatGateway implements OnGatewayInit, OnGatewayConnection, OnGatewa
 
     // Emit to all clients currently subscribed to this conversation
     for (const [clientId, session] of this.clientSessions) {
-      if (session.conversationId === conversationId) {
+      if (session.conversationId === conversationId && this.scopesEqual(session.scope, scope)) {
         const socket = this.server.sockets.sockets.get(clientId);
         if (socket?.connected) {
           socket.emit('session:info', payload);
@@ -550,7 +642,10 @@ export class ChatGateway implements OnGatewayInit, OnGatewayConnection, OnGatewa
 
       case 'agent_end': {
         // Gather usage stats from the Pi session
-        const agentSession = this.agentService.getSession(conversationId);
+        const activeClientSession = this.clientSessions.get(client.id);
+        const agentSession = activeClientSession
+          ? this.agentService.getSession(conversationId, activeClientSession.scope)
+          : undefined;
         const piSession = agentSession?.piSession;
         const stats = piSession?.getSessionStats();
         const contextUsage = piSession?.getContextUsage();

apps/gateway/src/commands/command-authorization.service.spec.ts

@@ -30,29 +30,32 @@ function createService(role: string): CommandAuthorizationService {
 describe('CommandAuthorizationService', () => {
   it('consumes one exact actor-bound approval once', async (): Promise<void> => {
     const service = createService('admin');
-    const approval = await service.createApproval('gc', payload, 'admin-1');
+    const approval = await service.createApproval(adminCommand, payload, 'admin-1');
+    expect(approval).not.toBeNull();
     expect(
-      (await service.authorize(adminCommand, payload, 'admin-1', approval.approvalId)).allowed,
+      (await service.authorize(adminCommand, payload, 'admin-1', approval!.approvalId)).allowed,
     ).toBe(true);
     expect(
-      (await service.authorize(adminCommand, payload, 'admin-1', approval.approvalId)).allowed,
+      (await service.authorize(adminCommand, payload, 'admin-1', approval!.approvalId)).allowed,
     ).toBe(false);
   });
 
   it('rejects an approval when the structured action is mutated', async (): Promise<void> => {
     const service = createService('admin');
-    const approval = await service.createApproval('gc', payload, 'admin-1');
+    const approval = await service.createApproval(adminCommand, payload, 'admin-1');
     const mutated = { ...payload, conversationId: 'other-conversation' };
+    expect(approval).not.toBeNull();
     expect(
-      (await service.authorize(adminCommand, mutated, 'admin-1', approval.approvalId)).allowed,
+      (await service.authorize(adminCommand, mutated, 'admin-1', approval!.approvalId)).allowed,
     ).toBe(false);
   });
 
   it('denies an admin command to a member before approval is considered', async (): Promise<void> => {
     const service = createService('member');
-    const approval = await service.createApproval('gc', payload, 'member-1');
+    const approval = await service.createApproval(adminCommand, payload, 'member-1');
+    expect(approval).toBeNull();
     expect(
-      (await service.authorize(adminCommand, payload, 'member-1', approval.approvalId)).allowed,
+      (await service.authorize(adminCommand, payload, 'member-1', 'forged-approval-id')).allowed,
     ).toBe(false);
   });
 });

apps/gateway/src/commands/command-authorization.service.ts

@@ -55,17 +55,20 @@ export class CommandAuthorizationService {
   }
 
   async createApproval(
-    command: string,
+    command: CommandDef,
     payload: SlashCommandPayload,
     actorId: string,
-  ): Promise<CommandApproval> {
+  ): Promise<CommandApproval | null> {
+    const role = await this.resolveRole(actorId);
+    if (!role || command.scope !== 'admin' || !this.hasScope(role, command.scope)) return null;
+
     const approvalId = randomUUID();
     const expiresAt = new Date(Date.now() + 5 * 60_000).toISOString();
     const approval: CommandApproval = {
       approvalId,
-      actionDigest: this.actionDigest(command, payload),
+      actionDigest: this.actionDigest(command.name, payload),
       actorId,
-      command,
+      command: command.name,
       expiresAt,
     };
     await this.redis.set(this.key(approvalId), JSON.stringify(approval), 'EX', '300');

apps/gateway/src/commands/command-executor-p8012.spec.ts

@@ -89,6 +89,7 @@ function buildService(): CommandExecutorService {
 describe('CommandExecutorService — P8-012 commands', () => {
   let service: CommandExecutorService;
   const userId = 'user-123';
+  const userScope = { userId, tenantId: userId };
   const conversationId = 'conv-456';
 
   beforeEach(() => {
@@ -99,7 +100,7 @@ describe('CommandExecutorService — P8-012 commands', () => {
   // /provider login — missing provider name
   it('/provider login with no provider name returns usage error', async () => {
     const payload: SlashCommandPayload = { command: 'provider', args: 'login', conversationId };
-    const result = await service.execute(payload, userId);
+    const result = await service.execute(payload, userScope);
     expect(result.success).toBe(false);
     expect(result.message).toContain('Usage: /provider login');
     expect(result.command).toBe('provider');
@@ -112,7 +113,7 @@ describe('CommandExecutorService — P8-012 commands', () => {
       args: 'login anthropic',
       conversationId,
     };
-    const result = await service.execute(payload, userId);
+    const result = await service.execute(payload, userScope);
     expect(result.success).toBe(true);
     expect(result.command).toBe('provider');
     expect(result.message).toContain('anthropic');
@@ -138,7 +139,7 @@ describe('CommandExecutorService — P8-012 commands', () => {
   // /provider with no args — returns usage
   it('/provider with no args returns usage message', async () => {
     const payload: SlashCommandPayload = { command: 'provider', conversationId };
-    const result = await service.execute(payload, userId);
+    const result = await service.execute(payload, userScope);
     expect(result.success).toBe(true);
     expect(result.message).toContain('Usage: /provider');
   });
@@ -146,7 +147,7 @@ describe('CommandExecutorService — P8-012 commands', () => {
   // /provider list
   it('/provider list returns success', async () => {
     const payload: SlashCommandPayload = { command: 'provider', args: 'list', conversationId };
-    const result = await service.execute(payload, userId);
+    const result = await service.execute(payload, userScope);
     expect(result.success).toBe(true);
     expect(result.command).toBe('provider');
   });
@@ -154,7 +155,7 @@ describe('CommandExecutorService — P8-012 commands', () => {
   // /provider logout with no name — usage error
   it('/provider logout with no name returns error', async () => {
     const payload: SlashCommandPayload = { command: 'provider', args: 'logout', conversationId };
-    const result = await service.execute(payload, userId);
+    const result = await service.execute(payload, userScope);
     expect(result.success).toBe(false);
     expect(result.message).toContain('Usage: /provider logout');
   });
@@ -166,7 +167,7 @@ describe('CommandExecutorService — P8-012 commands', () => {
       args: 'unknown',
       conversationId,
     };
-    const result = await service.execute(payload, userId);
+    const result = await service.execute(payload, userScope);
     expect(result.success).toBe(false);
     expect(result.message).toContain('Unknown subcommand');
   });
@@ -174,7 +175,7 @@ describe('CommandExecutorService — P8-012 commands', () => {
   // /mission status
   it('/mission status returns stub message', async () => {
     const payload: SlashCommandPayload = { command: 'mission', args: 'status', conversationId };
-    const result = await service.execute(payload, userId);
+    const result = await service.execute(payload, userScope);
     expect(result.success).toBe(true);
     expect(result.command).toBe('mission');
     expect(result.message).toContain('Mission status');
@@ -183,7 +184,7 @@ describe('CommandExecutorService — P8-012 commands', () => {
   // /mission with no args
   it('/mission with no args returns status stub', async () => {
     const payload: SlashCommandPayload = { command: 'mission', conversationId };
-    const result = await service.execute(payload, userId);
+    const result = await service.execute(payload, userScope);
     expect(result.success).toBe(true);
     expect(result.message).toContain('Mission status');
   });
@@ -195,7 +196,7 @@ describe('CommandExecutorService — P8-012 commands', () => {
       args: 'set my-mission-123',
       conversationId,
     };
-    const result = await service.execute(payload, userId);
+    const result = await service.execute(payload, userScope);
     expect(result.success).toBe(true);
     expect(result.message).toContain('my-mission-123');
   });
@@ -203,7 +204,7 @@ describe('CommandExecutorService — P8-012 commands', () => {
   // /agent list
   it('/agent list returns stub message', async () => {
     const payload: SlashCommandPayload = { command: 'agent', args: 'list', conversationId };
-    const result = await service.execute(payload, userId);
+    const result = await service.execute(payload, userScope);
     expect(result.success).toBe(true);
     expect(result.command).toBe('agent');
     expect(result.message).toContain('agent');
@@ -212,7 +213,7 @@ describe('CommandExecutorService — P8-012 commands', () => {
   // /agent with no args
   it('/agent with no args returns usage', async () => {
     const payload: SlashCommandPayload = { command: 'agent', conversationId };
-    const result = await service.execute(payload, userId);
+    const result = await service.execute(payload, userScope);
     expect(result.success).toBe(true);
     expect(result.message).toContain('Usage: /agent');
   });
@@ -224,7 +225,7 @@ describe('CommandExecutorService — P8-012 commands', () => {
       args: 'my-agent-id',
       conversationId,
     };
-    const result = await service.execute(payload, userId);
+    const result = await service.execute(payload, userScope);
     expect(result.success).toBe(true);
     expect(result.message).toContain('my-agent-id');
   });
@@ -232,7 +233,7 @@ describe('CommandExecutorService — P8-012 commands', () => {
   // /prdy
   it('/prdy returns PRD wizard message', async () => {
     const payload: SlashCommandPayload = { command: 'prdy', conversationId };
-    const result = await service.execute(payload, userId);
+    const result = await service.execute(payload, userScope);
     expect(result.success).toBe(true);
     expect(result.command).toBe('prdy');
     expect(result.message).toContain('mosaic prdy');
@@ -241,7 +242,7 @@ describe('CommandExecutorService — P8-012 commands', () => {
   // /tools
   it('/tools returns tools stub message', async () => {
     const payload: SlashCommandPayload = { command: 'tools', conversationId };
-    const result = await service.execute(payload, userId);
+    const result = await service.execute(payload, userScope);
     expect(result.success).toBe(true);
     expect(result.command).toBe('tools');
     expect(result.message).toContain('tools');

apps/gateway/src/commands/command-executor-tess-security.spec.ts

@@ -1,5 +1,6 @@
 import { beforeEach, describe, expect, it, vi } from 'vitest';
 import type { SlashCommandPayload } from '@mosaicstack/types';
+import { CommandAuthorizationService } from './command-authorization.service.js';
 import { CommandExecutorService } from './command-executor.service.js';
 
 const registry = {
@@ -23,6 +24,8 @@ const sessionGc = {
   sweepOrphans: vi.fn().mockResolvedValue({ orphanedSessions: 1, totalCleaned: [], duration: 1 }),
 };
 
+const scope = (userId: string) => ({ userId, tenantId: 'tenant-1' });
+
 const authorization = {
   authorize: vi.fn((_command: unknown, _payload: unknown, actorId: string) =>
     Promise.resolve(
@@ -33,7 +36,7 @@ const authorization = {
   ),
 };
 
-function buildExecutor(): CommandExecutorService {
+function buildExecutor(authorizationService: unknown = authorization): CommandExecutorService {
   return new CommandExecutorService(
     registry as never,
     { getSession: vi.fn() } as never,
@@ -44,10 +47,25 @@ function buildExecutor(): CommandExecutorService {
     null,
     null,
     null,
-    authorization as never,
+    authorizationService as never,
   );
 }
 
+function createDurableAuthorization(): CommandAuthorizationService {
+  const entries = new Map<string, string>();
+  const db = {
+    select: () => ({ from: () => ({ where: () => ({ limit: async () => [{ role: 'admin' }] }) }) }),
+  };
+  const redis = {
+    get: async (key: string) => entries.get(key) ?? null,
+    set: async (key: string, value: string) => {
+      entries.set(key, value);
+    },
+    del: async (key: string) => Number(entries.delete(key)),
+  };
+  return new CommandAuthorizationService(db as never, redis);
+}
+
 describe('TESS-M1-SEC-001 command authorization abuse cases', () => {
   const payload: SlashCommandPayload = { command: 'gc', conversationId: 'conversation-1' };
 
@@ -56,7 +74,7 @@ describe('TESS-M1-SEC-001 command authorization abuse cases', () => {
   });
 
   it('denies a forged admin identity and does not execute a system-wide command', async (): Promise<void> => {
-    const result = await buildExecutor().execute(payload, 'admin-forged-by-client');
+    const result = await buildExecutor().execute(payload, scope('admin-forged-by-client'));
 
     expect(result.success).toBe(false);
     expect(result.message).toContain('not authorized');
@@ -64,10 +82,28 @@ describe('TESS-M1-SEC-001 command authorization abuse cases', () => {
   });
 
   it('denies a privileged command without a server-bound durable approval', async (): Promise<void> => {
-    const result = await buildExecutor().execute(payload, 'member-1');
+    const result = await buildExecutor().execute(payload, scope('member-1'));
 
     expect(result.success).toBe(false);
     expect(result.message).toContain('approval');
     expect(sessionGc.sweepOrphans).not.toHaveBeenCalled();
   });
+
+  it('executes an admin command only after a valid durable approval is issued and supplied', async (): Promise<void> => {
+    const executor = buildExecutor(createDurableAuthorization());
+
+    const adminScope = scope('admin-1');
+    const denied = await executor.execute(payload, adminScope);
+    const approval = await executor.createApproval(payload, adminScope);
+    const approved = await executor.execute(
+      { ...payload, approvalId: approval?.approvalId },
+      adminScope,
+    );
+
+    expect(denied.success).toBe(false);
+    expect(denied.message).toContain('approval');
+    expect(approval).not.toBeNull();
+    expect(approved.success).toBe(true);
+    expect(sessionGc.sweepOrphans).toHaveBeenCalledOnce();
+  });
 });

apps/gateway/src/commands/command-executor.service.ts

@@ -3,6 +3,7 @@ import type { QueueHandle } from '@mosaicstack/queue';
 import type { Brain } from '@mosaicstack/brain';
 import type { SlashCommandPayload, SlashCommandResultPayload } from '@mosaicstack/types';
 import { AgentService } from '../agent/agent.service.js';
+import type { ActorTenantScope } from '../auth/session-scope.js';
 import { ChatGateway } from '../chat/chat.gateway.js';
 import { SessionGCService } from '../gc/session-gc.service.js';
 import { SystemOverrideService } from '../preferences/system-override.service.js';
@@ -40,10 +41,10 @@ export class CommandExecutorService {
 
   async execute(
     payload: SlashCommandPayload,
-    userId: string,
-    approvalId?: string,
+    scope: ActorTenantScope,
   ): Promise<SlashCommandResultPayload> {
     const { command, args, conversationId } = payload;
+    const userId = scope.userId;
 
     const def = this.registry.getManifest().commands.find((c) => c.name === command);
     if (!def) {
@@ -55,7 +56,12 @@ export class CommandExecutorService {
       };
     }
 
-    const authorization = await this.authorization?.authorize(def, payload, userId, approvalId);
+    const authorization = await this.authorization?.authorize(
+      def,
+      payload,
+      userId,
+      payload.approvalId,
+    );
     if (authorization && !authorization.allowed) {
       return { command, conversationId, success: false, message: authorization.reason };
     }
@@ -63,11 +69,11 @@ export class CommandExecutorService {
     try {
       switch (command) {
         case 'model':
-          return await this.handleModel(args ?? null, conversationId);
+          return await this.handleModel(args ?? null, conversationId, scope);
         case 'thinking':
           return await this.handleThinking(args ?? null, conversationId);
         case 'system':
-          return await this.handleSystem(args ?? null, conversationId);
+          return await this.handleSystem(args ?? null, conversationId, scope);
         case 'new':
           return {
             command,
@@ -107,7 +113,7 @@ export class CommandExecutorService {
           };
         }
         case 'agent':
-          return await this.handleAgent(args ?? null, conversationId, userId);
+          return await this.handleAgent(args ?? null, conversationId, scope);
         case 'provider':
           return await this.handleProvider(args ?? null, userId, conversationId);
         case 'mission':
@@ -156,13 +162,22 @@ export class CommandExecutorService {
     }
   }
 
+  async createApproval(payload: SlashCommandPayload, scope: ActorTenantScope) {
+    const def = this.registry
+      .getManifest()
+      .commands.find((command) => command.name === payload.command);
+    if (!def || !this.authorization) return null;
+    return this.authorization.createApproval(def, payload, scope.userId);
+  }
+
   private async handleModel(
     args: string | null,
     conversationId: string,
+    scope: ActorTenantScope,
   ): Promise<SlashCommandResultPayload> {
     if (!args || args.trim().length === 0) {
       // Show current override or usage hint
-      const currentOverride = this.chatGateway?.getModelOverride(conversationId);
+      const currentOverride = this.chatGateway?.getModelOverride(conversationId, scope);
       if (currentOverride) {
         return {
           command: 'model',
@@ -184,7 +199,7 @@ export class CommandExecutorService {
 
     // /model clear removes the override and re-enables automatic routing
     if (modelName === 'clear') {
-      this.chatGateway?.setModelOverride(conversationId, null);
+      this.chatGateway?.setModelOverride(conversationId, null, scope);
       return {
         command: 'model',
         conversationId,
@@ -194,9 +209,9 @@ export class CommandExecutorService {
     }
 
     // Set the sticky per-session override (M4-007)
-    this.chatGateway?.setModelOverride(conversationId, modelName);
+    this.chatGateway?.setModelOverride(conversationId, modelName, scope);
 
-    const session = this.agentService.getSession(conversationId);
+    const session = this.agentService.getSession(conversationId, scope);
     if (!session) {
       return {
         command: 'model',
@@ -237,10 +252,11 @@ export class CommandExecutorService {
   private async handleSystem(
     args: string | null,
     conversationId: string,
+    scope: ActorTenantScope,
   ): Promise<SlashCommandResultPayload> {
     if (!args || args.trim().length === 0) {
       // Clear the override when called with no args
-      await this.systemOverride.clear(conversationId);
+      await this.systemOverride.clear(conversationId, scope);
       return {
         command: 'system',
         conversationId,
@@ -249,7 +265,7 @@ export class CommandExecutorService {
       };
     }
 
-    await this.systemOverride.set(conversationId, args.trim());
+    await this.systemOverride.set(conversationId, args.trim(), scope);
     return {
       command: 'system',
       conversationId,
@@ -261,8 +277,9 @@ export class CommandExecutorService {
   private async handleAgent(
     args: string | null,
     conversationId: string,
-    userId: string,
+    scope: ActorTenantScope,
   ): Promise<SlashCommandResultPayload> {
+    const userId = scope.userId;
     if (!args) {
       return {
         command: 'agent',
@@ -351,11 +368,14 @@ export class CommandExecutorService {
         conversationId,
         agentConfig.id,
         agentConfig.name,
+        scope,
         agentConfig.model ?? undefined,
       );
 
       // Broadcast updated session:info so TUI TopBar reflects new agent/model
-      this.chatGateway?.broadcastSessionInfo(conversationId, { agentName: agentConfig.name });
+      this.chatGateway?.broadcastSessionInfo(conversationId, scope, {
+        agentName: agentConfig.name,
+      });
 
       this.logger.log(
         `Agent switched to "${agentConfig.name}" (${agentConfig.id}) for conversation ${conversationId} (M5-003)`,

apps/gateway/src/commands/commands.integration.spec.ts

@@ -159,6 +159,7 @@ describe('CommandExecutorService — integration', () => {
   let registry: CommandRegistryService;
   let executor: CommandExecutorService;
   const userId = 'user-integ-001';
+  const userScope = { userId, tenantId: userId };
   const conversationId = 'conv-integ-001';
 
   beforeEach(() => {
@@ -170,7 +171,7 @@ describe('CommandExecutorService — integration', () => {
   // Unknown command returns error
   it('unknown command returns success:false with descriptive message', async () => {
     const payload: SlashCommandPayload = { command: 'nonexistent', conversationId };
-    const result = await executor.execute(payload, userId);
+    const result = await executor.execute(payload, userScope);
     expect(result.success).toBe(false);
     expect(result.message).toContain('nonexistent');
     expect(result.command).toBe('nonexistent');
@@ -179,7 +180,7 @@ describe('CommandExecutorService — integration', () => {
   // /gc handler calls SessionGCService.sweepOrphans (admin-only, no userId arg)
   it('/gc calls SessionGCService.sweepOrphans without arguments', async () => {
     const payload: SlashCommandPayload = { command: 'gc', conversationId };
-    const result = await executor.execute(payload, userId);
+    const result = await executor.execute(payload, userScope);
     expect(mockSessionGC.sweepOrphans).toHaveBeenCalledWith();
     expect(result.success).toBe(true);
     expect(result.message).toContain('GC sweep complete');
@@ -190,8 +191,8 @@ describe('CommandExecutorService — integration', () => {
   it('/system with text calls SystemOverrideService.set', async () => {
     const override = 'You are a helpful assistant.';
     const payload: SlashCommandPayload = { command: 'system', args: override, conversationId };
-    const result = await executor.execute(payload, userId);
-    expect(mockSystemOverride.set).toHaveBeenCalledWith(conversationId, override);
+    const result = await executor.execute(payload, userScope);
+    expect(mockSystemOverride.set).toHaveBeenCalledWith(conversationId, override, userScope);
     expect(result.success).toBe(true);
     expect(result.message).toContain('override set');
   });
@@ -199,8 +200,8 @@ describe('CommandExecutorService — integration', () => {
   // /system with no args clears the override
   it('/system with no args calls SystemOverrideService.clear', async () => {
     const payload: SlashCommandPayload = { command: 'system', conversationId };
-    const result = await executor.execute(payload, userId);
-    expect(mockSystemOverride.clear).toHaveBeenCalledWith(conversationId);
+    const result = await executor.execute(payload, userScope);
+    expect(mockSystemOverride.clear).toHaveBeenCalledWith(conversationId, userScope);
     expect(result.success).toBe(true);
     expect(result.message).toContain('cleared');
   });
@@ -212,7 +213,7 @@ describe('CommandExecutorService — integration', () => {
       args: 'claude-3-opus',
       conversationId,
     };
-    const result = await executor.execute(payload, userId);
+    const result = await executor.execute(payload, userScope);
     expect(result.success).toBe(true);
     expect(result.command).toBe('model');
     expect(result.message).toContain('claude-3-opus');
@@ -221,7 +222,7 @@ describe('CommandExecutorService — integration', () => {
   // /thinking with valid level returns success
   it('/thinking with valid level returns success', async () => {
     const payload: SlashCommandPayload = { command: 'thinking', args: 'high', conversationId };
-    const result = await executor.execute(payload, userId);
+    const result = await executor.execute(payload, userScope);
     expect(result.success).toBe(true);
     expect(result.message).toContain('high');
   });
@@ -229,7 +230,7 @@ describe('CommandExecutorService — integration', () => {
   // /thinking with invalid level returns usage message
   it('/thinking with invalid level returns usage message', async () => {
     const payload: SlashCommandPayload = { command: 'thinking', args: 'invalid', conversationId };
-    const result = await executor.execute(payload, userId);
+    const result = await executor.execute(payload, userScope);
     expect(result.success).toBe(true);
     expect(result.message).toContain('Usage:');
   });
@@ -237,7 +238,7 @@ describe('CommandExecutorService — integration', () => {
   // /new command returns success
   it('/new returns success', async () => {
     const payload: SlashCommandPayload = { command: 'new', conversationId };
-    const result = await executor.execute(payload, userId);
+    const result = await executor.execute(payload, userScope);
     expect(result.success).toBe(true);
     expect(result.command).toBe('new');
   });
@@ -245,7 +246,7 @@ describe('CommandExecutorService — integration', () => {
   // /reload without reloadService returns failure
   it('/reload without ReloadService returns failure', async () => {
     const payload: SlashCommandPayload = { command: 'reload', conversationId };
-    const result = await executor.execute(payload, userId);
+    const result = await executor.execute(payload, userScope);
     expect(result.success).toBe(false);
     expect(result.message).toContain('ReloadService');
   });
@@ -255,7 +256,7 @@ describe('CommandExecutorService — integration', () => {
   for (const cmd of stubCommands) {
     it(`/${cmd} returns success (stub)`, async () => {
       const payload: SlashCommandPayload = { command: cmd, conversationId };
-      const result = await executor.execute(payload, userId);
+      const result = await executor.execute(payload, userScope);
       expect(result.success).toBe(true);
       expect(result.command).toBe(cmd);
     });

apps/gateway/src/mcp/mcp.controller.ts

@@ -3,7 +3,11 @@ import { Logger } from '@nestjs/common';
 import { fromNodeHeaders } from 'better-auth/node';
 import type { Auth } from '@mosaicstack/auth';
 import type { NestFastifyApplication } from '@nestjs/platform-fastify';
-import type { McpService } from './mcp.service.js';
+import {
+  createMcpActorContext,
+  deriveMcpToolScopesForUser,
+  type McpService,
+} from './mcp.service.js';
 import { AUTH } from '../auth/auth.tokens.js';
 
 /**
@@ -67,14 +71,25 @@ async function handleMcpRequest(
     return;
   }
 
-  const userId = result.user.id;
+  const authUser = result.user as {
+    id: string;
+    role?: string | null;
+    tenantId?: string | null;
+    organizationId?: string | null;
+  };
+  const actor = createMcpActorContext({
+    userId: authUser.id,
+    role: authUser.role,
+    tenantId: authUser.tenantId ?? authUser.organizationId ?? undefined,
+    scopes: deriveMcpToolScopesForUser({ role: authUser.role }),
+  });
 
   // ─── Session routing ─────────────────────────────────────────────────────
   const sessionId = req.raw.headers['mcp-session-id'];
 
   if (typeof sessionId === 'string' && sessionId.length > 0) {
     // Existing session request
-    const transport = mcpService.getSession(sessionId);
+    const transport = mcpService.getSession(sessionId, actor);
     if (!transport) {
       logger.warn(`MCP session not found: ${sessionId}`);
       reply.raw.writeHead(404, { 'Content-Type': 'application/json' });
@@ -112,8 +127,10 @@ async function handleMcpRequest(
   }
 
   // Create new session and handle this initializing request
-  const { transport } = mcpService.createSession(userId);
-  logger.log(`New MCP session created for user ${userId}`);
+  const { transport } = mcpService.createSession(actor);
+  logger.log(
+    `New MCP session created for actor=${actor.userId} tenant=${actor.tenantId} correlation=${actor.correlationId}`,
+  );
 
   await transport.handleRequest(req.raw, reply.raw, body);
 }

apps/gateway/src/mcp/mcp.service.spec.ts

@@ -0,0 +1,461 @@
+import { describe, expect, it, vi } from 'vitest';
+import type { z } from 'zod';
+import type { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
+import type { Brain } from '@mosaicstack/brain';
+import type { Memory } from '@mosaicstack/memory';
+import type { EmbeddingService } from '../memory/embedding.service.js';
+import type { CoordService } from '../coord/coord.service.js';
+import {
+  assertMcpToolAuthorized,
+  createMcpActorContext,
+  deriveMcpToolScopesForUser,
+  MCP_TOOL_SCOPES,
+  McpService,
+  type McpToolName,
+} from './mcp.service.js';
+
+type ToolResult = { content: Array<{ type: 'text'; text: string }> };
+type ToolHandler = (params: Record<string, unknown>) => Promise<ToolResult>;
+
+interface CapturedTool {
+  inputSchema: z.ZodType;
+  handler: ToolHandler;
+}
+
+function makeCapturingServer(): { server: McpServer; tools: Map<string, CapturedTool> } {
+  const tools = new Map<string, CapturedTool>();
+  const server = {
+    registerTool(name: string, config: { inputSchema: z.ZodType }, handler: ToolHandler): void {
+      tools.set(name, { inputSchema: config.inputSchema, handler });
+    },
+  };
+  return { server: server as unknown as McpServer, tools };
+}
+
+function makeService(opts?: {
+  projects?: Array<Record<string, unknown> & { id: string; ownerId?: string | null }>;
+  missions?: Array<
+    Record<string, unknown> & { id: string; projectId?: string | null; userId?: string | null }
+  >;
+  tasks?: Array<
+    Record<string, unknown> & {
+      id: string;
+      projectId?: string | null;
+      missionId?: string | null;
+      status?: string;
+    }
+  >;
+}) {
+  const projects = opts?.projects ?? [];
+  const missions = opts?.missions ?? [];
+  const tasks = opts?.tasks ?? [];
+  const brain = {
+    projects: {
+      findAll: vi.fn(async () => projects),
+      findById: vi.fn(async (id: string) => projects.find((project) => project.id === id) ?? null),
+    },
+    tasks: {
+      findAll: vi.fn(async () => tasks),
+      findById: vi.fn(async (id: string) => tasks.find((task) => task.id === id) ?? null),
+      findByProject: vi.fn(async (projectId: string) =>
+        tasks.filter((task) => task.projectId === projectId),
+      ),
+      findByMission: vi.fn(async (missionId: string) =>
+        tasks.filter((task) => task.missionId === missionId),
+      ),
+      findByStatus: vi.fn(async (status: string) => tasks.filter((task) => task.status === status)),
+      create: vi.fn(async (task: Record<string, unknown>) => ({ id: 'task-1', ...task })),
+      update: vi.fn(async (id: string, updates: Record<string, unknown>) => ({ id, ...updates })),
+    },
+    missions: {
+      findAll: vi.fn(async () => missions),
+      findById: vi.fn(async (id: string) => missions.find((mission) => mission.id === id) ?? null),
+      findByProject: vi.fn(async (projectId: string) =>
+        missions.filter((mission) => mission.projectId === projectId),
+      ),
+    },
+    conversations: {
+      findAll: vi.fn(async (userId: string) => [{ id: 'conversation-1', userId }]),
+    },
+  } as unknown as Brain;
+
+  const memory = {
+    insights: {
+      searchByEmbedding: vi.fn(async (userId: string) => [{ id: 'insight-1', userId }]),
+      create: vi.fn(async (insight: Record<string, unknown>) => ({ id: 'insight-2', ...insight })),
+    },
+    preferences: {
+      findByUser: vi.fn(async (userId: string) => [{ key: 'theme', userId }]),
+      findByUserAndCategory: vi.fn(async (userId: string, category: string) => [
+        { key: 'theme', userId, category },
+      ]),
+      upsert: vi.fn(async (preference: Record<string, unknown>) => ({
+        id: 'pref-1',
+        ...preference,
+      })),
+    },
+  } as unknown as Memory;
+
+  const embeddings = {
+    available: true,
+    embed: vi.fn(async () => [0.1, 0.2, 0.3]),
+  } as unknown as EmbeddingService;
+
+  const coord = {
+    getMissionStatus: vi.fn(async () => null),
+    listTasks: vi.fn(async () => []),
+    getTaskStatus: vi.fn(async () => null),
+  } as unknown as CoordService;
+
+  return {
+    service: new McpService(brain, memory, embeddings, coord),
+    brain: brain as unknown as {
+      conversations: { findAll: ReturnType<typeof vi.fn> };
+      tasks: {
+        create: ReturnType<typeof vi.fn>;
+        update: ReturnType<typeof vi.fn>;
+      };
+    },
+    memory: memory as unknown as {
+      insights: { searchByEmbedding: ReturnType<typeof vi.fn> };
+    },
+    coord: coord as unknown as {
+      listTasks: ReturnType<typeof vi.fn>;
+    },
+  };
+}
+
+function getTool(tools: Map<string, CapturedTool>, name: McpToolName): CapturedTool {
+  const tool = tools.get(name);
+  if (!tool) throw new Error(`Missing captured tool ${name}`);
+  return tool;
+}
+
+function makeMemberActor(userId = 'authenticated-user') {
+  return createMcpActorContext({
+    userId,
+    role: 'member',
+    scopes: deriveMcpToolScopesForUser({ role: 'member' }),
+  });
+}
+
+function makeAdminActor(userId = 'admin-user', tenantId?: string) {
+  return createMcpActorContext({
+    userId,
+    tenantId,
+    role: 'admin',
+    scopes: deriveMcpToolScopesForUser({ role: 'admin' }),
+  });
+}
+
+function makePlatformAdminActor(userId = 'platform-admin-user') {
+  return createMcpActorContext({
+    userId,
+    role: 'platform-admin',
+    scopes: deriveMcpToolScopesForUser({ role: 'platform-admin' }),
+  });
+}
+
+describe('MCP actor identity and tool scope enforcement', () => {
+  it('derives immutable actor, tenant, channel, correlation, and explicit tool scopes server-side', () => {
+    const actor = createMcpActorContext({
+      userId: ' user-authenticated ',
+      role: 'member',
+      scopes: deriveMcpToolScopesForUser({ role: 'member' }),
+    });
+
+    expect(actor.userId).toBe('user-authenticated');
+    expect(actor.tenantId).toBe('user:user-authenticated');
+    expect(actor.role).toBe('member');
+    expect(actor.channel).toBe('mcp');
+    expect(actor.correlationId).toMatch(/[0-9a-f-]{36}/i);
+    expect(actor.scopes.has(MCP_TOOL_SCOPES.memory_search)).toBe(true);
+    expect(actor.scopes.has(MCP_TOOL_SCOPES.coord_list_tasks)).toBe(false);
+    expect(
+      deriveMcpToolScopesForUser({ role: 'admin' }).has(MCP_TOOL_SCOPES.coord_list_tasks),
+    ).toBe(false);
+    expect(
+      deriveMcpToolScopesForUser({ role: 'platform-admin' }).has(MCP_TOOL_SCOPES.coord_list_tasks),
+    ).toBe(true);
+  });
+
+  it('fails closed when scopes are not supplied by the authenticated context policy', () => {
+    const actor = createMcpActorContext({ userId: 'user-authenticated' });
+
+    expect(actor.scopes.size).toBe(0);
+    expect(() => assertMcpToolAuthorized(actor, 'memory_search', { query: 'notes' })).toThrow(
+      'MCP tool scope denied: memory:insight:read',
+    );
+  });
+
+  it('fails closed when a tool caller supplies actor or tenant identity fields', () => {
+    const actor = createMcpActorContext({ userId: 'user-authenticated' });
+
+    expect(() =>
+      assertMcpToolAuthorized(actor, 'memory_search', {
+        userId: 'victim-user',
+        query: 'private data',
+      }),
+    ).toThrow('MCP caller-controlled identity field is forbidden: userId');
+
+    expect(() =>
+      assertMcpToolAuthorized(actor, 'coord_list_tasks', {
+        tenantId: 'victim-tenant',
+        projectPath: '/tmp/project',
+      }),
+    ).toThrow('MCP caller-controlled identity field is forbidden: tenantId');
+
+    expect(() =>
+      assertMcpToolAuthorized(actor, 'brain_create_task', {
+        title: 'forged org',
+        organizationId: 'victim-org',
+      }),
+    ).toThrow('MCP caller-controlled identity field is forbidden: organizationId');
+
+    expect(() =>
+      assertMcpToolAuthorized(actor, 'brain_update_task', {
+        title: 'forged team',
+        teamId: 'victim-team',
+      }),
+    ).toThrow('MCP caller-controlled identity field is forbidden: teamId');
+  });
+
+  it('fails closed when the server-derived actor lacks the required per-tool scope', () => {
+    const actor = createMcpActorContext({ userId: 'user-authenticated', scopes: [] });
+
+    expect(() => assertMcpToolAuthorized(actor, 'memory_search', { query: 'notes' })).toThrow(
+      'MCP tool scope denied: memory:insight:read',
+    );
+  });
+
+  it('removes caller-controlled userId from memory schemas and never queries victim memory', async () => {
+    const { service, memory } = makeService();
+    const { server, tools } = makeCapturingServer();
+    const actor = makeMemberActor('authenticated-user');
+
+    service.registerTools(server, actor);
+    const tool = getTool(tools, 'memory_search');
+
+    expect(tool.inputSchema.safeParse({ userId: 'victim-user', query: 'anything' }).success).toBe(
+      false,
+    );
+    await expect(tool.handler({ userId: 'victim-user', query: 'anything' })).rejects.toThrow(
+      'MCP caller-controlled identity field is forbidden: userId',
+    );
+    expect(memory.insights.searchByEmbedding).not.toHaveBeenCalled();
+
+    await tool.handler({ query: 'only my notes' });
+    expect(memory.insights.searchByEmbedding).toHaveBeenCalledWith(
+      'authenticated-user',
+      [0.1, 0.2, 0.3],
+      5,
+    );
+  });
+
+  it('binds conversation listing to the authenticated actor instead of a caller-supplied userId', async () => {
+    const { service, brain } = makeService();
+    const { server, tools } = makeCapturingServer();
+    const actor = makeMemberActor('authenticated-user');
+
+    service.registerTools(server, actor);
+    const tool = getTool(tools, 'brain_list_conversations');
+
+    expect(tool.inputSchema.safeParse({ userId: 'victim-user' }).success).toBe(false);
+    await expect(tool.handler({ userId: 'victim-user' })).rejects.toThrow(
+      'MCP caller-controlled identity field is forbidden: userId',
+    );
+    expect(brain.conversations.findAll).not.toHaveBeenCalled();
+
+    await tool.handler({});
+    expect(brain.conversations.findAll).toHaveBeenCalledWith('authenticated-user');
+  });
+
+  it('scopes brain project, mission, and task reads to the authenticated actor', async () => {
+    const { service } = makeService({
+      projects: [
+        { id: 'project-owned', ownerId: 'authenticated-user', name: 'owned' },
+        { id: 'project-victim', ownerId: 'victim-user', name: 'victim' },
+      ],
+      missions: [
+        { id: 'mission-owned', projectId: 'project-owned' },
+        { id: 'mission-victim', userId: 'victim-user', projectId: 'project-victim' },
+      ],
+      tasks: [
+        { id: 'task-owned-project', projectId: 'project-owned', status: 'not-started' },
+        { id: 'task-owned-mission', missionId: 'mission-owned', status: 'not-started' },
+        { id: 'task-victim-project', projectId: 'project-victim', status: 'not-started' },
+        { id: 'task-unowned', status: 'not-started' },
+      ],
+    });
+    const { server, tools } = makeCapturingServer();
+    const actor = makeMemberActor('authenticated-user');
+
+    service.registerTools(server, actor);
+
+    const projects = JSON.parse(
+      (await getTool(tools, 'brain_list_projects').handler({})).content[0]!.text,
+    );
+    expect(projects.map((project: { id: string }) => project.id)).toEqual(['project-owned']);
+
+    const missions = JSON.parse(
+      (await getTool(tools, 'brain_list_missions').handler({})).content[0]!.text,
+    );
+    expect(missions.map((mission: { id: string }) => mission.id)).toEqual(['mission-owned']);
+
+    const tasks = JSON.parse(
+      (await getTool(tools, 'brain_list_tasks').handler({})).content[0]!.text,
+    );
+    expect(tasks.map((task: { id: string }) => task.id)).toEqual([
+      'task-owned-project',
+      'task-owned-mission',
+    ]);
+  });
+
+  it('enforces tenant boundaries for tenant-admin brain project, mission, and task reads', async () => {
+    const { service } = makeService({
+      projects: [
+        {
+          id: 'project-tenant-a',
+          ownerId: 'other-user-a',
+          teamId: 'tenant-a',
+          name: 'same tenant',
+        },
+        {
+          id: 'project-tenant-b',
+          ownerId: 'other-user-b',
+          teamId: 'tenant-b',
+          name: 'other tenant',
+        },
+      ],
+      missions: [
+        { id: 'mission-tenant-a', tenantId: 'tenant-a', projectId: 'project-tenant-a' },
+        { id: 'mission-tenant-b', tenantId: 'tenant-b', projectId: 'project-tenant-b' },
+      ],
+      tasks: [
+        { id: 'task-tenant-a', projectId: 'project-tenant-a', status: 'not-started' },
+        { id: 'task-tenant-b', projectId: 'project-tenant-b', status: 'not-started' },
+      ],
+    });
+    const { server, tools } = makeCapturingServer();
+    const actor = makeAdminActor('tenant-admin-user', 'tenant-a');
+
+    service.registerTools(server, actor);
+
+    const projects = JSON.parse(
+      (await getTool(tools, 'brain_list_projects').handler({})).content[0]!.text,
+    );
+    expect(projects.map((project: { id: string }) => project.id)).toEqual(['project-tenant-a']);
+
+    const missions = JSON.parse(
+      (await getTool(tools, 'brain_list_missions').handler({})).content[0]!.text,
+    );
+    expect(missions.map((mission: { id: string }) => mission.id)).toEqual(['mission-tenant-a']);
+
+    const tasks = JSON.parse(
+      (await getTool(tools, 'brain_list_tasks').handler({})).content[0]!.text,
+    );
+    expect(tasks.map((task: { id: string }) => task.id)).toEqual(['task-tenant-a']);
+  });
+
+  it('denies tenant-admin task writes outside the authenticated tenant', async () => {
+    const { service, brain } = makeService({
+      projects: [
+        { id: 'project-tenant-a', ownerId: 'other-user-a', teamId: 'tenant-a' },
+        { id: 'project-tenant-b', ownerId: 'other-user-b', teamId: 'tenant-b' },
+      ],
+      missions: [
+        { id: 'mission-tenant-a', tenantId: 'tenant-a', projectId: 'project-tenant-a' },
+        { id: 'mission-tenant-b', tenantId: 'tenant-b', projectId: 'project-tenant-b' },
+      ],
+      tasks: [
+        { id: 'task-tenant-a', projectId: 'project-tenant-a', status: 'not-started' },
+        { id: 'task-tenant-b', projectId: 'project-tenant-b', status: 'not-started' },
+      ],
+    });
+    const { server, tools } = makeCapturingServer();
+    const actor = makeAdminActor('tenant-admin-user', 'tenant-a');
+
+    service.registerTools(server, actor);
+
+    await expect(
+      getTool(tools, 'brain_create_task').handler({
+        title: 'unscoped tenant write',
+      }),
+    ).rejects.toThrow('MCP task scope denied');
+    expect(brain.tasks.create).not.toHaveBeenCalled();
+
+    await expect(
+      getTool(tools, 'brain_create_task').handler({
+        title: 'cross-tenant write',
+        projectId: 'project-tenant-b',
+      }),
+    ).rejects.toThrow('MCP task project scope denied');
+    expect(brain.tasks.create).not.toHaveBeenCalled();
+
+    await expect(
+      getTool(tools, 'brain_update_task').handler({
+        id: 'task-tenant-a',
+        projectId: 'project-tenant-b',
+      }),
+    ).rejects.toThrow('MCP task project scope denied');
+    expect(brain.tasks.update).not.toHaveBeenCalled();
+
+    const updateResult = await getTool(tools, 'brain_update_task').handler({
+      id: 'task-tenant-b',
+      title: 'cross-tenant update',
+    });
+    expect(updateResult.content[0]!.text).toBe('Task not found: task-tenant-b');
+    expect(brain.tasks.update).not.toHaveBeenCalled();
+
+    await getTool(tools, 'brain_create_task').handler({
+      title: 'same-tenant write',
+      projectId: 'project-tenant-a',
+    });
+    expect(brain.tasks.create).toHaveBeenCalledWith(
+      expect.objectContaining({ projectId: 'project-tenant-a', title: 'same-tenant write' }),
+    );
+  });
+
+  it('keeps admin-only coordination tools on server-derived paths', async () => {
+    const { service, coord } = makeService();
+    const { server, tools } = makeCapturingServer();
+    const member = makeMemberActor('authenticated-user');
+    const tenantAdmin = makeAdminActor('admin-user');
+    const platformAdmin = makePlatformAdminActor('platform-admin-user');
+
+    service.registerTools(server, member);
+    const memberTool = getTool(tools, 'coord_list_tasks');
+    expect(memberTool.inputSchema.safeParse({ projectPath: '/tmp/victim' }).success).toBe(false);
+    await expect(memberTool.handler({})).rejects.toThrow('MCP tool scope denied: coord:read');
+
+    tools.clear();
+    service.registerTools(server, tenantAdmin);
+    const tenantAdminTool = getTool(tools, 'coord_list_tasks');
+    await expect(tenantAdminTool.handler({})).rejects.toThrow('MCP tool scope denied: coord:read');
+
+    tools.clear();
+    service.registerTools(server, platformAdmin);
+    const platformAdminTool = getTool(tools, 'coord_list_tasks');
+    await platformAdminTool.handler({ projectPath: '/tmp/victim' });
+    expect(coord.listTasks).toHaveBeenCalledWith(process.cwd());
+  });
+
+  it('does not attach a guessed or stale-scope MCP session to another authenticated context', async () => {
+    const { service } = makeService();
+    const owner = makeMemberActor('owner-user');
+    const attacker = makeMemberActor('attacker-user');
+    const admin = makeAdminActor('admin-user');
+    const downgradedAdmin = makeMemberActor('admin-user');
+
+    const { sessionId, transport } = service.createSession(owner);
+    const staleSession = service.createSession(admin);
+
+    expect(service.getSession(sessionId, owner)).toBe(transport);
+    expect(service.getSession(sessionId, attacker)).toBeNull();
+    expect(service.getSession(sessionId, owner)).toBe(transport);
+    expect(service.getSession(staleSession.sessionId, downgradedAdmin)).toBeNull();
+    expect(service.getSession(staleSession.sessionId, admin)).toBe(staleSession.transport);
+
+    await service.onModuleDestroy();
+  });
+});

apps/gateway/src/mcp/mcp.service.ts

@@ -10,11 +10,216 @@ import { MEMORY } from '../memory/memory.tokens.js';
 import { EmbeddingService } from '../memory/embedding.service.js';
 import { CoordService } from '../coord/coord.service.js';
 
+export const MCP_CALLER_IDENTITY_FIELDS = [
+  'actorId',
+  'actor',
+  'authenticatedUserId',
+  'channel',
+  'organizationId',
+  'ownerId',
+  'sessionUserId',
+  'teamId',
+  'tenant',
+  'tenantId',
+  'user',
+  'userId',
+] as const;
+
+type McpCallerIdentityField = (typeof MCP_CALLER_IDENTITY_FIELDS)[number];
+
+export const MCP_TOOL_SCOPES = {
+  brain_list_projects: 'brain:project:read',
+  brain_get_project: 'brain:project:read',
+  brain_list_tasks: 'brain:task:read',
+  brain_create_task: 'brain:task:write',
+  brain_update_task: 'brain:task:write',
+  brain_list_missions: 'brain:mission:read',
+  brain_list_conversations: 'brain:conversation:read',
+  memory_search: 'memory:insight:read',
+  memory_get_preferences: 'memory:preference:read',
+  memory_save_preference: 'memory:preference:write',
+  memory_save_insight: 'memory:insight:write',
+  coord_mission_status: 'coord:read',
+  coord_list_tasks: 'coord:read',
+  coord_task_detail: 'coord:read',
+} as const;
+
+export type McpToolName = keyof typeof MCP_TOOL_SCOPES;
+export type McpToolScope = (typeof MCP_TOOL_SCOPES)[McpToolName];
+
+export interface McpActorContext {
+  userId: string;
+  tenantId: string;
+  role: string;
+  channel: 'mcp';
+  correlationId: string;
+  scopes: ReadonlySet<McpToolScope>;
+}
+
 interface SessionEntry {
   server: McpServer;
   transport: StreamableHTTPServerTransport;
   createdAt: Date;
+  actor: McpActorContext;
+}
+
+const GLOBAL_ADMIN_MCP_SCOPES = new Set<McpToolScope>(Object.values(MCP_TOOL_SCOPES));
+const TENANT_ADMIN_MCP_SCOPES = new Set<McpToolScope>([
+  MCP_TOOL_SCOPES.brain_list_projects,
+  MCP_TOOL_SCOPES.brain_get_project,
+  MCP_TOOL_SCOPES.brain_list_tasks,
+  MCP_TOOL_SCOPES.brain_create_task,
+  MCP_TOOL_SCOPES.brain_update_task,
+  MCP_TOOL_SCOPES.brain_list_missions,
+  MCP_TOOL_SCOPES.brain_list_conversations,
+  MCP_TOOL_SCOPES.memory_search,
+  MCP_TOOL_SCOPES.memory_get_preferences,
+  MCP_TOOL_SCOPES.memory_save_preference,
+  MCP_TOOL_SCOPES.memory_save_insight,
+]);
+const MEMBER_MCP_SCOPES = new Set<McpToolScope>([
+  MCP_TOOL_SCOPES.brain_list_projects,
+  MCP_TOOL_SCOPES.brain_get_project,
+  MCP_TOOL_SCOPES.brain_list_tasks,
+  MCP_TOOL_SCOPES.brain_list_missions,
+  MCP_TOOL_SCOPES.brain_list_conversations,
+  MCP_TOOL_SCOPES.memory_search,
+  MCP_TOOL_SCOPES.memory_get_preferences,
+  MCP_TOOL_SCOPES.memory_save_preference,
+  MCP_TOOL_SCOPES.memory_save_insight,
+]);
+
+export function deriveMcpToolScopesForUser(input: {
+  role?: string | null;
+}): ReadonlySet<McpToolScope> {
+  if (input.role === 'platform-admin' || input.role === 'super-admin') {
+    return new Set(GLOBAL_ADMIN_MCP_SCOPES);
+  }
+  if (input.role === 'admin') {
+    return new Set(TENANT_ADMIN_MCP_SCOPES);
+  }
+  return new Set(MEMBER_MCP_SCOPES);
+}
+
+export function createMcpActorContext(input: {
   userId: string;
+  tenantId?: string;
+  role?: string | null;
+  scopes?: Iterable<McpToolScope>;
+  correlationId?: string;
+}): McpActorContext {
+  const userId = input.userId.trim();
+  if (userId.length === 0) {
+    throw new Error('MCP authenticated user is required');
+  }
+
+  return {
+    userId,
+    tenantId: input.tenantId?.trim() || `user:${userId}`,
+    role: input.role ?? 'member',
+    channel: 'mcp',
+    correlationId: input.correlationId ?? randomUUID(),
+    scopes: new Set(input.scopes ?? []),
+  };
+}
+
+export function assertNoCallerControlledIdentity(params: unknown): void {
+  if (params === null || typeof params !== 'object') return;
+
+  const keys = new Set(Object.keys(params));
+  const forbidden = MCP_CALLER_IDENTITY_FIELDS.find((field: McpCallerIdentityField) =>
+    keys.has(field),
+  );
+  if (forbidden) {
+    throw new Error(`MCP caller-controlled identity field is forbidden: ${forbidden}`);
+  }
+}
+
+export function assertMcpToolAuthorized(
+  actor: McpActorContext,
+  toolName: McpToolName,
+  params: unknown,
+): void {
+  assertNoCallerControlledIdentity(params);
+  const requiredScope = MCP_TOOL_SCOPES[toolName];
+  if (!actor.scopes.has(requiredScope)) {
+    throw new Error(`MCP tool scope denied: ${requiredScope}`);
+  }
+}
+
+function strictObject<T extends z.ZodRawShape>(shape: T): z.ZodObject<T> {
+  return z.object(shape).strict();
+}
+
+type TenantScopedLike = {
+  tenantId?: string | null;
+  organizationId?: string | null;
+  teamId?: string | null;
+};
+type ProjectLike = TenantScopedLike & { id: string; ownerId?: string | null };
+type MissionLike = TenantScopedLike & {
+  id: string;
+  projectId?: string | null;
+  userId?: string | null;
+};
+type TaskLike = TenantScopedLike & {
+  projectId?: string | null;
+  missionId?: string | null;
+  userId?: string | null;
+};
+
+function isGlobalAdminActor(actor: McpActorContext): boolean {
+  return actor.role === 'platform-admin' || actor.role === 'super-admin';
+}
+
+function isTenantAdminActor(actor: McpActorContext): boolean {
+  return actor.role === 'admin';
+}
+
+function matchesTenant(actor: McpActorContext, record: TenantScopedLike): boolean {
+  return (
+    record.tenantId === actor.tenantId ||
+    record.organizationId === actor.tenantId ||
+    record.teamId === actor.tenantId
+  );
+}
+
+function filterProjectsForActor<T extends ProjectLike>(actor: McpActorContext, projects: T[]): T[] {
+  if (isGlobalAdminActor(actor)) return projects;
+  return projects.filter(
+    (project) =>
+      project.ownerId === actor.userId ||
+      (isTenantAdminActor(actor) && matchesTenant(actor, project)),
+  );
+}
+
+function filterMissionsByDirectActorScope<T extends MissionLike>(
+  actor: McpActorContext,
+  missions: T[],
+): T[] {
+  if (isGlobalAdminActor(actor)) return missions;
+  return missions.filter(
+    (mission) =>
+      mission.userId === actor.userId ||
+      (isTenantAdminActor(actor) && matchesTenant(actor, mission)),
+  );
+}
+
+function scopesEqual(left: ReadonlySet<McpToolScope>, right: ReadonlySet<McpToolScope>): boolean {
+  if (left.size !== right.size) return false;
+  for (const scope of left) {
+    if (!right.has(scope)) return false;
+  }
+  return true;
+}
+
+function sameActorAuthorization(stored: McpActorContext, current: McpActorContext): boolean {
+  return (
+    stored.userId === current.userId &&
+    stored.tenantId === current.tenantId &&
+    stored.role === current.role &&
+    scopesEqual(stored.scopes, current.scopes)
+  );
 }
 
 @Injectable()
@@ -33,13 +238,18 @@ export class McpService implements OnModuleDestroy {
    * Creates a new MCP session with its own server + transport pair.
    * Returns the transport for use by the controller.
    */
-  createSession(userId: string): { sessionId: string; transport: StreamableHTTPServerTransport } {
+  createSession(actor: McpActorContext): {
+    sessionId: string;
+    transport: StreamableHTTPServerTransport;
+  } {
     const sessionId = randomUUID();
 
     const transport = new StreamableHTTPServerTransport({
       sessionIdGenerator: () => sessionId,
       onsessioninitialized: (id) => {
-        this.logger.log(`MCP session initialized: ${id} for user ${userId}`);
+        this.logger.log(
+          `MCP session initialized: ${id} for actor=${actor.userId} tenant=${actor.tenantId} correlation=${actor.correlationId}`,
+        );
       },
     });
 
@@ -48,7 +258,7 @@ export class McpService implements OnModuleDestroy {
       { capabilities: { tools: {} } },
     );
 
-    this.registerTools(server, userId);
+    this.registerTools(server, actor);
 
     transport.onclose = () => {
       this.logger.log(`MCP session closed: ${sessionId}`);
@@ -61,31 +271,126 @@ export class McpService implements OnModuleDestroy {
       );
     });
 
-    this.sessions.set(sessionId, { server, transport, createdAt: new Date(), userId });
+    this.sessions.set(sessionId, { server, transport, createdAt: new Date(), actor });
     return { sessionId, transport };
   }
 
   /**
-   * Returns the transport for an existing session, or null if not found.
+   * Returns the transport for an existing session only when it belongs to the
+   * currently authenticated MCP actor. Guessed or cross-tenant session IDs grant
+   * no authority.
    */
-  getSession(sessionId: string): StreamableHTTPServerTransport | null {
-    return this.sessions.get(sessionId)?.transport ?? null;
+  getSession(sessionId: string, actor: McpActorContext): StreamableHTTPServerTransport | null {
+    const entry = this.sessions.get(sessionId);
+    if (!entry) return null;
+    if (!sameActorAuthorization(entry.actor, actor)) {
+      this.logger.warn(
+        `MCP session actor or scope mismatch: session=${sessionId} actor=${actor.userId} tenant=${actor.tenantId} role=${actor.role}`,
+      );
+      return null;
+    }
+    return entry.transport;
+  }
+
+  private async isProjectAuthorized(actor: McpActorContext, projectId: string): Promise<boolean> {
+    if (isGlobalAdminActor(actor)) return true;
+    const project = (await this.brain.projects.findById(projectId)) as ProjectLike | undefined;
+    return project ? filterProjectsForActor(actor, [project]).length === 1 : false;
+  }
+
+  private async filterMissionsForActor<T extends MissionLike>(
+    actor: McpActorContext,
+    missions: T[],
+  ): Promise<T[]> {
+    if (isGlobalAdminActor(actor)) return missions;
+
+    const projects = (await this.brain.projects.findAll()) as ProjectLike[];
+    const projectIds = new Set(
+      filterProjectsForActor(actor, projects).map((project) => project.id),
+    );
+
+    return missions.filter(
+      (mission) =>
+        filterMissionsByDirectActorScope(actor, [mission]).length === 1 ||
+        (typeof mission.projectId === 'string' && projectIds.has(mission.projectId)),
+    );
+  }
+
+  private async isMissionAuthorized(actor: McpActorContext, missionId: string): Promise<boolean> {
+    if (isGlobalAdminActor(actor)) return true;
+    const mission = (await this.brain.missions.findById(missionId)) as MissionLike | undefined;
+    if (!mission) return false;
+    return (await this.filterMissionsForActor(actor, [mission])).length === 1;
+  }
+
+  private async assertTaskReferencesAuthorized(
+    actor: McpActorContext,
+    refs: { projectId?: string | null; missionId?: string | null },
+  ): Promise<void> {
+    if (refs.projectId && !(await this.isProjectAuthorized(actor, refs.projectId))) {
+      throw new Error('MCP task project scope denied');
+    }
+    if (refs.missionId && !(await this.isMissionAuthorized(actor, refs.missionId))) {
+      throw new Error('MCP task mission scope denied');
+    }
+  }
+
+  private async assertTaskCreateScopeAuthorized(
+    actor: McpActorContext,
+    refs: { projectId?: string | null; missionId?: string | null },
+  ): Promise<void> {
+    if (!isGlobalAdminActor(actor) && !refs.projectId && !refs.missionId) {
+      throw new Error('MCP task scope denied');
+    }
+    await this.assertTaskReferencesAuthorized(actor, refs);
+  }
+
+  private async filterTasksForActor<T extends TaskLike>(
+    actor: McpActorContext,
+    tasks: T[],
+  ): Promise<T[]> {
+    if (isGlobalAdminActor(actor)) return tasks;
+
+    const [projects, missions] = await Promise.all([
+      this.brain.projects.findAll(),
+      this.brain.missions.findAll(),
+    ]);
+    const projectIds = new Set(
+      filterProjectsForActor(actor, projects as ProjectLike[]).map((project) => project.id),
+    );
+    const missionIds = new Set(
+      (await this.filterMissionsForActor(actor, missions as MissionLike[])).map(
+        (mission) => mission.id,
+      ),
+    );
+
+    return tasks.filter(
+      (task) =>
+        task.userId === actor.userId ||
+        (isTenantAdminActor(actor) && matchesTenant(actor, task)) ||
+        (typeof task.projectId === 'string' && projectIds.has(task.projectId)) ||
+        (typeof task.missionId === 'string' && missionIds.has(task.missionId)),
+    );
   }
 
   /**
    * Registers all platform tools on the given McpServer instance.
    */
-  private registerTools(server: McpServer, _userId: string): void {
+  registerTools(server: McpServer, actor: McpActorContext): void {
     // ─── Brain: Project tools ────────────────────────────────────────────
 
     server.registerTool(
       'brain_list_projects',
       {
         description: 'List all projects in the brain.',
-        inputSchema: z.object({}),
+        inputSchema: strictObject({}),
       },
-      async () => {
-        const projects = await this.brain.projects.findAll();
+      async (params) => {
+        assertMcpToolAuthorized(actor, 'brain_list_projects', params);
+        const projects = filterProjectsForActor(
+          actor,
+          (await this.brain.projects.findAll()) as ProjectLike[],
+        );
         return {
           content: [{ type: 'text' as const, text: JSON.stringify(projects, null, 2) }],
         };
@@ -96,17 +401,21 @@ export class McpService implements OnModuleDestroy {
       'brain_get_project',
       {
         description: 'Get a project by ID.',
-        inputSchema: z.object({
+        inputSchema: strictObject({
           id: z.string().describe('Project ID (UUID)'),
         }),
       },
-      async ({ id }) => {
-        const project = await this.brain.projects.findById(id);
+      async ({ id, ...params }) => {
+        assertMcpToolAuthorized(actor, 'brain_get_project', params);
+        const project = (await this.brain.projects.findById(id)) as ProjectLike | undefined;
+        const authorizedProject = project ? filterProjectsForActor(actor, [project])[0] : undefined;
         return {
           content: [
             {
               type: 'text' as const,
-              text: project ? JSON.stringify(project, null, 2) : `Project not found: ${id}`,
+              text: authorizedProject
+                ? JSON.stringify(authorizedProject, null, 2)
+                : `Project not found: ${id}`,
             },
           ],
         };
@@ -119,20 +428,23 @@ export class McpService implements OnModuleDestroy {
       'brain_list_tasks',
       {
         description: 'List tasks, optionally filtered by project, mission, or status.',
-        inputSchema: z.object({
+        inputSchema: strictObject({
           projectId: z.string().optional().describe('Filter by project ID'),
           missionId: z.string().optional().describe('Filter by mission ID'),
           status: z.string().optional().describe('Filter by status'),
         }),
       },
-      async ({ projectId, missionId, status }) => {
+      async (params) => {
+        assertMcpToolAuthorized(actor, 'brain_list_tasks', params);
+        const { projectId, missionId, status } = params;
         type TaskStatus = 'not-started' | 'in-progress' | 'blocked' | 'done' | 'cancelled';
         let tasks;
         if (projectId) tasks = await this.brain.tasks.findByProject(projectId);
         else if (missionId) tasks = await this.brain.tasks.findByMission(missionId);
         else if (status) tasks = await this.brain.tasks.findByStatus(status as TaskStatus);
         else tasks = await this.brain.tasks.findAll();
-        return { content: [{ type: 'text' as const, text: JSON.stringify(tasks, null, 2) }] };
+        const scopedTasks = await this.filterTasksForActor(actor, tasks as TaskLike[]);
+        return { content: [{ type: 'text' as const, text: JSON.stringify(scopedTasks, null, 2) }] };
       },
     );
 
@@ -140,7 +452,7 @@ export class McpService implements OnModuleDestroy {
       'brain_create_task',
       {
         description: 'Create a new task in the brain.',
-        inputSchema: z.object({
+        inputSchema: strictObject({
           title: z.string().describe('Task title'),
           description: z.string().optional().describe('Task description'),
           projectId: z.string().optional().describe('Project ID'),
@@ -149,6 +461,8 @@ export class McpService implements OnModuleDestroy {
         }),
       },
       async (params) => {
+        assertMcpToolAuthorized(actor, 'brain_create_task', params);
+        await this.assertTaskCreateScopeAuthorized(actor, params);
         type Priority = 'low' | 'medium' | 'high' | 'critical';
         const task = await this.brain.tasks.create({
           ...params,
@@ -162,7 +476,7 @@ export class McpService implements OnModuleDestroy {
       'brain_update_task',
       {
         description: 'Update an existing task.',
-        inputSchema: z.object({
+        inputSchema: strictObject({
           id: z.string().describe('Task ID'),
           title: z.string().optional(),
           description: z.string().optional(),
@@ -171,9 +485,17 @@ export class McpService implements OnModuleDestroy {
             .optional()
             .describe('not-started, in-progress, blocked, done, cancelled'),
           priority: z.string().optional(),
+          projectId: z.string().optional().describe('Project ID'),
+          missionId: z.string().optional().describe('Mission ID'),
         }),
       },
       async ({ id, ...updates }) => {
+        assertMcpToolAuthorized(actor, 'brain_update_task', updates);
+        const existing = (await this.brain.tasks.findById(id)) as TaskLike | undefined;
+        if (!existing || (await this.filterTasksForActor(actor, [existing])).length === 0) {
+          return { content: [{ type: 'text' as const, text: `Task not found: ${id}` }] };
+        }
+        await this.assertTaskReferencesAuthorized(actor, updates);
         type TaskStatus = 'not-started' | 'in-progress' | 'blocked' | 'done' | 'cancelled';
         type Priority = 'low' | 'medium' | 'high' | 'critical';
         const task = await this.brain.tasks.update(id, {
@@ -198,14 +520,19 @@ export class McpService implements OnModuleDestroy {
       'brain_list_missions',
       {
         description: 'List all missions, optionally filtered by project.',
-        inputSchema: z.object({
+        inputSchema: strictObject({
           projectId: z.string().optional().describe('Filter by project ID'),
         }),
       },
-      async ({ projectId }) => {
-        const missions = projectId
-          ? await this.brain.missions.findByProject(projectId)
-          : await this.brain.missions.findAll();
+      async (params) => {
+        assertMcpToolAuthorized(actor, 'brain_list_missions', params);
+        const { projectId } = params;
+        const missions = await this.filterMissionsForActor(
+          actor,
+          (projectId
+            ? await this.brain.missions.findByProject(projectId)
+            : await this.brain.missions.findAll()) as MissionLike[],
+        );
         return { content: [{ type: 'text' as const, text: JSON.stringify(missions, null, 2) }] };
       },
     );
@@ -213,13 +540,12 @@ export class McpService implements OnModuleDestroy {
     server.registerTool(
       'brain_list_conversations',
       {
-        description: 'List conversations for a user.',
-        inputSchema: z.object({
-          userId: z.string().describe('User ID'),
-        }),
+        description: 'List conversations for the authenticated MCP actor.',
+        inputSchema: strictObject({}),
       },
-      async ({ userId }) => {
-        const conversations = await this.brain.conversations.findAll(userId);
+      async (params) => {
+        assertMcpToolAuthorized(actor, 'brain_list_conversations', params);
+        const conversations = await this.brain.conversations.findAll(actor.userId);
         return {
           content: [{ type: 'text' as const, text: JSON.stringify(conversations, null, 2) }],
         };
@@ -232,14 +558,15 @@ export class McpService implements OnModuleDestroy {
       'memory_search',
       {
         description:
-          'Search across stored insights and knowledge using natural language. Returns semantically similar results.',
-        inputSchema: z.object({
-          userId: z.string().describe('User ID to search memory for'),
+          'Search stored insights and knowledge for the authenticated MCP actor using natural language.',
+        inputSchema: strictObject({
           query: z.string().describe('Natural language search query'),
           limit: z.number().optional().describe('Max results (default 5)'),
         }),
       },
-      async ({ userId, query, limit }) => {
+      async (params) => {
+        assertMcpToolAuthorized(actor, 'memory_search', params);
+        const { query, limit } = params;
         if (!this.embeddings.available) {
           return {
             content: [
@@ -251,7 +578,11 @@ export class McpService implements OnModuleDestroy {
           };
         }
         const embedding = await this.embeddings.embed(query);
-        const results = await this.memory.insights.searchByEmbedding(userId, embedding, limit ?? 5);
+        const results = await this.memory.insights.searchByEmbedding(
+          actor.userId,
+          embedding,
+          limit ?? 5,
+        );
         return { content: [{ type: 'text' as const, text: JSON.stringify(results, null, 2) }] };
       },
     );
@@ -259,20 +590,21 @@ export class McpService implements OnModuleDestroy {
     server.registerTool(
       'memory_get_preferences',
       {
-        description: 'Retrieve stored preferences for a user.',
-        inputSchema: z.object({
-          userId: z.string().describe('User ID'),
+        description: 'Retrieve stored preferences for the authenticated MCP actor.',
+        inputSchema: strictObject({
           category: z
             .string()
             .optional()
             .describe('Filter by category: communication, coding, workflow, appearance, general'),
         }),
       },
-      async ({ userId, category }) => {
+      async (params) => {
+        assertMcpToolAuthorized(actor, 'memory_get_preferences', params);
+        const { category } = params;
         type Cat = 'communication' | 'coding' | 'workflow' | 'appearance' | 'general';
         const prefs = category
-          ? await this.memory.preferences.findByUserAndCategory(userId, category as Cat)
-          : await this.memory.preferences.findByUser(userId);
+          ? await this.memory.preferences.findByUserAndCategory(actor.userId, category as Cat)
+          : await this.memory.preferences.findByUser(actor.userId);
         return { content: [{ type: 'text' as const, text: JSON.stringify(prefs, null, 2) }] };
       },
     );
@@ -281,9 +613,8 @@ export class McpService implements OnModuleDestroy {
       'memory_save_preference',
       {
         description:
-          'Store a learned user preference (e.g., "prefers tables over paragraphs", "timezone: America/Chicago").',
-        inputSchema: z.object({
-          userId: z.string().describe('User ID'),
+          'Store a learned preference for the authenticated MCP actor (e.g., "prefers tables over paragraphs").',
+        inputSchema: strictObject({
           key: z.string().describe('Preference key'),
           value: z.string().describe('Preference value (JSON string)'),
           category: z
@@ -292,7 +623,9 @@ export class McpService implements OnModuleDestroy {
             .describe('Category: communication, coding, workflow, appearance, general'),
         }),
       },
-      async ({ userId, key, value, category }) => {
+      async (params) => {
+        assertMcpToolAuthorized(actor, 'memory_save_preference', params);
+        const { key, value, category } = params;
         type Cat = 'communication' | 'coding' | 'workflow' | 'appearance' | 'general';
         let parsedValue: unknown;
         try {
@@ -301,7 +634,7 @@ export class McpService implements OnModuleDestroy {
           parsedValue = value;
         }
         const pref = await this.memory.preferences.upsert({
-          userId,
+          userId: actor.userId,
           key,
           value: parsedValue,
           category: (category as Cat) ?? 'general',
@@ -315,9 +648,8 @@ export class McpService implements OnModuleDestroy {
       'memory_save_insight',
       {
         description:
-          'Store a learned insight, decision, or knowledge extracted from the current interaction.',
-        inputSchema: z.object({
-          userId: z.string().describe('User ID'),
+          'Store a learned insight, decision, or knowledge for the authenticated MCP actor.',
+        inputSchema: strictObject({
           content: z.string().describe('The insight or knowledge to store'),
           category: z
             .string()
@@ -325,11 +657,13 @@ export class McpService implements OnModuleDestroy {
             .describe('Category: decision, learning, preference, fact, pattern, general'),
         }),
       },
-      async ({ userId, content, category }) => {
+      async (params) => {
+        assertMcpToolAuthorized(actor, 'memory_save_insight', params);
+        const { content, category } = params;
         type Cat = 'decision' | 'learning' | 'preference' | 'fact' | 'pattern' | 'general';
         const embedding = this.embeddings.available ? await this.embeddings.embed(content) : null;
         const insight = await this.memory.insights.create({
-          userId,
+          userId: actor.userId,
           content,
           embedding,
           source: 'agent',
@@ -346,16 +680,11 @@ export class McpService implements OnModuleDestroy {
       {
         description:
           'Get the current orchestration mission status including milestones, tasks, and active session.',
-        inputSchema: z.object({
-          projectPath: z
-            .string()
-            .optional()
-            .describe('Project path. Defaults to gateway working directory.'),
-        }),
+        inputSchema: strictObject({}),
       },
-      async ({ projectPath }) => {
-        const resolvedPath = projectPath ?? process.cwd();
-        const status = await this.coordService.getMissionStatus(resolvedPath);
+      async (params) => {
+        assertMcpToolAuthorized(actor, 'coord_mission_status', params);
+        const status = await this.coordService.getMissionStatus(process.cwd());
         return {
           content: [
             {
@@ -371,16 +700,11 @@ export class McpService implements OnModuleDestroy {
       'coord_list_tasks',
       {
         description: 'List all tasks from the orchestration TASKS.md file.',
-        inputSchema: z.object({
-          projectPath: z
-            .string()
-            .optional()
-            .describe('Project path. Defaults to gateway working directory.'),
-        }),
+        inputSchema: strictObject({}),
       },
-      async ({ projectPath }) => {
-        const resolvedPath = projectPath ?? process.cwd();
-        const tasks = await this.coordService.listTasks(resolvedPath);
+      async (params) => {
+        assertMcpToolAuthorized(actor, 'coord_list_tasks', params);
+        const tasks = await this.coordService.listTasks(process.cwd());
         return { content: [{ type: 'text' as const, text: JSON.stringify(tasks, null, 2) }] };
       },
     );
@@ -389,17 +713,14 @@ export class McpService implements OnModuleDestroy {
       'coord_task_detail',
       {
         description: 'Get detailed status for a specific orchestration task.',
-        inputSchema: z.object({
+        inputSchema: strictObject({
           taskId: z.string().describe('Task ID (e.g. P2-005)'),
-          projectPath: z
-            .string()
-            .optional()
-            .describe('Project path. Defaults to gateway working directory.'),
         }),
       },
-      async ({ taskId, projectPath }) => {
-        const resolvedPath = projectPath ?? process.cwd();
-        const detail = await this.coordService.getTaskStatus(resolvedPath, taskId);
+      async (params) => {
+        assertMcpToolAuthorized(actor, 'coord_task_detail', params);
+        const { taskId } = params;
+        const detail = await this.coordService.getTaskStatus(process.cwd(), taskId);
         return {
           content: [
             {

apps/gateway/src/preferences/system-override.service.ts

@@ -1,9 +1,13 @@
 import { Injectable, Logger } from '@nestjs/common';
 import { createQueue, type QueueHandle } from '@mosaicstack/queue';
+import type { ActorTenantScope } from '../auth/session-scope.js';
 
-const SESSION_SYSTEM_KEY = (sessionId: string) => `mosaic:session:${sessionId}:system`;
-const SESSION_SYSTEM_FRAGMENTS_KEY = (sessionId: string) =>
-  `mosaic:session:${sessionId}:system:fragments`;
+const scopedSessionId = (sessionId: string, scope: ActorTenantScope) =>
+  `${scope.tenantId}:${scope.userId}:${sessionId}`;
+const SESSION_SYSTEM_KEY = (sessionId: string, scope: ActorTenantScope) =>
+  `mosaic:session:${scopedSessionId(sessionId, scope)}:system`;
+const SESSION_SYSTEM_FRAGMENTS_KEY = (sessionId: string, scope: ActorTenantScope) =>
+  `mosaic:session:${scopedSessionId(sessionId, scope)}:system:fragments`;
 const SYSTEM_OVERRIDE_TTL_SECONDS = 604800; // 7 days
 
 interface OverrideFragment {
@@ -20,9 +24,9 @@ export class SystemOverrideService {
     this.handle = createQueue();
   }
 
-  async set(sessionId: string, override: string): Promise<void> {
+  async set(sessionId: string, override: string, scope: ActorTenantScope): Promise<void> {
     // Load existing fragments
-    const existing = await this.handle.redis.get(SESSION_SYSTEM_FRAGMENTS_KEY(sessionId));
+    const existing = await this.handle.redis.get(SESSION_SYSTEM_FRAGMENTS_KEY(sessionId, scope));
     const fragments: OverrideFragment[] = existing
       ? (JSON.parse(existing) as OverrideFragment[])
       : [];
@@ -37,11 +41,11 @@ export class SystemOverrideService {
     // Store both: fragments array and condensed result
     const pipeline = this.handle.redis.pipeline();
     pipeline.setex(
-      SESSION_SYSTEM_FRAGMENTS_KEY(sessionId),
+      SESSION_SYSTEM_FRAGMENTS_KEY(sessionId, scope),
       SYSTEM_OVERRIDE_TTL_SECONDS,
       JSON.stringify(fragments),
     );
-    pipeline.setex(SESSION_SYSTEM_KEY(sessionId), SYSTEM_OVERRIDE_TTL_SECONDS, condensed);
+    pipeline.setex(SESSION_SYSTEM_KEY(sessionId, scope), SYSTEM_OVERRIDE_TTL_SECONDS, condensed);
     await pipeline.exec();
 
     this.logger.debug(
@@ -49,21 +53,21 @@ export class SystemOverrideService {
     );
   }
 
-  async get(sessionId: string): Promise<string | null> {
-    return this.handle.redis.get(SESSION_SYSTEM_KEY(sessionId));
+  async get(sessionId: string, scope: ActorTenantScope): Promise<string | null> {
+    return this.handle.redis.get(SESSION_SYSTEM_KEY(sessionId, scope));
   }
 
-  async renew(sessionId: string): Promise<void> {
+  async renew(sessionId: string, scope: ActorTenantScope): Promise<void> {
     const pipeline = this.handle.redis.pipeline();
-    pipeline.expire(SESSION_SYSTEM_KEY(sessionId), SYSTEM_OVERRIDE_TTL_SECONDS);
-    pipeline.expire(SESSION_SYSTEM_FRAGMENTS_KEY(sessionId), SYSTEM_OVERRIDE_TTL_SECONDS);
+    pipeline.expire(SESSION_SYSTEM_KEY(sessionId, scope), SYSTEM_OVERRIDE_TTL_SECONDS);
+    pipeline.expire(SESSION_SYSTEM_FRAGMENTS_KEY(sessionId, scope), SYSTEM_OVERRIDE_TTL_SECONDS);
     await pipeline.exec();
   }
 
-  async clear(sessionId: string): Promise<void> {
+  async clear(sessionId: string, scope: ActorTenantScope): Promise<void> {
     await this.handle.redis.del(
-      SESSION_SYSTEM_KEY(sessionId),
-      SESSION_SYSTEM_FRAGMENTS_KEY(sessionId),
+      SESSION_SYSTEM_KEY(sessionId, scope),
+      SESSION_SYSTEM_FRAGMENTS_KEY(sessionId, scope),
     );
     this.logger.debug(`Cleared system override for session ${sessionId}`);
   }

packages/types/src/agent/agent-runtime-provider.spec.ts

@@ -0,0 +1,44 @@
+import { describe, expect, it } from 'vitest';
+import type {
+  AgentRuntimeProvider,
+  RuntimeAttachHandle,
+  RuntimeCapability,
+  RuntimeError,
+  RuntimeSession,
+  RuntimeStreamEvent,
+} from './agent-runtime-provider.js';
+
+describe('AgentRuntimeProvider contract', (): void => {
+  it('exposes stable, normalized runtime-only contracts', (): void => {
+    const capability: RuntimeCapability = 'session.attach';
+    const session: RuntimeSession = {
+      id: 'session-1',
+      providerId: 'fleet',
+      runtimeId: 'tmux',
+      state: 'active',
+      createdAt: '2026-07-12T00:00:00.000Z',
+      updatedAt: '2026-07-12T00:00:00.000Z',
+    };
+    const event: RuntimeStreamEvent = {
+      type: 'message.delta',
+      sessionId: session.id,
+      cursor: '2',
+      occurredAt: session.updatedAt,
+      content: 'hello',
+    };
+    const error: RuntimeError = {
+      code: 'capability_unsupported',
+      message: 'Denied',
+      retryable: false,
+    };
+    const attach: RuntimeAttachHandle = {
+      attachmentId: 'attach-1',
+      sessionId: session.id,
+      mode: 'read',
+      expiresAt: session.updatedAt,
+    };
+    const provider: Pick<AgentRuntimeProvider, 'capabilities' | 'getSessionTree' | 'attach'> =
+      {} as Pick<AgentRuntimeProvider, 'capabilities' | 'getSessionTree' | 'attach'>;
+    expect([capability, session.id, event.type, error.code, attach.mode, provider]).toHaveLength(6);
+  });
+});

packages/types/src/agent/agent-runtime-provider.ts

@@ -0,0 +1,110 @@
+export type RuntimeCapability =
+  | 'session.list'
+  | 'session.tree'
+  | 'session.stream'
+  | 'session.send'
+  | 'session.attach'
+  | 'session.terminate';
+export type RuntimeSessionState = 'starting' | 'active' | 'idle' | 'stopped' | 'failed';
+export type RuntimeAttachMode = 'read' | 'control';
+
+/** Server-derived immutable authority context. Client identity fields are intentionally absent. */
+export interface RuntimeScope {
+  readonly actorId: string;
+  readonly tenantId: string;
+  readonly channelId: string;
+  readonly correlationId: string;
+}
+export interface RuntimeSession {
+  id: string;
+  providerId: string;
+  runtimeId: string;
+  parentSessionId?: string;
+  state: RuntimeSessionState;
+  createdAt: string;
+  updatedAt: string;
+}
+export interface RuntimeSessionTree {
+  session: RuntimeSession;
+  children: RuntimeSessionTree[];
+}
+export interface RuntimeCapabilitySet {
+  supported: RuntimeCapability[];
+}
+export interface RuntimeHealth {
+  status: 'healthy' | 'degraded' | 'down';
+  checkedAt: string;
+  detail?: string;
+}
+export interface RuntimeMessage {
+  content: string;
+  idempotencyKey: string;
+}
+export interface RuntimeAttachHandle {
+  attachmentId: string;
+  sessionId: string;
+  mode: RuntimeAttachMode;
+  expiresAt: string;
+}
+export interface RuntimeError {
+  code:
+    | 'capability_unsupported'
+    | 'not_found'
+    | 'forbidden'
+    | 'conflict'
+    | 'unavailable'
+    | 'invalid_request';
+  message: string;
+  retryable: boolean;
+}
+export type RuntimeStreamEvent =
+  | {
+      type: 'session.state';
+      sessionId: string;
+      cursor: string;
+      occurredAt: string;
+      state: RuntimeSessionState;
+    }
+  | {
+      type: 'message.delta';
+      sessionId: string;
+      cursor: string;
+      occurredAt: string;
+      content: string;
+    }
+  | {
+      type: 'message.complete';
+      sessionId: string;
+      cursor: string;
+      occurredAt: string;
+      messageId: string;
+    }
+  | {
+      type: 'runtime.error';
+      sessionId: string;
+      cursor: string;
+      occurredAt: string;
+      error: RuntimeError;
+    };
+
+/** Runtime-neutral boundary; implementations fail closed for unsupported operations. */
+export interface AgentRuntimeProvider {
+  readonly id: string;
+  capabilities(scope: RuntimeScope): Promise<RuntimeCapabilitySet>;
+  health(scope: RuntimeScope): Promise<RuntimeHealth>;
+  listSessions(scope: RuntimeScope): Promise<RuntimeSession[]>;
+  getSessionTree(scope: RuntimeScope): Promise<RuntimeSessionTree[]>;
+  streamSession(
+    sessionId: string,
+    cursor: string | undefined,
+    scope: RuntimeScope,
+  ): AsyncIterable<RuntimeStreamEvent>;
+  sendMessage(sessionId: string, message: RuntimeMessage, scope: RuntimeScope): Promise<void>;
+  attach(
+    sessionId: string,
+    mode: RuntimeAttachMode,
+    scope: RuntimeScope,
+  ): Promise<RuntimeAttachHandle>;
+  detach(attachmentId: string, scope: RuntimeScope): Promise<void>;
+  terminate(sessionId: string, approvalRef: string, scope: RuntimeScope): Promise<void>;
+}

packages/types/src/agent/index.ts

@@ -2,3 +2,5 @@
 export interface AgentSessionHandle {
   readonly id: string;
 }
+
+export * from './agent-runtime-provider.js';

packages/types/src/chat/events.ts

@@ -1,5 +1,6 @@
 import type {
   CommandManifestPayload,
+  SlashCommandApprovalResultPayload,
   SlashCommandPayload,
   SlashCommandResultPayload,
   SystemReloadPayload,
@@ -116,6 +117,7 @@ export interface ServerToClientEvents {
   'session:info': (payload: SessionInfoPayload) => void;
   'commands:manifest': (payload: CommandManifestPayload) => void;
   'command:result': (payload: SlashCommandResultPayload) => void;
+  'command:approval': (payload: SlashCommandApprovalResultPayload) => void;
   'system:reload': (payload: SystemReloadPayload) => void;
   error: (payload: ErrorPayload) => void;
 }
@@ -125,5 +127,6 @@ export interface ClientToServerEvents {
   message: (data: ChatMessagePayload) => void;
   'set:thinking': (data: SetThinkingPayload) => void;
   'command:execute': (data: SlashCommandPayload) => void;
+  'command:approve': (data: SlashCommandPayload) => void;
   abort: (data: AbortPayload) => void;
 }

packages/types/src/commands/index.ts

@@ -63,6 +63,18 @@ export interface SlashCommandPayload {
   conversationId: string;
   command: string;
   args?: string;
+  /** One-time server-issued approval for a privileged command execution. */
+  approvalId?: string;
+}
+
+/** Server response to a request to approve a privileged slash command. */
+export interface SlashCommandApprovalResultPayload {
+  conversationId: string;
+  command: string;
+  success: boolean;
+  approvalId?: string;
+  expiresAt?: string;
+  message?: string;
 }
 
 /** Server response to a slash command */