diff --git a/apps/api/src/app.module.ts b/apps/api/src/app.module.ts
index ee50a1e..23c4cd2 100644
--- a/apps/api/src/app.module.ts
+++ b/apps/api/src/app.module.ts
@@ -39,6 +39,7 @@ import { FederationModule } from "./federation/federation.module";
 import { CredentialsModule } from "./credentials/credentials.module";
 import { MosaicTelemetryModule } from "./mosaic-telemetry";
 import { SpeechModule } from "./speech/speech.module";
+import { DashboardModule } from "./dashboard/dashboard.module";
 import { RlsContextInterceptor } from "./common/interceptors/rls-context.interceptor";
 
 @Module({
@@ -101,6 +102,7 @@ import { RlsContextInterceptor } from "./common/interceptors/rls-context.interce
     CredentialsModule,
     MosaicTelemetryModule,
     SpeechModule,
+    DashboardModule,
   ],
   controllers: [AppController, CsrfController],
   providers: [
diff --git a/apps/api/src/dashboard/dashboard.controller.spec.ts b/apps/api/src/dashboard/dashboard.controller.spec.ts
new file mode 100644
index 0000000..8b3f15c
--- /dev/null
+++ b/apps/api/src/dashboard/dashboard.controller.spec.ts
@@ -0,0 +1,143 @@
+import { describe, it, expect, beforeEach, vi } from "vitest";
+import { Test, TestingModule } from "@nestjs/testing";
+import { DashboardController } from "./dashboard.controller";
+import { DashboardService } from "./dashboard.service";
+import { AuthGuard } from "../auth/guards/auth.guard";
+import { WorkspaceGuard } from "../common/guards/workspace.guard";
+import { PermissionGuard } from "../common/guards/permission.guard";
+import type { DashboardSummaryDto } from "./dto";
+
+describe("DashboardController", () => {
+  let controller: DashboardController;
+  let service: DashboardService;
+
+  const mockWorkspaceId = "550e8400-e29b-41d4-a716-446655440001";
+
+  const mockSummary: DashboardSummaryDto = {
+    metrics: {
+      activeAgents: 3,
+      tasksCompleted: 12,
+      totalTasks: 25,
+      tasksInProgress: 5,
+      activeProjects: 4,
+      errorRate: 2.5,
+    },
+    recentActivity: [
+      {
+        id: "550e8400-e29b-41d4-a716-446655440010",
+        action: "CREATED",
+        entityType: "TASK",
+        entityId: "550e8400-e29b-41d4-a716-446655440011",
+        details: { title: "New task" },
+        userId: "550e8400-e29b-41d4-a716-446655440002",
+        createdAt: "2026-02-22T12:00:00.000Z",
+      },
+    ],
+    activeJobs: [
+      {
+        id: "550e8400-e29b-41d4-a716-446655440020",
+        type: "code-task",
+        status: "RUNNING",
+        progressPercent: 45,
+        createdAt: "2026-02-22T11:00:00.000Z",
+        updatedAt: "2026-02-22T11:30:00.000Z",
+        steps: [
+          {
+            id: "550e8400-e29b-41d4-a716-446655440030",
+            name: "Setup",
+            status: "COMPLETED",
+            phase: "SETUP",
+          },
+        ],
+      },
+    ],
+    tokenBudget: [
+      {
+        model: "agent-1",
+        used: 5000,
+        limit: 10000,
+      },
+    ],
+  };
+
+  const mockDashboardService = {
+    getSummary: vi.fn(),
+  };
+
+  const mockAuthGuard = {
+    canActivate: vi.fn(() => true),
+  };
+
+  const mockWorkspaceGuard = {
+    canActivate: vi.fn(() => true),
+  };
+
+  const mockPermissionGuard = {
+    canActivate: vi.fn(() => true),
+  };
+
+  beforeEach(async () => {
+    const module: TestingModule = await Test.createTestingModule({
+      controllers: [DashboardController],
+      providers: [
+        {
+          provide: DashboardService,
+          useValue: mockDashboardService,
+        },
+      ],
+    })
+      .overrideGuard(AuthGuard)
+      .useValue(mockAuthGuard)
+      .overrideGuard(WorkspaceGuard)
+      .useValue(mockWorkspaceGuard)
+      .overrideGuard(PermissionGuard)
+      .useValue(mockPermissionGuard)
+      .compile();
+
+    controller = module.get<DashboardController>(DashboardController);
+    service = module.get<DashboardService>(DashboardService);
+
+    vi.clearAllMocks();
+  });
+
+  it("should be defined", () => {
+    expect(controller).toBeDefined();
+  });
+
+  describe("getSummary", () => {
+    it("should return dashboard summary for workspace", async () => {
+      mockDashboardService.getSummary.mockResolvedValue(mockSummary);
+
+      const result = await controller.getSummary(mockWorkspaceId);
+
+      expect(result).toEqual(mockSummary);
+      expect(service.getSummary).toHaveBeenCalledWith(mockWorkspaceId);
+    });
+
+    it("should return empty arrays when no data exists", async () => {
+      const emptySummary: DashboardSummaryDto = {
+        metrics: {
+          activeAgents: 0,
+          tasksCompleted: 0,
+          totalTasks: 0,
+          tasksInProgress: 0,
+          activeProjects: 0,
+          errorRate: 0,
+        },
+        recentActivity: [],
+        activeJobs: [],
+        tokenBudget: [],
+      };
+
+      mockDashboardService.getSummary.mockResolvedValue(emptySummary);
+
+      const result = await controller.getSummary(mockWorkspaceId);
+
+      expect(result).toEqual(emptySummary);
+      expect(result.metrics.errorRate).toBe(0);
+      expect(result.recentActivity).toHaveLength(0);
+      expect(result.activeJobs).toHaveLength(0);
+      expect(result.tokenBudget).toHaveLength(0);
+    });
+  });
+});
diff --git a/apps/api/src/dashboard/dashboard.controller.ts b/apps/api/src/dashboard/dashboard.controller.ts
new file mode 100644
index 0000000..58f4454
--- /dev/null
+++ b/apps/api/src/dashboard/dashboard.controller.ts
@@ -0,0 +1,31 @@
+import { Controller, Get, UseGuards } from "@nestjs/common";
+import { DashboardService } from "./dashboard.service";
+import { AuthGuard } from "../auth/guards/auth.guard";
+import { WorkspaceGuard, PermissionGuard } from "../common/guards";
+import { Workspace, Permission, RequirePermission } from "../common/decorators";
+
+/**
+ * Controller for dashboard endpoints.
+ * Returns aggregated summary data for the workspace dashboard.
+ *
+ * Guards are applied in order:
+ * 1. AuthGuard - Verifies user authentication
+ * 2. WorkspaceGuard - Validates workspace access and sets RLS context
+ * 3. PermissionGuard - Checks role-based permissions
+ */
+@Controller("dashboard")
+@UseGuards(AuthGuard, WorkspaceGuard, PermissionGuard)
+export class DashboardController {
+  constructor(private readonly dashboardService: DashboardService) {}
+
+  /**
+   * GET /api/dashboard/summary
+   * Returns aggregated metrics, recent activity, active jobs, and token budgets
+   * Requires: Any workspace member (including GUEST)
+   */
+  @Get("summary")
+  @RequirePermission(Permission.WORKSPACE_ANY)
+  async getSummary(@Workspace() workspaceId: string) {
+    return this.dashboardService.getSummary(workspaceId);
+  }
+}
diff --git a/apps/api/src/dashboard/dashboard.module.ts b/apps/api/src/dashboard/dashboard.module.ts
new file mode 100644
index 0000000..9d54cba
--- /dev/null
+++ b/apps/api/src/dashboard/dashboard.module.ts
@@ -0,0 +1,13 @@
+import { Module } from "@nestjs/common";
+import { DashboardController } from "./dashboard.controller";
+import { DashboardService } from "./dashboard.service";
+import { PrismaModule } from "../prisma/prisma.module";
+import { AuthModule } from "../auth/auth.module";
+
+@Module({
+  imports: [PrismaModule, AuthModule],
+  controllers: [DashboardController],
+  providers: [DashboardService],
+  exports: [DashboardService],
+})
+export class DashboardModule {}
diff --git a/apps/api/src/dashboard/dashboard.service.ts b/apps/api/src/dashboard/dashboard.service.ts
new file mode 100644
index 0000000..96ae855
--- /dev/null
+++ b/apps/api/src/dashboard/dashboard.service.ts
@@ -0,0 +1,187 @@
+import { Injectable } from "@nestjs/common";
+import { AgentStatus, ProjectStatus, RunnerJobStatus, TaskStatus } from "@prisma/client";
+import { PrismaService } from "../prisma/prisma.service";
+import type {
+  DashboardSummaryDto,
+  ActiveJobDto,
+  RecentActivityDto,
+  TokenBudgetEntryDto,
+} from "./dto";
+
+/**
+ * Service for aggregating dashboard summary data.
+ * Executes all queries in parallel to minimize latency.
+ */
+@Injectable()
+export class DashboardService {
+  constructor(private readonly prisma: PrismaService) {}
+
+  /**
+   * Get aggregated dashboard summary for a workspace
+   */
+  async getSummary(workspaceId: string): Promise<DashboardSummaryDto> {
+    const now = new Date();
+    const oneDayAgo = new Date(now.getTime() - 24 * 60 * 60 * 1000);
+
+    // Execute all queries in parallel
+    const [
+      activeAgents,
+      tasksCompleted,
+      totalTasks,
+      tasksInProgress,
+      activeProjects,
+      failedJobsLast24h,
+      totalJobsLast24h,
+      recentActivityRows,
+      activeJobRows,
+      tokenBudgetRows,
+    ] = await Promise.all([
+      // Active agents: IDLE, WORKING, WAITING
+      this.prisma.agent.count({
+        where: {
+          workspaceId,
+          status: { in: [AgentStatus.IDLE, AgentStatus.WORKING, AgentStatus.WAITING] },
+        },
+      }),
+
+      // Tasks completed
+      this.prisma.task.count({
+        where: {
+          workspaceId,
+          status: TaskStatus.COMPLETED,
+        },
+      }),
+
+      // Total tasks
+      this.prisma.task.count({
+        where: { workspaceId },
+      }),
+
+      // Tasks in progress
+      this.prisma.task.count({
+        where: {
+          workspaceId,
+          status: TaskStatus.IN_PROGRESS,
+        },
+      }),
+
+      // Active projects
+      this.prisma.project.count({
+        where: {
+          workspaceId,
+          status: ProjectStatus.ACTIVE,
+        },
+      }),
+
+      // Failed jobs in last 24h (for error rate)
+      this.prisma.runnerJob.count({
+        where: {
+          workspaceId,
+          status: RunnerJobStatus.FAILED,
+          createdAt: { gte: oneDayAgo },
+        },
+      }),
+
+      // Total jobs in last 24h (for error rate)
+      this.prisma.runnerJob.count({
+        where: {
+          workspaceId,
+          createdAt: { gte: oneDayAgo },
+        },
+      }),
+
+      // Recent activity: last 10 entries
+      this.prisma.activityLog.findMany({
+        where: { workspaceId },
+        orderBy: { createdAt: "desc" },
+        take: 10,
+      }),
+
+      // Active jobs: PENDING, QUEUED, RUNNING with steps
+      this.prisma.runnerJob.findMany({
+        where: {
+          workspaceId,
+          status: {
+            in: [RunnerJobStatus.PENDING, RunnerJobStatus.QUEUED, RunnerJobStatus.RUNNING],
+          },
+        },
+        include: {
+          steps: {
+            select: {
+              id: true,
+              name: true,
+              status: true,
+              phase: true,
+            },
+            orderBy: { ordinal: "asc" },
+          },
+        },
+        orderBy: { createdAt: "desc" },
+      }),
+
+      // Token budgets for workspace (active, not yet completed)
+      this.prisma.tokenBudget.findMany({
+        where: {
+          workspaceId,
+          completedAt: null,
+        },
+        select: {
+          agentId: true,
+          totalTokensUsed: true,
+          allocatedTokens: true,
+        },
+      }),
+    ]);
+
+    // Compute error rate
+    const errorRate = totalJobsLast24h > 0 ? (failedJobsLast24h / totalJobsLast24h) * 100 : 0;
+
+    // Map recent activity
+    const recentActivity: RecentActivityDto[] = recentActivityRows.map((row) => ({
+      id: row.id,
+      action: row.action,
+      entityType: row.entityType,
+      entityId: row.entityId,
+      details: row.details,
+      userId: row.userId,
+      createdAt: row.createdAt.toISOString(),
+    }));
+
+    // Map active jobs (RunnerJob lacks updatedAt; use startedAt or createdAt as proxy)
+    const activeJobs: ActiveJobDto[] = activeJobRows.map((row) => ({
+      id: row.id,
+      type: row.type,
+      status: row.status,
+      progressPercent: row.progressPercent,
+      createdAt: row.createdAt.toISOString(),
+      updatedAt: (row.startedAt ?? row.createdAt).toISOString(),
+      steps: row.steps.map((step) => ({
+        id: step.id,
+        name: step.name,
+        status: step.status,
+        phase: step.phase,
+      })),
+    }));
+
+    // Map token budget entries
+    const tokenBudget: TokenBudgetEntryDto[] = tokenBudgetRows.map((row) => ({
+      model: row.agentId,
+      used: row.totalTokensUsed,
+      limit: row.allocatedTokens,
+    }));
+
+    return {
+      metrics: {
+        activeAgents,
+        tasksCompleted,
+        totalTasks,
+        tasksInProgress,
+        activeProjects,
+        errorRate: Math.round(errorRate * 100) / 100,
+      },
+      recentActivity,
+      activeJobs,
+      tokenBudget,
+    };
+  }
+}
diff --git a/apps/api/src/dashboard/dto/dashboard-summary.dto.ts b/apps/api/src/dashboard/dto/dashboard-summary.dto.ts
new file mode 100644
index 0000000..9feef5c
--- /dev/null
+++ b/apps/api/src/dashboard/dto/dashboard-summary.dto.ts
@@ -0,0 +1,53 @@
+/**
+ * Dashboard Summary DTO
+ * Defines the response shape for the dashboard summary endpoint.
+ */
+
+export class DashboardMetricsDto {
+  activeAgents!: number;
+  tasksCompleted!: number;
+  totalTasks!: number;
+  tasksInProgress!: number;
+  activeProjects!: number;
+  errorRate!: number;
+}
+
+export class RecentActivityDto {
+  id!: string;
+  action!: string;
+  entityType!: string;
+  entityId!: string;
+  details!: unknown;
+  userId!: string;
+  createdAt!: string;
+}
+
+export class ActiveJobStepDto {
+  id!: string;
+  name!: string;
+  status!: string;
+  phase!: string;
+}
+
+export class ActiveJobDto {
+  id!: string;
+  type!: string;
+  status!: string;
+  progressPercent!: number;
+  createdAt!: string;
+  updatedAt!: string;
+  steps!: ActiveJobStepDto[];
+}
+
+export class TokenBudgetEntryDto {
+  model!: string;
+  used!: number;
+  limit!: number;
+}
+
+export class DashboardSummaryDto {
+  metrics!: DashboardMetricsDto;
+  recentActivity!: RecentActivityDto[];
+  activeJobs!: ActiveJobDto[];
+  tokenBudget!: TokenBudgetEntryDto[];
+}
diff --git a/apps/api/src/dashboard/dto/index.ts b/apps/api/src/dashboard/dto/index.ts
new file mode 100644
index 0000000..bc6cb94
--- /dev/null
+++ b/apps/api/src/dashboard/dto/index.ts
@@ -0,0 +1 @@
+export * from "./dashboard-summary.dto";