fix(api,web): separate workspace context from auth session (#534)

BetterAuth session responses contain only identity fields — workspace
context (workspaceId, currentWorkspaceId) was never returned, causing
"Workspace ID is required" on every guarded endpoint after login.

Add GET /api/workspaces endpoint (AuthGuard only, no WorkspaceGuard)
that returns user workspace memberships with auto-provisioning for
new users. Frontend auth-context now fetches workspaces after session
check and persists the default to localStorage. Race condition in
auto-provisioning is guarded by re-querying inside the transaction.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/api/src/workspaces/workspaces.service.spec.ts

@@ -0,0 +1,229 @@
+import { describe, it, expect, beforeEach, vi } from "vitest";
+import { Test, TestingModule } from "@nestjs/testing";
+import { WorkspacesService } from "./workspaces.service";
+import { PrismaService } from "../prisma/prisma.service";
+import { WorkspaceMemberRole } from "@prisma/client";
+
+describe("WorkspacesService", () => {
+  let service: WorkspacesService;
+
+  const mockUserId = "550e8400-e29b-41d4-a716-446655440001";
+  const mockWorkspaceId = "550e8400-e29b-41d4-a716-446655440002";
+
+  const mockWorkspace = {
+    id: mockWorkspaceId,
+    name: "Test Workspace",
+    ownerId: mockUserId,
+    settings: {},
+    matrixRoomId: null,
+    createdAt: new Date("2026-01-01"),
+    updatedAt: new Date("2026-01-01"),
+  };
+
+  const mockMembership = {
+    workspaceId: mockWorkspaceId,
+    userId: mockUserId,
+    role: WorkspaceMemberRole.OWNER,
+    joinedAt: new Date("2026-01-01"),
+    workspace: {
+      id: mockWorkspaceId,
+      name: "Test Workspace",
+      ownerId: mockUserId,
+      createdAt: new Date("2026-01-01"),
+    },
+  };
+
+  const mockPrismaService = {
+    workspaceMember: {
+      findMany: vi.fn(),
+      create: vi.fn(),
+    },
+    workspace: {
+      create: vi.fn(),
+    },
+    $transaction: vi.fn(),
+  };
+
+  beforeEach(async () => {
+    const module: TestingModule = await Test.createTestingModule({
+      providers: [
+        WorkspacesService,
+        {
+          provide: PrismaService,
+          useValue: mockPrismaService,
+        },
+      ],
+    }).compile();
+
+    service = module.get<WorkspacesService>(WorkspacesService);
+
+    vi.clearAllMocks();
+  });
+
+  describe("getUserWorkspaces", () => {
+    it("should return all workspaces user is a member of", async () => {
+      mockPrismaService.workspaceMember.findMany.mockResolvedValueOnce([mockMembership]);
+
+      const result = await service.getUserWorkspaces(mockUserId);
+
+      expect(result).toEqual([
+        {
+          id: mockWorkspaceId,
+          name: "Test Workspace",
+          ownerId: mockUserId,
+          role: WorkspaceMemberRole.OWNER,
+          createdAt: mockMembership.workspace.createdAt,
+        },
+      ]);
+      expect(mockPrismaService.workspaceMember.findMany).toHaveBeenCalledWith({
+        where: { userId: mockUserId },
+        include: {
+          workspace: {
+            select: { id: true, name: true, ownerId: true, createdAt: true },
+          },
+        },
+        orderBy: { joinedAt: "asc" },
+      });
+    });
+
+    it("should return multiple workspaces ordered by joinedAt", async () => {
+      const secondWorkspace = {
+        ...mockMembership,
+        workspaceId: "ws-2",
+        role: WorkspaceMemberRole.MEMBER,
+        joinedAt: new Date("2026-02-01"),
+        workspace: {
+          id: "ws-2",
+          name: "Second Workspace",
+          ownerId: "other-user",
+          createdAt: new Date("2026-02-01"),
+        },
+      };
+
+      mockPrismaService.workspaceMember.findMany.mockResolvedValueOnce([
+        mockMembership,
+        secondWorkspace,
+      ]);
+
+      const result = await service.getUserWorkspaces(mockUserId);
+
+      expect(result).toHaveLength(2);
+      expect(result[0].id).toBe(mockWorkspaceId);
+      expect(result[1].id).toBe("ws-2");
+      expect(result[1].role).toBe(WorkspaceMemberRole.MEMBER);
+    });
+
+    it("should auto-provision a default workspace when user has no memberships", async () => {
+      mockPrismaService.workspaceMember.findMany.mockResolvedValueOnce([]);
+      mockPrismaService.$transaction.mockImplementationOnce(
+        async (fn: (tx: typeof mockPrismaService) => Promise<unknown>) => {
+          const txMock = {
+            workspaceMember: {
+              findFirst: vi.fn().mockResolvedValueOnce(null),
+              create: vi.fn().mockResolvedValueOnce({}),
+            },
+            workspace: {
+              create: vi.fn().mockResolvedValueOnce(mockWorkspace),
+            },
+          };
+          return fn(txMock as unknown as typeof mockPrismaService);
+        }
+      );
+
+      const result = await service.getUserWorkspaces(mockUserId);
+
+      expect(result).toHaveLength(1);
+      expect(result[0].name).toBe("Test Workspace");
+      expect(result[0].role).toBe(WorkspaceMemberRole.OWNER);
+      expect(mockPrismaService.$transaction).toHaveBeenCalledTimes(1);
+    });
+
+    it("should return existing workspace if one was created between initial check and transaction", async () => {
+      // Simulates a race condition: initial findMany returns [], but inside the
+      // transaction another request already created a workspace.
+      mockPrismaService.workspaceMember.findMany.mockResolvedValueOnce([]);
+      mockPrismaService.$transaction.mockImplementationOnce(
+        async (fn: (tx: typeof mockPrismaService) => Promise<unknown>) => {
+          const txMock = {
+            workspaceMember: {
+              findFirst: vi.fn().mockResolvedValueOnce(mockMembership),
+            },
+            workspace: {
+              create: vi.fn(),
+            },
+          };
+          return fn(txMock as unknown as typeof mockPrismaService);
+        }
+      );
+
+      const result = await service.getUserWorkspaces(mockUserId);
+
+      expect(result).toHaveLength(1);
+      expect(result[0].id).toBe(mockWorkspaceId);
+      expect(result[0].name).toBe("Test Workspace");
+    });
+
+    it("should create workspace with correct data during auto-provisioning", async () => {
+      mockPrismaService.workspaceMember.findMany.mockResolvedValueOnce([]);
+
+      let capturedWorkspaceData: unknown;
+      let capturedMemberData: unknown;
+
+      mockPrismaService.$transaction.mockImplementationOnce(
+        async (fn: (tx: typeof mockPrismaService) => Promise<unknown>) => {
+          const txMock = {
+            workspaceMember: {
+              findFirst: vi.fn().mockResolvedValueOnce(null),
+              create: vi.fn().mockImplementation((args: unknown) => {
+                capturedMemberData = args;
+                return {};
+              }),
+            },
+            workspace: {
+              create: vi.fn().mockImplementation((args: unknown) => {
+                capturedWorkspaceData = args;
+                return mockWorkspace;
+              }),
+            },
+          };
+          return fn(txMock as unknown as typeof mockPrismaService);
+        }
+      );
+
+      await service.getUserWorkspaces(mockUserId);
+
+      expect(capturedWorkspaceData).toEqual({
+        data: {
+          name: "My Workspace",
+          ownerId: mockUserId,
+          settings: {},
+        },
+      });
+      expect(capturedMemberData).toEqual({
+        data: {
+          workspaceId: mockWorkspaceId,
+          userId: mockUserId,
+          role: WorkspaceMemberRole.OWNER,
+        },
+      });
+    });
+
+    it("should not auto-provision when user already has workspaces", async () => {
+      mockPrismaService.workspaceMember.findMany.mockResolvedValueOnce([mockMembership]);
+
+      await service.getUserWorkspaces(mockUserId);
+
+      expect(mockPrismaService.$transaction).not.toHaveBeenCalled();
+    });
+
+    it("should propagate database errors", async () => {
+      mockPrismaService.workspaceMember.findMany.mockRejectedValueOnce(
+        new Error("Database connection failed")
+      );
+
+      await expect(service.getUserWorkspaces(mockUserId)).rejects.toThrow(
+        "Database connection failed"
+      );
+    });
+  });
+});