fix(teams): prevent concurrent slug collision with sequential retry (#499)

apps/backend/prisma/schema.prisma

@@ -30,8 +30,10 @@ model User {
   viewedCards   CardView[]     @relation("cardViewer")
   followLogs    FollowLog[]
   organizer     Event[]    
-  attendedEvents           EventAttendee[] 
+  attendedEvents EventAttendee[] 
 
+  ownedTeams       Team[]          @relation("TeamOwner")
+  teamMemberships  TeamMember[]    @relation("TeamMember")
 
   @@unique([provider, providerId])
   @@map("users")
@@ -154,4 +156,42 @@ model EventAttendee {
   user User @relation(fields: [userId],references: [id])
 
   @@unique([userId, eventId])
+}
+
+enum TeamRole {
+  OWNER
+  ADMIN
+  MEMBER
+}
+
+model Team{
+  id String @id @default(uuid())
+  name String 
+  slug String @unique
+  description String? 
+  avatarUrl String? 
+  ownerId String 
+  createdAt DateTime @default(now()) 
+  updatedAt DateTime @updatedAt
+
+  owner User @relation("TeamOwner", fields: [ownerId], references: [id], onDelete: Restrict)
+  members TeamMember[] @relation("TeamMember")
+
+  @@map("teams")
+  @@index([slug])
+}
+
+model TeamMember{
+  id String @id @default(uuid())
+  teamId String
+  userId String
+  role TeamRole
+  joinedAt DateTime 
+
+  team Team @relation("TeamMember",fields: [teamId] , references: [id])
+  user User @relation("TeamMember",fields: [userId] , references: [id])
+
+  @@unique([userId, teamId])
+  @@index([userId])
+  @@map("team_members")
 }

apps/backend/src/__tests__/slug.test.ts

@@ -0,0 +1,74 @@
+import { describe, it, expect, vi } from 'vitest';
+
+import { createSlug, generateUniqueSlug } from '../utils/slug';
+
+describe('createSlug', () => {
+  it('lowercases and trims input', () => {
+    expect(createSlug('  Hello World  ')).toBe('hello-world');
+  });
+
+  it('replaces spaces with hyphens', () => {
+    expect(createSlug('My Team Name')).toBe('my-team-name');
+  });
+
+  it('strips non-alphanumeric characters', () => {
+    expect(createSlug('DevCard @Core!')).toBe('devcard-core');
+  });
+
+  it('collapses multiple hyphens', () => {
+    expect(createSlug('a--b---c')).toBe('a-b-c');
+  });
+
+  it('removes leading and trailing hyphens', () => {
+    expect(createSlug('--team--')).toBe('team');
+  });
+});
+
+describe('generateUniqueSlug', () => {
+  it('returns base slug when it is available', async () => {
+    const slugExists = vi.fn().mockResolvedValue(false);
+    const result = await generateUniqueSlug('My Team', slugExists);
+    expect(result).toBe('my-team');
+    expect(slugExists).toHaveBeenCalledOnce();
+  });
+
+  it('returns sequential numeric suffix when base slug is taken', async () => {
+    const slugExists = vi.fn()
+      .mockResolvedValueOnce(true)  // my-team taken
+      .mockResolvedValueOnce(false); // my-team-1 free
+    const result = await generateUniqueSlug('My Team', slugExists);
+    expect(result).toBe('my-team-1');
+  });
+
+  it('increments suffix deterministically until a free slot is found', async () => {
+    const slugExists = vi.fn()
+      .mockResolvedValueOnce(true)  // my-team
+      .mockResolvedValueOnce(true)  // my-team-1
+      .mockResolvedValueOnce(true)  // my-team-2
+      .mockResolvedValueOnce(false); // my-team-3 free
+    const result = await generateUniqueSlug('My Team', slugExists);
+    expect(result).toBe('my-team-3');
+  });
+
+  it('throws when all 10 suffix candidates are taken', async () => {
+    const slugExists = vi.fn().mockResolvedValue(true);
+    await expect(generateUniqueSlug('My Team', slugExists)).rejects.toThrow(
+      'Unable to generate unique slug',
+    );
+    expect(slugExists).toHaveBeenCalledTimes(11); // base + 10 suffixes
+  });
+
+  it('produces consistent slugs across concurrent calls for different inputs', async () => {
+    const takenSlugs = new Set<string>();
+    const slugExists = vi.fn(async (slug: string) => takenSlugs.has(slug));
+
+    const [a, b] = await Promise.all([
+      generateUniqueSlug('Alpha Team', slugExists),
+      generateUniqueSlug('Beta Team', slugExists),
+    ]);
+
+    expect(a).toBe('alpha-team');
+    expect(b).toBe('beta-team');
+    expect(a).not.toBe(b);
+  });
+});