fix(auth): match email addresses case-insensitively everywhere

Login and the OIDC fallback match emails case-insensitively, but the
password reset lookup and the admin create and edit checks compared
exactly. An account stored as Foo@x.com never got a reset mail, and an
admin could create bob@x next to Bob@x, after which login picked
whichever row came first. The signup collision check and the first-user
count also move inside the signup transaction.

server/src/db/repositories/Users.repository.ts

@@ -693,15 +693,15 @@ export class UsersRepository extends TrekRepository<Users> {
   // ---------------------------------------------------------------------
 
   /**
-   * `SELECT id, email, password_hash, oidc_sub FROM users WHERE email = ?
-   *  AND COALESCE(is_guest, 0) = 0` — case-SENSITIVE on `email`, unlike
-   * every other email lookup in this repository (no `LOWER()` in the legacy
-   * statement here); kept exactly as written, not "fixed" to match the
-   * others (parity is law).
+   * `SELECT id, email, password_hash, oidc_sub FROM users WHERE LOWER(email)
+   *  = LOWER(?) AND COALESCE(is_guest, 0) = 0`. Case-insensitive like login:
+   * the caller lowercases the address it was given, and an exact match never
+   * found an account stored as `Foo@x.com`, which then got no reset mail.
    */
   async findForPasswordReset(email: string): Promise<PasswordResetLookup | null> {
+    const platform = this.getEntityManager().getPlatform();
     const row = await this.findOne(
-      { email, is_guest: 0 },
+      { [lower(platform, 'email')]: lowerParam(platform, email), is_guest: 0 },
       { fields: ['id', 'email', 'password_hash', 'oidc_sub'] },
     );
     return row ? { id: row.id, email: row.email, password_hash: row.password_hash, oidc_sub: row.oidc_sub ?? null } : null;
@@ -928,15 +928,22 @@ export class UsersRepository extends TrekRepository<Users> {
   // ---------------------------------------------------------------------
 
   /**
-   * `SELECT id FROM users WHERE LOWER(email) = LOWER(?) AND id != ? AND COALESCE(is_guest, 0) = 0`
+   * `SELECT id FROM users WHERE LOWER(email) = LOWER(?) [AND id != ?] AND COALESCE(is_guest, 0) = 0`
    *
    * Both sides folded by SQLite's own `LOWER()` (`lowerParam` binds the RAW
-   * value) — program rule 18.
+   * value) — program rule 18. Every email collision check goes through here
+   * (profile, admin create and update), because login and the OIDC fallback
+   * match case-insensitively: a second account that differs only in case
+   * would make them pick whichever row comes first.
    */
-  async findIdByEmailCI(email: string, excludeId: number): Promise<number | null> {
+  async findIdByEmailCI(email: string, excludeId?: number): Promise<number | null> {
     const platform = this.getEntityManager().getPlatform();
     const row = await this.findOne(
-      { [lower(platform, 'email')]: lowerParam(platform, email), id: { $ne: excludeId }, is_guest: 0 },
+      {
+        [lower(platform, 'email')]: lowerParam(platform, email),
+        ...(excludeId === undefined ? {} : { id: { $ne: excludeId } }),
+        is_guest: 0,
+      },
       { fields: ['id'] },
     );
     return row?.id ?? null;
@@ -1513,12 +1520,6 @@ export class UsersRepository extends TrekRepository<Users> {
     return row?.id ?? null;
   }
 
-  /** AD3 (`createUser`) — `SELECT id FROM users WHERE email = ? AND COALESCE(is_guest, 0) = 0`. Case-sensitive, same reasoning as {@link findIdByUsernameExact}. */
-  async findIdByEmailExact(email: string): Promise<number | null> {
-    const row = await this.findOne({ email, is_guest: 0 }, { fields: ['id'] });
-    return row?.id ?? null;
-  }
-
   /**
    * AD4 (`createUser`'s write) — `INSERT INTO users (username, email,
    * password_hash, role) VALUES (?, ?, ?, ?)`. Only these four columns are
@@ -1564,12 +1565,6 @@ export class UsersRepository extends TrekRepository<Users> {
     return row?.id ?? null;
   }
 
-  /** AD8 (`updateUser`) — `SELECT id FROM users WHERE email = ? AND id != ? AND COALESCE(is_guest, 0) = 0`. Case-sensitive, excludes self, same reasoning as {@link findIdByUsernameExactExcluding}. */
-  async findIdByEmailExactExcluding(email: string, excludeId: number): Promise<number | null> {
-    const row = await this.findOne({ email, id: { $ne: excludeId }, is_guest: 0 }, { fields: ['id'] });
-    return row?.id ?? null;
-  }
-
   /**
    * AD11 (`updateUser`, inside `uow.transactional` alongside AD12/AD13) —
    * `UPDATE users SET username=COALESCE(?,username), email=COALESCE(?,email),

server/src/nest/admin/admin.service.ts

@@ -170,7 +170,7 @@ export class AdminService {
     const existingUsername = await this.users.findIdByUsernameExact(username);
     if (existingUsername) return { error: 'Username already taken', status: 409 };
 
-    const existingEmail = await this.users.findIdByEmailExact(email);
+    const existingEmail = await this.users.findIdByEmailCI(email);
     if (existingEmail) return { error: 'Email already taken', status: 409 };
 
     const passwordHash = bcrypt.hashSync(password, BCRYPT_COST);
@@ -211,7 +211,7 @@ export class AdminService {
       if (conflict) return { error: 'Username already taken', status: 409 };
     }
     if (email && email !== user.email) {
-      const conflict = await this.users.findIdByEmailExactExcluding(email, userId);
+      const conflict = await this.users.findIdByEmailCI(email, userId);
       if (conflict) return { error: 'Email already taken', status: 409 };
     }
 

server/src/nest/auth/auth.service.ts

@@ -479,20 +479,21 @@ export class AuthService {
       return { error: 'Invalid email format', status: 400 };
     }
 
-    // Ignore guests (#1362): their synthetic username/email must never block a real signup.
-    const existingUserId = await this.usersRepo.findIdByEmailOrUsernameCI(email, username);
-    if (existingUserId !== null) {
-      return { error: 'Registration failed. Please try different credentials.', status: 409 };
-    }
-
     const password_hash = bcrypt.hashSync(password, BCRYPT_COST);
-    const isFirstUser = userCount === 0;
-    const role = isFirstUser ? 'admin' : 'user';
 
     try {
       // One transaction for the whole signup: a mid-sequence throw (invite
       // bookkeeping, trip auto-join) must not leave a half-registered user.
+      // The collision check and the first-user count run inside it too, so two
+      // signups at once cannot both pass the check or both become admin.
       return await this.uow.transactional(async () => {
+        // Ignore guests (#1362): their synthetic username/email must never block a real signup.
+        const existingUserId = await this.usersRepo.findIdByEmailOrUsernameCI(email, username);
+        if (existingUserId !== null) {
+          return { error: 'Registration failed. Please try different credentials.', status: 409 };
+        }
+        const isFirstUser = (await this.usersRepo.countNonGuest()) === 0;
+        const role = isFirstUser ? 'admin' : 'user';
         const inserted = await this.usersRepo.insertUser({
           username, email, password_hash, role, first_seen_version: readEnv().app.appVersion || '0.0.0',
         });

server/tests/unit/db/repositories/Users.repository.test.ts

@@ -514,12 +514,12 @@ describe('UsersRepository', () => {
     });
   });
 
-  describe('findForPasswordReset (AU36) — case-SENSITIVE email, unlike every other email lookup here', () => {
-    it('USERSREPO-035: matches the exact case only', async () => {
+  describe('findForPasswordReset (AU36) — case-insensitive, like login', () => {
+    it('USERSREPO-035: finds an address stored with capitals from the lowercased input the service passes', async () => {
       const { user } = createUser(testDb, { email: 'Exact@Example.com' });
-      const row = await users.findForPasswordReset('Exact@Example.com');
-      expect(row?.id).toBe(user.id);
-      expect(await users.findForPasswordReset('exact@example.com')).toBeNull(); // no LOWER() in the legacy statement
+      expect((await users.findForPasswordReset('exact@example.com'))?.id).toBe(user.id);
+      expect((await users.findForPasswordReset('Exact@Example.com'))?.id).toBe(user.id);
+      expect(await users.findForPasswordReset('other@example.com')).toBeNull();
     });
 
     it('USERSREPO-036: excludes a guest', async () => {
@@ -1063,13 +1063,13 @@ describe('UsersRepository — admin (AD1-AD17) read methods, full-key parity', (
     expect(rows.map((r) => r.id)).toEqual(expect.arrayContaining([admin.id, plain.id]));
   });
 
-  it('USERSREPO-079 (AD2/AD3): findIdByUsernameExact/findIdByEmailExact are case-sensitive and exclude guests', async () => {
+  it('USERSREPO-079 (AD2/AD3): findIdByUsernameExact is case-sensitive, the email check is not, and both exclude guests', async () => {
     expect(await users.findIdByUsernameExact('ad-admin')).toBe(admin.id);
     expect(await users.findIdByUsernameExact('AD-ADMIN')).toBeNull(); // case-sensitive, unlike findIdByUsernameCIAny
     expect(await users.findIdByUsernameExact('ad-guest')).toBeNull(); // guest excluded
-    expect(await users.findIdByEmailExact('ad-plain@example.com')).toBe(plain.id);
-    expect(await users.findIdByEmailExact('AD-PLAIN@EXAMPLE.COM')).toBeNull();
-    expect(await users.findIdByEmailExact('ad-guest@example.com')).toBeNull();
+    expect(await users.findIdByEmailCI('ad-plain@example.com')).toBe(plain.id);
+    expect(await users.findIdByEmailCI('AD-PLAIN@EXAMPLE.COM')).toBe(plain.id);
+    expect(await users.findIdByEmailCI('ad-guest@example.com')).toBeNull();
   });
 
   it('USERSREPO-080 (AD4/AD5): insertAdminCreatedUser stores exactly the four named columns, every other column left to the entity default, then findAdminSummary re-selects it', async () => {
@@ -1097,14 +1097,15 @@ describe('UsersRepository — admin (AD1-AD17) read methods, full-key parity', (
     expect(await users.findAdminSummary(999999)).toBeNull();
   });
 
-  it('USERSREPO-082 (AD7/AD8): findIdByUsernameExactExcluding/findIdByEmailExactExcluding exclude the caller\'s own row, case-sensitive, guests excluded', async () => {
+  it('USERSREPO-082 (AD7/AD8): findIdByUsernameExactExcluding/findIdByEmailCI exclude the caller\'s own row and guests', async () => {
     // Renaming plain to admin's own username, excluding plain's own id, must
     // still find admin's row — that's the whole point of the check.
     expect(await users.findIdByUsernameExactExcluding('ad-admin', plain.id)).toBe(admin.id);
     expect(await users.findIdByUsernameExactExcluding('ad-plain', plain.id)).toBeNull(); // excludes self
     expect(await users.findIdByUsernameExactExcluding('ad-guest', plain.id)).toBeNull(); // guest excluded
-    expect(await users.findIdByEmailExactExcluding('ad-admin@example.com', plain.id)).toBe(admin.id);
-    expect(await users.findIdByEmailExactExcluding('ad-plain@example.com', plain.id)).toBeNull();
+    expect(await users.findIdByEmailCI('ad-admin@example.com', plain.id)).toBe(admin.id);
+    expect(await users.findIdByEmailCI('AD-ADMIN@example.com', plain.id)).toBe(admin.id);
+    expect(await users.findIdByEmailCI('ad-plain@example.com', plain.id)).toBeNull();
   });
 
   it('USERSREPO-083 (AD11): applyAdminEdit only touches the keys supplied (coalesceParam semantics) and always stamps updated_at', async () => {

server/tests/unit/nest/admin.service.test.ts

@@ -975,7 +975,7 @@ describe('createUser — the pre-existing uniqueness-check TOCTOU window (AD2-4,
     // INSERT — the two statements are two separate, un-transacted repository
     // calls, exactly as the legacy raw SQL was.
     const usersRepo = await createTestUsersRepo(testDb);
-    const spy = vi.spyOn(usersRepo, 'findIdByEmailExact').mockResolvedValueOnce(null);
+    const spy = vi.spyOn(usersRepo, 'findIdByEmailCI').mockResolvedValueOnce(null);
 
     // The pre-check said "clear," but `users.email` carries its own UNIQUE
     // index (`Migration20200101000000_baseline_schema.ts`) — that's what
@@ -990,4 +990,15 @@ describe('createUser — the pre-existing uniqueness-check TOCTOU window (AD2-4,
 
     spy.mockRestore();
   });
+
+  it('ADMIN-SVC-095 — an address that differs only in case is already taken, on create and on update', async () => {
+    const { user: existing } = createUser(testDb, { email: 'Case@Test.example.com' });
+    const { user: other } = createUser(testDb, { email: 'other-case@test.example.com' });
+
+    await expect(svcCreateUser({ username: 'caseuser', email: 'case@test.example.com', password: 'ValidPass1!' }))
+      .resolves.toEqual({ error: 'Email already taken', status: 409 });
+    await expect(updateUser(String(other.id), { email: 'CASE@TEST.EXAMPLE.COM' }))
+      .resolves.toEqual({ error: 'Email already taken', status: 409 });
+    expect(existing.id).toBeGreaterThan(0);
+  });
 });