diff --git a/src/components/admin/users/user-form.tsx b/src/components/admin/users/user-form.tsx
index ccb19d44..80bc79aa 100644
--- a/src/components/admin/users/user-form.tsx
+++ b/src/components/admin/users/user-form.tsx
@@ -93,6 +93,9 @@ function UserFormBody({ open, onOpenChange, user, onSuccess }: UserFormProps) {
   // password here. Toggle off to set one manually.
   const [sendSetupEmail, setSendSetupEmail] = useState(true);
   const [displayName, setDisplayName] = useState(user?.displayName ?? '');
+  // New users: optional sign-in username (they can also sign in with their
+  // email). Lowercased on the way out; the API validates shape + uniqueness.
+  const [username, setUsername] = useState('');
   const [phoneValue, setPhoneValue] = useState<PhoneInputValue | null>(
     user?.phone ? { e164: user.phone, country: 'US' } : null,
   );
@@ -153,6 +156,7 @@ function UserFormBody({ open, onOpenChange, user, onSuccess }: UserFormProps) {
             password: sendSetupEmail ? undefined : password,
             sendSetupEmail,
             displayName,
+            username: username.trim() ? username.trim().toLowerCase() : undefined,
             phone: phoneE164 ?? undefined,
             roleId,
             residentialAccess,
@@ -236,6 +240,26 @@ function UserFormBody({ open, onOpenChange, user, onSuccess }: UserFormProps) {
                 </p>
               </div>
 
+              {!isEdit && (
+                <div className="space-y-2">
+                  <Label htmlFor="user-username">Username (optional)</Label>
+                  <Input
+                    id="user-username"
+                    value={username}
+                    onChange={(e) => setUsername(e.target.value)}
+                    placeholder="e.g. abbie"
+                    autoCapitalize="none"
+                    autoCorrect="off"
+                    spellCheck={false}
+                  />
+                  <p className="text-xs text-muted-foreground">
+                    Lets them sign in with a short username instead of their email. 2–30 lowercase
+                    letters, digits, dot, underscore, or hyphen. Leave blank to sign in by email
+                    only.
+                  </p>
+                </div>
+              )}
+
               <div className="space-y-2">
                 <Label htmlFor="user-email">Email</Label>
                 <Input
diff --git a/src/lib/db/schema/users.ts b/src/lib/db/schema/users.ts
index b673f61c..0550d239 100644
--- a/src/lib/db/schema/users.ts
+++ b/src/lib/db/schema/users.ts
@@ -303,10 +303,10 @@ export const userProfiles = pgTable(
     displayName: text('display_name').notNull(),
     /**
      * Optional sign-in alias. Lowercase a-z0-9 plus dot/underscore/hyphen,
-     * 3–30 chars (shape pinned by `chk_user_profiles_username_shape`).
-     * Case-insensitive uniqueness is enforced by a partial unique index on
-     * LOWER(username); NULL allows the column to coexist with users who
-     * still sign in by email. See migration 0054.
+     * 2–30 chars (shape enforced in-app by `USERNAME_REGEX` in
+     * `@/lib/validators/username`). Case-insensitive uniqueness is enforced
+     * by a partial unique index on LOWER(username); NULL allows the column to
+     * coexist with users who still sign in by email. See migration 0054.
      */
     username: text('username'),
     avatarUrl: text('avatar_url'),
diff --git a/src/lib/services/users.service.ts b/src/lib/services/users.service.ts
index c23e5e18..c7a9b3db 100644
--- a/src/lib/services/users.service.ts
+++ b/src/lib/services/users.service.ts
@@ -1,10 +1,11 @@
-import { and, eq } from 'drizzle-orm';
+import { and, eq, sql } from 'drizzle-orm';
 
 import { db } from '@/lib/db';
 import { account, session, user, userProfiles, userPortRoles, roles, ports } from '@/lib/db/schema';
 import { auth } from '@/lib/auth';
 import { createAuditLog, type AuditMeta } from '@/lib/audit';
 import { ConflictError, ForbiddenError, NotFoundError, ValidationError } from '@/lib/errors';
+import { USERNAME_REGEX, isReservedUsername } from '@/lib/validators/username';
 import { emitToRoom } from '@/lib/socket/server';
 import { sendEmail } from '@/lib/email';
 import { adminEmailChangeEmail } from '@/lib/email/templates/admin-email-change';
@@ -153,6 +154,31 @@ export async function createUser(portId: string, data: CreateUserInput, meta: Au
   });
   if (!role) throw new ValidationError('Invalid role ID');
 
+  // Optional sign-in username. Validated up front (before the auth user is
+  // minted) so an invalid/taken username can't leave an orphaned account.
+  // Mirrors the self-service /api/v1/me checks: shape + reserved + unique.
+  let username: string | null = null;
+  if (data.username && data.username.trim()) {
+    const candidate = data.username.trim().toLowerCase();
+    if (!USERNAME_REGEX.test(candidate)) {
+      throw new ValidationError(
+        'Username must be 2–30 lowercase letters, digits, dot, underscore, or hyphen.',
+      );
+    }
+    if (isReservedUsername(candidate)) {
+      throw new ValidationError('That username is reserved. Please pick another.');
+    }
+    const taken = await db
+      .select({ userId: userProfiles.userId })
+      .from(userProfiles)
+      .where(sql`LOWER(${userProfiles.username}) = ${candidate}`)
+      .limit(1);
+    if (taken.length > 0) {
+      throw new ConflictError('That username is already taken.');
+    }
+    username = candidate;
+  }
+
   // Two onboarding modes:
   //   - setup-email (default when no password is supplied): provision the
   //     account with a throwaway random password the admin never sees, then
@@ -179,6 +205,7 @@ export async function createUser(portId: string, data: CreateUserInput, meta: Au
   await db.insert(userProfiles).values({
     userId: newUserId,
     displayName: data.displayName,
+    username,
     firstName: data.firstName ?? null,
     lastName: data.lastName ?? null,
     phone: data.phone ?? null,
diff --git a/src/lib/validators/users.ts b/src/lib/validators/users.ts
index 27a2fe60..059af9d1 100644
--- a/src/lib/validators/users.ts
+++ b/src/lib/validators/users.ts
@@ -13,6 +13,9 @@ export const createUserSchema = z
      *  password. When false, `password` must be supplied inline. */
     sendSetupEmail: z.boolean().optional(),
     displayName: z.string().min(1).max(200),
+    /** Optional sign-in username. Shape/uniqueness/reserved checks run in the
+     *  service (mirrors the self-service /api/v1/me path). Omit for email-only. */
+    username: z.string().optional(),
     firstName: z.string().min(1).max(200).nullable().optional(),
     lastName: z.string().min(1).max(200).nullable().optional(),
     phone: z.string().optional(),