diff --git a/app/Events/ChatMessageSent.php b/app/Events/ChatMessageSent.php
index debc56a9..f163b26d 100644
--- a/app/Events/ChatMessageSent.php
+++ b/app/Events/ChatMessageSent.php
@@ -31,14 +31,22 @@ public function __construct(ChatMessage $chatMessage)
             'reply_to_content' => $chatMessage->reply_to_content,
             'reactions' => $chatMessage->getFormattedReactions(null),
             'created_at' => $chatMessage->created_at->toIso8601String(),
-            'user' => [
+            'user' => $chatMessage->user ? [
                 'id' => $chatMessage->user->id,
                 'name' => $chatMessage->user->name,
                 'username' => $chatMessage->user->username,
                 'image_url' => $chatMessage->user->image_url,
                 'institution' => $chatMessage->user->institution,
                 'is_verified' => $chatMessage->user->is_verified,
-                'roles' => $chatMessage->user->roles->pluck('name')->toArray(),
+                'roles' => $chatMessage->user->roles ? $chatMessage->user->roles->pluck('name')->toArray() : [],
+            ] : [
+                'id' => null,
+                'name' => 'Deleted User',
+                'username' => null,
+                'image_url' => null,
+                'institution' => null,
+                'is_verified' => false,
+                'roles' => [],
             ],
         ];
     }
diff --git a/app/Http/Controllers/AuthController.php b/app/Http/Controllers/AuthController.php
index 81514adb..ce1768f1 100644
--- a/app/Http/Controllers/AuthController.php
+++ b/app/Http/Controllers/AuthController.php
@@ -12,6 +12,7 @@
 use Illuminate\Support\Facades\Auth;
 use Illuminate\Support\Facades\Http;
 use Illuminate\Support\Facades\Storage;
+use Illuminate\Support\Facades\Validator;
 use Illuminate\Support\Str;
 use Inertia\Inertia;
 use Laravel\Socialite\Facades\Socialite;
@@ -131,6 +132,39 @@ public function showOnboarding(Request $request)
         ]);
     }
 
+    public function checkUsername(Request $request)
+    {
+        $validator = Validator::make($request->all(), [
+            'username' => [
+                'required',
+                'string',
+                'min:3',
+                'max:30',
+                'regex:/^[a-zA-Z0-9_]+$/',
+                'unique:users,username',
+                new CleanText,
+            ],
+        ], [
+            'username.required' => 'Please choose a username.',
+            'username.min' => 'Username must be at least 3 characters.',
+            'username.max' => 'Username cannot exceed 30 characters.',
+            'username.regex' => "Username can only contain letters, numbers, and underscores. Dots aren't allowed.",
+            'username.unique' => 'This username is already taken. Please choose another one.',
+        ]);
+
+        if ($validator->fails()) {
+            return response()->json([
+                'available' => false,
+                'message' => $validator->errors()->first('username'),
+            ], 422);
+        }
+
+        return response()->json([
+            'available' => true,
+            'message' => 'Username is available.',
+        ]);
+    }
+
     public function completeOnboarding(Request $request)
     {
         if (Auth::check()) {
diff --git a/app/Http/Controllers/ChatController.php b/app/Http/Controllers/ChatController.php
index 5be50636..09cf4d41 100644
--- a/app/Http/Controllers/ChatController.php
+++ b/app/Http/Controllers/ChatController.php
@@ -74,7 +74,7 @@ public function index(Request $request)
                 'reply_to_content' => $msg->deleted_at ? null : $msg->reply_to_content,
                 'reactions' => $msg->getFormattedReactions($user?->id),
                 'created_at' => $msg->created_at->toIso8601String(),
-                'user' => [
+                'user' => $msg->user ? [
                     'id' => $msg->user->id,
                     'name' => $msg->user->name,
                     'username' => $msg->user->username,
@@ -82,6 +82,14 @@ public function index(Request $request)
                     'institution' => $msg->user->institution,
                     'is_verified' => $msg->user->is_verified,
                     'roles' => $msg->user->roles->pluck('name')->toArray(),
+                ] : [
+                    'id' => null,
+                    'name' => 'Deleted User',
+                    'username' => null,
+                    'image_url' => null,
+                    'institution' => null,
+                    'is_verified' => false,
+                    'roles' => [],
                 ],
             ]);
 
diff --git a/database/migrations/2026_09_24_214500_make_user_id_nullable_on_chat_messages_table.php b/database/migrations/2026_09_24_214500_make_user_id_nullable_on_chat_messages_table.php
new file mode 100644
index 00000000..5c60287f
--- /dev/null
+++ b/database/migrations/2026_09_24_214500_make_user_id_nullable_on_chat_messages_table.php
@@ -0,0 +1,36 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\DB;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::table('chat_messages', function (Blueprint $table) {
+            $table->dropForeign(['user_id']);
+            $table->foreignId('user_id')->nullable()->change();
+            $table->foreign('user_id')->references('id')->on('users')->nullOnDelete();
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        // Delete orphaned messages without an author before restoring NOT NULL
+        DB::table('chat_messages')->whereNull('user_id')->delete();
+
+        Schema::table('chat_messages', function (Blueprint $table) {
+            $table->dropForeign(['user_id']);
+            $table->foreignId('user_id')->nullable(false)->change();
+            $table->foreign('user_id')->references('id')->on('users')->cascadeOnDelete();
+        });
+    }
+};
diff --git a/resources/js/components/navigation/Navigation.tsx b/resources/js/components/navigation/Navigation.tsx
index 60ac61e6..6fa5cd0b 100644
--- a/resources/js/components/navigation/Navigation.tsx
+++ b/resources/js/components/navigation/Navigation.tsx
@@ -841,6 +841,9 @@ export const SiteBottomNav = defineComponent({
     name: 'SiteBottomNav',
     setup() {
         const page = usePage();
+        const user = computed(
+            () => page.props.auth?.user as AuthedUser | undefined,
+        );
         const currentUrl = computed(() => String(page.url));
         const bottomNavItems = computed(() =>
             primaryNavItems.filter((i) => i.showInBottom !== false),
@@ -848,6 +851,30 @@ export const SiteBottomNav = defineComponent({
 
         const homeHref = computed(() => preferredHomeHref(currentUrl.value));
 
+        const authItemHref = computed(() => {
+            if (!user.value) {
+                return '/login';
+            }
+
+            return user.value.username
+                ? `/u/${user.value.username}`
+                : '/profile';
+        });
+
+        const isAuthItemActive = computed(() => {
+            if (user.value) {
+                return (
+                    currentUrl.value.startsWith('/profile') ||
+                    currentUrl.value.startsWith('/u/')
+                );
+            }
+
+            return (
+                currentUrl.value.startsWith('/login') ||
+                currentUrl.value.startsWith('/register')
+            );
+        });
+
         const isActive = (href: string, match?: (url: string) => boolean) => {
             if (match) {
                 return match(currentUrl.value);
@@ -899,6 +926,38 @@ export const SiteBottomNav = defineComponent({
                             </span>
                         </Link>
                     ))}
+
+                    <Link
+                        href={authItemHref.value}
+                        class={[
+                            'flex min-w-0 flex-1 flex-col items-center gap-1 rounded-xl px-2 py-2 transition-all duration-150 ease-out',
+                            isAuthItemActive.value
+                                ? 'text-slate-900 dark:text-white'
+                                : 'text-slate-500 hover:text-slate-700 dark:text-slate-400 dark:hover:text-slate-200',
+                        ]}
+                    >
+                        <MaterialIcon
+                            name={user.value ? 'person' : 'login'}
+                            size={26}
+                            filled={isAuthItemActive.value}
+                            weight={400}
+                            class={`shrink-0 transition-transform duration-150 ${
+                                isAuthItemActive.value
+                                    ? 'scale-[1.02] text-slate-900 dark:text-white'
+                                    : 'text-slate-500 dark:text-slate-400'
+                            }`}
+                        />
+                        <span
+                            class={[
+                                'text-[10px] leading-none tracking-wide antialiased',
+                                isAuthItemActive.value
+                                    ? 'font-bold'
+                                    : 'font-medium',
+                            ]}
+                        >
+                            {user.value ? 'Profile' : 'Login'}
+                        </span>
+                    </Link>
                 </div>
             </nav>
         );
diff --git a/resources/js/pages/Chat/Index.vue b/resources/js/pages/Chat/Index.vue
index bde6cb12..f7c81d11 100644
--- a/resources/js/pages/Chat/Index.vue
+++ b/resources/js/pages/Chat/Index.vue
@@ -20,6 +20,7 @@ import {
     Radio,
     AtSign,
     Users,
+    UserX,
 } from 'lucide-vue-next';
 import { ref, computed, onMounted, onUnmounted, nextTick, watch } from 'vue';
 import AuthModal from '@/components/AuthModal.vue';
@@ -34,9 +35,9 @@ import { getCsrfToken } from '@/lib/useCsrf';
 import { formatDateDivider, formatTime } from '@/lib/useDate';
 
 interface ChatUser {
-    id: number;
+    id: number | null;
     name: string;
-    username: string;
+    username: string | null;
     image_url: string | null;
     institution: string | null;
     is_verified: boolean;
@@ -1163,9 +1164,11 @@ const submitReport = async () => {
             },
             body: JSON.stringify({
                 message_id: reportingMessage.value.id,
-                reported_user_id: reportingMessage.value.user.id,
-                reported_user_name: reportingMessage.value.user.name,
-                reported_user_username: reportingMessage.value.user.username,
+                reported_user_id: reportingMessage.value.user?.id || null,
+                reported_user_name:
+                    reportingMessage.value.user?.name || 'Deleted User',
+                reported_user_username:
+                    reportingMessage.value.user?.username || null,
                 message_content: reportingMessage.value.content,
                 message_sent_at: reportingMessage.value.created_at,
                 reason: reportReason.value,
@@ -1340,6 +1343,10 @@ const isGroupedWithPrevious = (idx: number) => {
         return false;
     }
 
+    if (!prev.user?.id || !curr.user?.id) {
+        return false;
+    }
+
     if (Number(prev.user.id) !== Number(curr.user.id)) {
         return false;
     }
@@ -1358,6 +1365,10 @@ const isBanModalOpen = ref(false);
 const selectedUserToBan = ref<ChatBanUser | null>(null);
 
 const openBanModal = (user: ChatUser) => {
+    if (!user.id) {
+        return;
+    }
+
     closeMobileActions();
     selectedUserToBan.value = {
         id: user.id,
@@ -1598,6 +1609,7 @@ onUnmounted(() => {
                         class="group relative flex items-start gap-2.5 rounded-xl px-2.5 py-1.5 transition-colors duration-150 sm:gap-3 sm:px-3 sm:py-2"
                         :class="[
                             currentUser &&
+                            msg.user?.id &&
                             Number(currentUser.id) === Number(msg.user.id)
                                 ? 'bg-indigo-50/30 dark:bg-indigo-950/15'
                                 : 'hover:bg-slate-50/80 dark:hover:bg-zinc-800/40',
@@ -1612,28 +1624,37 @@ onUnmounted(() => {
                     >
                         <!-- Left Avatar Gutter -->
                         <div class="w-8 shrink-0 sm:w-9">
-                            <Link
-                                v-if="!isGroupedWithPrevious(idx)"
-                                :href="`/u/${msg.user.username}`"
-                                class="flex h-8 w-8 items-center justify-center overflow-hidden rounded-full font-semibold transition hover:opacity-85 sm:h-9 sm:w-9"
-                                :class="
-                                    currentUser &&
-                                    Number(currentUser.id) ===
-                                        Number(msg.user.id)
-                                        ? 'bg-indigo-600 text-white'
-                                        : 'bg-slate-100 text-slate-700 dark:bg-zinc-800 dark:text-zinc-300'
-                                "
-                            >
-                                <img
-                                    v-if="msg.user.image_url"
-                                    :src="msg.user.image_url"
-                                    :alt="msg.user.name"
-                                    class="h-full w-full object-cover"
-                                />
-                                <span v-else class="text-xs uppercase">
-                                    {{ msg.user.name?.charAt(0) || 'U' }}
-                                </span>
-                            </Link>
+                            <template v-if="!isGroupedWithPrevious(idx)">
+                                <Link
+                                    v-if="msg.user?.id && msg.user.username"
+                                    :href="`/u/${msg.user.username}`"
+                                    class="flex h-8 w-8 items-center justify-center overflow-hidden rounded-full font-semibold transition hover:opacity-85 sm:h-9 sm:w-9"
+                                    :class="
+                                        currentUser &&
+                                        Number(currentUser.id) ===
+                                            Number(msg.user.id)
+                                            ? 'bg-indigo-600 text-white'
+                                            : 'bg-slate-100 text-slate-700 dark:bg-zinc-800 dark:text-zinc-300'
+                                    "
+                                >
+                                    <img
+                                        v-if="msg.user.image_url"
+                                        :src="msg.user.image_url"
+                                        :alt="msg.user.name"
+                                        class="h-full w-full object-cover"
+                                    />
+                                    <span v-else class="text-xs uppercase">
+                                        {{ msg.user.name?.charAt(0) || 'U' }}
+                                    </span>
+                                </Link>
+                                <div
+                                    v-else
+                                    class="flex h-8 w-8 items-center justify-center overflow-hidden rounded-full bg-slate-100 text-slate-400 sm:h-9 sm:w-9 dark:bg-zinc-800 dark:text-zinc-500"
+                                    title="Deleted User"
+                                >
+                                    <UserX class="h-4 w-4" />
+                                </div>
+                            </template>
                             <span
                                 v-else
                                 class="block text-center text-[9px] text-slate-300 opacity-0 transition-opacity group-hover:opacity-100 dark:text-zinc-600"
@@ -1647,29 +1668,41 @@ onUnmounted(() => {
                             <!-- Header Info (Shown on First in Group) -->
                             <div
                                 v-if="!isGroupedWithPrevious(idx)"
-                                class="flex items-baseline gap-1.5"
+                                class="flex items-center gap-1.5"
                             >
                                 <Link
+                                    v-if="msg.user?.id && msg.user.username"
                                     :href="`/u/${msg.user.username}`"
-                                    class="truncate text-xs font-bold text-slate-900 transition hover:text-indigo-600 dark:text-zinc-100 dark:hover:text-indigo-400"
+                                    class="inline-flex items-center gap-1 truncate text-xs font-bold text-slate-900 transition hover:text-indigo-600 dark:text-zinc-100 dark:hover:text-indigo-400"
                                 >
-                                    {{ msg.user.name }}
+                                    <span class="truncate">{{
+                                        msg.user.name
+                                    }}</span>
+                                    <VerifiedBadge
+                                        v-if="msg.user?.is_verified"
+                                    />
                                 </Link>
+                                <span
+                                    v-else
+                                    class="truncate text-xs font-semibold text-slate-500 italic dark:text-zinc-400"
+                                >
+                                    {{ msg.user?.name || 'Deleted User' }}
+                                </span>
 
                                 <span
                                     v-if="
                                         currentUser &&
+                                        msg.user?.id &&
                                         Number(currentUser.id) ===
                                             Number(msg.user.id)
                                     "
-                                    class="py-0.2 rounded-md bg-indigo-100 px-1 text-[9px] font-bold text-indigo-700 dark:bg-indigo-900/60 dark:text-indigo-300"
+                                    class="rounded-md bg-indigo-100 px-1 py-0.5 text-[9px] leading-none font-bold text-indigo-700 dark:bg-indigo-900/60 dark:text-indigo-300"
                                 >
                                     You
                                 </span>
 
-                                <VerifiedBadge v-if="msg.user.is_verified" />
-
                                 <span
+                                    v-if="msg.user?.username"
                                     class="truncate text-[11px] text-slate-400 dark:text-zinc-500"
                                 >
                                     @{{ msg.user.username }}
@@ -1874,13 +1907,14 @@ onUnmounted(() => {
                             <button
                                 v-if="
                                     (can('manage chat') || canDelete) &&
+                                    msg.user?.id &&
                                     Number(currentUser?.id) !==
                                         Number(msg.user.id)
                                 "
                                 type="button"
                                 @click.stop="openBanModal(msg.user)"
                                 class="cursor-pointer rounded-lg p-1 text-slate-400 hover:bg-rose-50 hover:text-rose-600 dark:text-zinc-400 dark:hover:bg-rose-950/40 dark:hover:text-rose-400"
-                                :title="`Ban @${msg.user.username}`"
+                                :title="`Ban @${msg.user.username || msg.user.name}`"
                             >
                                 <Ban class="h-3.5 w-3.5" />
                             </button>
@@ -1891,8 +1925,9 @@ onUnmounted(() => {
                                     !msg.is_deleted &&
                                     !msg.deleted_at &&
                                     currentUser &&
-                                    Number(currentUser.id) !==
-                                        Number(msg.user.id)
+                                    (!msg.user?.id ||
+                                        Number(currentUser.id) !==
+                                            Number(msg.user.id))
                                 "
                                 type="button"
                                 @click.stop="openReportModal(msg)"
@@ -1923,6 +1958,7 @@ onUnmounted(() => {
                             v-if="
                                 (!msg.is_deleted && !msg.deleted_at) ||
                                 ((can('manage chat') || canDelete) &&
+                                    msg.user?.id &&
                                     Number(currentUser?.id) !==
                                         Number(msg.user.id))
                             "
@@ -2060,7 +2096,7 @@ onUnmounted(() => {
                         <span class="truncate">
                             Replying to
                             <strong class="font-semibold">{{
-                                activeReplyTo.user.name
+                                activeReplyTo.user?.name || 'Deleted User'
                             }}</strong
                             >:
                             <span class="italic opacity-80"
@@ -2353,8 +2389,9 @@ onUnmounted(() => {
                         <button
                             v-if="
                                 currentUser &&
-                                Number(currentUser.id) !==
-                                    Number(mobileActionMessage.user.id) &&
+                                (!mobileActionMessage.user?.id ||
+                                    Number(currentUser.id) !==
+                                        Number(mobileActionMessage.user.id)) &&
                                 !mobileActionMessage.is_deleted &&
                                 !mobileActionMessage.deleted_at
                             "
@@ -2370,6 +2407,7 @@ onUnmounted(() => {
                         <button
                             v-if="
                                 (can('manage chat') || canDelete) &&
+                                mobileActionMessage.user?.id &&
                                 Number(currentUser?.id) !==
                                     Number(mobileActionMessage.user.id)
                             "
@@ -2472,9 +2510,15 @@ onUnmounted(() => {
                                 <span
                                     class="font-semibold text-slate-700 dark:text-zinc-300"
                                 >
-                                    {{ reportingMessage.user.name }} (@{{
-                                        reportingMessage.user.username
-                                    }})
+                                    {{
+                                        reportingMessage.user?.name ||
+                                        'Deleted User'
+                                    }}
+                                    <template
+                                        v-if="reportingMessage.user?.username"
+                                    >
+                                        (@{{ reportingMessage.user.username }})
+                                    </template>
                                 </span>
                                 <span>{{
                                     formatTime(reportingMessage.created_at)
diff --git a/resources/js/pages/auth/Onboarding.vue b/resources/js/pages/auth/Onboarding.vue
index 131969ed..4f6015e5 100644
--- a/resources/js/pages/auth/Onboarding.vue
+++ b/resources/js/pages/auth/Onboarding.vue
@@ -14,6 +14,7 @@ import {
 import { computed, onUnmounted, ref } from 'vue';
 import VerifiedBadge from '@/components/VerifiedBadge.vue';
 import { compressImage } from '@/lib/imageCompression';
+import { getCsrfToken } from '@/lib/useCsrf';
 
 interface OnboardingUser {
     google_id: string;
@@ -41,7 +42,8 @@ const page = usePage();
 const flashError = computed(() => (page.props as any).flash?.error);
 
 const currentStep = ref<1 | 2>(1);
-const termsAccepted = ref(false);
+
+const isCheckingUsername = ref(false);
 
 const getInitialAppreciations = (suggested: Contributor[] = []): number[] => {
     if (suggested.length === 0) {
@@ -77,6 +79,60 @@ const isCompressing = ref(false);
 const contributors = computed(() => props.suggestedContributors || []);
 const hasContributors = computed(() => contributors.value.length > 0);
 
+const checkUsernameAvailability = async (
+    usernameValue: string,
+): Promise<boolean> => {
+    const trimmed = usernameValue.trim();
+
+    if (!trimmed) {
+        form.errors.username = 'Please choose a username.';
+
+        return false;
+    }
+
+    if (!/^[a-zA-Z0-9_]{3,30}$/.test(trimmed)) {
+        form.errors.username =
+            "Username must be 3-30 characters (letters, numbers, underscores). Dots aren't allowed.";
+
+        return false;
+    }
+
+    isCheckingUsername.value = true;
+
+    try {
+        const response = await fetch('/api/check-username', {
+            method: 'POST',
+            headers: {
+                'Content-Type': 'application/json',
+                Accept: 'application/json',
+                'X-CSRF-TOKEN': getCsrfToken(),
+            },
+            body: JSON.stringify({ username: trimmed }),
+        });
+
+        const data = await response.json().catch(() => ({}));
+
+        if (!response.ok || data?.available === false) {
+            const errorMsg =
+                data?.message ||
+                data?.errors?.username?.[0] ||
+                'This username is already taken. Please choose another one.';
+            form.errors.username = errorMsg;
+
+            return false;
+        }
+
+        form.errors.username = '';
+    } catch {
+        form.errors.username =
+            'Network error. Please check your connection and try again.';
+
+        return false;
+    } finally {
+        isCheckingUsername.value = false;
+    }
+};
+
 const handleImageChange = async (e: Event) => {
     const target = e.target as HTMLInputElement;
     const rawFile = target.files?.[0];
@@ -174,7 +230,7 @@ const selectAllContributors = () => {
     }
 };
 
-const goToStep2 = () => {
+const goToStep2 = async () => {
     form.errors.name = '';
     form.errors.username = '';
     form.errors.school = '';
@@ -204,6 +260,13 @@ const goToStep2 = () => {
         return;
     }
 
+    // Immediately check username availability against database on clicking Continue
+    const isAvailable = await checkUsernameAvailability(form.username.trim());
+
+    if (!isAvailable) {
+        return;
+    }
+
     if (!hasContributors.value) {
         submit();
 
@@ -214,7 +277,7 @@ const goToStep2 = () => {
 };
 
 const submit = () => {
-    if (isCompressing.value || form.errors.image || !termsAccepted.value) {
+    if (isCompressing.value || isCheckingUsername.value || form.errors.image) {
         return;
     }
 
@@ -406,12 +469,7 @@ const getContributorAvatar = (contributor: Contributor) => {
                     </div>
 
                     <!-- Onboarding Form Inputs -->
-                    <form
-                        @submit.prevent="
-                            hasContributors ? goToStep2() : submit()
-                        "
-                        class="space-y-4"
-                    >
+                    <form @submit.prevent="goToStep2" class="space-y-4">
                         <!-- Full Name -->
                         <div>
                             <label
@@ -464,11 +522,14 @@ const getContributorAvatar = (contributor: Contributor) => {
                                 </div>
                                 <input
                                     v-model="form.username"
+                                    @input="form.errors.username = ''"
                                     type="text"
                                     id="username"
                                     required
                                     placeholder="your_username"
-                                    :disabled="form.processing"
+                                    :disabled="
+                                        form.processing || isCheckingUsername
+                                    "
                                     class="ph-no-mask w-full rounded-xl border border-slate-300 bg-white py-2.5 pr-3.5 pl-10 text-sm text-slate-900 transition outline-none placeholder:text-slate-400 focus:border-indigo-500 focus:ring-2 focus:ring-indigo-500/20 disabled:bg-slate-50 disabled:text-slate-500 dark:border-gray-700 dark:bg-gray-800/80 dark:text-gray-100 dark:placeholder:text-gray-500 dark:focus:border-indigo-400 dark:focus:ring-indigo-400/20 dark:disabled:bg-gray-800/50 dark:disabled:text-gray-400"
                                     :class="{
                                         'border-rose-500 focus:ring-rose-500/20 dark:border-rose-500 dark:focus:border-rose-400 dark:focus:ring-rose-400/20':
@@ -550,22 +611,28 @@ const getContributorAvatar = (contributor: Contributor) => {
                         <div class="pt-2">
                             <button
                                 type="submit"
-                                :disabled="form.processing || isCompressing"
+                                :disabled="
+                                    form.processing ||
+                                    isCompressing ||
+                                    isCheckingUsername
+                                "
                                 class="flex w-full items-center justify-center gap-2 rounded-2xl bg-indigo-600 px-4 py-3.5 text-sm font-bold text-white shadow-xs transition-all hover:bg-indigo-700 hover:shadow-md active:scale-[0.98] disabled:cursor-not-allowed disabled:opacity-50 dark:bg-indigo-500 dark:hover:bg-indigo-600"
                             >
                                 <Loader2
-                                    v-if="form.processing"
+                                    v-if="form.processing || isCheckingUsername"
                                     class="h-4 w-4 animate-spin"
                                 />
                                 <span>
                                     {{
-                                        form.processing
-                                            ? 'Please wait...'
+                                        form.processing || isCheckingUsername
+                                            ? 'Checking username...'
                                             : 'Continue'
                                     }}
                                 </span>
                                 <ArrowRight
-                                    v-if="!form.processing"
+                                    v-if="
+                                        !form.processing && !isCheckingUsername
+                                    "
                                     class="h-4 w-4"
                                 />
                             </button>
@@ -694,40 +761,28 @@ const getContributorAvatar = (contributor: Contributor) => {
                         {{ form.errors.appreciations }}
                     </p>
 
-                    <!-- Terms & Privacy Agreement Tickmark -->
-                    <div class="pt-1">
-                        <label
-                            class="flex cursor-pointer items-start gap-2.5 text-xs text-slate-600 dark:text-gray-300"
+                    <!-- Terms & Privacy Notice (Implied Consent) -->
+                    <p
+                        class="pt-1 text-center text-[11px] leading-relaxed text-slate-500 dark:text-gray-400"
+                    >
+                        অ্যাকাউন্ট তৈরির মাধ্যমে আপনি আমাদের
+                        <Link
+                            href="/terms-service"
+                            target="_blank"
+                            class="font-semibold text-slate-700 underline decoration-slate-300 hover:text-indigo-600 dark:text-gray-300 dark:hover:text-indigo-400"
                         >
-                            <input
-                                v-model="termsAccepted"
-                                type="checkbox"
-                                class="mt-0.5 h-4 w-4 rounded border-slate-300 text-indigo-600 focus:ring-indigo-500 dark:border-gray-700 dark:bg-gray-900"
-                            />
-                            <span
-                                class="text-[11px] leading-relaxed select-none"
-                            >
-                                আমি
-                                <Link
-                                    href="/terms-service"
-                                    target="_blank"
-                                    class="font-semibold text-slate-800 underline decoration-slate-300 hover:text-indigo-600 dark:text-gray-200 dark:hover:text-indigo-400"
-                                >
-                                    Terms & Conditions
-                                </Link>
-                                এবং
-                                <Link
-                                    href="/privacy-policy"
-                                    target="_blank"
-                                    class="font-semibold text-slate-800 underline decoration-slate-300 hover:text-indigo-600 dark:text-gray-200 dark:hover:text-indigo-400"
-                                >
-                                    Privacy Policy
-                                </Link>
-                                পড়েছি এবং আমার তথ্য কীভাবে সুরক্ষিত ও ব্যবহৃত
-                                হবে তা জেনেই অ্যাকাউন্ট তৈরি করছি।
-                            </span>
-                        </label>
-                    </div>
+                            Terms & Conditions
+                        </Link>
+                        এবং
+                        <Link
+                            href="/privacy-policy"
+                            target="_blank"
+                            class="font-semibold text-slate-700 underline decoration-slate-300 hover:text-indigo-600 dark:text-gray-300 dark:hover:text-indigo-400"
+                        >
+                            Privacy Policy
+                        </Link>
+                        -তে সম্মতি দিচ্ছেন।
+                    </p>
 
                     <!-- Navigation Buttons -->
                     <div class="flex items-center gap-3 pt-2">
@@ -744,7 +799,7 @@ const getContributorAvatar = (contributor: Contributor) => {
                         <button
                             type="button"
                             @click="submit"
-                            :disabled="form.processing || !termsAccepted"
+                            :disabled="form.processing"
                             class="flex flex-1 items-center justify-center gap-2 rounded-2xl bg-indigo-600 px-4 py-3.5 text-sm font-bold text-white shadow-xs transition-all hover:bg-indigo-700 hover:shadow-md active:scale-[0.98] disabled:cursor-not-allowed disabled:opacity-50 dark:bg-indigo-500 dark:hover:bg-indigo-600"
                         >
                             <Loader2
diff --git a/routes/web.php b/routes/web.php
index aee68ccd..6e44d715 100644
--- a/routes/web.php
+++ b/routes/web.php
@@ -109,6 +109,7 @@
     Route::get('/auth/google', [AuthController::class, 'redirectToGoogle'])->name('auth.google');
     Route::get('/auth/google/callback', [AuthController::class, 'handleGoogleCallback'])->name('auth.google.callback');
     Route::get('/onboarding', [AuthController::class, 'showOnboarding'])->name('onboarding');
+    Route::post('/api/check-username', [AuthController::class, 'checkUsername'])->name('api.check-username');
     Route::post('/onboarding', [AuthController::class, 'completeOnboarding'])->name('onboarding.complete');
 
     Route::get('/blogs', [BlogController::class, 'index'])->name('blogs.index');
diff --git a/tests/Feature/AuthenticationTest.php b/tests/Feature/AuthenticationTest.php
index e095ad61..d48cdd84 100644
--- a/tests/Feature/AuthenticationTest.php
+++ b/tests/Feature/AuthenticationTest.php
@@ -217,6 +217,45 @@
     $this->assertGuest();
 });
 
+test('checking username availability endpoint returns available status for unique username', function () {
+    $response = $this->postJson('/api/check-username', [
+        'username' => 'unique_handle_123',
+    ]);
+
+    $response->assertOk()
+        ->assertJson([
+            'available' => true,
+            'message' => 'Username is available.',
+        ]);
+});
+
+test('checking username availability endpoint returns 422 for taken username', function () {
+    User::factory()->create([
+        'username' => 'existing_user',
+    ]);
+
+    $response = $this->postJson('/api/check-username', [
+        'username' => 'existing_user',
+    ]);
+
+    $response->assertStatus(422)
+        ->assertJson([
+            'available' => false,
+            'message' => 'This username is already taken. Please choose another one.',
+        ]);
+});
+
+test('checking username availability endpoint rejects invalid formats and dots', function () {
+    $response = $this->postJson('/api/check-username', [
+        'username' => 'invalid.user.name',
+    ]);
+
+    $response->assertStatus(422)
+        ->assertJson([
+            'available' => false,
+        ]);
+});
+
 test('completing onboarding requires school field', function () {
     $response = $this->withSession([
         'onboarding_user' => [