diff --git a/app/api/announcements/route.ts b/app/api/announcements/route.ts
index c922561..1251797 100644
--- a/app/api/announcements/route.ts
+++ b/app/api/announcements/route.ts
@@ -1,67 +1,102 @@
-import { auth } from '@clerk/nextjs/server'
-import { NextRequest, NextResponse } from 'next/server'
-import { connectDB } from '@/lib/mongodb'
-import { Announcement } from '@/models/Announcement'
-import { z } from 'zod'
+import { auth } from "@clerk/nextjs/server";
+import { NextRequest, NextResponse } from "next/server";
+import { connectDB } from "@/lib/mongodb";
+import { Announcement } from "@/models/Announcement";
+import { z } from "zod";
 
 const AnnouncementSchema = z.object({
-  title: z.string().min(1),
-  content: z.string().min(1),
-  audience: z.string().optional(),
-  category: z.enum(['academic', 'events', 'admin', 'general']).optional(),
+  title: z.string().trim().min(1),
+  content: z.string().trim().min(1),
+  audience: z.enum(["All", "Students", "Staff"]).optional(),
+  category: z.enum(["academic", "events", "admin", "general"]).optional(),
   pinned: z.boolean().optional(),
-})
+});
 
 export async function GET(req: NextRequest) {
-  const { userId } = await auth()
-  if (!userId) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+  const { userId } = await auth();
+  if (!userId)
+    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
 
   try {
-    await connectDB()
-    const { searchParams } = new URL(req.url)
+    await connectDB();
+    const { searchParams } = new URL(req.url);
 
     // Parse and validate limit
-    const limitStr = searchParams.get('limit') ?? '50'
-    let limit = parseInt(limitStr, 10)
+    const limitStr = searchParams.get("limit") ?? "50";
+    let limit = parseInt(limitStr, 10);
     if (!Number.isFinite(limit) || limit <= 0) {
-      limit = 50
+      limit = 50;
     }
-    limit = Math.min(limit, 100) // Cap at 100
+    limit = Math.min(limit, 100); // Cap at 100
 
     const announcements = await Announcement.find({ teacherId: userId })
       .sort({ pinned: -1, createdAt: -1 })
       .limit(limit)
-      .lean()
+      .lean();
 
-    return NextResponse.json(announcements)
+    return NextResponse.json(announcements);
   } catch (error) {
-    console.error('GET /api/announcements error:', error instanceof Error ? error.message : error)
-    return NextResponse.json({ error: 'Internal server error' }, { status: 500 })
+    console.error(
+      "GET /api/announcements error:",
+      error instanceof Error ? error.message : error,
+    );
+    return NextResponse.json(
+      { error: "Internal server error" },
+      { status: 500 },
+    );
   }
 }
 
 export async function POST(req: NextRequest) {
-  const { userId } = await auth()
-  if (!userId) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+  const { userId } = await auth();
+  if (!userId)
+    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
 
   try {
-    await connectDB()
-    let body
+    await connectDB();
+    let body;
     try {
-      body = await req.json()
+      body = await req.json();
     } catch {
-      return NextResponse.json({ error: 'Invalid JSON in request body' }, { status: 400 })
+      return NextResponse.json(
+        { error: "Invalid JSON in request body" },
+        { status: 400 },
+      );
     }
-    
-    const parsed = AnnouncementSchema.safeParse(body)
-    if (!parsed.success) return NextResponse.json({ error: parsed.error.flatten() }, { status: 400 })
 
-    const announcement = await Announcement.create({ ...parsed.data, teacherId: userId })
-    return NextResponse.json(announcement, { status: 201 })
+    const recentCount = await Announcement.countDocuments({
+      teacherId: userId,
+      createdAt: { $gte: new Date(Date.now() - 60 * 1000) },
+    });
+
+    if (recentCount > 10) {
+      return NextResponse.json({ error: "Too many requests" }, { status: 429 });
+    }
+
+    const parsed = AnnouncementSchema.safeParse(body);
+    if (!parsed.success)
+      return NextResponse.json(
+        { error: parsed.error.flatten() },
+        { status: 400 },
+      );
+    const data = parsed.data;
+
+    const announcement = await Announcement.create({
+      title: data.title,
+      content: data.content,
+      audience: data.audience ?? "all",
+      category: data.category ?? "general",
+      pinned: data.pinned ?? false,
+      teacherId: userId,
+    });
+    return NextResponse.json(announcement, { status: 201 });
   } catch (error) {
     if (error instanceof Error) {
-      console.error('POST /api/announcements error:', error.message)
+      console.error("POST /api/announcements error:", error.message);
     }
-    return NextResponse.json({ error: 'Internal server error' }, { status: 500 })
+    return NextResponse.json(
+      { error: "Internal server error" },
+      { status: 500 },
+    );
   }
 }
diff --git a/app/api/assignments/route.ts b/app/api/assignments/route.ts
index 19021d8..3cb02e1 100644
--- a/app/api/assignments/route.ts
+++ b/app/api/assignments/route.ts
@@ -1,91 +1,120 @@
-import { auth } from '@clerk/nextjs/server'
-import { NextRequest, NextResponse } from 'next/server'
-import { connectDB } from '@/lib/mongodb'
-import { Assignment } from '@/models/Assignment'
-import { z } from 'zod'
+import { auth } from "@clerk/nextjs/server";
+import { NextRequest, NextResponse } from "next/server";
+import { connectDB } from "@/lib/mongodb";
+import { Assignment } from "@/models/Assignment";
+import { z } from "zod";
 
 const AssignmentSchema = z.object({
-  title: z.string().min(1),
-  description: z.string().optional(),
-  subject: z.string().min(1),
-  class: z.string().min(1),
-  deadline: z.string().min(1),
-  maxMarks: z.number().min(1).optional(),
-  status: z.enum(['active', 'closed']).optional(),
-  kanbanStatus: z.enum(['todo', 'in_progress', 'submitted']).optional(),
-})
+  title: z.string().trim().min(1),
+  description: z.string().trim().optional(),
+  subject: z.string().trim().min(1),
+  class: z.string().trim().min(1),
+  deadline: z.coerce.date(),
+  maxMarks: z.coerce.number().min(1).optional(),
+  status: z.enum(["active", "closed"]).default("active"),
+  kanbanStatus: z.enum(["todo", "in_progress", "submitted"]).default("todo"),
+});
 
 export async function GET(req: NextRequest) {
-  const { userId } = await auth()
-  if (!userId) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+  const { userId } = await auth();
+  if (!userId)
+    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
 
   try {
-    await connectDB()
-    const { searchParams } = new URL(req.url)
-    const status = searchParams.get('status')
-    
+    await connectDB();
+    const { searchParams } = new URL(req.url);
+    const status = searchParams.get("status");
+
     // Parse and validate pagination
-    const pageStr = searchParams.get('page') ?? '1'
-    const limitStr = searchParams.get('limit') ?? '20'
-    
-    let page = parseInt(pageStr, 10)
-    let limit = parseInt(limitStr, 10)
-    
-    if (!Number.isFinite(page) || page < 1) page = 1
-    if (!Number.isFinite(limit) || limit < 1) limit = 20
-    limit = Math.min(limit, 100) // Cap at 100
+    const pageStr = searchParams.get("page") ?? "1";
+    const limitStr = searchParams.get("limit") ?? "20";
+
+    let page = parseInt(pageStr, 10);
+    let limit = parseInt(limitStr, 10);
 
-    const query: Record<string, unknown> = { teacherId: userId }
-    if (status) query.status = status
+    if (!Number.isFinite(page) || page < 1) page = 1;
+    if (!Number.isFinite(limit) || limit < 1) limit = 20;
+    limit = Math.min(limit, 100); // Cap at 100
+
+    const query: Record<string, unknown> = { teacherId: userId };
+    if (status && !["active", "closed"].includes(status)) {
+      return NextResponse.json({ error: "Invalid status" }, { status: 400 });
+    }
+    if (status) query.status = status;
 
-    const skip = (page - 1) * limit
+    const skip = (page - 1) * limit;
     const assignments = await Assignment.find(query)
       .sort({ createdAt: -1 })
       .skip(skip)
       .limit(limit)
-      .lean()
-    
-    const total = await Assignment.countDocuments(query)
+      .lean();
 
-    return NextResponse.json({ assignments, total, page, pages: Math.ceil(total / limit) })
+    const total = await Assignment.countDocuments(query);
+
+    return NextResponse.json({
+      assignments,
+      total,
+      page,
+      pages: Math.ceil(total / limit),
+    });
   } catch (error) {
     if (error instanceof Error) {
-      console.error('GET /api/assignments error:', error.message)
+      console.error("GET /api/assignments error:", error.message);
     }
-    return NextResponse.json({ error: error instanceof Error ? error.stack : 'Internal server error' }, { status: 500 })
+    return NextResponse.json(
+      { error: "Internal server error" },
+      { status: 500 },
+    );
   }
 }
 
 export async function POST(req: NextRequest) {
-  const { userId } = await auth()
-  if (!userId) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+  const { userId } = await auth();
+  if (!userId)
+    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
 
   try {
-    await connectDB()
-    
-    let body
+    await connectDB();
+
+    let body;
     try {
-      body = await req.json()
+      body = await req.json();
     } catch {
-      return NextResponse.json({ error: 'Invalid JSON in request body' }, { status: 400 })
+      return NextResponse.json(
+        { error: "Invalid JSON in request body" },
+        { status: 400 },
+      );
     }
-    
-    const parsed = AssignmentSchema.safeParse(body)
-    if (!parsed.success) return NextResponse.json({ error: parsed.error.flatten() }, { status: 400 })
+
+    const parsed = AssignmentSchema.safeParse(body);
+    if (!parsed.success)
+      return NextResponse.json(
+        { error: parsed.error.flatten() },
+        { status: 400 },
+      );
 
     try {
-      const assignment = await Assignment.create({ ...parsed.data, teacherId: userId })
-      return NextResponse.json(assignment, { status: 201 })
+      const assignment = await Assignment.create({
+        ...parsed.data,
+        teacherId: userId,
+      });
+      return NextResponse.json(assignment, { status: 201 });
     } catch (dbError) {
       if (dbError instanceof Error) {
-        console.error('Assignment.create error:', dbError.message)
+        console.error("Assignment.create error:", dbError.message);
       }
-      return NextResponse.json({ error: 'Failed to create assignment' }, { status: 500 })
+      return NextResponse.json(
+        { error: "Failed to create assignment" },
+        { status: 500 },
+      );
     }
   } catch (error) {
     if (error instanceof Error) {
-      console.error('POST /api/assignments error:', error.message)
+      console.error("POST /api/assignments error:", error.message);
     }
-    return NextResponse.json({ error: 'Internal server error' }, { status: 500 })
+    return NextResponse.json(
+      { error: "Internal server error" },
+      { status: 500 },
+    );
   }
 }
diff --git a/app/api/profile/route.ts b/app/api/profile/route.ts
index a3d98bf..4f74bcd 100644
--- a/app/api/profile/route.ts
+++ b/app/api/profile/route.ts
@@ -1,114 +1,103 @@
-import { auth, currentUser } from '@clerk/nextjs/server'
-import { NextRequest, NextResponse } from 'next/server'
-import { connectDB } from '@/lib/mongodb'
-import { Teacher } from '@/models/Teacher'
+import { auth, currentUser } from "@clerk/nextjs/server";
+import { NextRequest, NextResponse } from "next/server";
+import { connectDB } from "@/lib/mongodb";
+import { Teacher } from "@/models/Teacher";
+import { updateSchema } from "@/lib/schemas";
 
 export async function GET(req: NextRequest) {
-  const { searchParams } = new URL(req.url)
-  const queryUserId = searchParams.get('userId')
+  const { searchParams } = new URL(req.url);
+  const queryUserId = searchParams.get("userId");
 
-  let userId: string | null = queryUserId
+  let userId: string | null = queryUserId;
   if (!userId) {
-    const session = await auth()
-    userId = session.userId
+    const session = await auth();
+    userId = session.userId;
   }
-  if (!userId) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+  if (!userId)
+    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
 
   try {
-    await connectDB()
-    let teacher = await Teacher.findOne({ clerkId: userId }).lean()
+    await connectDB();
+    let teacher = await Teacher.findOne({ clerkId: userId }).lean();
 
     if (!teacher) {
-      const clerkUser = await currentUser()
+      const clerkUser = await currentUser();
       const created = await Teacher.create({
         clerkId: userId,
-        name: clerkUser?.fullName ?? '',
-        email: clerkUser?.emailAddresses[0]?.emailAddress ?? '',
-        department: '',
+        name: clerkUser?.fullName ?? "",
+        email: clerkUser?.emailAddresses[0]?.emailAddress ?? "",
+        department: "",
         subjects: [],
-      })
-      teacher = created.toObject()
+      });
+      teacher = created.toObject();
     }
 
-    return NextResponse.json(teacher)
+    return NextResponse.json(teacher);
   } catch (error) {
-    console.error('GET /api/profile error:', error instanceof Error ? error.message : error)
-    return NextResponse.json({ error: 'Internal server error' }, { status: 500 })
+    console.error(
+      "GET /api/profile error:",
+      error instanceof Error ? error.message : error,
+    );
+    return NextResponse.json(
+      { error: "Internal server error" },
+      { status: 500 },
+    );
   }
 }
 
 export async function PUT(req: NextRequest) {
-  const { userId } = await auth()
-  if (!userId) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+  const { userId } = await auth();
+  if (!userId)
+    return NextResponse.json({ error: "Unauthorized" }, { status: 401 });
 
   try {
-    await connectDB()
-    
-    let body
+    await connectDB();
+
+    let body;
     try {
-      body = await req.json()
+      body = await req.json();
     } catch {
-      return NextResponse.json({ error: 'Invalid JSON in request body' }, { status: 400 })
+      return NextResponse.json(
+        { error: "Invalid JSON in request body" },
+        { status: 400 },
+      );
     }
-    
-    const { name, department, subjects, phone, bio, academicHistory } = body
 
-    // Validate input
-    if (typeof name !== 'string' || !name.trim()) {
-      return NextResponse.json({ error: 'name must be a non-empty string' }, { status: 400 })
-    }
-    if (department !== undefined && typeof department !== 'string') {
-      return NextResponse.json({ error: 'department must be a string' }, { status: 400 })
-    }
-    if (!Array.isArray(subjects) || !subjects.every((s) => typeof s === 'string')) {
-      return NextResponse.json({ error: 'subjects must be an array of strings' }, { status: 400 })
-    }
-    if (phone !== undefined && typeof phone !== 'string') {
-      return NextResponse.json({ error: 'phone must be a string' }, { status: 400 })
-    }
-    if (bio !== undefined && typeof bio !== 'string') {
-      return NextResponse.json({ error: 'bio must be a string' }, { status: 400 })
-    }
-    if (academicHistory !== undefined) {
-      if (
-        !Array.isArray(academicHistory) ||
-        academicHistory.length > 20 ||
-        !academicHistory.every(
-          (entry: unknown) =>
-            entry !== null &&
-            typeof entry === 'object' &&
-            typeof (entry as Record<string, unknown>).year === 'string' &&
-            typeof (entry as Record<string, unknown>).title === 'string',
-        )
-      ) {
-        return NextResponse.json(
-          { error: 'academicHistory must be an array of objects with string year and title (max 20 items)' },
-          { status: 400 },
-        )
-      }
+    const { name, department, subjects, phone, bio, academicHistory } = body;
+
+    const parsed = updateSchema.safeParse(body);
+
+    if (!parsed.success) {
+      return NextResponse.json(
+        { error: parsed.error.flatten() },
+        { status: 400 },
+      );
     }
 
-    const updatePayload: Record<string, unknown> = { name, subjects }
-    if (department !== undefined) updatePayload.department = department
-    if (phone !== undefined) updatePayload.phone = phone
-    if (bio !== undefined) updatePayload.bio = bio
-    if (academicHistory !== undefined) updatePayload.academicHistory = academicHistory
+    const data = parsed.data;
+
+    const updatePayload = Object.fromEntries(
+      Object.entries(data).filter(([_, v]) => v !== undefined),
+    );
 
     const teacher = await Teacher.findOneAndUpdate(
       { clerkId: userId },
       { $set: updatePayload },
-      { new: true }
-    )
-    
+      { new: true },
+    );
+
     if (!teacher) {
-      return NextResponse.json({ error: 'Teacher not found' }, { status: 404 })
+      return NextResponse.json({ error: "Teacher not found" }, { status: 404 });
     }
 
-    return NextResponse.json(teacher)
+    return NextResponse.json(teacher);
   } catch (error) {
     if (error instanceof Error) {
-      console.error('PUT /api/profile error:', error.message)
+      console.error("PUT /api/profile error:", error.message);
     }
-    return NextResponse.json({ error: 'Internal server error' }, { status: 500 })
+    return NextResponse.json(
+      { error: "Internal server error" },
+      { status: 500 },
+    );
   }
 }
diff --git a/app/dashboard/announcements/AnnouncementsClient.tsx b/app/dashboard/announcements/AnnouncementsClient.tsx
index 0de73bb..7991416 100644
--- a/app/dashboard/announcements/AnnouncementsClient.tsx
+++ b/app/dashboard/announcements/AnnouncementsClient.tsx
@@ -1,178 +1,232 @@
-'use client'
-
-import { useEffect, useState, useCallback } from 'react'
-import { useForm } from 'react-hook-form'
-import { Button } from '@/components/ui/Button'
-import { Modal } from '@/components/ui/Modal'
-import { Badge } from '@/components/ui/Badge'
-import { useToast } from '@/components/ui/Toast'
-import { TableSkeleton } from '@/components/ui/Skeleton'
+"use client";
+
+import { useEffect, useState, useCallback } from "react";
+import { useForm } from "react-hook-form";
+import { Button } from "@/components/ui/Button";
+import { Modal } from "@/components/ui/Modal";
+import { Badge } from "@/components/ui/Badge";
+import { useToast } from "@/components/ui/Toast";
+import { TableSkeleton } from "@/components/ui/Skeleton";
 import { ConfirmModal } from "@/components/ui/ConfirmModal";
+import { formatZodError } from "@/lib/utils";
+
+type Category = "academic" | "events" | "admin" | "general";
 
 interface Announcement {
-  _id: string
-  title: string
-  content: string
-  audience: string
-  category: string
-  pinned: boolean
-  createdAt: string
+  _id: string;
+  title: string;
+  content: string;
+  audience?: string;
+  category: Category;
+  pinned: boolean;
+  createdAt: string;
 }
 
 interface FormData {
-  title: string
-  content: string
-  audience: string
-  category: string
-  pinned: boolean
+  title: string;
+  content: string;
+  audience: string;
+  category: Category;
+  pinned: boolean;
 }
 
-type CategoryFilter = 'all' | 'academic' | 'events' | 'admin' | 'general'
+type CategoryFilter = "all" | "academic" | "events" | "admin" | "general";
 
 const CATEGORY_FILTERS: { value: CategoryFilter; label: string }[] = [
-  { value: 'all', label: 'All' },
-  { value: 'academic', label: 'Academic' },
-  { value: 'events', label: 'Events' },
-  { value: 'admin', label: 'Admin' },
-  { value: 'general', label: 'General' },
-]
-
-const CATEGORY_BADGE: Record<string, 'info' | 'success' | 'warning' | 'purple' | 'default'> = {
-  academic: 'info',
-  events: 'success',
-  admin: 'warning',
-  general: 'default',
-}
+  { value: "all", label: "All" },
+  { value: "academic", label: "Academic" },
+  { value: "events", label: "Events" },
+  { value: "admin", label: "Admin" },
+  { value: "general", label: "General" },
+];
+
+const CATEGORY_BADGE: Record<
+  string,
+  "info" | "success" | "warning" | "purple" | "default"
+> = {
+  academic: "info",
+  events: "success",
+  admin: "warning",
+  general: "default",
+};
 
 function timeAgo(date: string) {
-  const diff = Date.now() - new Date(date).getTime()
-  const mins = Math.floor(diff / 60000)
-  if (mins < 60) return `${mins}m ago`
-  const hrs = Math.floor(mins / 60)
-  if (hrs < 24) return `${hrs}h ago`
-  return `${Math.floor(hrs / 24)}d ago`
+  const diff = Date.now() - new Date(date).getTime();
+  const mins = Math.floor(diff / 60000);
+  if (mins < 60) return `${mins}m ago`;
+  const hrs = Math.floor(mins / 60);
+  if (hrs < 24) return `${hrs}h ago`;
+  return `${Math.floor(hrs / 24)}d ago`;
 }
 
 function useReadState() {
   const [readIds, setReadIds] = useState<Set<string>>(() => {
-    if (typeof window === 'undefined') return new Set()
+    if (typeof window === "undefined") return new Set();
     try {
-      const stored = localStorage.getItem("announcement_read_ids")
-      if (stored) return new Set(JSON.parse(stored) as string[])
+      const stored = localStorage.getItem("announcement_read_ids");
+      if (stored) return new Set(JSON.parse(stored) as string[]);
     } catch {
       // Silently ignore JSON parse errors
     }
-    return new Set()
+    return new Set();
   });
 
   const markRead = useCallback((id: string) => {
     setReadIds((prev) => {
-      if (prev.has(id)) return prev
-      const next = new Set(prev)
-      next.add(id)
-      try { localStorage.setItem('announcement_read_ids', JSON.stringify([...next])) } catch {}
-      return next
-    })
-  }, [])
+      if (prev.has(id)) return prev;
+      const next = new Set(prev);
+      next.add(id);
+      try {
+        localStorage.setItem(
+          "announcement_read_ids",
+          JSON.stringify([...next]),
+        );
+      } catch {}
+      return next;
+    });
+  }, []);
 
   const markAllRead = useCallback((ids: string[]) => {
     setReadIds((prev) => {
-      const next = new Set(prev)
-      for (const id of ids) next.add(id)
-      try { localStorage.setItem('announcement_read_ids', JSON.stringify([...next])) } catch {}
-      return next
-    })
-  }, [])
-
-  return { readIds, markRead, markAllRead }
+      const next = new Set(prev);
+      for (const id of ids) next.add(id);
+      try {
+        localStorage.setItem(
+          "announcement_read_ids",
+          JSON.stringify([...next]),
+        );
+      } catch {}
+      return next;
+    });
+  }, []);
+
+  return { readIds, markRead, markAllRead };
 }
 
 export function AnnouncementsClient() {
-  const { toast } = useToast()
-  const [announcements, setAnnouncements] = useState<Announcement[]>([])
-  const [loading, setLoading] = useState(true)
-  const [modalOpen, setModalOpen] = useState(false)
-  const [editing, setEditing] = useState<Announcement | null>(null)
-  const [categoryFilter, setCategoryFilter] = useState<CategoryFilter>('all')
-  const [expandedId, setExpandedId] = useState<string | null>(null)
+  const { toast } = useToast();
+  const [announcements, setAnnouncements] = useState<Announcement[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [modalOpen, setModalOpen] = useState(false);
+  const [editing, setEditing] = useState<Announcement | null>(null);
+  const [categoryFilter, setCategoryFilter] = useState<CategoryFilter>("all");
+  const [expandedId, setExpandedId] = useState<string | null>(null);
   const [deleteTarget, setDeleteTarget] = useState<Announcement | null>(null);
-  const { readIds, markRead, markAllRead } = useReadState()
-
-  const { register, handleSubmit, reset, formState: { isSubmitting, errors } } = useForm<FormData>()
+  const { readIds, markRead, markAllRead } = useReadState();
+
+  const {
+    register,
+    handleSubmit,
+    reset,
+    formState: { isSubmitting, errors },
+  } = useForm<FormData>({
+    defaultValues: {
+      title: "",
+      content: "",
+      audience: "All",
+      category: "general",
+      pinned: false,
+    },
+  });
 
   const fetchAnnouncements = useCallback(async () => {
-    setLoading(true)
+    setLoading(true);
     try {
-      const res = await fetch('/api/announcements')
-      if (!res.ok) throw new Error(`Failed to fetch announcements: ${res.status}`)
-      const data = await res.json()
-      setAnnouncements(Array.isArray(data) ? data : [])
+      const res = await fetch("/api/announcements");
+      if (!res.ok)
+        throw new Error(`Failed to fetch announcements: ${res.status}`);
+      const data = await res.json();
+      setAnnouncements(Array.isArray(data) ? data : []);
     } catch (error) {
-      toast(error instanceof Error ? error.message : 'Failed to load', 'error')
+      toast(error instanceof Error ? error.message : "Failed to load", "error");
     } finally {
-      setLoading(false)
+      setLoading(false);
     }
-  }, [toast])
+  }, [toast]);
 
-  useEffect(() => { fetchAnnouncements() }, [fetchAnnouncements])
+  useEffect(() => {
+    fetchAnnouncements();
+  }, [fetchAnnouncements]);
 
-  const filtered = categoryFilter === 'all'
-    ? announcements
-    : announcements.filter((a) => (a.category || 'general') === categoryFilter)
+  const filtered =
+    categoryFilter === "all"
+      ? announcements
+      : announcements.filter(
+          (a) => (a.category || "general") === categoryFilter,
+        );
 
-  const unreadCount = announcements.filter((a) => !readIds.has(a._id)).length
+  const unreadCount = announcements.filter((a) => !readIds.has(a._id)).length;
 
   const openAdd = () => {
-    setEditing(null)
-    reset({ audience: 'All', category: 'general', pinned: false })
-    setModalOpen(true)
-  }
+    setEditing(null);
+    reset({ audience: "All", category: "general", pinned: false });
+    setModalOpen(true);
+  };
 
   const openEdit = (a: Announcement) => {
-    setEditing(a)
-    reset({ title: a.title, content: a.content, audience: a.audience, category: a.category || 'general', pinned: a.pinned })
-    setModalOpen(true)
-  }
+    setEditing(a);
+    reset({
+      title: a.title,
+      content: a.content,
+      audience: a.audience || "All",
+      category: a.category || "general",
+      pinned: a.pinned,
+    });
+    setModalOpen(true);
+  };
 
   const toggleExpand = (id: string) => {
-    setExpandedId((prev) => (prev === id ? null : id))
-    markRead(id)
-  }
+    setExpandedId((prev) => (prev === id ? null : id));
+    markRead(id);
+  };
 
   const onSubmit = async (data: FormData) => {
-    const url = editing ? `/api/announcements/${editing._id}` : '/api/announcements'
-    const method = editing ? 'PUT' : 'POST'
+    const url = editing
+      ? `/api/announcements/${editing._id}`
+      : "/api/announcements";
+    const method = editing ? "PUT" : "POST";
     try {
       const res = await fetch(url, {
         method,
-        headers: { 'Content-Type': 'application/json' },
+        headers: { "Content-Type": "application/json" },
         body: JSON.stringify(data),
-      })
-      if (res.ok) {
-        toast(editing ? 'Announcement updated!' : 'Announcement posted!', 'success')
-        setModalOpen(false)
-        fetchAnnouncements()
-      } else {
-        toast('Failed to save announcement', 'error')
+      });
+      const result = await res.json();
+      console.log(result);
+      if (!res.ok) {
+        const submitErrros = formatZodError(result.error);
+        submitErrros.forEach((res) => {
+          toast(res, "error");
+        });
+        return;
       }
+
+      toast(
+        editing ? "Announcement updated!" : "Announcement posted!",
+        "success",
+      );
+      setModalOpen(false);
+      fetchAnnouncements();
     } catch (error) {
-      toast(error instanceof Error ? error.message : 'Network error', 'error')
+      toast(error instanceof Error ? error.message : "Network error", "error");
     }
-  }
+  };
 
   const togglePin = async (a: Announcement) => {
     try {
       const res = await fetch(`/api/announcements/${a._id}`, {
-        method: 'PUT',
-        headers: { 'Content-Type': 'application/json' },
+        method: "PUT",
+        headers: { "Content-Type": "application/json" },
         body: JSON.stringify({ pinned: !a.pinned }),
-      })
-      if (res.ok) { toast(a.pinned ? 'Unpinned' : 'Pinned!', 'success'); fetchAnnouncements() }
-      else toast('Failed to update', 'error')
+      });
+      if (res.ok) {
+        toast(a.pinned ? "Unpinned" : "Pinned!", "success");
+        fetchAnnouncements();
+      } else toast("Failed to update", "error");
     } catch (error) {
-      toast(error instanceof Error ? error.message : 'Network error', 'error')
+      toast(error instanceof Error ? error.message : "Network error", "error");
     }
-  }
+  };
 
   const executeDelete = async () => {
     if (!deleteTarget) return;
diff --git a/app/dashboard/assignments/AssignmentsClient.tsx b/app/dashboard/assignments/AssignmentsClient.tsx
index e0e7f13..79f0cbb 100644
--- a/app/dashboard/assignments/AssignmentsClient.tsx
+++ b/app/dashboard/assignments/AssignmentsClient.tsx
@@ -1,36 +1,36 @@
-'use client'
+"use client";
 
 import { useEffect, useState, useCallback, useRef, useMemo } from "react";
-import { useForm } from 'react-hook-form'
-import { Button } from '@/components/ui/Button'
-import { Modal } from '@/components/ui/Modal'
-import { Badge } from '@/components/ui/Badge'
-import { useToast } from '@/components/ui/Toast'
+import { useForm } from "react-hook-form";
+import { Button } from "@/components/ui/Button";
+import { Modal } from "@/components/ui/Modal";
+import { Badge } from "@/components/ui/Badge";
+import { useToast } from "@/components/ui/Toast";
 import { ConfirmModal } from "@/components/ui/ConfirmModal";
 
 interface Assignment {
-  _id: string
-  title: string
-  description: string
-  subject: string
-  class: string
-  deadline: string
-  status: 'active' | 'closed'
-  kanbanStatus: 'todo' | 'in_progress' | 'submitted'
-  maxMarks: number
-  createdAt: string
+  _id: string;
+  title: string;
+  description: string;
+  subject: string;
+  class: string;
+  deadline: string;
+  status: "active" | "closed";
+  kanbanStatus: "todo" | "in_progress" | "submitted";
+  maxMarks: number;
+  createdAt: string;
 }
 
 interface FormData {
-  title: string
-  description: string
-  subject: string
-  class: string
-  deadline: string
-  maxMarks: number
+  title: string;
+  description: string;
+  subject: string;
+  class: string;
+  deadline: string;
+  maxMarks: number;
 }
 
-type KanbanCol = 'todo' | 'in_progress' | 'submitted'
+type KanbanCol = "todo" | "in_progress" | "submitted";
 
 const COLUMNS: {
   id: KanbanCol;
@@ -59,7 +59,9 @@ const COLUMNS: {
 ];
 
 function daysUntil(deadline: string) {
-  return Math.ceil((new Date(deadline).getTime() - Date.now()) / (1000 * 60 * 60 * 24))
+  return Math.ceil(
+    (new Date(deadline).getTime() - Date.now()) / (1000 * 60 * 60 * 24),
+  );
 }
 
 function DeadlineBadge({ deadline }: { deadline: string }) {
@@ -241,11 +243,11 @@ function AssignmentDrawer({
 }
 
 export function AssignmentsClient() {
-  const { toast } = useToast()
-  const [assignments, setAssignments] = useState<Assignment[]>([])
-  const [loading, setLoading] = useState(true)
-  const [modalOpen, setModalOpen] = useState(false)
-  const [editing, setEditing] = useState<Assignment | null>(null)
+  const { toast } = useToast();
+  const [assignments, setAssignments] = useState<Assignment[]>([]);
+  const [loading, setLoading] = useState(true);
+  const [modalOpen, setModalOpen] = useState(false);
+  const [editing, setEditing] = useState<Assignment | null>(null);
   const [drawerAssignment, setDrawerAssignment] = useState<Assignment | null>(
     null,
   );
@@ -283,8 +285,7 @@ export function AssignmentsClient() {
       setAssignments(
         raw.map((a) => ({
           ...a,
-          kanbanStatus:
-            a.kanbanStatus ?? (a.status === "closed" ? "submitted" : "todo"),
+          kanbanStatus: a.kanbanStatus,
         })),
       );
     } catch (error) {
@@ -359,7 +360,11 @@ export function AssignmentsClient() {
       const res = await fetch(url, {
         method,
         headers: { "Content-Type": "application/json" },
-        body: JSON.stringify({ ...data, maxMarks: Number(data.maxMarks) }),
+        body: JSON.stringify({
+          ...data,
+          deadline: new Date(data.deadline).toISOString(),
+          maxMarks: Number(data.maxMarks),
+        }),
       });
       if (res.ok) {
         toast(
@@ -464,10 +469,16 @@ export function AssignmentsClient() {
     return (
       <div className="grid grid-cols-1 md:grid-cols-3 gap-4 min-h-100">
         {COLUMNS.map((col) => (
-          <div key={col.id} className={`rounded-2xl border-t-4 border border-gray-200 dark:border-slate-700 bg-white dark:bg-slate-800 p-4 animate-pulse ${col.accent}`}>
+          <div
+            key={col.id}
+            className={`rounded-2xl border-t-4 border border-gray-200 dark:border-slate-700 bg-white dark:bg-slate-800 p-4 animate-pulse ${col.accent}`}
+          >
             <div className="h-5 w-24 bg-gray-200 dark:bg-slate-700 rounded mb-4" />
             {[1, 2].map((i) => (
-              <div key={i} className="rounded-xl bg-gray-100 dark:bg-slate-700/50 p-4 mb-3 space-y-2">
+              <div
+                key={i}
+                className="rounded-xl bg-gray-100 dark:bg-slate-700/50 p-4 mb-3 space-y-2"
+              >
                 <div className="h-4 bg-gray-200 dark:bg-slate-600 rounded w-3/4" />
                 <div className="h-3 bg-gray-200 dark:bg-slate-600 rounded w-1/2" />
               </div>
@@ -475,7 +486,7 @@ export function AssignmentsClient() {
           </div>
         ))}
       </div>
-    )
+    );
   }
 
   return (
diff --git a/app/dashboard/profile/ProfileClient.tsx b/app/dashboard/profile/ProfileClient.tsx
index 71e235e..fa8c236 100644
--- a/app/dashboard/profile/ProfileClient.tsx
+++ b/app/dashboard/profile/ProfileClient.tsx
@@ -1,107 +1,129 @@
-'use client'
+"use client";
 
-import { useEffect, useRef, useState } from 'react'
+import { useEffect, useRef, useState } from "react";
 import Image from "next/image";
-import { useForm } from 'react-hook-form'
-import { useUser } from '@clerk/nextjs'
-import { Button } from '@/components/ui/Button'
-import { useToast } from '@/components/ui/Toast'
-import { CardSkeleton } from '@/components/ui/Skeleton'
+import { useForm } from "react-hook-form";
+import { useUser } from "@clerk/nextjs";
+import { Button } from "@/components/ui/Button";
+import { useToast } from "@/components/ui/Toast";
+import { CardSkeleton } from "@/components/ui/Skeleton";
 import { ConfirmModal } from "@/components/ui/ConfirmModal";
+import { formatZodError } from "@/lib/utils";
 
 interface AcademicHistoryEntry {
-  year: string
-  title: string
-  description?: string
+  year: string;
+  title: string;
+  description?: string;
 }
 
 interface TeacherProfile {
-  name: string
-  email: string
-  department: string
-  subjects: string[]
-  phone: string
-  bio: string
-  academicHistory: AcademicHistoryEntry[]
-  createdAt?: string
+  name: string;
+  email: string;
+  department: string;
+  subjects: string[];
+  phone: string;
+  bio: string;
+  academicHistory: AcademicHistoryEntry[];
+  createdAt?: string;
 }
 
 interface FormData {
-  name: string
-  department: string
-  subjectsRaw: string
-  phone: string
-  bio: string
+  name: string;
+  department: string;
+  subjectsRaw: string;
+  phone: string;
+  bio: string;
 }
 
 interface TimelineFormData {
-  year: string
-  title: string
-  description: string
+  year: string;
+  title: string;
+  description: string;
 }
 
 export function ProfileClient() {
-  const { user } = useUser()
-  const { toast } = useToast()
-  const [loading, setLoading] = useState(true)
-  const [profile, setProfile] = useState<TeacherProfile | null>(null)
-  const [editing, setEditing] = useState(false)
-  const [avatarUploading, setAvatarUploading] = useState(false)
-  const [timelineModalOpen, setTimelineModalOpen] = useState(false)
-  const [editingEntry, setEditingEntry] = useState<{ index: number; entry: AcademicHistoryEntry } | null>(null)
+  const { user } = useUser();
+  const { toast } = useToast();
+  const [loading, setLoading] = useState(true);
+  const [profile, setProfile] = useState<TeacherProfile | null>(null);
+  const [editing, setEditing] = useState(false);
+  const [savingHistory, setSavingHistory] = useState(false);
+  const [avatarUploading, setAvatarUploading] = useState(false);
+  const [timelineModalOpen, setTimelineModalOpen] = useState(false);
+  const [editingEntry, setEditingEntry] = useState<{
+    index: number;
+    entry: AcademicHistoryEntry;
+  } | null>(null);
   const [deleteEntryIndex, setDeleteEntryIndex] = useState<number | null>(null);
-  const avatarInputRef = useRef<HTMLInputElement>(null)
+  const avatarInputRef = useRef<HTMLInputElement>(null);
 
-  const { register, handleSubmit, reset, formState: { isSubmitting } } = useForm<FormData>()
+  const {
+    register,
+    handleSubmit,
+    reset,
+    formState: { isSubmitting },
+  } = useForm<FormData>();
   const {
     register: tlRegister,
     handleSubmit: tlHandleSubmit,
     reset: tlReset,
     formState: { isSubmitting: tlSubmitting, errors: tlErrors },
-  } = useForm<TimelineFormData>()
+  } = useForm<TimelineFormData>();
 
   useEffect(() => {
     async function load() {
-      setLoading(true)
+      setLoading(true);
       try {
-        const res = await fetch('/api/profile')
-        if (!res.ok) throw new Error(`Failed to load profile: ${res.status}`)
-        const data = await res.json()
-        setProfile(data)
+        const res = await fetch("/api/profile");
+        if (!res.ok) throw new Error(`Failed to load profile: ${res.status}`);
+        const data = await res.json();
+        setProfile(data);
         reset({
           name: data.name,
           department: data.department,
-          subjectsRaw: (data.subjects ?? []).join(', '),
+          subjectsRaw: (data.subjects ?? []).join(", "),
           phone: data.phone,
           bio: data.bio,
-        })
+        });
       } catch (err) {
-        toast(err instanceof Error ? err.message : 'Failed to load profile', 'error')
+        toast(
+          err instanceof Error ? err.message : "Failed to load profile",
+          "error",
+        );
       } finally {
-        setLoading(false)
+        setLoading(false);
       }
     }
-    load()
-  }, [reset, toast])
+    load();
+  }, [reset, toast]);
 
   // ── Avatar upload via Clerk ──
   const handleAvatarChange = async (e: React.ChangeEvent<HTMLInputElement>) => {
-    const file = e.target.files?.[0]
-    if (!file || !user) return
-    if (!file.type.startsWith('image/')) { toast('Please select an image file', 'error'); return }
-    if (file.size > 5 * 1024 * 1024) { toast('Image must be under 5 MB', 'error'); return }
+    const file = e.target.files?.[0];
+    if (!file || !user) return;
+    if (!file.type.startsWith("image/")) {
+      toast("Please select an image file", "error");
+      return;
+    }
+    if (file.size > 5 * 1024 * 1024) {
+      toast("Image must be under 5 MB", "error");
+      return;
+    }
 
-    setAvatarUploading(true)
+    setAvatarUploading(true);
     try {
-      await user.setProfileImage({ file })
-      toast('Avatar updated!', 'success')
+      await user.setProfileImage({ file });
+      toast("Avatar updated!", "success");
     } catch (err) {
-      toast(err instanceof Error ? err.message : 'Failed to upload avatar', 'error')
+      toast(
+        err instanceof Error ? err.message : "Failed to upload avatar",
+        "error",
+      );
     } finally {
-      setAvatarUploading(false)
-      e.target.value = ''
+      setAvatarUploading(false);
+      e.target.value = "";
     }
-  }
+  };
 
   // ── Profile form submit ──
   const onSubmit = async (data: FormData) => {
@@ -111,27 +133,32 @@ export function ProfileClient() {
       .map((s) => s.trim())
       .filter(Boolean);
     const subjects = Array.from(new Set(subjectsArray));
+    const payload: any = {};
+
+    if (data.name.trim()) payload.name = data.name.trim();
+    if (data.department.trim()) payload.department = data.department.trim();
+    if (subjects.length) payload.subjects = subjects;
+    if (data.phone.trim()) payload.phone = data.phone.trim();
+    if (data.bio.trim()) payload.bio = data.bio.trim();
+
     try {
       const res = await fetch("/api/profile", {
         method: "PUT",
         headers: { "Content-Type": "application/json" },
-        body: JSON.stringify({
-          name: data.name,
-          department: data.department,
-          subjects,
-          phone: data.phone,
-          bio: data.bio,
-          academicHistory: profile?.academicHistory ?? [],
-        }),
+        body: JSON.stringify(payload),
       });
-      if (res.ok) {
-        const updated = await res.json();
-        setProfile(updated);
-        toast("Profile updated!", "success");
-        setEditing(false);
-      } else {
-        toast("Failed to update profile", "error");
+      const result = await res.json();
+      if (!res.ok) {
+        const submitErrors = formatZodError(result.error);
+        submitErrors.forEach((error) => {
+          toast(error, "error");
+        });
+        return;
       }
+
+      setProfile(result);
+      toast("Profile updated!", "success");
+      setEditing(false);
     } catch (error) {
       toast(
         `Network error: ${error instanceof Error ? error.message : "Failed to update profile"}`,
@@ -150,7 +177,6 @@ export function ProfileClient() {
         method: "PUT",
         headers: { "Content-Type": "application/json" },
         body: JSON.stringify({
-          ...profile,
           academicHistory: history,
         }),
       });
@@ -173,32 +199,42 @@ export function ProfileClient() {
   };
 
   const openAddEntry = () => {
-    setEditingEntry(null)
-    tlReset({ year: String(new Date().getFullYear()), title: '', description: '' })
-    setTimelineModalOpen(true)
-  }
+    setEditingEntry(null);
+    tlReset({
+      year: String(new Date().getFullYear()),
+      title: "",
+      description: "",
+    });
+    setTimelineModalOpen(true);
+  };
 
   const openEditEntry = (index: number, entry: AcademicHistoryEntry) => {
-    setEditingEntry({ index, entry })
-    tlReset({ year: entry.year, title: entry.title, description: entry.description ?? '' })
-    setTimelineModalOpen(true)
-  }
+    setEditingEntry({ index, entry });
+    tlReset({
+      year: entry.year,
+      title: entry.title,
+      description: entry.description ?? "",
+    });
+    setTimelineModalOpen(true);
+  };
 
   const onTimelineSubmit = async (data: TimelineFormData) => {
-    const current = [...(profile?.academicHistory ?? [])]
+    const current = [...(profile?.academicHistory ?? [])];
     if (editingEntry !== null) {
-      current[editingEntry.index] = data
+      current[editingEntry.index] = data;
     } else {
-      current.push(data)
+      current.push(data);
     }
     // sort descending by year
-    current.sort((a, b) => b.year.localeCompare(a.year))
+    current.sort((a, b) => Number(b.year) - Number(a.year));
+    setSavingHistory(true);
     const success = await saveHistory(current);
+    setSavingHistory(false);
     if (success) {
       toast("Academic history saved!", "success");
       setTimelineModalOpen(false);
     }
-  }
+  };
 
   const executeDeleteEntry = async () => {
     if (deleteEntryIndex === null) return;
@@ -216,7 +252,7 @@ export function ProfileClient() {
         <CardSkeleton />
         <CardSkeleton />
       </div>
-    )
+    );
   }
 
   return (
@@ -395,7 +431,9 @@ export function ProfileClient() {
                 Subjects (comma-separated)
               </label>
               <input
-                {...register("subjectsRaw")}
+                {...register("subjectsRaw", {
+                  validate: (val) => val.trim().length > 0 || "Required",
+                })}
                 className="input w-full"
                 placeholder="Mathematics, Physics, Programming"
               />
@@ -469,7 +507,12 @@ export function ProfileClient() {
           <h3 className="text-base font-semibold text-gray-900 dark:text-white">
             Academic History
           </h3>
-          <Button size="sm" variant="outline" onClick={openAddEntry}>
+          <Button
+            size="sm"
+            variant="outline"
+            onClick={openAddEntry}
+            disabled={savingHistory}
+          >
             <svg
               className="h-4 w-4"
               fill="none"
diff --git a/lib/schemas.ts b/lib/schemas.ts
new file mode 100644
index 0000000..d516488
--- /dev/null
+++ b/lib/schemas.ts
@@ -0,0 +1,18 @@
+import { z } from "zod";
+
+export const updateSchema = z.object({
+  name: z.string().min(1).optional(),
+  department: z.string().optional(),
+  subjects: z.array(z.string()).optional(),
+  phone: z.string().optional(),
+  bio: z.string().optional(),
+  academicHistory: z
+    .array(
+      z.object({
+        year: z.string(),
+        title: z.string(),
+      }),
+    )
+    .max(20)
+    .optional(),
+});
diff --git a/lib/utils.ts b/lib/utils.ts
new file mode 100644
index 0000000..d96e2bc
--- /dev/null
+++ b/lib/utils.ts
@@ -0,0 +1,18 @@
+export function formatZodError(error: any) {
+  const messages: string[] = [];
+
+  if (error.formErrors?.length) {
+    messages.push(...error.formErrors);
+  }
+
+  if (error.fieldErrors) {
+    for (const key in error.fieldErrors) {
+      const errs = error.fieldErrors[key];
+      if (errs) {
+        messages.push(...errs.map((e: string) => `${key}: ${e}`));
+      }
+    }
+  }
+
+  return messages;
+}
diff --git a/package-lock.json b/package-lock.json
index 54cfc6a..b57d7f8 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1782,7 +1782,7 @@
       "version": "19.2.14",
       "resolved": "https://registry.npmjs.org/@types/react/-/react-19.2.14.tgz",
       "integrity": "sha512-ilcTH/UniCkMdtexkoCN0bI7pMcJDvmQFPvuPvmEaYA/NSfFTAgdUSLAoVjaRJm7+6PvcM+q1zYOwS4wTYMF9w==",
-      "devOptional": true,
+      "dev": true,
       "license": "MIT",
       "dependencies": {
         "csstype": "^3.2.2"
@@ -2948,7 +2948,7 @@
       "version": "3.2.3",
       "resolved": "https://registry.npmjs.org/csstype/-/csstype-3.2.3.tgz",
       "integrity": "sha512-z1HGKcYy2xA8AGQfwrn0PAy+PB7X/GSj3UVJW9qKyn43xWa+gl5nXmU4qqLMRzWVLFC8KusUX8T/0kCiOYpAIQ==",
-      "devOptional": true,
+      "dev": true,
       "license": "MIT"
     },
     "node_modules/d3-array": {
@@ -6104,6 +6104,7 @@
       "version": "16.13.1",
       "resolved": "https://registry.npmjs.org/react-is/-/react-is-16.13.1.tgz",
       "integrity": "sha512-24e6ynE2H+OKt4kqsOvNd8kBpV65zoxbA4BVsEOB3ARVWQki/DHzaUoC5KuON/BiccDaCCTZBuOcfZs70kR8bQ==",
+      "dev": true,
       "license": "MIT"
     },
     "node_modules/react-redux": {
diff --git a/tsconfig.json b/tsconfig.json
index 3a13f90..4e424f9 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,7 +1,11 @@
 {
   "compilerOptions": {
     "target": "ES2017",
-    "lib": ["dom", "dom.iterable", "esnext"],
+    "lib": [
+      "dom",
+      "dom.iterable",
+      "esnext"
+    ],
     "allowJs": true,
     "skipLibCheck": true,
     "strict": true,
@@ -19,7 +23,9 @@
       }
     ],
     "paths": {
-      "@/*": ["./*"]
+      "@/*": [
+        "./*"
+      ]
     }
   },
   "include": [
@@ -28,7 +34,10 @@
     "**/*.tsx",
     ".next/types/**/*.ts",
     ".next/dev/types/**/*.ts",
-    "**/*.mts"
+    "**/*.mts",
+    ".next/dev/dev/types/**/*.ts"
   ],
-  "exclude": ["node_modules"]
+  "exclude": [
+    "node_modules"
+  ]
 }