diff --git a/src/app/api/admin/sections/[key]/route.ts b/src/app/api/admin/sections/[key]/route.ts
index 33d5b3e..5b5a17e 100644
--- a/src/app/api/admin/sections/[key]/route.ts
+++ b/src/app/api/admin/sections/[key]/route.ts
@@ -2,6 +2,7 @@ import { NextRequest, NextResponse } from "next/server";
 import { getSection, setSection, SECTION_KEYS } from "@/lib/db";
 import { siteContent } from "@/data/content";
 import { revalidatePath } from "next/cache";
+import { invalidateContentCache } from "@/lib/content";
 
 type Params = { params: Promise<{ key: string }> };
 
@@ -34,6 +35,7 @@ export async function PUT(request: NextRequest, { params }: Params) {
 
   const data = await request.json();
   setSection(key, data);
+  invalidateContentCache();
   revalidatePath("/");
 
   return NextResponse.json({ ok: true });
diff --git a/src/app/api/group-booking/route.ts b/src/app/api/group-booking/route.ts
index a31ce7f..7f6906c 100644
--- a/src/app/api/group-booking/route.ts
+++ b/src/app/api/group-booking/route.ts
@@ -1,6 +1,7 @@
 import { NextRequest, NextResponse } from "next/server";
 import { addGroupBooking } from "@/lib/db";
 import { checkRateLimit, getClientIp } from "@/lib/rateLimit";
+import { sanitizeName, sanitizePhone, sanitizeHandle, sanitizeText } from "@/lib/validation";
 
 export async function POST(request: NextRequest) {
   const ip = getClientIp(request);
@@ -15,17 +16,23 @@ export async function POST(request: NextRequest) {
     const body = await request.json();
     const { name, phone, groupInfo, instagram, telegram } = body;
 
-    if (!name || typeof name !== "string" || !phone || typeof phone !== "string") {
-      return NextResponse.json({ error: "name and phone are required" }, { status: 400 });
+    const cleanName = sanitizeName(name);
+    if (!cleanName) {
+      return NextResponse.json({ error: "Имя обязательно" }, { status: 400 });
     }
 
-    const cleanName = name.trim().slice(0, 100);
-    const cleanPhone = phone.trim().slice(0, 30);
-    const cleanGroup = typeof groupInfo === "string" ? groupInfo.trim().slice(0, 200) : undefined;
-    const cleanIg = typeof instagram === "string" ? instagram.trim().slice(0, 100) : undefined;
-    const cleanTg = typeof telegram === "string" ? telegram.trim().slice(0, 100) : undefined;
+    const cleanPhone = sanitizePhone(phone);
+    if (!cleanPhone) {
+      return NextResponse.json({ error: "Телефон обязателен" }, { status: 400 });
+    }
 
-    const id = addGroupBooking(cleanName, cleanPhone, cleanGroup, cleanIg, cleanTg);
+    const id = addGroupBooking(
+      cleanName,
+      cleanPhone,
+      sanitizeText(groupInfo),
+      sanitizeHandle(instagram),
+      sanitizeHandle(telegram)
+    );
     return NextResponse.json({ ok: true, id });
   } catch (err) {
     console.error("[group-booking] POST error:", err);
diff --git a/src/app/api/master-class-register/route.ts b/src/app/api/master-class-register/route.ts
index 2c461d8..9d37990 100644
--- a/src/app/api/master-class-register/route.ts
+++ b/src/app/api/master-class-register/route.ts
@@ -1,6 +1,7 @@
 import { NextResponse } from "next/server";
 import { addMcRegistration } from "@/lib/db";
 import { checkRateLimit, getClientIp } from "@/lib/rateLimit";
+import { sanitizeName, sanitizePhone, sanitizeHandle, sanitizeText } from "@/lib/validation";
 
 export async function POST(request: Request) {
   const ip = getClientIp(request);
@@ -15,25 +16,26 @@ export async function POST(request: Request) {
     const body = await request.json();
     const { masterClassTitle, name, phone, instagram, telegram } = body;
 
-    if (!masterClassTitle || typeof masterClassTitle !== "string" || masterClassTitle.length > 200) {
+    const cleanTitle = sanitizeText(masterClassTitle, 200);
+    if (!cleanTitle) {
       return NextResponse.json({ error: "masterClassTitle is required" }, { status: 400 });
     }
-    if (!name || typeof name !== "string" || !name.trim() || name.length > 100) {
-      return NextResponse.json({ error: "name is required (max 100 chars)" }, { status: 400 });
+
+    const cleanName = sanitizeName(name);
+    if (!cleanName) {
+      return NextResponse.json({ error: "Имя обязательно" }, { status: 400 });
     }
-    if (!phone || typeof phone !== "string" || !phone.trim()) {
+
+    const cleanPhone = sanitizePhone(phone);
+    if (!cleanPhone) {
       return NextResponse.json({ error: "Телефон обязателен" }, { status: 400 });
     }
 
-    const cleanIg = instagram && typeof instagram === "string" ? instagram.trim().slice(0, 100) : "";
-    const cleanTg = telegram && typeof telegram === "string" ? telegram.trim().slice(0, 100) : undefined;
-    const cleanPhone = phone.trim().slice(0, 30);
-
     const id = addMcRegistration(
-      masterClassTitle.trim().slice(0, 200),
-      name.trim().slice(0, 100),
-      cleanIg,
-      cleanTg,
+      cleanTitle,
+      cleanName,
+      sanitizeHandle(instagram) ?? "",
+      sanitizeHandle(telegram),
       cleanPhone
     );
 
diff --git a/src/app/api/open-day-register/route.ts b/src/app/api/open-day-register/route.ts
index 66a2a22..0e889c6 100644
--- a/src/app/api/open-day-register/route.ts
+++ b/src/app/api/open-day-register/route.ts
@@ -6,6 +6,7 @@ import {
   getOpenDayEvent,
 } from "@/lib/db";
 import { checkRateLimit, getClientIp } from "@/lib/rateLimit";
+import { sanitizeName, sanitizePhone, sanitizeHandle } from "@/lib/validation";
 
 export async function POST(request: NextRequest) {
   const ip = getClientIp(request);
@@ -20,17 +21,18 @@ export async function POST(request: NextRequest) {
     const body = await request.json();
     const { classId, eventId, name, phone, instagram, telegram } = body;
 
-    if (!classId || !eventId || !name || !phone) {
-      return NextResponse.json({ error: "classId, eventId, name, phone are required" }, { status: 400 });
+    if (!classId || !eventId) {
+      return NextResponse.json({ error: "classId and eventId are required" }, { status: 400 });
     }
 
-    const cleanName = (name as string).trim().slice(0, 100);
-    const cleanPhone = (phone as string).replace(/\D/g, "").slice(0, 15);
-    const cleanIg = instagram ? (instagram as string).trim().slice(0, 100) : undefined;
-    const cleanTg = telegram ? (telegram as string).trim().slice(0, 100) : undefined;
+    const cleanName = sanitizeName(name);
+    if (!cleanName) {
+      return NextResponse.json({ error: "Имя обязательно" }, { status: 400 });
+    }
 
+    const cleanPhone = sanitizePhone(phone);
     if (!cleanPhone) {
-      return NextResponse.json({ error: "Invalid phone" }, { status: 400 });
+      return NextResponse.json({ error: "Телефон обязателен" }, { status: 400 });
     }
 
     // Check not already booked
@@ -41,8 +43,8 @@ export async function POST(request: NextRequest) {
     const id = addOpenDayBooking(classId, eventId, {
       name: cleanName,
       phone: cleanPhone,
-      instagram: cleanIg,
-      telegram: cleanTg,
+      instagram: sanitizeHandle(instagram),
+      telegram: sanitizeHandle(telegram),
     });
 
     // Return total bookings for this person (for discount calculation)
diff --git a/src/components/sections/About.tsx b/src/components/sections/About.tsx
index 4e21817..146c5e9 100644
--- a/src/components/sections/About.tsx
+++ b/src/components/sections/About.tsx
@@ -30,8 +30,8 @@ export function About({ data: about, stats }: AboutProps) {
         </Reveal>
 
         <div className="mt-14 mx-auto max-w-2xl space-y-8 text-center">
-          {about.paragraphs.map((text, i) => (
-            <Reveal key={i}>
+          {about.paragraphs.map((text) => (
+            <Reveal key={text}>
               <p className="text-xl leading-relaxed text-neutral-600 dark:text-neutral-300 sm:text-2xl">
                 {text}
               </p>
diff --git a/src/components/sections/News.tsx b/src/components/sections/News.tsx
index 71e9f83..6c1b845 100644
--- a/src/components/sections/News.tsx
+++ b/src/components/sections/News.tsx
@@ -132,9 +132,9 @@ export function News({ data }: NewsProps) {
           {rest.length > 0 && (
             <Reveal>
               <div className="rounded-2xl bg-neutral-50/80 px-5 sm:px-6 dark:bg-white/[0.02]">
-                {rest.map((item, i) => (
+                {rest.map((item) => (
                   <CompactArticle
-                    key={i}
+                    key={item.title}
                     item={item}
                     onClick={() => setSelected(item)}
                   />
diff --git a/src/components/sections/Schedule.tsx b/src/components/sections/Schedule.tsx
index 2edb93c..b90cade 100644
--- a/src/components/sections/Schedule.tsx
+++ b/src/components/sections/Schedule.tsx
@@ -1,6 +1,6 @@
 "use client";
 
-import { useState, useMemo, useCallback } from "react";
+import { useReducer, useMemo, useCallback } from "react";
 import { SignupModal } from "@/components/ui/SignupModal";
 import { CalendarDays, Users, LayoutGrid } from "lucide-react";
 import { SectionHeading } from "@/components/ui/SectionHeading";
@@ -16,20 +16,74 @@ import type { SiteContent } from "@/types/content";
 type ViewMode = "days" | "groups";
 type LocationMode = "all" | number;
 
+interface ScheduleState {
+  locationMode: LocationMode;
+  viewMode: ViewMode;
+  filterTrainer: string | null;
+  filterType: string | null;
+  filterStatus: StatusFilter;
+  filterTime: TimeFilter;
+  filterDaySet: Set<string>;
+  bookingGroup: string | null;
+}
+
+type ScheduleAction =
+  | { type: "SET_LOCATION"; mode: LocationMode }
+  | { type: "SET_VIEW"; mode: ViewMode }
+  | { type: "SET_TRAINER"; value: string | null }
+  | { type: "SET_TYPE"; value: string | null }
+  | { type: "SET_STATUS"; value: StatusFilter }
+  | { type: "SET_TIME"; value: TimeFilter }
+  | { type: "TOGGLE_DAY"; day: string }
+  | { type: "SET_BOOKING"; value: string | null }
+  | { type: "CLEAR_FILTERS" };
+
+const initialState: ScheduleState = {
+  locationMode: "all",
+  viewMode: "days",
+  filterTrainer: null,
+  filterType: null,
+  filterStatus: "all",
+  filterTime: "all",
+  filterDaySet: new Set(),
+  bookingGroup: null,
+};
+
+function scheduleReducer(state: ScheduleState, action: ScheduleAction): ScheduleState {
+  switch (action.type) {
+    case "SET_LOCATION":
+      return { ...initialState, viewMode: state.viewMode, locationMode: action.mode };
+    case "SET_VIEW":
+      return { ...state, viewMode: action.mode };
+    case "SET_TRAINER":
+      return { ...state, filterTrainer: action.value };
+    case "SET_TYPE":
+      return { ...state, filterType: action.value };
+    case "SET_STATUS":
+      return { ...state, filterStatus: action.value };
+    case "SET_TIME":
+      return { ...state, filterTime: action.value };
+    case "TOGGLE_DAY": {
+      const next = new Set(state.filterDaySet);
+      if (next.has(action.day)) next.delete(action.day);
+      else next.add(action.day);
+      return { ...state, filterDaySet: next };
+    }
+    case "SET_BOOKING":
+      return { ...state, bookingGroup: action.value };
+    case "CLEAR_FILTERS":
+      return { ...state, filterTrainer: null, filterType: null, filterStatus: "all", filterTime: "all", filterDaySet: new Set() };
+  }
+}
+
 interface ScheduleProps {
   data: SiteContent["schedule"];
   classItems?: { name: string; color?: string }[];
 }
 
 export function Schedule({ data: schedule, classItems }: ScheduleProps) {
-  const [locationMode, setLocationMode] = useState<LocationMode>("all");
-  const [viewMode, setViewMode] = useState<ViewMode>("days");
-  const [filterTrainer, setFilterTrainer] = useState<string | null>(null);
-  const [filterType, setFilterType] = useState<string | null>(null);
-  const [filterStatus, setFilterStatus] = useState<StatusFilter>("all");
-  const [filterTime, setFilterTime] = useState<TimeFilter>("all");
-  const [filterDaySet, setFilterDaySet] = useState<Set<string>>(new Set());
-  const [bookingGroup, setBookingGroup] = useState<string | null>(null);
+  const [state, dispatch] = useReducer(scheduleReducer, initialState);
+  const { locationMode, viewMode, filterTrainer, filterType, filterStatus, filterTime, filterDaySet, bookingGroup } = state;
 
   const isAllMode = locationMode === "all";
 
@@ -38,13 +92,18 @@ export function Schedule({ data: schedule, classItems }: ScheduleProps) {
     if (el) el.scrollIntoView({ behavior: "smooth", block: "start" });
   }, []);
 
+  const setFilterTrainer = useCallback((value: string | null) => dispatch({ type: "SET_TRAINER", value }), []);
+  const setFilterType = useCallback((value: string | null) => dispatch({ type: "SET_TYPE", value }), []);
+  const setFilterStatus = useCallback((value: StatusFilter) => dispatch({ type: "SET_STATUS", value }), []);
+  const setFilterTime = useCallback((value: TimeFilter) => dispatch({ type: "SET_TIME", value }), []);
+
   const setFilterTrainerFromCard = useCallback((trainer: string | null) => {
-    setFilterTrainer(trainer);
+    dispatch({ type: "SET_TRAINER", value: trainer });
     if (trainer) scrollToSchedule();
   }, [scrollToSchedule]);
 
   const setFilterTypeFromCard = useCallback((type: string | null) => {
-    setFilterType(type);
+    dispatch({ type: "SET_TYPE", value: type });
     if (type) scrollToSchedule();
   }, [scrollToSchedule]);
 
@@ -146,11 +205,7 @@ export function Schedule({ data: schedule, classItems }: ScheduleProps) {
   const hasActiveFilter = !!(filterTrainer || filterType || filterStatus !== "all" || filterTime !== "all" || filterDaySet.size > 0);
 
   function clearFilters() {
-    setFilterTrainer(null);
-    setFilterType(null);
-    setFilterStatus("all");
-    setFilterTime("all");
-    setFilterDaySet(new Set());
+    dispatch({ type: "CLEAR_FILTERS" });
   }
 
   // Available days for the day filter
@@ -160,17 +215,11 @@ export function Schedule({ data: schedule, classItems }: ScheduleProps) {
   );
 
   function toggleDay(day: string) {
-    setFilterDaySet((prev) => {
-      const next = new Set(prev);
-      if (next.has(day)) next.delete(day);
-      else next.add(day);
-      return next;
-    });
+    dispatch({ type: "TOGGLE_DAY", day });
   }
 
   function switchLocation(mode: LocationMode) {
-    setLocationMode(mode);
-    clearFilters();
+    dispatch({ type: "SET_LOCATION", mode });
   }
 
   const activeTabClass = "bg-gold text-black shadow-[0_0_20px_rgba(201,169,110,0.3)]";
@@ -232,7 +281,7 @@ export function Schedule({ data: schedule, classItems }: ScheduleProps) {
           <div className="mt-4 flex justify-center">
             <div className="inline-flex rounded-xl border border-neutral-200 bg-neutral-100 p-1 dark:border-white/[0.08] dark:bg-white/[0.04]">
               <button
-                onClick={() => setViewMode("days")}
+                onClick={() => dispatch({ type: "SET_VIEW", mode: "days" })}
                 className={`inline-flex items-center gap-1.5 rounded-lg px-4 py-2 text-xs font-medium transition-all duration-200 cursor-pointer ${
                   viewMode === "days"
                     ? "bg-white text-neutral-900 shadow-sm dark:bg-white/10 dark:text-white"
@@ -243,7 +292,7 @@ export function Schedule({ data: schedule, classItems }: ScheduleProps) {
                 По дням
               </button>
               <button
-                onClick={() => setViewMode("groups")}
+                onClick={() => dispatch({ type: "SET_VIEW", mode: "groups" })}
                 className={`inline-flex items-center gap-1.5 rounded-lg px-4 py-2 text-xs font-medium transition-all duration-200 cursor-pointer ${
                   viewMode === "groups"
                     ? "bg-white text-neutral-900 shadow-sm dark:bg-white/10 dark:text-white"
@@ -331,13 +380,13 @@ export function Schedule({ data: schedule, classItems }: ScheduleProps) {
             filterTrainer={filterTrainer}
             setFilterTrainer={setFilterTrainerFromCard}
             showLocation={isAllMode}
-            onBook={setBookingGroup}
+            onBook={(v) => dispatch({ type: "SET_BOOKING", value: v })}
           />
         </Reveal>
       )}
       <SignupModal
         open={bookingGroup !== null}
-        onClose={() => setBookingGroup(null)}
+        onClose={() => dispatch({ type: "SET_BOOKING", value: null })}
         subtitle={bookingGroup ?? undefined}
         endpoint="/api/group-booking"
         extraBody={{ groupInfo: bookingGroup }}
diff --git a/src/lib/content.ts b/src/lib/content.ts
index d5e64a6..8930ce2 100644
--- a/src/lib/content.ts
+++ b/src/lib/content.ts
@@ -2,12 +2,28 @@ import { getSiteContent } from "@/lib/db";
 import { siteContent as fallback } from "@/data/content";
 import type { SiteContent } from "@/types/content";
 
+let cached: { data: SiteContent; expiresAt: number } | null = null;
+const CACHE_TTL = 5 * 60 * 1000; // 5 minutes
+
 export function getContent(): SiteContent {
+  const now = Date.now();
+  if (cached && now < cached.expiresAt) {
+    return cached.data;
+  }
+
   try {
     const content = getSiteContent();
-    if (content) return content;
+    if (content) {
+      cached = { data: content, expiresAt: now + CACHE_TTL };
+      return content;
+    }
     return fallback;
   } catch {
     return fallback;
   }
 }
+
+/** Invalidate the content cache (call after admin edits). */
+export function invalidateContentCache() {
+  cached = null;
+}
diff --git a/src/lib/validation.ts b/src/lib/validation.ts
new file mode 100644
index 0000000..8fb2e4f
--- /dev/null
+++ b/src/lib/validation.ts
@@ -0,0 +1,27 @@
+/**
+ * Shared input sanitization for public registration endpoints.
+ */
+
+export function sanitizeName(name: unknown): string | null {
+  if (!name || typeof name !== "string") return null;
+  const clean = name.trim().slice(0, 100);
+  return clean || null;
+}
+
+export function sanitizePhone(phone: unknown): string | null {
+  if (!phone || typeof phone !== "string") return null;
+  const clean = phone.replace(/\D/g, "").slice(0, 15);
+  return clean.length >= 9 ? clean : null;
+}
+
+export function sanitizeHandle(value: unknown): string | undefined {
+  if (!value || typeof value !== "string") return undefined;
+  const clean = value.trim().slice(0, 100);
+  return clean || undefined;
+}
+
+export function sanitizeText(value: unknown, maxLength: number = 200): string | undefined {
+  if (!value || typeof value !== "string") return undefined;
+  const clean = value.trim().slice(0, maxLength);
+  return clean || undefined;
+}