feat: enhance CSS and components for Telegram Mini App performance

- Updated CSS to utilize viewport variables for safe area insets and stable height, improving layout consistency across devices.
- Introduced haptic feedback triggers in various components to enhance user interaction, mimicking native Telegram behavior.
- Added functionality to detect Android performance class, minimizing animations on low-performance devices for better user experience.
- Refactored components to incorporate new CSS classes for content safety and improved responsiveness.

webapp-next/src/app/globals.css

@@ -174,7 +174,7 @@ html::-webkit-scrollbar {
   margin-right: auto;
   padding: 12px;
   padding-top: 0;
-  padding-bottom: env(safe-area-inset-bottom, 12px);
+  padding-bottom: var(--tg-viewport-content-safe-area-inset-bottom, env(safe-area-inset-bottom, 12px));
   border-radius: 12px;
 }
 
@@ -261,9 +261,25 @@ html::-webkit-scrollbar {
   }
 }
 
+/* Android low-performance devices: minimize animations (Telegram User-Agent). */
+[data-perf="low"] *,
+[data-perf="low"] *::before,
+[data-perf="low"] *::after {
+  animation-duration: 0.01ms !important;
+  animation-iteration-count: 1 !important;
+  transition-duration: 0.01ms !important;
+}
+
 /* Safe area for Telegram Mini App (notch / status bar). */
 .pt-safe {
-  padding-top: env(safe-area-inset-top, 0);
+  padding-top: var(--tg-viewport-content-safe-area-inset-top, env(safe-area-inset-top, 0));
+}
+
+/* Content safe area: top/bottom only to avoid overlap with Telegram header/bottom bar (Bot API 8.0+).
+   Horizontal padding is left to layout classes (e.g. px-3) so indents are preserved when viewport vars are 0. */
+.content-safe {
+  padding-top: var(--tg-viewport-content-safe-area-inset-top, env(safe-area-inset-top, 0));
+  padding-bottom: var(--tg-viewport-content-safe-area-inset-bottom, env(safe-area-inset-bottom, 0));
 }
 
 /* Sticky calendar header: shadow when scrolled (useStickyScroll). */
@@ -305,7 +321,7 @@ html::-webkit-scrollbar {
   body {
     margin: 0;
     padding: 0;
-    min-height: 100vh;
+    min-height: var(--tg-viewport-stable-height, 100vh);
     background: var(--bg);
     color: var(--text);
     font-family: system-ui, -apple-system, sans-serif;

webapp-next/src/app/page.tsx

@@ -50,7 +50,7 @@ export default function Home() {
   const content = accessDenied ? (
     <AccessDeniedScreen primaryAction="reload" />
   ) : currentView === "currentDuty" ? (
-    <div className="mx-auto flex min-h-screen w-full max-w-[var(--max-width-app)] flex-col bg-background px-3 pb-6 pt-safe">
+    <div className="content-safe mx-auto flex min-h-screen w-full max-w-[var(--max-width-app)] flex-col bg-background px-3 pb-6">
       <CurrentDutyView
         onBack={handleBackFromCurrentDuty}
         openedFromPin={startParam === "duty"}
@@ -62,9 +62,9 @@ export default function Home() {
 
   return (
     <div
+      className="min-h-[var(--tg-viewport-stable-height,100vh)]"
       style={{
         visibility: appContentReady ? "visible" : "hidden",
-        minHeight: "100vh",
       }}
     >
       {content}

webapp-next/src/components/CalendarPage.tsx

@@ -17,6 +17,7 @@ import { CalendarGrid } from "@/components/calendar/CalendarGrid";
 import { DutyList } from "@/components/duty/DutyList";
 import { DayDetail, type DayDetailHandle } from "@/components/day-detail";
 import { ErrorState } from "@/components/states/ErrorState";
+import { triggerHapticLight } from "@/lib/telegram-haptic";
 
 /** Fallback height (px) until ResizeObserver reports the sticky block size. Matches --calendar-block-min-height + pb-2 (260 + 8). */
 const STICKY_HEIGHT_FALLBACK_PX = 268;
@@ -90,10 +91,12 @@ export function CalendarPage({ isAllowed, initDataRaw }: CalendarPageProps) {
   const navDisabled = loading || accessDenied || selectedDay !== null;
   const handlePrevMonth = useCallback(() => {
     if (navDisabled) return;
+    triggerHapticLight();
     prevMonth();
   }, [navDisabled, prevMonth]);
   const handleNextMonth = useCallback(() => {
     if (navDisabled) return;
+    triggerHapticLight();
     nextMonth();
   }, [navDisabled, nextMonth]);
 
@@ -133,7 +136,7 @@ export function CalendarPage({ isAllowed, initDataRaw }: CalendarPageProps) {
   }, [loading, accessDenied, setAppContentReady]);
 
   return (
-    <div className="mx-auto flex min-h-screen w-full max-w-[var(--max-width-app)] flex-col bg-background px-3 pb-6 pt-safe">
+    <div className="content-safe mx-auto flex min-h-screen w-full max-w-[var(--max-width-app)] flex-col bg-background px-3 pb-6">
       <div
         ref={calendarStickyRef}
         className="sticky top-0 z-10 min-h-[var(--calendar-block-min-height)] bg-background pb-2"

webapp-next/src/components/calendar/CalendarDay.tsx

@@ -9,6 +9,7 @@ import React, { useMemo } from "react";
 import { useTranslation } from "@/i18n/use-translation";
 import { dateKeyToDDMM } from "@/lib/date-utils";
 import { cn } from "@/lib/utils";
+import { triggerHapticLight } from "@/lib/telegram-haptic";
 import type { DutyWithUser } from "@/types";
 import { DayIndicators } from "./DayIndicators";
 
@@ -89,6 +90,7 @@ function CalendarDayInner({
       )}
       onClick={(e) => {
         if (isOtherMonth) return;
+        triggerHapticLight();
         onDayClick(dateKey, e.currentTarget.getBoundingClientRect());
       }}
     >

webapp-next/src/components/current-duty/CurrentDutyView.tsx

@@ -20,6 +20,7 @@ import {
   formatHHMM,
 } from "@/lib/date-utils";
 import { getRemainingTime, findCurrentDuty } from "@/lib/current-duty";
+import { triggerHapticLight } from "@/lib/telegram-haptic";
 import { ContactLinks } from "@/components/contact/ContactLinks";
 import { Button } from "@/components/ui/button";
 import {
@@ -145,10 +146,12 @@ export function CurrentDutyView({ onBack, openedFromPin = false }: CurrentDutyVi
   }, [onBack]);
 
   const handleBack = () => {
+    triggerHapticLight();
     onBack();
   };
 
   const handleClose = () => {
+    triggerHapticLight();
     if (closeMiniApp.isAvailable()) {
       closeMiniApp();
     } else {
@@ -213,6 +216,7 @@ export function CurrentDutyView({ onBack, openedFromPin = false }: CurrentDutyVi
 
   if (state === "error") {
     const handleRetry = () => {
+      triggerHapticLight();
       setState("loading");
       loadTodayDuties();
     };

webapp-next/src/components/day-detail/DayDetail.tsx

@@ -27,6 +27,7 @@ import { DayDetailContent } from "./DayDetailContent";
 import type { CalendarEvent, DutyWithUser } from "@/types";
 import { cn } from "@/lib/utils";
 import { useAppStore } from "@/store/app-store";
+import { triggerHapticLight } from "@/lib/telegram-haptic";
 
 /** Empty state for day detail: date and "no duties or events" message. */
 function DayDetailEmpty({ dateKey }: { dateKey: string }) {
@@ -120,6 +121,7 @@ export const DayDetail = React.forwardRef<DayDetailHandle, DayDetailProps>(
 
     /** Start close animation; actual unmount happens in onCloseAnimationEnd (or fallback timeout). */
     const requestClose = React.useCallback(() => {
+      triggerHapticLight();
       setExiting(true);
     }, []);
 

webapp-next/src/components/duty/DutyTimelineCard.tsx

@@ -13,6 +13,7 @@ import {
   formatHHMM,
 } from "@/lib/date-utils";
 import { cn } from "@/lib/utils";
+import { triggerHapticLight } from "@/lib/telegram-haptic";
 import { ContactLinks } from "@/components/contact/ContactLinks";
 import { Button } from "@/components/ui/button";
 import type { DutyWithUser } from "@/types";
@@ -77,6 +78,7 @@ export function DutyTimelineCard({
   const flipped = isControlled ? (isFlipped ?? false) : localFlipped;
 
   const handleFlipToBack = () => {
+    triggerHapticLight();
     if (isControlled) {
       onFlipChange?.(true);
     } else {
@@ -86,6 +88,7 @@ export function DutyTimelineCard({
   };
 
   const handleFlipToFront = () => {
+    triggerHapticLight();
     if (isControlled) {
       onFlipChange?.(false);
     } else {

webapp-next/src/components/providers/TelegramProvider.tsx

@@ -6,15 +6,20 @@ import {
   mountMiniAppSync,
   mountThemeParamsSync,
   bindThemeParamsCssVars,
+  mountViewport,
+  bindViewportCssVars,
+  unmountViewport,
 } from "@telegram-apps/sdk-react";
 import { fixSurfaceContrast } from "@/hooks/use-telegram-theme";
+import { applyAndroidPerformanceClass } from "@/lib/telegram-android-perf";
 
 /**
  * Wraps the app with Telegram Mini App SDK initialization.
  * Calls init(acceptCustomStyles), mounts theme params (binds --tg-theme-* CSS vars),
- * and mounts the mini app. Does not call ready() here — the app calls
+ * mounts the mini app, then mounts viewport and binds viewport CSS vars
- * callMiniAppReadyOnce() from lib/telegram-ready when the first visible screen
+ * (--tg-viewport-stable-height, --tg-viewport-content-safe-area-inset-*, etc.).
- * has finished loading, so Telegram keeps its native loading animation until then.
+ * Does not call ready() here — the app calls callMiniAppReadyOnce() from
+ * lib/telegram-ready when the first visible screen has finished loading.
  * Theme is set before first paint by the inline script in layout.tsx (URL hash);
  * useTelegramTheme() in the app handles ongoing theme changes.
  */
@@ -39,7 +44,26 @@ export function TelegramProvider({
       mountMiniAppSync();
     }
 
-    return cleanup;
+    applyAndroidPerformanceClass();
+
+    let unbindViewportCssVars: (() => void) | undefined;
+    if (mountViewport.isAvailable()) {
+      mountViewport()
+        .then(() => {
+          if (bindViewportCssVars.isAvailable()) {
+            unbindViewportCssVars = bindViewportCssVars();
+          }
+        })
+        .catch(() => {
+          // Viewport not supported (e.g. not in Mini App); ignore.
+        });
+    }
+
+    return () => {
+      unbindViewportCssVars?.();
+      unmountViewport();
+      cleanup();
+    };
   }, []);
 
   return <>{children}</>;

webapp-next/src/components/states/AccessDeniedScreen.tsx

@@ -8,6 +8,7 @@
 import { useEffect } from "react";
 import { getLang, translate } from "@/i18n/messages";
 import { useAppStore } from "@/store/app-store";
+import { triggerHapticLight } from "@/lib/telegram-haptic";
 
 export interface AccessDeniedScreenProps {
   /** Optional detail from API 403 response, shown below the hint. */
@@ -40,6 +41,7 @@ export function AccessDeniedScreen({
   const hasDetail = Boolean(serverDetail && String(serverDetail).trim());
 
   const handleClick = () => {
+    triggerHapticLight();
     if (primaryAction === "reload") {
       if (typeof window !== "undefined") {
         window.location.reload();

webapp-next/src/components/states/ErrorState.tsx

@@ -8,6 +8,7 @@
 import { useTranslation } from "@/i18n/use-translation";
 import { Button } from "@/components/ui/button";
 import { cn } from "@/lib/utils";
+import { triggerHapticLight } from "@/lib/telegram-haptic";
 
 export interface ErrorStateProps {
   /** Error message to display. If not provided, uses generic i18n message. */
@@ -65,7 +66,10 @@ export function ErrorState({ message, onRetry, className }: ErrorStateProps) {
           variant="default"
           size="sm"
           className="mt-1 bg-primary text-primary-foreground hover:opacity-90 focus-visible:outline-2 focus-visible:outline-accent focus-visible:outline-offset-2"
-          onClick={onRetry}
+          onClick={() => {
+            triggerHapticLight();
+            onRetry();
+          }}
         >
           {t("error.retry")}
         </Button>

webapp-next/src/hooks/use-telegram-theme.test.ts

@@ -16,6 +16,7 @@ vi.mock("@telegram-apps/sdk-react", () => ({
   isThemeParamsDark: vi.fn(),
   setMiniAppBackgroundColor: { isAvailable: vi.fn(() => false) },
   setMiniAppHeaderColor: { isAvailable: vi.fn(() => false) },
+  setMiniAppBottomBarColor: { isAvailable: vi.fn(() => false) },
 }));
 
 describe("getFallbackScheme", () => {

webapp-next/src/hooks/use-telegram-theme.ts

@@ -6,6 +6,7 @@ import {
   isThemeParamsDark,
   setMiniAppBackgroundColor,
   setMiniAppHeaderColor,
+  setMiniAppBottomBarColor,
 } from "@telegram-apps/sdk-react";
 
 /**
@@ -69,6 +70,9 @@ export function applyTheme(scheme?: "dark" | "light"): void {
   if (setMiniAppHeaderColor.isAvailable()) {
     setMiniAppHeaderColor("bg_color");
   }
+  if (setMiniAppBottomBarColor.isAvailable()) {
+    setMiniAppBottomBarColor("bottom_bar_bg_color");
+  }
 }
 
 /**

webapp-next/src/lib/telegram-android-perf.ts

@@ -0,0 +1,26 @@
+/**
+ * Detects Android Telegram Mini App performance class from User-Agent and sets
+ * data-perf on document.documentElement so CSS can reduce animations on low-end devices.
+ * @see https://core.telegram.org/bots/webapps#additional-data-in-user-agent
+ */
+
+import { retrieveAndroidDeviceData } from "@telegram-apps/sdk-react";
+
+const DATA_ATTR = "data-perf";
+
+/**
+ * Runs once: if running in Telegram on Android with LOW performance class,
+ * sets data-perf="low" on the document root for CSS to minimize animations.
+ */
+export function applyAndroidPerformanceClass(): void {
+  if (typeof document === "undefined") return;
+  try {
+    const data = retrieveAndroidDeviceData();
+    const perf = data?.performanceClass;
+    if (perf === "LOW") {
+      document.documentElement.setAttribute(DATA_ATTR, "low");
+    }
+  } catch {
+    // Not in Telegram or not Android; ignore.
+  }
+}

webapp-next/src/lib/telegram-haptic.ts

@@ -0,0 +1,19 @@
+/**
+ * Triggers Telegram Mini App haptic feedback when available.
+ * Use on primary actions and key interactions to mimic native Telegram behavior.
+ */
+
+import { hapticFeedbackImpactOccurred } from "@telegram-apps/sdk-react";
+
+/**
+ * Triggers light impact haptic feedback. No-op when not in Telegram or unsupported.
+ */
+export function triggerHapticLight(): void {
+  try {
+    if (hapticFeedbackImpactOccurred.isAvailable()) {
+      hapticFeedbackImpactOccurred("light");
+    }
+  } catch {
+    // SDK not available; ignore.
+  }
+}

webapp-next/src/lib/telegram-ready.ts

@@ -1,15 +1,17 @@
 /**
- * Single-call wrapper for Telegram Mini App ready().
+ * Single-call wrapper for Telegram Mini App ready() and expand().
  * Called once when the first visible screen has finished loading so Telegram
  * hides its native loading animation only after our content is ready.
+ * Also expands the Mini App to full height when supported.
  */
 
-import { miniAppReady } from "@telegram-apps/sdk-react";
+import { miniAppReady, expandViewport } from "@telegram-apps/sdk-react";
 
 let readyCalled = false;
 
 /**
- * Calls Telegram miniAppReady() at most once per session.
+ * Calls Telegram miniAppReady() at most once per session, then expandViewport()
+ * when available so the app opens to full height.
  * Safe when SDK is unavailable (e.g. non-Telegram environment).
  */
 export function callMiniAppReadyOnce(): void {
@@ -19,6 +21,9 @@ export function callMiniAppReadyOnce(): void {
       miniAppReady();
       readyCalled = true;
     }
+    if (expandViewport.isAvailable()) {
+      expandViewport();
+    }
   } catch {
     // SDK not available or not in Mini App context; no-op.
   }