added swipe gestures

src/App.tsx

@@ -2,8 +2,14 @@ import { lazy, Suspense } from 'react'
 import { BrowserRouter, Routes, Route, Navigate } from 'react-router-dom'
 import { AuthProvider } from './contexts/AuthContext'
 import { ProtectedRoute } from './components/ProtectedRoute'
+import { useSwipeNav } from './hooks/useSwipeNav'
 import './App.css'
 
+function SwipeNavHandler() {
+  useSwipeNav()
+  return null
+}
+
 const HomePage = lazy(() => import('./pages/HomePage'))
 const HistoryPage = lazy(() => import('./pages/HistoryPage'))
 const SettingsPage = lazy(() => import('./pages/SettingsPage'))
@@ -16,6 +22,7 @@ function App() {
   return (
     <AuthProvider>
       <BrowserRouter>
+        <SwipeNavHandler />
         <Suspense fallback={null}>
         <Routes>
           <Route path="/" element={<LoginPage />} />

src/hooks/useSwipeNav.ts

@@ -0,0 +1,83 @@
+import { useEffect } from 'react'
+import { useNavigate, useLocation } from 'react-router-dom'
+
+const PAGES = ['/write', '/history', '/settings']
+const SWIPE_THRESHOLD = 55   // minimum horizontal px to count as a swipe
+const DESKTOP_BREAKPOINT = 860
+
+/** Walk up the DOM and return true if any ancestor is horizontally scrollable */
+function isInHScrollable(el: Element | null): boolean {
+  while (el && el !== document.body) {
+    const style = window.getComputedStyle(el)
+    const ox = style.overflowX
+    if ((ox === 'scroll' || ox === 'auto') && el.scrollWidth > el.clientWidth) {
+      return true
+    }
+    el = el.parentElement
+  }
+  return false
+}
+
+/** Swipe left/right to navigate between the three main pages (mobile only) */
+export function useSwipeNav() {
+  const navigate = useNavigate()
+  const location = useLocation()
+
+  useEffect(() => {
+    let startX = 0
+    let startY = 0
+    let startTarget: Element | null = null
+    let cancelled = false
+
+    const onTouchStart = (e: TouchEvent) => {
+      startX = e.touches[0].clientX
+      startY = e.touches[0].clientY
+      startTarget = e.target as Element
+      cancelled = false
+    }
+
+    const onTouchMove = (e: TouchEvent) => {
+      // If vertical movement dominates early, cancel the swipe so we never
+      // accidentally navigate while the user is scrolling.
+      const dx = Math.abs(e.touches[0].clientX - startX)
+      const dy = Math.abs(e.touches[0].clientY - startY)
+      if (!cancelled && dy > dx && dy > 10) cancelled = true
+    }
+
+    const onTouchEnd = (e: TouchEvent) => {
+      if (cancelled) return
+      if (window.innerWidth >= DESKTOP_BREAKPOINT) return
+
+      const dx = e.changedTouches[0].clientX - startX
+      const dy = e.changedTouches[0].clientY - startY
+
+      // Must be predominantly horizontal
+      if (Math.abs(dx) <= Math.abs(dy)) return
+      // Must clear the distance threshold
+      if (Math.abs(dx) < SWIPE_THRESHOLD) return
+      // Don't swipe-navigate when inside a horizontal scroll container
+      if (isInHScrollable(startTarget)) return
+      // Don't swipe-navigate when a modal/overlay is open
+      if (document.querySelector('.confirm-modal-overlay, .cropper-overlay, .reminder-modal-overlay')) return
+
+      const idx = PAGES.indexOf(location.pathname)
+      if (idx === -1) return
+
+      if (dx < 0 && idx < PAGES.length - 1) {
+        navigate(PAGES[idx + 1])   // swipe left  → next page
+      } else if (dx > 0 && idx > 0) {
+        navigate(PAGES[idx - 1])   // swipe right → previous page
+      }
+    }
+
+    document.addEventListener('touchstart', onTouchStart, { passive: true })
+    document.addEventListener('touchmove',  onTouchMove,  { passive: true })
+    document.addEventListener('touchend',   onTouchEnd,   { passive: true })
+
+    return () => {
+      document.removeEventListener('touchstart', onTouchStart)
+      document.removeEventListener('touchmove',  onTouchMove)
+      document.removeEventListener('touchend',   onTouchEnd)
+    }
+  }, [navigate, location.pathname])
+}