fix: mobile UX — GPS permission flow, traffic toggle, overflow

GPS permission:
- Remove silent mount-time getCurrentPosition calls that cause iOS Safari
  to cache a "denied" state without ever prompting the user
- LocateButton always retries getCurrentPosition on tap (user gesture)
- Only show "denied" toast on PERMISSION_DENIED (code 1), not timeout
- MapView watchPosition now starts only after confirmed grant, not unconditionally

Traffic toggle:
- Fix isStyleLoaded() race in LayerControl — if style not loaded when
  toggle fires, defer to map.once("style.load") instead of silently bailing
- Change outside-click handler from mousedown to pointerdown for mobile

Mobile UX (from prior session):
- Add LocateButton component (crosshair GPS locate/re-center)
- Reposition layer control + locate button to top-right on mobile
  (below MapLibre nav controls, above bottom sheet)
- ModeSelector: add min-w-0 to prevent flex overflow at 390px
- StopItem: remove button visible on touch (60% opacity vs hover-only)
- Panel: overflow-x-hidden + safe-area-inset-bottom on mobile sheet
- Body overflow-x guard on mobile viewports

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/LayerControl.jsx

@@ -40,27 +40,49 @@ export default function LayerControl({ mapRef }) {
 
   // Apply layers when prefs change
   useEffect(() => {
-    const map = mapRef?.current?.getMap?.()
-    if (!map || !map.isStyleLoaded()) return
+    const mapView = mapRef?.current
+    if (!mapView) return
+    const map = mapView.getMap?.()
+    if (!map) return
 
-    if (hillshade && hasFeature('has_hillshade')) {
-      mapRef.current.addHillshadeLayer?.()
+    const apply = () => {
+      if (hillshade && hasFeature('has_hillshade')) {
+        mapView.addHillshadeLayer?.()
+      } else {
+        mapView.removeHillshadeLayer?.()
+      }
+    }
+
+    if (map.isStyleLoaded()) {
+      apply()
     } else {
-      mapRef.current.removeHillshadeLayer?.()
+      map.once('style.load', apply)
     }
     savePrefs({ hillshade, traffic })
+    return () => map.off('style.load', apply)
   }, [hillshade, mapRef])
 
   useEffect(() => {
-    const map = mapRef?.current?.getMap?.()
-    if (!map || !map.isStyleLoaded()) return
+    const mapView = mapRef?.current
+    if (!mapView) return
+    const map = mapView.getMap?.()
+    if (!map) return
 
-    if (traffic && hasFeature('has_traffic_overlay')) {
-      mapRef.current.addTrafficLayer?.()
+    const apply = () => {
+      if (traffic && hasFeature('has_traffic_overlay')) {
+        mapView.addTrafficLayer?.()
+      } else {
+        mapView.removeTrafficLayer?.()
+      }
+    }
+
+    if (map.isStyleLoaded()) {
+      apply()
     } else {
-      mapRef.current.removeTrafficLayer?.()
+      map.once('style.load', apply)
     }
     savePrefs({ hillshade, traffic })
+    return () => map.off('style.load', apply)
   }, [traffic, mapRef])
 
   // Close on outside click
@@ -71,8 +93,8 @@ export default function LayerControl({ mapRef }) {
         setOpen(false)
       }
     }
-    document.addEventListener('mousedown', handleClick)
-    return () => document.removeEventListener('mousedown', handleClick)
+    document.addEventListener('pointerdown', handleClick)
+    return () => document.removeEventListener('pointerdown', handleClick)
   }, [open])
 
   const showHillshade = hasFeature('has_hillshade')

src/components/LocateButton.jsx

@@ -0,0 +1,54 @@
+import { Locate } from 'lucide-react'
+import toast from 'react-hot-toast'
+import { useStore } from '../store'
+
+export default function LocateButton({ mapRef }) {
+  const handleClick = () => {
+    const { userLocation } = useStore.getState()
+
+    // If we have a cached location, fly immediately for instant feedback
+    if (userLocation) {
+      mapRef.current?.flyTo(userLocation.lat, userLocation.lon, 14)
+    }
+
+    // Always request fresh position — never trust cached permission state.
+    // iOS Safari can "forget" a silent mount-time denial between requests,
+    // and a user-gesture-triggered call is more likely to prompt.
+    navigator.geolocation.getCurrentPosition(
+      (pos) => {
+        const loc = { lat: pos.coords.latitude, lon: pos.coords.longitude }
+        useStore.getState().setUserLocation(loc)
+        useStore.getState().setGeoPermission('granted')
+        // Fly to fresh position if we didn't have a cached one
+        if (!userLocation) {
+          mapRef.current?.flyTo(loc.lat, loc.lon, 14)
+        }
+      },
+      (err) => {
+        if (err.code === 1) {
+          // PERMISSION_DENIED — user explicitly denied
+          useStore.getState().setGeoPermission('denied')
+          toast('Location access denied.\nEnable in browser settings.', { icon: '\u{1F4CD}' })
+        } else if (err.code === 3 && !userLocation) {
+          // TIMEOUT — only toast if we have no cached location
+          toast('Location timed out. Try again.', { icon: '\u23F1\uFE0F' })
+        }
+        // POSITION_UNAVAILABLE (code 2): silent, likely temporary
+      },
+      { enableHighAccuracy: true, timeout: 10000 }
+    )
+  }
+
+  if (!navigator.geolocation) return null
+
+  return (
+    <button
+      className="locate-btn"
+      onClick={handleClick}
+      title="My location"
+      aria-label="Center map on my location"
+    >
+      <Locate size={18} />
+    </button>
+  )
+}

src/components/MapView.jsx

@@ -197,36 +197,6 @@ const MapView = forwardRef(function MapView(_, ref) {
 
     map.addControl(new maplibregl.NavigationControl(), 'top-right')
 
-    // GPS tracking — creates chevron or dot marker
-    if (navigator.geolocation) {
-      navigator.geolocation.getCurrentPosition(
-        (pos) => {
-          const { latitude, longitude } = pos.coords
-          if (useStore.getState().stops.length === 0) {
-            map.flyTo({ center: [longitude, latitude], zoom: 12, duration: 1500 })
-          }
-          useStore.getState().setUserLocation({ lat: latitude, lon: longitude })
-          useStore.getState().setGeoPermission('granted')
-          createOrUpdateGpsMarker(map, latitude, longitude, null)
-        },
-        () => {
-          useStore.getState().setGeoPermission('denied')
-        },
-        { enableHighAccuracy: false, timeout: 8000, maximumAge: 300000 }
-      )
-
-      // Watch for heading changes
-      watchIdRef.current = navigator.geolocation.watchPosition(
-        (pos) => {
-          const { latitude, longitude, heading } = pos.coords
-          useStore.getState().setUserLocation({ lat: latitude, lon: longitude })
-          createOrUpdateGpsMarker(map, latitude, longitude, heading)
-        },
-        () => {},
-        { enableHighAccuracy: true, maximumAge: 5000 }
-      )
-    }
-
     // Map click — drop pin and reverse geocode
     map.on('click', (e) => {
       // If a stop pin was just clicked, skip the pin-drop
@@ -335,7 +305,34 @@ const MapView = forwardRef(function MapView(_, ref) {
     }
   }
 
-  // Swap map theme when store.theme changes
+  // React to permission changes from LocateButton (when user grants after initial denial)
+  useEffect(() => {
+    const map = mapInstance.current
+    if (!map || geoPermission !== 'granted') return
+
+    // If marker already exists, watchPosition is already running — nothing to do
+    if (gpsMarkerRef.current) return
+
+    // Permission was just granted (likely from LocateButton) — create marker + start tracking
+    const loc = useStore.getState().userLocation
+    if (loc) {
+      createOrUpdateGpsMarker(map, loc.lat, loc.lon, null)
+    }
+
+    if (!watchIdRef.current) {
+      watchIdRef.current = navigator.geolocation.watchPosition(
+        (pos) => {
+          const { latitude, longitude, heading } = pos.coords
+          useStore.getState().setUserLocation({ lat: latitude, lon: longitude })
+          createOrUpdateGpsMarker(map, latitude, longitude, heading)
+        },
+        () => {},
+        { enableHighAccuracy: true, maximumAge: 5000 }
+      )
+    }
+  }, [geoPermission])
+
+    // Swap map theme when store.theme changes
   useEffect(() => {
     const map = mapInstance.current
     if (!map || currentThemeRef.current === theme) return

src/components/ModeSelector.jsx

@@ -26,7 +26,7 @@ export default function ModeSelector() {
             role="radio"
             aria-checked={active}
             onClick={() => setMode(m.id)}
-            className="flex-1 flex items-center justify-center gap-1.5 py-2 px-2 text-xs font-medium transition-colors duration-100"
+            className="flex-1 min-w-0 flex items-center justify-center gap-1.5 py-2 px-2 text-xs font-medium transition-colors duration-100"
             style={{
               background: active ? 'var(--accent-muted)' : 'transparent',
               color: active ? 'var(--accent)' : 'var(--text-secondary)',

src/components/Panel.jsx

@@ -215,7 +215,7 @@ export default function Panel({ onManeuverClick }) {
       </div>
 
       {sheetState !== 'collapsed' && (
-        <div className="px-4 pb-4 overflow-y-auto h-[calc(100%-2rem)]">
+        <div className="px-4 pb-4 overflow-y-auto overflow-x-hidden h-[calc(100%-2rem)]" style={{ paddingBottom: 'max(1rem, env(safe-area-inset-bottom))' }}>
           {header}
           {content}
         </div>

src/components/StopItem.jsx

@@ -66,7 +66,7 @@ export default function StopItem({ stop, index, total, indexOffset = 0 }) {
       {/* Remove button */}
       <button
         onClick={() => removeStop(stop.id)}
-        className="opacity-0 group-hover:opacity-100 transition-opacity p-0.5"
+        className="stop-remove-btn p-0.5"
         style={{ color: 'var(--text-tertiary)' }}
         aria-label={`Remove stop ${stop.name}`}
       >