fix(mobile): the map compass stands above the base-layer switcher

Beside it the two round controls read as one crowded row over the dock; on the switcher's own left edge, one gap above it, they form a column.

client/src/mobile/screens/trip/map/MMapArea.tsx

@@ -21,11 +21,13 @@ import type { ViewportPadding } from '../../../../utils/mapViewport'
 const NO_POIS: Poi[] = []
 
 /**
- * The compass stands one gap to the right of the base-layer switcher both engines draw
- * in the bottom left corner. Worked out from the switcher's own numbers rather than
- * written down as 70, so moving or resizing the switcher carries the compass along.
+ * The compass stands one gap above the base-layer switcher both engines draw in the
+ * bottom left corner, on the same left edge, so the two round controls form a column
+ * instead of a row. Worked out from the switcher's own numbers, so moving or resizing
+ * the switcher carries the compass along.
  */
-const COMPASS_LEFT = MAP_LAYER_SWITCHER_INSET + MAP_ROUND_CONTROL_SIZE + 8
+const COMPASS_LEFT = MAP_LAYER_SWITCHER_INSET
+const COMPASS_RAISE = MAP_ROUND_CONTROL_SIZE + 8
 
 /** The safe-area insets at the top and the bottom of the screen, in pixels. */
 interface SafeInsets {
@@ -436,14 +438,12 @@ export default function MMapArea({ planner, shell }: MMapAreaProps) {
       )}
 
       {/* Compass, GL maps only (Leaflet cannot rotate). Both engines draw the base-layer
-          switcher in the bottom left corner, so the compass sits beside it rather than in
-          the corner: at `left-3` it started 8px left of the switcher and ran on under it,
-          reading as a second button showing through the frosted shell. Same
-          --bottom-nav-h band as the locate button's `right: 12`, so the round controls
-          still share one line. The left offset is inline because it is computed from the
-          switcher's own numbers. */}
+          switcher in the bottom left corner, so the compass stands on top of it, on the
+          same left edge: beside it the two read as one crowded row next to the dock.
+          The offsets are inline because they are computed from the switcher's own
+          numbers. */}
       {mapActive && glMap && (
-        <div className="pointer-events-none absolute z-[25]" style={{ left: COMPASS_LEFT, bottom: 'calc(var(--bottom-nav-h, 84px) + 12px)' }}>
+        <div className="pointer-events-none absolute z-[25]" style={{ left: COMPASS_LEFT, bottom: `calc(var(--bottom-nav-h, 84px) + ${12 + COMPASS_RAISE}px)` }}>
           <MapCompassPill map={glMap} />
         </div>
       )}

client/tests/unit/mobile/trip/MMapArea.test.tsx

@@ -194,15 +194,12 @@ describe('MMapArea', () => {
     expect(segment.style.flexGrow).toBe('1')
   })
 
-  it('FE-MOB-MAPAREA-002: the compass rides the same bottom offset as the locate button', () => {
+  it('FE-MOB-MAPAREA-002: the compass stands on top of the base-layer switcher', () => {
     const { container } = renderArea()
 
-    // LocationButton hard-codes `right: 12` off the same variable, so matching
-    // the offset here is what keeps the two round controls on one line.
-    expect(compassBand(container)?.style.bottom).toBe('calc(var(--bottom-nav-h, 84px) + 12px)')
-    // Beside the base-layer switcher both engines draw in the corner: its inset, its
-    // size and one gap. In the corner itself it lay under the switcher's frosted shell.
-    expect(compassBand(container)?.style.left).toBe(`${MAP_LAYER_SWITCHER_INSET + MAP_ROUND_CONTROL_SIZE + 8}px`)
+    // The switcher's band, raised by its size and one gap, on the switcher's own left edge.
+    expect(compassBand(container)?.style.bottom).toBe(`calc(var(--bottom-nav-h, 84px) + ${12 + MAP_ROUND_CONTROL_SIZE + 8}px)`)
+    expect(compassBand(container)?.style.left).toBe(`${MAP_LAYER_SWITCHER_INSET}px`)
     expect(compassBand(container)?.className).not.toContain('left-3')
   })
 
@@ -347,8 +344,8 @@ describe('MMapArea', () => {
     for (const shellOver of [{ trTab: 'plan' }, { trTab: 'roadtrip', mapFront: true }] as Partial<MTripShellApi>[]) {
       const { container, unmount } = renderArea(shellOver)
 
-      expect(parseFloat(compassBand(container)?.style.left ?? '0'))
-        .toBeGreaterThanOrEqual(MAP_LAYER_SWITCHER_INSET + MAP_ROUND_CONTROL_SIZE)
+      // Above the switcher: raised past its full height, so the two never overlap.
+      expect(compassBand(container)?.style.bottom).toContain(`+ ${12 + MAP_ROUND_CONTROL_SIZE + 8}px`)
       // With the renderer mocked, the compass is still the one element in this layer
       // that sets --bottom-nav-h inline; its left offset joined the same style object.
       expect(container.querySelectorAll('[style*="--bottom-nav-h"]')).toHaveLength(1)