fix: refine map controls and garage layout

frontend/src/features/map/mapViewport.test.ts

@@ -0,0 +1,53 @@
+import { describe, expect, it } from 'vitest'
+
+import {
+  clampMapPan,
+  clientPointToMapPercent,
+  minimumCoverZoom,
+  zoomPanAtPoint,
+} from '@/features/map/mapViewport'
+
+describe('map viewport geometry', () => {
+  const metrics = {
+    canvasHeight: 900,
+    canvasWidth: 600,
+    viewportHeight: 720,
+    viewportWidth: 360,
+  }
+
+  it('raises the minimum zoom until the canvas covers the viewport', () => {
+    expect(minimumCoverZoom(metrics)).toBe(0.8)
+  })
+
+  it('clamps panning so no empty edge enters the viewport', () => {
+    expect(clampMapPan({ x: 999, y: -999 }, 1, metrics)).toEqual({
+      x: 120,
+      y: -90,
+    })
+  })
+
+  it('converts scaled client positions into bounded map percentages', () => {
+    const canvas = { height: 800, left: 100, top: 50, width: 400 }
+
+    expect(clientPointToMapPercent({ x: 300, y: 250 }, canvas)).toEqual({
+      x: 0.5,
+      y: 0.25,
+    })
+    expect(clientPointToMapPercent({ x: 900, y: -100 }, canvas)).toEqual({
+      x: 1,
+      y: 0,
+    })
+  })
+
+  it('keeps the focal map point stationary while zooming', () => {
+    expect(
+      zoomPanAtPoint(
+        { x: 20, y: -10 },
+        1,
+        2,
+        { x: 270, y: 180 },
+        { x: 360, y: 720 },
+      ),
+    ).toEqual({ x: -50, y: 160 })
+  })
+})