diff --git a/src/systems/CameraSystem.ts b/src/systems/CameraSystem.ts
index a41b456..51df78c 100644
--- a/src/systems/CameraSystem.ts
+++ b/src/systems/CameraSystem.ts
@@ -26,6 +26,7 @@ export class CameraSystem {
   private middlePanActive = false
   private lastPanX = 0
   private lastPanY = 0
+  private debugCross?: Phaser.GameObjects.Graphics
 
   constructor(scene: Phaser.Scene, adapter: LocalAdapter) {
     this.scene = scene
@@ -52,10 +53,22 @@ export class CameraSystem {
       d:     kb.addKey(Phaser.Input.Keyboard.KeyCodes.D),
     }
 
+    // Debug cross at viewport center (fixed to screen, not world)
+    this.debugCross = this.scene.add.graphics()
+    this.debugCross.setScrollFactor(0).setDepth(999)
+    this.debugCross.lineStyle(2, 0xff0000, 1)
+    const cx = cam.width / 2
+    const cy = cam.height / 2
+    this.debugCross.lineBetween(cx - 12, cy, cx + 12, cy)
+    this.debugCross.lineBetween(cx, cy - 12, cx, cy + 12)
+
     // Scroll wheel zoom
-    this.scene.input.on('wheel', (_ptr: Phaser.Input.Pointer, _objs: unknown, _dx: number, dy: number) => {
+    this.scene.input.on('wheel', (ptr: Phaser.Input.Pointer, _objs: unknown, _dx: number, dy: number) => {
       const newZoom = Phaser.Math.Clamp(cam.zoom - Math.sign(dy) * ZOOM_STEP, MIN_ZOOM, MAX_ZOOM)
       cam.setZoom(newZoom)
+      const centerX = cam.scrollX + cam.width  / (2 * cam.zoom)
+      const centerY = cam.scrollY + cam.height / (2 * cam.zoom)
+      console.log(`[zoom] ptr.x=${ptr.x.toFixed(0)} ptr.y=${ptr.y.toFixed(0)} | ptr.worldX=${ptr.worldX.toFixed(0)} ptr.worldY=${ptr.worldY.toFixed(0)} | center=(${centerX.toFixed(0)}, ${centerY.toFixed(0)}) zoom=${cam.zoom.toFixed(2)}`)
     })
 
     // Middle-click pan: start on button down