✨ implement zoom-to-mouse in CameraSystem

Replaces plain cam.setZoom() with zoom-to-mouse: after each zoom step
the scroll is corrected by (mouseOffset from center) * (1/zBefore - 1/zAfter),
keeping the world point under the cursor fixed. Also fixes getCenterWorld()
which previously divided by zoom incorrectly. Added JSDoc to all methods.

.claude/settings.local.json

@@ -0,0 +1,35 @@
+{
+  "permissions": {
+    "allow": [
+      "Bash(curl:)",
+      "Bash(curl -s \"https://git.zally.dev/api/v1/repos/tekki/nissefolk/issues/1\" -H \"Authorization: token de54ccf9eadd5950a6ea5fa264b6404acdecc732\")",
+      "Bash(python3 -m json.tool)",
+      "Bash(curl -s \"https://git.zally.dev/api/v1/repos/tekki/nissefolk/issues/1/timeline\" -H \"Authorization: token de54ccf9eadd5950a6ea5fa264b6404acdecc732\")",
+      "Bash(curl:*)",
+      "Bash(python3 -c \":*)",
+      "Bash(git checkout:*)",
+      "Bash(npx tsc:*)",
+      "Bash(npm run:*)",
+      "Bash(/usr/local/bin/npm run:*)",
+      "Bash(/home/tekki/.nvm/versions/node/v24.14.0/bin/npm run:*)",
+      "Bash(export PATH=\"/home/tekki/.nvm/versions/node/v24.14.0/bin:$PATH\")",
+      "Bash(git add:*)",
+      "Bash(git commit:*)",
+      "Bash(git push:*)",
+      "Bash(python3 -c \"import sys,json; d=json.load\\(sys.stdin\\); print\\(d.get\\(''''html_url'''', d.get\\(''''message'''',''''''''\\)\\)\\)\")",
+      "Bash(git pull:*)",
+      "Bash(for id:*)",
+      "Bash(do echo:*)",
+      "Bash(python3 -c \"import sys,json; d=json.load\\(sys.stdin\\); print\\(d.get\\(''''html_url'''',''''''''\\)\\)\")",
+      "Bash(TOKEN=\"de54ccf9eadd5950a6ea5fa264b6404acdecc732\" BASE=\"https://git.zally.dev/api/v1/repos/tekki/nissefolk\" __NEW_LINE_2bc8ebfb809e4939__ for id in 5 6 7 9)",
+      "Bash(TOKEN=\"de54ccf9eadd5950a6ea5fa264b6404acdecc732\")",
+      "Bash(BASE=\"https://git.zally.dev/api/v1/repos/tekki/nissefolk\")",
+      "Bash(__NEW_LINE_5d5fe245d6f316dc__ for:*)",
+      "Bash(do)",
+      "Bash(done)",
+      "Bash(python3 -c \"import sys,json; d=json.load\\(sys.stdin\\); print\\(d.get\\(''''html_url'''',''''''''\\), d.get\\(''''number'''',''''''''\\), d.get\\(''''message'''',''''''''\\)\\)\")",
+      "Bash(git remote:*)",
+      "Bash(python3 -c \"import sys,json; d=json.load\\(sys.stdin\\); print\\(d.get\\(''''login'''',''''''''\\), d.get\\(''''message'''',''''''''\\)\\)\")"
+    ]
+  }
+}

game-test.log

@@ -0,0 +1,5 @@
+{"t":1774091984264,"event":"snapshot","zoom":1,"scrollX":321,"scrollY":562,"vpScreen":{"w":958,"h":475},"vpWorld":{"w":958,"h":475},"vpTiles":{"w":29.938,"h":14.844},"centerWorld":{"x":800,"y":799.5},"mouse":{"screen":{"x":0,"y":0},"world":{"x":0,"y":0}}}
+{"t":1774091986280,"event":"snapshot","zoom":1,"scrollX":321,"scrollY":562,"vpScreen":{"w":958,"h":475},"vpWorld":{"w":958,"h":475},"vpTiles":{"w":29.938,"h":14.844},"centerWorld":{"x":800,"y":799.5},"mouse":{"screen":{"x":288,"y":400},"world":{"x":609,"y":961.5}}}
+{"t":1774091988280,"event":"snapshot","zoom":1,"scrollX":321,"scrollY":562,"vpScreen":{"w":958,"h":475},"vpWorld":{"w":958,"h":475},"vpTiles":{"w":29.938,"h":14.844},"centerWorld":{"x":800,"y":799.5},"mouse":{"screen":{"x":288,"y":400},"world":{"x":609,"y":961.5}}}
+{"t":1774091990281,"event":"snapshot","zoom":1,"scrollX":321,"scrollY":562,"vpScreen":{"w":958,"h":475},"vpWorld":{"w":958,"h":475},"vpTiles":{"w":29.938,"h":14.844},"centerWorld":{"x":800,"y":799.5},"mouse":{"screen":{"x":288,"y":400},"world":{"x":609,"y":961.5}}}
+{"t":1774091992281,"event":"snapshot","zoom":1,"scrollX":321,"scrollY":562,"vpScreen":{"w":958,"h":475},"vpWorld":{"w":958,"h":475},"vpTiles":{"w":29.938,"h":14.844},"centerWorld":{"x":800,"y":799.5},"mouse":{"screen":{"x":288,"y":400},"world":{"x":609,"y":961.5}}}

src/systems/CameraSystem.ts

@@ -27,11 +27,19 @@ export class CameraSystem {
   private lastPanX = 0
   private lastPanY = 0
 
+  /**
+   * @param scene   - The Phaser scene this system belongs to
+   * @param adapter - Network adapter used to persist camera position
+   */
   constructor(scene: Phaser.Scene, adapter: LocalAdapter) {
     this.scene = scene
     this.adapter = adapter
   }
 
+  /**
+   * Initializes the camera: restores saved position, registers keyboard keys,
+   * sets up scroll-wheel zoom-to-mouse, and middle-click pan.
+   */
   create(): void {
     const state = stateManager.getState()
     const cam = this.scene.cameras.main
@@ -52,10 +60,22 @@ export class CameraSystem {
       d:     kb.addKey(Phaser.Input.Keyboard.KeyCodes.D),
     }
 
-    // Scroll wheel zoom
-    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)
+    // Scroll wheel: zoom-to-mouse.
+    // Phaser zooms from the screen center, so the world point under the mouse
+    // is corrected by shifting scroll by the mouse offset from center.
+    this.scene.input.on('wheel', (ptr: Phaser.Input.Pointer, _objs: unknown, _dx: number, dy: number) => {
+      const zoomBefore = cam.zoom
+      const newZoom = Phaser.Math.Clamp(zoomBefore - Math.sign(dy) * ZOOM_STEP, MIN_ZOOM, MAX_ZOOM)
       cam.setZoom(newZoom)
+
+      const factor = 1 / zoomBefore - 1 / newZoom
+      cam.scrollX += (ptr.x - cam.width  / 2) * factor
+      cam.scrollY += (ptr.y - cam.height / 2) * factor
+
+      const worldW = WORLD_TILES * 32
+      const worldH = WORLD_TILES * 32
+      cam.scrollX = Phaser.Math.Clamp(cam.scrollX, 0, worldW - cam.width  / newZoom)
+      cam.scrollY = Phaser.Math.Clamp(cam.scrollY, 0, worldH - cam.height / newZoom)
     })
 
     // Middle-click pan: start on button down
@@ -86,6 +106,10 @@ export class CameraSystem {
     })
   }
 
+  /**
+   * Moves the camera via keyboard input and periodically saves the position.
+   * @param delta - Frame delta in milliseconds
+   */
   update(delta: number): void {
     const cam = this.scene.cameras.main
     const speed = CAMERA_SPEED * (delta / 1000) / cam.zoom
@@ -103,7 +127,7 @@ export class CameraSystem {
 
     if (dx !== 0 && dy !== 0) { dx *= 0.707; dy *= 0.707 }
 
-    const worldW = WORLD_TILES * 32  // TILE_SIZE hardcoded since WORLD_PX may not exist
+    const worldW = WORLD_TILES * 32
     const worldH = WORLD_TILES * 32
     cam.scrollX = Phaser.Math.Clamp(cam.scrollX + dx, 0, worldW - cam.width / cam.zoom)
     cam.scrollY = Phaser.Math.Clamp(cam.scrollY + dy, 0, worldH - cam.height / cam.zoom)
@@ -120,14 +144,24 @@ export class CameraSystem {
     }
   }
 
+  /**
+   * Returns the world coordinates of the visual camera center.
+   * Phaser zooms from the screen center, so the center world point
+   * is scrollX + screenWidth/2 (independent of zoom level).
+   * @returns World position of the screen center
+   */
   getCenterWorld(): { x: number; y: number } {
     const cam = this.scene.cameras.main
     return {
-      x: cam.scrollX + cam.width / (2 * cam.zoom),
-      y: cam.scrollY + cam.height / (2 * cam.zoom),
+      x: cam.scrollX + cam.width  / 2,
+      y: cam.scrollY + cam.height / 2,
     }
   }
 
+  /**
+   * Returns the tile coordinates of the visual camera center.
+   * @returns Tile position (integer) of the screen center
+   */
   getCenterTile(): { tileX: number; tileY: number } {
     const { x, y } = this.getCenterWorld()
     return { tileX: Math.floor(x / 32), tileY: Math.floor(y / 32) }

src/test/ZoomMouseScene.ts

@@ -0,0 +1,364 @@
+import Phaser from 'phaser'
+import { TILE_SIZE } from '../config'
+
+const GRID_TILES      = 500    // world size in tiles
+const MIN_ZOOM        = 0.25
+const MAX_ZOOM        = 4.0
+const ZOOM_STEP       = 0.1
+const MARKER_EVERY    = 10     // small crosshair every N tiles
+const LABEL_EVERY     = 50     // coordinate label every N tiles
+const CAMERA_SPEED    = 400    // px/s
+const SNAPSHOT_EVERY  = 2000   // ms between periodic log snapshots
+
+/**
+ * Second test scene: zoom-to-mouse behavior.
+ * After each zoom step, scrollX/Y is corrected so the world point
+ * under the mouse stays at the same screen position.
+ *
+ * Formula:
+ *   newScrollX = scrollX + (mouseX - screenW/2) * (1/zoomBefore - 1/zoomAfter)
+ *   newScrollY = scrollY + (mouseY - screenH/2) * (1/zoomBefore - 1/zoomAfter)
+ *
+ * Controls: Scroll wheel to zoom, WASD / Arrow keys to pan, Tab to switch scene.
+ */
+export class ZoomMouseScene extends Phaser.Scene {
+  private logText!: Phaser.GameObjects.Text
+  private hudCamera!: Phaser.Cameras.Scene2D.Camera
+  private worldObjects: Phaser.GameObjects.GameObject[] = []
+  private hudObjects: Phaser.GameObjects.GameObject[] = []
+  private keys!: {
+    up:    Phaser.Input.Keyboard.Key
+    down:  Phaser.Input.Keyboard.Key
+    left:  Phaser.Input.Keyboard.Key
+    right: Phaser.Input.Keyboard.Key
+    w:     Phaser.Input.Keyboard.Key
+    s:     Phaser.Input.Keyboard.Key
+    a:     Phaser.Input.Keyboard.Key
+    d:     Phaser.Input.Keyboard.Key
+    tab:   Phaser.Input.Keyboard.Key
+  }
+  private snapshotTimer = 0
+
+  constructor() {
+    super({ key: 'ZoomMouse' })
+  }
+
+  create(): void {
+    fetch('/api/log', { method: 'DELETE' })
+    this.writeLog('scene_start', { scene: 'ZoomMouse', tileSize: TILE_SIZE, gridTiles: GRID_TILES })
+
+    this.drawGrid()
+    this.setupCamera()
+    this.setupInput()
+    this.createHUD()
+    this.setupCameras()
+  }
+
+  /**
+   * Draws the static world grid into world space.
+   * All objects are registered in worldObjects for HUD-camera exclusion.
+   */
+  private drawGrid(): void {
+    const worldPx = GRID_TILES * TILE_SIZE
+    const g = this.add.graphics()
+    this.worldObjects.push(g)
+
+    g.fillStyle(0x111318)
+    g.fillRect(0, 0, worldPx, worldPx)
+
+    g.lineStyle(1, 0x222233, 0.5)
+    for (let i = 0; i <= GRID_TILES; i++) {
+      const p = i * TILE_SIZE
+      g.lineBetween(p, 0, p, worldPx)
+      g.lineBetween(0, p, worldPx, p)
+    }
+
+    for (let tx = 0; tx <= GRID_TILES; tx += MARKER_EVERY) {
+      for (let ty = 0; ty <= GRID_TILES; ty += MARKER_EVERY) {
+        const px = tx * TILE_SIZE
+        const py = ty * TILE_SIZE
+        const isLabel = tx % LABEL_EVERY === 0 && ty % LABEL_EVERY === 0
+        const color   = isLabel ? 0xffff00 : 0x44aaff
+        const arm     = isLabel ? 10 : 6
+
+        g.lineStyle(1, color, isLabel ? 1.0 : 0.7)
+        g.lineBetween(px - arm, py, px + arm, py)
+        g.lineBetween(px, py - arm, px, py + arm)
+
+        g.fillStyle(color, 1.0)
+        g.fillCircle(px, py, isLabel ? 2.5 : 1.5)
+      }
+    }
+
+    for (let tx = 0; tx <= GRID_TILES; tx += LABEL_EVERY) {
+      for (let ty = 0; ty <= GRID_TILES; ty += LABEL_EVERY) {
+        const label = this.add.text(
+          tx * TILE_SIZE + 4,
+          ty * TILE_SIZE + 4,
+          `${tx},${ty}`,
+          { fontSize: '9px', color: '#aaddff', fontFamily: 'monospace' }
+        ).setDepth(1)
+        this.worldObjects.push(label)
+      }
+    }
+
+    g.lineStyle(2, 0xff8844, 1.0)
+    g.strokeRect(0, 0, worldPx, worldPx)
+  }
+
+  /**
+   * Sets camera bounds and centers the view on the world.
+   */
+  private setupCamera(): void {
+    const cam = this.cameras.main
+    const worldPx = GRID_TILES * TILE_SIZE
+    cam.setBounds(0, 0, worldPx, worldPx)
+    cam.scrollX = worldPx / 2 - cam.width  / 2
+    cam.scrollY = worldPx / 2 - cam.height / 2
+  }
+
+  /**
+   * Registers scroll wheel zoom with mouse-anchor correction and keyboard keys.
+   * After cam.setZoom(), scrollX/Y is adjusted so the world point under the
+   * mouse stays at the same screen position.
+   */
+  private setupInput(): void {
+    const cam = this.cameras.main
+    const kb  = this.input.keyboard!
+
+    this.keys = {
+      up:    kb.addKey(Phaser.Input.Keyboard.KeyCodes.UP),
+      down:  kb.addKey(Phaser.Input.Keyboard.KeyCodes.DOWN),
+      left:  kb.addKey(Phaser.Input.Keyboard.KeyCodes.LEFT),
+      right: kb.addKey(Phaser.Input.Keyboard.KeyCodes.RIGHT),
+      w:     kb.addKey(Phaser.Input.Keyboard.KeyCodes.W),
+      s:     kb.addKey(Phaser.Input.Keyboard.KeyCodes.S),
+      a:     kb.addKey(Phaser.Input.Keyboard.KeyCodes.A),
+      d:     kb.addKey(Phaser.Input.Keyboard.KeyCodes.D),
+      tab:   kb.addKey(Phaser.Input.Keyboard.KeyCodes.TAB),
+    }
+
+    // Prevent Tab from switching browser focus
+    ;(this.keys.tab as unknown as { preventDefault: boolean }).preventDefault = true
+
+    this.keys.tab.on('down', () => {
+      this.scene.start('ZoomTest')
+    })
+
+    this.input.on('wheel', (
+      ptr:   Phaser.Input.Pointer,
+      _objs: unknown,
+      _dx:   number,
+      dy:    number
+    ) => {
+      const zoomBefore    = cam.zoom
+      const scrollXBefore = cam.scrollX
+      const scrollYBefore = cam.scrollY
+
+      const newZoom = Phaser.Math.Clamp(zoomBefore - Math.sign(dy) * ZOOM_STEP, MIN_ZOOM, MAX_ZOOM)
+      cam.setZoom(newZoom)
+
+      // Correct scroll so the world point under the mouse stays fixed.
+      // Phaser zooms from screen center, so the offset from center determines the shift.
+      const cw = cam.width
+      const ch = cam.height
+      const factor = 1 / zoomBefore - 1 / newZoom
+      cam.scrollX += (ptr.x - cw / 2) * factor
+      cam.scrollY += (ptr.y - ch / 2) * factor
+
+      // Clamp to world bounds
+      const worldPx = GRID_TILES * TILE_SIZE
+      cam.scrollX = Phaser.Math.Clamp(cam.scrollX, 0, worldPx - cw / cam.zoom)
+      cam.scrollY = Phaser.Math.Clamp(cam.scrollY, 0, worldPx - ch / cam.zoom)
+
+      setTimeout(() => {
+        this.writeLog('zoom', {
+          direction:      dy > 0 ? 'out' : 'in',
+          zoomBefore:     +zoomBefore.toFixed(4),
+          zoomAfter:      +cam.zoom.toFixed(4),
+          scrollX_before: +scrollXBefore.toFixed(2),
+          scrollY_before: +scrollYBefore.toFixed(2),
+          scrollX_after:  +cam.scrollX.toFixed(2),
+          scrollY_after:  +cam.scrollY.toFixed(2),
+          scrollX_delta:  +(cam.scrollX - scrollXBefore).toFixed(2),
+          scrollY_delta:  +(cam.scrollY - scrollYBefore).toFixed(2),
+          mouseScreen:    { x: +ptr.x.toFixed(1), y: +ptr.y.toFixed(1) },
+          mouseWorld_before: { x: +ptr.worldX.toFixed(2), y: +ptr.worldY.toFixed(2) },
+          centerWorld_after: {
+            x: +(cam.scrollX + cam.width / 2).toFixed(2),
+            y: +(cam.scrollY + cam.height / 2).toFixed(2),
+          },
+          vpTiles_after: {
+            w: +((cam.width  / cam.zoom) / TILE_SIZE).toFixed(3),
+            h: +((cam.height / cam.zoom) / TILE_SIZE).toFixed(3),
+          },
+        })
+      }, 0)
+    })
+  }
+
+  /**
+   * Creates all HUD elements: log overlay and screen-center crosshair.
+   * All objects are registered in hudObjects for main-camera exclusion.
+   */
+  private createHUD(): void {
+    const w = this.scale.width
+    const h = this.scale.height
+
+    const cross = this.add.graphics()
+    const arm = 16
+    cross.lineStyle(1, 0xff2222, 0.9)
+    cross.lineBetween(w / 2 - arm, h / 2, w / 2 + arm, h / 2)
+    cross.lineBetween(w / 2, h / 2 - arm, w / 2, h / 2 + arm)
+    cross.fillStyle(0xff2222, 1.0)
+    cross.fillCircle(w / 2, h / 2, 2)
+    this.hudObjects.push(cross)
+
+    this.logText = this.add.text(10, 10, '', {
+      fontSize: '13px',
+      color: '#e8e8e8',
+      backgroundColor: '#000000bb',
+      padding: { x: 10, y: 8 },
+      lineSpacing: 3,
+      fontFamily: 'monospace',
+    }).setDepth(100)
+    this.hudObjects.push(this.logText)
+  }
+
+  /**
+   * Adds a dedicated HUD camera (zoom=1, no scroll) and separates
+   * world objects from HUD objects so neither camera renders both layers.
+   */
+  private setupCameras(): void {
+    this.hudCamera = this.cameras.add(0, 0, this.scale.width, this.scale.height)
+    this.hudCamera.setScroll(0, 0)
+    this.hudCamera.setZoom(1)
+
+    this.cameras.main.ignore(this.hudObjects)
+    this.hudCamera.ignore(this.worldObjects)
+  }
+
+  update(_time: number, delta: number): void {
+    this.handleKeyboard(delta)
+    this.updateOverlay()
+
+    this.snapshotTimer += delta
+    if (this.snapshotTimer >= SNAPSHOT_EVERY) {
+      this.snapshotTimer = 0
+      this.writeSnapshot()
+    }
+  }
+
+  /**
+   * Moves camera with WASD / arrow keys at CAMERA_SPEED px/s (world space).
+   * @param delta - Frame delta in milliseconds
+   */
+  private handleKeyboard(delta: number): void {
+    const cam     = this.cameras.main
+    const speed   = CAMERA_SPEED * (delta / 1000) / cam.zoom
+    const worldPx = GRID_TILES * TILE_SIZE
+
+    let dx = 0, dy = 0
+    if (this.keys.left.isDown  || this.keys.a.isDown) dx -= speed
+    if (this.keys.right.isDown || this.keys.d.isDown) dx += speed
+    if (this.keys.up.isDown    || this.keys.w.isDown) dy -= speed
+    if (this.keys.down.isDown  || this.keys.s.isDown) dy += speed
+
+    if (dx !== 0 && dy !== 0) { dx *= 0.707; dy *= 0.707 }
+
+    cam.scrollX = Phaser.Math.Clamp(cam.scrollX + dx, 0, worldPx - cam.width  / cam.zoom)
+    cam.scrollY = Phaser.Math.Clamp(cam.scrollY + dy, 0, worldPx - cam.height / cam.zoom)
+  }
+
+  /**
+   * Recomputes and renders all diagnostic values to the HUD overlay each frame.
+   * centerWorld uses the corrected formula: scrollX + screenWidth/2.
+   */
+  private updateOverlay(): void {
+    const cam = this.cameras.main
+    const ptr = this.input.activePointer
+
+    const vpWidthPx     = cam.width  / cam.zoom
+    const vpHeightPx    = cam.height / cam.zoom
+    const vpWidthTiles  = vpWidthPx  / TILE_SIZE
+    const vpHeightTiles = vpHeightPx / TILE_SIZE
+
+    // Phaser zooms from screen center, so visual center = scrollX + screenWidth/2
+    const centerWorldX  = cam.scrollX + cam.width  / 2
+    const centerWorldY  = cam.scrollY + cam.height / 2
+    const centerTileX   = Math.floor(centerWorldX / TILE_SIZE)
+    const centerTileY   = Math.floor(centerWorldY / TILE_SIZE)
+
+    const mouseTileX    = Math.floor(ptr.worldX / TILE_SIZE)
+    const mouseTileY    = Math.floor(ptr.worldY / TILE_SIZE)
+    const renderer      = this.game.renderer.type === Phaser.WEBGL ? 'WebGL' : 'Canvas'
+
+    const lines = [
+      '── ZOOM TEST  [Zoom-to-Mouse] ──',
+      '',
+      `Zoom:              ${cam.zoom.toFixed(4)}`,
+      `scrollX / scrollY: ${cam.scrollX.toFixed(2)} / ${cam.scrollY.toFixed(2)}`,
+      '',
+      `Viewport (screen): ${cam.width} × ${cam.height} px`,
+      `Viewport (world):  ${vpWidthPx.toFixed(2)} × ${vpHeightPx.toFixed(2)} px`,
+      `Viewport (tiles):  ${vpWidthTiles.toFixed(3)} × ${vpHeightTiles.toFixed(3)}`,
+      '',
+      `Center world:      ${centerWorldX.toFixed(2)}, ${centerWorldY.toFixed(2)}`,
+      `Center tile:       ${centerTileX}, ${centerTileY}`,
+      '',
+      `Mouse screen:      ${ptr.x.toFixed(1)}, ${ptr.y.toFixed(1)}`,
+      `Mouse world:       ${ptr.worldX.toFixed(2)}, ${ptr.worldY.toFixed(2)}`,
+      `Mouse tile:        ${mouseTileX}, ${mouseTileY}`,
+      '',
+      `Canvas:            ${this.scale.width} × ${this.scale.height} px`,
+      `TILE_SIZE:         ${TILE_SIZE} px`,
+      `roundPixels:       ${(this.game.renderer.config as Record<string, unknown>)['roundPixels']}`,
+      `Renderer:          ${renderer}`,
+      '',
+      '[Scroll] Zoom   [WASD / ↑↓←→] Pan   [Tab] → Default',
+    ]
+
+    this.logText.setText(lines)
+  }
+
+  /**
+   * Writes a periodic full-state snapshot to the log.
+   */
+  private writeSnapshot(): void {
+    const cam = this.cameras.main
+    const ptr = this.input.activePointer
+    const vpW = cam.width  / cam.zoom
+    const vpH = cam.height / cam.zoom
+
+    this.writeLog('snapshot', {
+      zoom:        +cam.zoom.toFixed(4),
+      scrollX:     +cam.scrollX.toFixed(2),
+      scrollY:     +cam.scrollY.toFixed(2),
+      vpScreen:    { w: cam.width, h: cam.height },
+      vpWorld:     { w: +vpW.toFixed(2), h: +vpH.toFixed(2) },
+      vpTiles:     { w: +((vpW / TILE_SIZE).toFixed(3)), h: +((vpH / TILE_SIZE).toFixed(3)) },
+      centerWorld: {
+        x: +(cam.scrollX + cam.width  / 2).toFixed(2),
+        y: +(cam.scrollY + cam.height / 2).toFixed(2),
+      },
+      mouse: {
+        screen: { x: +ptr.x.toFixed(1), y: +ptr.y.toFixed(1) },
+        world:  { x: +ptr.worldX.toFixed(2), y: +ptr.worldY.toFixed(2) },
+      },
+    })
+  }
+
+  /**
+   * POSTs a structured log entry to the Vite dev server middleware.
+   * @param event - Event type label
+   * @param data  - Payload object to serialize as JSON
+   */
+  private writeLog(event: string, data: Record<string, unknown>): void {
+    const entry = JSON.stringify({ t: Date.now(), event, ...data })
+    fetch('/api/log', {
+      method: 'POST',
+      headers: { 'Content-Type': 'text/plain' },
+      body: entry,
+    }).catch(() => { /* swallow if dev server not running */ })
+  }
+}

src/test/ZoomTestScene.ts

@@ -1,22 +1,27 @@
 import Phaser from 'phaser'
 import { TILE_SIZE } from '../config'
 
-const GRID_TILES    = 50     // world size in tiles
-const MIN_ZOOM      = 0.25
-const MAX_ZOOM      = 4.0
-const ZOOM_STEP     = 0.1
-const MARKER_EVERY  = 5      // small crosshair every N tiles
-const LABEL_EVERY   = 10     // coordinate label every N tiles
-const CAMERA_SPEED  = 400    // px/s
+const GRID_TILES      = 500    // world size in tiles
+const MIN_ZOOM        = 0.25
+const MAX_ZOOM        = 4.0
+const ZOOM_STEP       = 0.1
+const MARKER_EVERY    = 10     // small crosshair every N tiles
+const LABEL_EVERY     = 50     // coordinate label every N tiles
+const CAMERA_SPEED    = 400    // px/s
+const SNAPSHOT_EVERY  = 2000   // ms between periodic log snapshots
 
 /**
  * First test scene: observes pure Phaser default zoom behavior.
  * No custom scroll compensation — cam.setZoom() only, zoom anchors to camera center.
+ * Logs zoom events and periodic snapshots to /api/log (written to game-test.log).
  *
  * Controls: Scroll wheel to zoom, WASD / Arrow keys to pan.
  */
 export class ZoomTestScene extends Phaser.Scene {
   private logText!: Phaser.GameObjects.Text
+  private hudCamera!: Phaser.Cameras.Scene2D.Camera
+  private worldObjects: Phaser.GameObjects.GameObject[] = []
+  private hudObjects: Phaser.GameObjects.GameObject[] = []
   private keys!: {
     up:    Phaser.Input.Keyboard.Key
     down:  Phaser.Input.Keyboard.Key
@@ -26,29 +31,34 @@ export class ZoomTestScene extends Phaser.Scene {
     s:     Phaser.Input.Keyboard.Key
     a:     Phaser.Input.Keyboard.Key
     d:     Phaser.Input.Keyboard.Key
+    tab:   Phaser.Input.Keyboard.Key
   }
+  private snapshotTimer = 0
 
   constructor() {
     super({ key: 'ZoomTest' })
   }
 
   create(): void {
+    // Clear log file at scene start
+    fetch('/api/log', { method: 'DELETE' })
+    this.writeLog('scene_start', { tileSize: TILE_SIZE, gridTiles: GRID_TILES })
+
     this.drawGrid()
     this.setupCamera()
     this.setupInput()
-    this.createOverlay()
+    this.createHUD()
+    this.setupCameras()
   }
 
   /**
    * Draws the static world grid into world space.
-   * - Faint tile lines on every tile boundary
-   * - Small green crosshairs every MARKER_EVERY tiles
-   * - Yellow labeled crosshairs every LABEL_EVERY tiles
-   * - Red world border
+   * All objects are registered in worldObjects for HUD-camera exclusion.
    */
   private drawGrid(): void {
     const worldPx = GRID_TILES * TILE_SIZE
     const g = this.add.graphics()
+    this.worldObjects.push(g)
 
     // Background fill
     g.fillStyle(0x111811)
@@ -83,12 +93,13 @@ export class ZoomTestScene extends Phaser.Scene {
     // Coordinate labels at LABEL_EVERY intersections
     for (let tx = 0; tx <= GRID_TILES; tx += LABEL_EVERY) {
       for (let ty = 0; ty <= GRID_TILES; ty += LABEL_EVERY) {
-        this.add.text(
+        const label = this.add.text(
           tx * TILE_SIZE + 4,
           ty * TILE_SIZE + 4,
           `${tx},${ty}`,
           { fontSize: '9px', color: '#ffff88', fontFamily: 'monospace' }
         ).setDepth(1)
+        this.worldObjects.push(label)
       }
     }
 
@@ -111,6 +122,7 @@ export class ZoomTestScene extends Phaser.Scene {
   /**
    * Registers scroll wheel zoom and stores keyboard key references.
    * Zoom uses cam.setZoom() only — pure Phaser default, anchors to camera center.
+   * Each zoom event is logged immediately with before/after state.
    */
   private setupInput(): void {
     const cam = this.cameras.main
@@ -125,23 +137,73 @@ export class ZoomTestScene extends Phaser.Scene {
       s:     kb.addKey(Phaser.Input.Keyboard.KeyCodes.S),
       a:     kb.addKey(Phaser.Input.Keyboard.KeyCodes.A),
       d:     kb.addKey(Phaser.Input.Keyboard.KeyCodes.D),
+      tab:   kb.addKey(Phaser.Input.Keyboard.KeyCodes.TAB),
     }
 
+    ;(this.keys.tab as unknown as { preventDefault: boolean }).preventDefault = true
+    this.keys.tab.on('down', () => {
+      this.scene.start('ZoomMouse')
+    })
+
     this.input.on('wheel', (
-      _ptr:  Phaser.Input.Pointer,
+      ptr:   Phaser.Input.Pointer,
       _objs: unknown,
       _dx:   number,
       dy:    number
     ) => {
+      const zoomBefore    = cam.zoom
+      const scrollXBefore = cam.scrollX
+      const scrollYBefore = cam.scrollY
+
       const newZoom = Phaser.Math.Clamp(cam.zoom - Math.sign(dy) * ZOOM_STEP, MIN_ZOOM, MAX_ZOOM)
       cam.setZoom(newZoom)
+
+      setTimeout(() => {
+        this.writeLog('zoom', {
+          direction:      dy > 0 ? 'out' : 'in',
+          zoomBefore:     +zoomBefore.toFixed(4),
+          zoomAfter:      +cam.zoom.toFixed(4),
+          scrollX_before: +scrollXBefore.toFixed(2),
+          scrollY_before: +scrollYBefore.toFixed(2),
+          scrollX_after:  +cam.scrollX.toFixed(2),
+          scrollY_after:  +cam.scrollY.toFixed(2),
+          scrollX_delta:  +(cam.scrollX - scrollXBefore).toFixed(2),
+          scrollY_delta:  +(cam.scrollY - scrollYBefore).toFixed(2),
+          mouseScreen:    { x: +ptr.x.toFixed(1), y: +ptr.y.toFixed(1) },
+          mouseWorld:     { x: +ptr.worldX.toFixed(2), y: +ptr.worldY.toFixed(2) },
+          centerWorld_after: {
+            x: +(cam.scrollX + (cam.width  / cam.zoom) / 2).toFixed(2),
+            y: +(cam.scrollY + (cam.height / cam.zoom) / 2).toFixed(2),
+          },
+          vpTiles_after: {
+            w: +((cam.width  / cam.zoom) / TILE_SIZE).toFixed(3),
+            h: +((cam.height / cam.zoom) / TILE_SIZE).toFixed(3),
+          },
+        })
+      }, 0)
     })
   }
 
   /**
-   * Creates the fixed HUD text overlay (scroll factor 0 = screen space).
+   * Creates all HUD elements: log overlay and screen-center crosshair.
+   * All objects are registered in hudObjects for main-camera exclusion.
+   * Uses a dedicated HUD camera (zoom=1, fixed) so elements are never scaled.
    */
-  private createOverlay(): void {
+  private createHUD(): void {
+    const w = this.scale.width
+    const h = this.scale.height
+
+    // Screen-center crosshair (red)
+    const cross = this.add.graphics()
+    const arm = 16
+    cross.lineStyle(1, 0xff2222, 0.9)
+    cross.lineBetween(w / 2 - arm, h / 2, w / 2 + arm, h / 2)
+    cross.lineBetween(w / 2, h / 2 - arm, w / 2, h / 2 + arm)
+    cross.fillStyle(0xff2222, 1.0)
+    cross.fillCircle(w / 2, h / 2, 2)
+    this.hudObjects.push(cross)
+
+    // Log text overlay
     this.logText = this.add.text(10, 10, '', {
       fontSize: '13px',
       color: '#e8e8e8',
@@ -149,14 +211,32 @@ export class ZoomTestScene extends Phaser.Scene {
       padding: { x: 10, y: 8 },
       lineSpacing: 3,
       fontFamily: 'monospace',
-    })
-      .setScrollFactor(0)
-      .setDepth(100)
+    }).setDepth(100)
+    this.hudObjects.push(this.logText)
+  }
+
+  /**
+   * Adds a dedicated HUD camera (zoom=1, no scroll) and separates
+   * world objects from HUD objects so neither camera renders both layers.
+   */
+  private setupCameras(): void {
+    this.hudCamera = this.cameras.add(0, 0, this.scale.width, this.scale.height)
+    this.hudCamera.setScroll(0, 0)
+    this.hudCamera.setZoom(1)
+
+    this.cameras.main.ignore(this.hudObjects)
+    this.hudCamera.ignore(this.worldObjects)
   }
 
   update(_time: number, delta: number): void {
     this.handleKeyboard(delta)
     this.updateOverlay()
+
+    this.snapshotTimer += delta
+    if (this.snapshotTimer >= SNAPSHOT_EVERY) {
+      this.snapshotTimer = 0
+      this.writeSnapshot()
+    }
   }
 
   /**
@@ -164,8 +244,8 @@ export class ZoomTestScene extends Phaser.Scene {
    * @param delta - Frame delta in milliseconds
    */
   private handleKeyboard(delta: number): void {
-    const cam   = this.cameras.main
-    const speed = CAMERA_SPEED * (delta / 1000) / cam.zoom
+    const cam     = this.cameras.main
+    const speed   = CAMERA_SPEED * (delta / 1000) / cam.zoom
     const worldPx = GRID_TILES * TILE_SIZE
 
     let dx = 0, dy = 0
@@ -187,27 +267,18 @@ export class ZoomTestScene extends Phaser.Scene {
     const cam = this.cameras.main
     const ptr = this.input.activePointer
 
-    // Viewport size in world pixels (what is actually visible)
-    const vpWidthPx   = cam.width  / cam.zoom
-    const vpHeightPx  = cam.height / cam.zoom
-
-    // Viewport size in tiles
+    const vpWidthPx     = cam.width  / cam.zoom
+    const vpHeightPx    = cam.height / cam.zoom
     const vpWidthTiles  = vpWidthPx  / TILE_SIZE
     const vpHeightTiles = vpHeightPx / TILE_SIZE
-
-    // Camera center in world coords
-    const centerWorldX = cam.scrollX + vpWidthPx  / 2
-    const centerWorldY = cam.scrollY + vpHeightPx / 2
-
-    // Tile under mouse
-    const mouseTileX = Math.floor(ptr.worldX / TILE_SIZE)
-    const mouseTileY = Math.floor(ptr.worldY / TILE_SIZE)
-
-    // Tile at camera center
-    const centerTileX = Math.floor(centerWorldX / TILE_SIZE)
-    const centerTileY = Math.floor(centerWorldY / TILE_SIZE)
-
-    const renderer = this.game.renderer.type === Phaser.WEBGL ? 'WebGL' : 'Canvas'
+    // Phaser zooms from screen center: visual center = scrollX + screenWidth/2
+    const centerWorldX  = cam.scrollX + cam.width  / 2
+    const centerWorldY  = cam.scrollY + cam.height / 2
+    const mouseTileX    = Math.floor(ptr.worldX / TILE_SIZE)
+    const mouseTileY    = Math.floor(ptr.worldY / TILE_SIZE)
+    const centerTileX   = Math.floor(centerWorldX / TILE_SIZE)
+    const centerTileY   = Math.floor(centerWorldY / TILE_SIZE)
+    const renderer      = this.game.renderer.type === Phaser.WEBGL ? 'WebGL' : 'Canvas'
 
     const lines = [
       '── ZOOM TEST  [Phaser default] ──',
@@ -231,9 +302,51 @@ export class ZoomTestScene extends Phaser.Scene {
       `roundPixels:       ${(this.game.renderer.config as Record<string, unknown>)['roundPixels']}`,
       `Renderer:          ${renderer}`,
       '',
-      '[Scroll] Zoom   [WASD / ↑↓←→] Pan',
+      '[Scroll] Zoom   [WASD / ↑↓←→] Pan   [Tab] → Mouse',
     ]
 
     this.logText.setText(lines)
   }
+
+  /**
+   * Writes a periodic full-state snapshot to the log.
+   */
+  private writeSnapshot(): void {
+    const cam = this.cameras.main
+    const ptr = this.input.activePointer
+    const vpW = cam.width  / cam.zoom
+    const vpH = cam.height / cam.zoom
+
+    this.writeLog('snapshot', {
+      zoom:        +cam.zoom.toFixed(4),
+      scrollX:     +cam.scrollX.toFixed(2),
+      scrollY:     +cam.scrollY.toFixed(2),
+      vpScreen:    { w: cam.width, h: cam.height },
+      vpWorld:     { w: +vpW.toFixed(2), h: +vpH.toFixed(2) },
+      vpTiles:     { w: +((vpW / TILE_SIZE).toFixed(3)), h: +((vpH / TILE_SIZE).toFixed(3)) },
+      centerWorld: {
+        x: +(cam.scrollX + cam.width  / 2).toFixed(2),
+        y: +(cam.scrollY + cam.height / 2).toFixed(2),
+      },
+      mouse: {
+        screen: { x: +ptr.x.toFixed(1), y: +ptr.y.toFixed(1) },
+        world:  { x: +ptr.worldX.toFixed(2), y: +ptr.worldY.toFixed(2) },
+      },
+    })
+  }
+
+  /**
+   * POSTs a structured log entry to the Vite dev server middleware.
+   * Written to game-test.log in the project root.
+   * @param event - Event type label
+   * @param data  - Payload object to serialize as JSON
+   */
+  private writeLog(event: string, data: Record<string, unknown>): void {
+    const entry = JSON.stringify({ t: Date.now(), event, ...data })
+    fetch('/api/log', {
+      method: 'POST',
+      headers: { 'Content-Type': 'text/plain' },
+      body: entry,
+    }).catch(() => { /* swallow if dev server not running */ })
+  }
 }

src/test/main.ts

@@ -1,12 +1,13 @@
 import Phaser from 'phaser'
 import { ZoomTestScene } from './ZoomTestScene'
+import { ZoomMouseScene } from './ZoomMouseScene'
 
 const config: Phaser.Types.Core.GameConfig = {
   type: Phaser.AUTO,
   width: window.innerWidth,
   height: window.innerHeight,
   backgroundColor: '#0d1a0d',
-  scene: [ZoomTestScene],
+  scene: [ZoomTestScene, ZoomMouseScene],
   scale: {
     mode: Phaser.Scale.RESIZE,
     autoCenter: Phaser.Scale.CENTER_BOTH,

vite.config.ts

@@ -1,11 +1,39 @@
 import { defineConfig } from 'vite'
 import { resolve } from 'path'
+import fs from 'fs'
+
+const LOG_FILE = resolve(__dirname, 'game-test.log')
 
 export default defineConfig({
   server: {
     port: 3000,
-    host: true
+    host: true,
   },
+  plugins: [
+    {
+      name: 'game-logger',
+      configureServer(server) {
+        server.middlewares.use('/api/log', (req, res) => {
+          if (req.method === 'POST') {
+            let body = ''
+            req.on('data', chunk => { body += chunk })
+            req.on('end', () => {
+              fs.appendFileSync(LOG_FILE, body + '\n', 'utf8')
+              res.writeHead(200)
+              res.end('ok')
+            })
+          } else if (req.method === 'DELETE') {
+            fs.writeFileSync(LOG_FILE, '', 'utf8')
+            res.writeHead(200)
+            res.end('cleared')
+          } else {
+            res.writeHead(405)
+            res.end()
+          }
+        })
+      },
+    },
+  ],
   build: {
     outDir: 'dist',
     assetsInlineLimit: 0,