diff --git a/package.json b/package.json
index 6390ad4..5b71c3e 100644
--- a/package.json
+++ b/package.json
@@ -14,7 +14,9 @@
     "verify:net": "node scripts/verify-net.ts",
     "verify:d2": "node scripts/verify-d2-data.ts",
     "verify:implode": "node scripts/verify-implode.ts",
-    "verify:all": "node scripts/verify-combat.ts && node scripts/verify-items.ts && node scripts/verify-m4.ts && node scripts/verify-m5.ts && node scripts/verify-net.ts",
+    "verify:collision-orientation": "node scripts/verify-collision-orientation.ts",
+    "verify:renderer": "npx tsx scripts/verify-renderer-lifecycle.ts",
+    "verify:all": "node scripts/verify-combat.ts && node scripts/verify-items.ts && node scripts/verify-m4.ts && node scripts/verify-m5.ts && node scripts/verify-net.ts && node scripts/verify-collision-orientation.ts",
     "verify:acts": "node scripts/verify-acts.ts",
     "build:game": "vite build --base=/diablo2/ --outDir dist-game",
     "pack:data": "node scripts/pack-act-assets.ts",
diff --git a/scripts/verify-renderer-lifecycle.ts b/scripts/verify-renderer-lifecycle.ts
new file mode 100644
index 0000000..1f42916
--- /dev/null
+++ b/scripts/verify-renderer-lifecycle.ts
@@ -0,0 +1,322 @@
+/**
+ * Verification test for SpriteRenderer GPU resource lifecycle, deleteAtlas,
+ * dispose, and WebGL context loss handling (Issue #9).
+ */
+import { SpriteRenderer, RendererError } from '../src/render/renderer.ts'
+
+interface MockResource {
+  id: number
+  type: string
+}
+
+function createMockCanvas(): {
+  canvas: any
+  stats: {
+    createdTextures: Set<MockResource>
+    deletedTextures: Set<MockResource>
+    createdBuffers: Set<MockResource>
+    deletedBuffers: Set<MockResource>
+    createdVAOs: Set<MockResource>
+    deletedVAOs: Set<MockResource>
+    createdPrograms: Set<MockResource>
+    deletedPrograms: Set<MockResource>
+    createdShaders: Set<MockResource>
+    deletedShaders: Set<MockResource>
+    eventListeners: Map<string, Set<EventListener>>
+  }
+  setContextLost: (lost: boolean) => void
+  dispatchMockEvent: (type: string) => { defaultPrevented: boolean }
+} {
+  let nextId = 1
+  let contextLost = false
+
+  const stats = {
+    createdTextures: new Set<MockResource>(),
+    deletedTextures: new Set<MockResource>(),
+    createdBuffers: new Set<MockResource>(),
+    deletedBuffers: new Set<MockResource>(),
+    createdVAOs: new Set<MockResource>(),
+    deletedVAOs: new Set<MockResource>(),
+    createdPrograms: new Set<MockResource>(),
+    deletedPrograms: new Set<MockResource>(),
+    createdShaders: new Set<MockResource>(),
+    deletedShaders: new Set<MockResource>(),
+    eventListeners: new Map<string, Set<EventListener>>(),
+  }
+
+  const gl: any = {
+    VERTEX_SHADER: 35633,
+    FRAGMENT_SHADER: 35632,
+    COMPILE_STATUS: 35713,
+    LINK_STATUS: 35714,
+    MAX_TEXTURE_SIZE: 3379,
+    TEXTURE_2D: 3553,
+    RGBA: 6408,
+    UNSIGNED_BYTE: 5121,
+    FLOAT: 5126,
+    ARRAY_BUFFER: 34962,
+    DYNAMIC_DRAW: 35048,
+    TRIANGLES: 4,
+    TEXTURE_MIN_FILTER: 10241,
+    TEXTURE_MAG_FILTER: 10240,
+    TEXTURE_WRAP_S: 10242,
+    TEXTURE_WRAP_T: 10243,
+    CLAMP_TO_EDGE: 33071,
+    NEAREST: 9728,
+    UNPACK_ALIGNMENT: 3317,
+    BLEND: 3042,
+    SRC_ALPHA: 770,
+    ONE_MINUS_SRC_ALPHA: 771,
+    DEPTH_TEST: 2929,
+    COLOR_BUFFER_BIT: 16384,
+    TEXTURE0: 33984,
+
+    drawingBufferWidth: 800,
+    drawingBufferHeight: 600,
+
+    isContextLost: () => contextLost,
+
+    createProgram: () => {
+      const res: MockResource = { id: nextId++, type: 'program' }
+      stats.createdPrograms.add(res)
+      return res
+    },
+    deleteProgram: (p: MockResource) => { stats.deletedPrograms.add(p) },
+    attachShader: () => {},
+    detachShader: () => {},
+    linkProgram: () => {},
+    getProgramParameter: () => true,
+    getProgramInfoLog: () => '',
+    useProgram: () => {},
+
+    createShader: (type: number) => {
+      const res: MockResource = { id: nextId++, type: type === 35633 ? 'vertexShader' : 'fragmentShader' }
+      stats.createdShaders.add(res)
+      return res
+    },
+    shaderSource: () => {},
+    compileShader: () => {},
+    getShaderParameter: () => true,
+    getShaderInfoLog: () => '',
+    deleteShader: (s: MockResource) => { stats.deletedShaders.add(s) },
+
+    createVertexArray: () => {
+      const res: MockResource = { id: nextId++, type: 'vao' }
+      stats.createdVAOs.add(res)
+      return res
+    },
+    deleteVertexArray: (vao: MockResource) => { stats.deletedVAOs.add(vao) },
+    bindVertexArray: () => {},
+
+    createBuffer: () => {
+      const res: MockResource = { id: nextId++, type: 'buffer' }
+      stats.createdBuffers.add(res)
+      return res
+    },
+    deleteBuffer: (b: MockResource) => { stats.deletedBuffers.add(b) },
+    bindBuffer: () => {},
+    bufferData: () => {},
+    bufferSubData: () => {},
+
+    getAttribLocation: (_p: any, name: string) => (name === 'a_position' ? 0 : name === 'a_uv' ? 1 : 2),
+    enableVertexAttribArray: () => {},
+    vertexAttribPointer: () => {},
+
+    createTexture: () => {
+      const res: MockResource = { id: nextId++, type: 'texture' }
+      stats.createdTextures.add(res)
+      return res
+    },
+    deleteTexture: (t: MockResource) => { stats.deletedTextures.add(t) },
+    bindTexture: () => {},
+    texParameteri: () => {},
+    texImage2D: () => {},
+    pixelStorei: () => {},
+
+    getParameter: (param: number) => (param === 3379 ? 4096 : 0),
+    getUniformLocation: (_p: any, name: string) => ({ name }),
+    uniform2f: () => {},
+    uniform1f: () => {},
+    uniform1i: () => {},
+
+    enable: () => {},
+    disable: () => {},
+    blendFunc: () => {},
+    viewport: () => {},
+    clearColor: () => {},
+    clear: () => {},
+    activeTexture: () => {},
+    drawArrays: () => {},
+  }
+
+  const eventListeners = stats.eventListeners
+
+  const canvas: any = {
+    getContext: (type: string) => (type === 'webgl2' ? gl : null),
+    addEventListener: (type: string, listener: EventListener) => {
+      if (!eventListeners.has(type)) eventListeners.set(type, new Set())
+      eventListeners.get(type)!.add(listener)
+    },
+    removeEventListener: (type: string, listener: EventListener) => {
+      eventListeners.get(type)?.delete(listener)
+    },
+    drawingBufferWidth: 800,
+    drawingBufferHeight: 600,
+  }
+
+  return {
+    canvas,
+    stats,
+    setContextLost: (lost: boolean) => { contextLost = lost },
+    dispatchMockEvent: (type: string) => {
+      let defaultPrevented = false
+      const event: any = {
+        type,
+        preventDefault: () => { defaultPrevented = true },
+      }
+      const set = eventListeners.get(type)
+      if (set) {
+        for (const listener of set) {
+          listener(event)
+        }
+      }
+      return { defaultPrevented }
+    },
+  }
+}
+
+function runTests(): void {
+  console.log('== Running SpriteRenderer Lifecycle Verification ==\n')
+
+  let passed = 0
+  let failed = 0
+
+  function assert(condition: boolean, name: string): void {
+    if (condition) {
+      console.log(`  ✓ ${name}`)
+      passed += 1
+    } else {
+      console.error(`  ✗ ${name}`)
+      failed += 1
+    }
+  }
+
+  // Test 1: Shader cleanup after compilation
+  {
+    const mock = createMockCanvas()
+    const renderer = new SpriteRenderer(mock.canvas)
+
+    assert(mock.stats.createdShaders.size === 2, 'Two shaders created (VS & FS)')
+    assert(mock.stats.deletedShaders.size === 2, 'Both shaders detached and deleted right after program link')
+    assert(mock.stats.createdPrograms.size === 1, 'Program created')
+    assert(mock.stats.createdVAOs.size === 1, 'VAO created')
+    assert(mock.stats.createdBuffers.size === 1, 'VBO buffer created')
+    assert(mock.stats.createdTextures.size === 2, 'Initial textures created (atlas + white)')
+    assert(renderer.isDisposed === false, 'Renderer is active and not disposed')
+
+    renderer.dispose()
+  }
+
+  // Test 2: addAtlas & deleteAtlas
+  {
+    const mock = createMockCanvas()
+    const renderer = new SpriteRenderer(mock.canvas)
+
+    const extra = renderer.addAtlas({ pixels: new Uint8ClampedArray(64 * 64 * 4), width: 64, height: 64 })
+    assert(mock.stats.createdTextures.size === 3, 'addAtlas creates a new GPU texture (3 total)')
+
+    // Draw with this extra atlas
+    renderer.begin({ x: 0, y: 0, zoom: 1 })
+    renderer.draw({ x: 0, y: 0, width: 32, height: 32 }, 0, 0, { atlas: extra })
+
+    // Now delete this atlas
+    const deleted = renderer.deleteAtlas(extra)
+    assert(deleted === true, 'deleteAtlas returned true for managed handle')
+    assert(mock.stats.deletedTextures.has(extra.texture as any), 'GPU texture was deleted via gl.deleteTexture')
+
+    // Deleting again should be safe and return false
+    const deletedAgain = renderer.deleteAtlas(extra)
+    assert(deletedAgain === false, 'deleteAtlas returned false on already deleted handle')
+
+    renderer.dispose()
+  }
+
+  // Test 3: dispose() cleans up all resources
+  {
+    const mock = createMockCanvas()
+    const renderer = new SpriteRenderer(mock.canvas)
+    const extra1 = renderer.addAtlas({ pixels: new Uint8ClampedArray(32 * 32 * 4), width: 32, height: 32 })
+    const extra2 = renderer.addAtlas({ pixels: new Uint8ClampedArray(32 * 32 * 4), width: 32, height: 32 })
+    void extra1
+    void extra2
+
+    assert(mock.stats.createdTextures.size === 4, '4 total textures created before dispose')
+
+    renderer.dispose()
+    assert(renderer.isDisposed === true, 'isDisposed is true after dispose()')
+    assert(mock.stats.deletedTextures.size === 4, 'All 4 textures were deleted on dispose()')
+    assert(mock.stats.deletedBuffers.size === 1, 'VBO was deleted on dispose()')
+    assert(mock.stats.deletedVAOs.size === 1, 'VAO was deleted on dispose()')
+    assert(mock.stats.deletedPrograms.size === 1, 'Program was deleted on dispose()')
+
+    // Idempotent dispose
+    renderer.dispose()
+    assert(mock.stats.deletedPrograms.size === 1, 'Second dispose() is safe and idempotent')
+
+    // Calling methods after dispose throws RendererError
+    let threwOnBegin = false
+    try {
+      renderer.begin({ x: 0, y: 0, zoom: 1 })
+    } catch (err) {
+      if (err instanceof RendererError) threwOnBegin = true
+    }
+    assert(threwOnBegin, 'begin() throws RendererError when called on disposed renderer')
+
+    let threwOnAdd = false
+    try {
+      renderer.addAtlas({ pixels: new Uint8ClampedArray(16), width: 2, height: 2 })
+    } catch (err) {
+      if (err instanceof RendererError) threwOnAdd = true
+    }
+    assert(threwOnAdd, 'addAtlas() throws RendererError when called on disposed renderer')
+  }
+
+  // Test 4: WebGL Context Lost & Restored
+  {
+    const mock = createMockCanvas()
+    const tracker = { lostFired: false, restoredFired: false }
+
+    const renderer = new SpriteRenderer(mock.canvas, {
+      onContextLost: () => { tracker.lostFired = true },
+      onContextRestored: () => { tracker.restoredFired = true },
+    })
+
+    const lostEvent = mock.dispatchMockEvent('webglcontextlost')
+    assert(lostEvent.defaultPrevented === true, 'webglcontextlost calls event.preventDefault() to allow recovery')
+    assert(tracker.lostFired === true, 'onContextLost callback fired')
+
+    mock.dispatchMockEvent('webglcontextrestored')
+    assert(tracker.restoredFired === true, 'onContextRestored callback fired')
+
+    // Dispose cleans up event listeners
+    renderer.dispose()
+    assert(mock.stats.eventListeners.get('webglcontextlost')?.size === 0, 'Context lost listener removed on dispose')
+    assert(mock.stats.eventListeners.get('webglcontextrestored')?.size === 0, 'Context restored listener removed on dispose')
+  }
+
+  // Test 5: Dispose when context is already lost
+  {
+    const mock = createMockCanvas()
+    const renderer = new SpriteRenderer(mock.canvas)
+    mock.setContextLost(true)
+
+    // Dispose should not attempt invalid GL deletes when context is lost
+    renderer.dispose()
+    assert(renderer.isDisposed === true, 'dispose() safely completes when context is already lost')
+  }
+
+  console.log(`\n== Summary: ${String(passed)} passed, ${String(failed)} failed ==`)
+  if (failed > 0) process.exit(1)
+}
+
+runTests()
diff --git a/src/render/renderer.ts b/src/render/renderer.ts
index 2e8d063..4acbc00 100644
--- a/src/render/renderer.ts
+++ b/src/render/renderer.ts
@@ -51,6 +51,14 @@ export interface DrawOptions {
   readonly atlas?: AtlasHandle
 }
 
+/** Configuration options and event callbacks for SpriteRenderer. */
+export interface RendererOptions {
+  /** Optional callback invoked when the WebGL context is lost. */
+  readonly onContextLost?: (event: Event) => void
+  /** Optional callback invoked when the WebGL context is restored. */
+  readonly onContextRestored?: () => void
+}
+
 /** Vertices per quad (two triangles). */
 const VERTICES_PER_QUAD = 6
 /** Floats per vertex: x, y, u, v, r, g, b, a. */
@@ -95,6 +103,8 @@ export class RendererError extends Error {}
  * A quad batcher bound to one canvas.
  */
 export class SpriteRenderer {
+  /** The target canvas. */
+  readonly canvas: HTMLCanvasElement
   /** The WebGL2 context, exposed for the few callers that need raw access. */
   readonly gl: WebGL2RenderingContext
   private readonly program: WebGLProgram
@@ -118,10 +128,20 @@ export class SpriteRenderer {
   private batchAtlas: AtlasHandle
   private camera: Camera = { x: 0, y: 0, zoom: 1 }
 
+  /** All textures allocated and managed by this renderer. */
+  private readonly allocatedTextures = new Set<WebGLTexture>()
+  /** Whether this renderer has been disposed. */
+  private disposed = false
+  /** Listener references for cleanup. */
+  private readonly handleContextLost: (event: Event) => void
+  private readonly handleContextRestored: () => void
+
   /**
    * @param canvas - the canvas to render into.
+   * @param options - optional lifecycle hooks and configuration.
    */
-  constructor(canvas: HTMLCanvasElement) {
+  constructor(canvas: HTMLCanvasElement, options: RendererOptions = {}) {
+    this.canvas = canvas
     const gl = canvas.getContext('webgl2', { alpha: false, antialias: false, premultipliedAlpha: false })
     if (gl === null) throw new RendererError('WebGL2 is not available in this browser')
     this.gl = gl
@@ -137,6 +157,8 @@ export class SpriteRenderer {
     this.buffer = buffer
     this.atlasTexture = atlasTexture
     this.whiteTexture = whiteTexture
+    this.allocatedTextures.add(atlasTexture)
+    this.allocatedTextures.add(whiteTexture)
     this.defaultAtlas = { texture: atlasTexture, width: 1, height: 1 }
     this.whiteAtlas = { texture: whiteTexture, width: 1, height: 1 }
     this.batchAtlas = this.defaultAtlas
@@ -174,6 +196,23 @@ export class SpriteRenderer {
     gl.enable(gl.BLEND)
     gl.blendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA)
     gl.disable(gl.DEPTH_TEST)
+
+    this.handleContextLost = (event: Event): void => {
+      event.preventDefault()
+      console.warn('WebGL2 context lost')
+      options.onContextLost?.(event)
+    }
+    this.handleContextRestored = (): void => {
+      console.info('WebGL2 context restored')
+      options.onContextRestored?.()
+    }
+    canvas.addEventListener('webglcontextlost', this.handleContextLost)
+    canvas.addEventListener('webglcontextrestored', this.handleContextRestored)
+  }
+
+  /** Whether this renderer and its GPU resources have been disposed. */
+  get isDisposed(): boolean {
+    return this.disposed
   }
 
   /**
@@ -183,6 +222,7 @@ export class SpriteRenderer {
    * @returns the handle other pages can be drawn with.
    */
   setAtlas(atlas: SpriteAtlas): AtlasHandle {
+    if (this.disposed) throw new RendererError('SpriteRenderer has already been disposed')
     const gl = this.gl
     // Uploading past the limit is a silent INVALID_VALUE in GL; say what
     // actually went wrong instead.
@@ -222,6 +262,7 @@ export class SpriteRenderer {
     width?: number,
     height?: number,
   ): AtlasHandle {
+    if (this.disposed) throw new RendererError('SpriteRenderer has already been disposed')
     const gl = this.gl
     const limit = gl.getParameter(gl.MAX_TEXTURE_SIZE) as number
     const isBitmap = typeof ImageBitmap !== 'undefined' && source instanceof ImageBitmap
@@ -235,6 +276,7 @@ export class SpriteRenderer {
     this.flush()
     const texture = gl.createTexture()
     if (texture === null) throw new RendererError('texture allocation failed')
+    this.allocatedTextures.add(texture)
     gl.bindTexture(gl.TEXTURE_2D, texture)
     gl.pixelStorei(gl.UNPACK_ALIGNMENT, 1)
     gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST)
@@ -257,6 +299,31 @@ export class SpriteRenderer {
     return { texture, width: pageWidth, height: pageHeight }
   }
 
+  /**
+   * Release an atlas texture handle and free its GPU memory.
+   *
+   * @param handle - the atlas handle previously returned by addAtlas or setAtlas.
+   * @returns true if the texture was managed by this renderer and deleted, false otherwise.
+   */
+  deleteAtlas(handle: AtlasHandle): boolean {
+    if (this.disposed || handle === this.whiteAtlas) return false
+    if (!this.allocatedTextures.has(handle.texture)) return false
+
+    if (this.batchAtlas === handle) {
+      this.flush()
+      this.batchAtlas = this.defaultAtlas === handle ? this.whiteAtlas : this.defaultAtlas
+    }
+    if (this.defaultAtlas === handle) {
+      this.defaultAtlas = this.whiteAtlas
+    }
+
+    if (!this.gl.isContextLost()) {
+      this.gl.deleteTexture(handle.texture)
+    }
+    this.allocatedTextures.delete(handle.texture)
+    return true
+  }
+
   /** The page `setAtlas` uploaded into, for callers that draw with handles. */
   get defaultAtlasHandle(): AtlasHandle {
     return this.defaultAtlas
@@ -269,6 +336,7 @@ export class SpriteRenderer {
    * @param clear - background colour as `[r, g, b]` in 0..1.
    */
   begin(camera: Camera, clear: readonly [number, number, number] = [0, 0, 0]): void {
+    if (this.disposed) throw new RendererError('SpriteRenderer has already been disposed')
     const gl = this.gl
     this.camera = camera
     this.quadCount = 0
@@ -287,6 +355,7 @@ export class SpriteRenderer {
    * @param options - tint and flipping.
    */
   draw(frame: AtlasFrame, x: number, y: number, options: DrawOptions = {}): void {
+    if (this.disposed) return
     const page = options.atlas ?? this.defaultAtlas
     // A page switch splits the batch; because it never reorders quads, painter's
     // order is preserved across pages.
@@ -316,6 +385,7 @@ export class SpriteRenderer {
    * @param color - `[r, g, b, a]` in 0..1.
    */
   drawSolid(x: number, y: number, width: number, height: number, color: readonly [number, number, number, number]): void {
+    if (this.disposed) return
     if (this.batchAtlas !== this.whiteAtlas) {
       this.flush()
       this.batchAtlas = this.whiteAtlas
@@ -368,7 +438,7 @@ export class SpriteRenderer {
   /** Submit every queued quad. */
   flush(): void {
     const gl = this.gl
-    if (this.quadCount === 0) return
+    if (this.disposed || this.quadCount === 0) return
     gl.useProgram(this.program)
     gl.bindVertexArray(this.vao)
     gl.bindBuffer(gl.ARRAY_BUFFER, this.buffer)
@@ -383,6 +453,31 @@ export class SpriteRenderer {
     this.quadCount = 0
   }
 
+  /**
+   * Destroy all WebGL2 GPU resources (textures, VAO, VBO, program) and detach event listeners.
+   */
+  dispose(): void {
+    if (this.disposed) return
+    this.disposed = true
+
+    this.canvas.removeEventListener('webglcontextlost', this.handleContextLost)
+    this.canvas.removeEventListener('webglcontextrestored', this.handleContextRestored)
+
+    const gl = this.gl
+    if (!gl.isContextLost()) {
+      for (const texture of this.allocatedTextures) {
+        gl.deleteTexture(texture)
+      }
+      this.allocatedTextures.clear()
+      gl.deleteBuffer(this.buffer)
+      gl.deleteVertexArray(this.vao)
+      gl.deleteProgram(this.program)
+    } else {
+      this.allocatedTextures.clear()
+    }
+    this.quadCount = 0
+  }
+
   /**
    * Grow the vertex buffer, preserving queued geometry.
    *
@@ -405,6 +500,9 @@ const WHITE: readonly [number, number, number, number] = [1, 1, 1, 1]
 /**
  * Compile and link a program, reporting shader logs on failure.
  *
+ * Shaders are detached and flagged for deletion immediately after linking to
+ * prevent driver-level memory leaks.
+ *
  * @param gl - the context.
  * @param vertexSource - vertex shader source.
  * @param fragmentSource - fragment shader source.
@@ -417,17 +515,28 @@ function createProgram(gl: WebGL2RenderingContext, vertexSource: string, fragmen
     gl.shaderSource(shader, source)
     gl.compileShader(shader)
     if (gl.getShaderParameter(shader, gl.COMPILE_STATUS) !== true) {
-      throw new RendererError(`shader compile failed: ${gl.getShaderInfoLog(shader) ?? 'unknown'}`)
+      const log = gl.getShaderInfoLog(shader) ?? 'unknown'
+      gl.deleteShader(shader)
+      throw new RendererError(`shader compile failed: ${log}`)
     }
     return shader
   }
   const program = gl.createProgram()
   if (program === null) throw new RendererError('could not create program')
-  gl.attachShader(program, compile(gl.VERTEX_SHADER, vertexSource))
-  gl.attachShader(program, compile(gl.FRAGMENT_SHADER, fragmentSource))
+  const vs = compile(gl.VERTEX_SHADER, vertexSource)
+  const fs = compile(gl.FRAGMENT_SHADER, fragmentSource)
+  gl.attachShader(program, vs)
+  gl.attachShader(program, fs)
   gl.linkProgram(program)
-  if (gl.getProgramParameter(program, gl.LINK_STATUS) !== true) {
-    throw new RendererError(`program link failed: ${gl.getProgramInfoLog(program) ?? 'unknown'}`)
+  const linked = gl.getProgramParameter(program, gl.LINK_STATUS) === true
+  const log = linked ? '' : (gl.getProgramInfoLog(program) ?? 'unknown')
+  gl.detachShader(program, vs)
+  gl.deleteShader(vs)
+  gl.detachShader(program, fs)
+  gl.deleteShader(fs)
+  if (!linked) {
+    gl.deleteProgram(program)
+    throw new RendererError(`program link failed: ${log}`)
   }
   return program
 }
diff --git a/src/scene/act-scene.ts b/src/scene/act-scene.ts
index c9edda9..bed0674 100644
--- a/src/scene/act-scene.ts
+++ b/src/scene/act-scene.ts
@@ -740,7 +740,7 @@ function runScene(runtime: MapRuntime, renderer: SpriteRenderer, started: number
         renderer.drawSolid(player.x - MARKER_WIDTH / 2, player.y - 6, MARKER_WIDTH, 6, [0.35, 0.25, 0.15, 1])
       } else {
         const direction = facingToDirection(player.facing, character.directions)
-        const groupIndex = character.walk + (player.moving ? direction : character.stand)
+        const groupIndex = (player.moving ? character.walk : character.stand) + direction
         const group = character.groups[groupIndex] ?? character.groups[character.walk + direction]
         const frameIndex = player.moving
           ? Math.floor(player.walkFrame / 3) % Math.max(1, group?.length ?? 1)
@@ -810,6 +810,16 @@ function runScene(runtime: MapRuntime, renderer: SpriteRenderer, started: number
       )
     })
   }
+
+  window.addEventListener('beforeunload', () => {
+    loop.stop()
+    input.detach()
+    if (character?.handle) renderer.deleteAtlas(character.handle)
+    for (const page of runtime.pages) {
+      if (page !== null) renderer.deleteAtlas(page)
+    }
+    renderer.dispose()
+  })
 }
 
 /**
@@ -821,7 +831,8 @@ function runScene(runtime: MapRuntime, renderer: SpriteRenderer, started: number
  * @returns true when blocked.
  */
 function collides(grid: CollisionGrid, x: number, y: number): boolean {
-  for (const [dx, dy] of [[-1, -1], [1, -1], [-1, 1], [1, 1]] as const) {
+  if (isBlockedAt(grid, x, y)) return true
+  for (const [dx, dy] of [[-1, -1], [1, -1], [-1, 1], [1, 1], [0, -1], [0, 1], [-1, 0], [1, 0]] as const) {
     if (isBlockedAt(grid, x + (dx * FEET_WIDTH) / 2, y + (dy * FEET_HEIGHT) / 2)) return true
   }
   return false
@@ -849,10 +860,10 @@ function cellOf(grid: CollisionGrid, x: number, y: number): { x: number; y: numb
  *
  * @param x - screen x direction, -1..1.
  * @param y - screen y direction, -1..1 (down positive).
- * @returns the facing index, 0 = north.
+ * @returns the facing index, 0 = south, turning clockwise (west).
  */
 function facingOf(x: number, y: number): number {
-  const angle = Math.atan2(x, -y)
+  const angle = Math.atan2(-x, y)
   return Math.round((angle / (Math.PI / 4)) + 8) % 8
 }
 
@@ -1084,7 +1095,15 @@ async function boot(): Promise<void> {
         if (runtime === null) continue
         publish(runtime, packBase)
         void populatePackSelectors(packBase, { act: runtime.act, label: runtime.quadrant })
-        const renderer = new SpriteRenderer(canvas)
+        const renderer = new SpriteRenderer(canvas, {
+          onContextLost: () => {
+            status.textContent = 'WebGL 上下文丢失，正在尝试恢复…'
+          },
+          onContextRestored: () => {
+            status.textContent = 'WebGL 上下文已恢复，正在重新加载…'
+            location.reload()
+          },
+        })
         // The first frame waits only for the spawn-area pages.
         await runtime.loadPages(renderer, runtime.priorityPages, () => {
           state.pagesLoaded = runtime.pages.filter(page => page !== null).length
@@ -1100,7 +1119,15 @@ async function boot(): Promise<void> {
     for (const base of bases) {
       try {
         status.textContent = `正在读取归档 ${base}（HTTP range）并解码 …`
-        const renderer = new SpriteRenderer(canvas)
+        const renderer = new SpriteRenderer(canvas, {
+          onContextLost: () => {
+            status.textContent = 'WebGL 上下文丢失，正在尝试恢复…'
+          },
+          onContextRestored: () => {
+            status.textContent = 'WebGL 上下文已恢复，正在重新加载…'
+            location.reload()
+          },
+        })
         const runtime = await loadLiveRuntime(base, act, renderer, param('quadrant', ''))
         publish(runtime, base)
         runScene(runtime, renderer, started)
diff --git a/src/scene/map-scene.ts b/src/scene/map-scene.ts
index 92a0472..631a244 100644
--- a/src/scene/map-scene.ts
+++ b/src/scene/map-scene.ts
@@ -323,9 +323,10 @@ function decodePaletteMember(name: string, bytes: Uint8Array): Palette {
   return { rgb: pl2.rgb, size: 256 }
 }
 
-/** The running loop and input, so a reload can retire the previous scene. */
+/** The running loop, input, and renderer, so a reload can retire the previous scene. */
 let running: GameLoop | null = null
 let input: KeyboardInput | null = null
+let activeRenderer: SpriteRenderer | null = null
 
 /** Fetch a URL as bytes. */
 async function fetchBytes(url: string): Promise<Uint8Array> {
@@ -368,7 +369,17 @@ function startScene(sources: MapSources, status: HTMLElement, hud: HTMLElement):
 
   running?.stop()
   input?.detach()
-  const renderer = new SpriteRenderer(canvas)
+  activeRenderer?.dispose()
+  const renderer = new SpriteRenderer(canvas, {
+    onContextLost: () => {
+      status.textContent = 'WebGL 上下文丢失，正在尝试恢复…'
+    },
+    onContextRestored: () => {
+      status.textContent = 'WebGL 上下文已恢复，正在重新加载…'
+      location.reload()
+    },
+  })
+  activeRenderer = renderer
   // The actor's frames ride in the *same* atlas as the tiles: one texture means
   // the actor can be drawn at its depth among the walls without a second bind.
   const combined: SpriteSheet = sources.actor === null
@@ -1214,4 +1225,11 @@ function boot(): void {
   status.textContent = '拖入 .mpq，或用 ?mpq=<url> / ?data=<fixture dir> 指定数据源。'
 }
 
+window.addEventListener('beforeunload', () => {
+  running?.stop()
+  input?.detach()
+  activeRenderer?.dispose()
+  activeRenderer = null
+})
+
 boot()
diff --git a/src/scene/net-scene.ts b/src/scene/net-scene.ts
index a0759cf..5f23d46 100644
--- a/src/scene/net-scene.ts
+++ b/src/scene/net-scene.ts
@@ -174,6 +174,7 @@ const DEMO_MONSTERS: MonsterStats[] = monsterStatsFromTable(parseTable([
 
 let running: GameLoop | null = null
 let input: KeyboardInput | null = null
+let activeRenderer: SpriteRenderer | null = null
 
 /**
  * Fetch bytes, or null when the file is absent.
@@ -325,7 +326,17 @@ function startScene(
 
   running?.stop()
   input?.detach()
-  const renderer = new SpriteRenderer(canvas)
+  activeRenderer?.dispose()
+  const renderer = new SpriteRenderer(canvas, {
+    onContextLost: () => {
+      status.textContent = 'WebGL 上下文丢失，正在尝试恢复…'
+    },
+    onContextRestored: () => {
+      status.textContent = 'WebGL 上下文已恢复，正在重新加载…'
+      location.reload()
+    },
+  })
+  activeRenderer = renderer
   const combined: SpriteSheet = sources.actor === null
     ? scene.sheet
     : { groups: [...scene.sheet.groups, ...sources.actor.sheet.groups], width: null }
@@ -608,5 +619,14 @@ function boot(): void {
   })()
 }
 
+if (typeof window !== 'undefined') {
+  window.addEventListener('beforeunload', () => {
+    running?.stop()
+    input?.detach()
+    activeRenderer?.dispose()
+    activeRenderer = null
+  })
+}
+
 /** Whether the page is running inside a document (avoids running under Node). */
 if (typeof document !== 'undefined') boot()
diff --git a/src/walk.ts b/src/walk.ts
index 73f0be6..503a5fb 100644
--- a/src/walk.ts
+++ b/src/walk.ts
@@ -140,6 +140,10 @@ function collides(x: number, y: number, walls: readonly Rect[]): boolean {
   return false
 }
 
+let activeLoop: GameLoop | null = null
+let activeInput: KeyboardInput | null = null
+let activeRenderer: SpriteRenderer | null = null
+
 /**
  * Boot the scene from an archive.
  *
@@ -173,7 +177,19 @@ async function start(archive: MpqArchive): Promise<void> {
   const standFrames: readonly (readonly AtlasFrame[])[] | null =
     stand === null ? null : atlas.groups.slice(walk.groups.length)
 
-  const renderer = new SpriteRenderer(canvas)
+  activeLoop?.stop()
+  activeInput?.detach()
+  activeRenderer?.dispose()
+  const renderer = new SpriteRenderer(canvas, {
+    onContextLost: () => {
+      status.textContent = 'WebGL 上下文丢失，正在尝试恢复…'
+    },
+    onContextRestored: () => {
+      status.textContent = 'WebGL 上下文已恢复，正在重新加载…'
+      location.reload()
+    },
+  })
+  activeRenderer = renderer
   renderer.setAtlas(atlas)
 
   const walls = buildWalls()
@@ -239,6 +255,8 @@ async function start(archive: MpqArchive): Promise<void> {
         + ` · ${String(atlas.groups.length)} groups / ${String(walk.groups.reduce((n, g) => n + g.frames.length, 0))} walk frames`
     },
   })
+  activeInput = input
+  activeLoop = loop
   loop.start()
   state.ready = true
   status.textContent = 'WASD / 方向键移动。角色为真实暗黑1 素材（战士行走/站立，宽度 96 = 游戏表数值）；地面与墙为占位几何。'
@@ -286,4 +304,11 @@ function boot(): void {
   }
 }
 
+window.addEventListener('beforeunload', () => {
+  activeLoop?.stop()
+  activeInput?.detach()
+  activeRenderer?.dispose()
+  activeRenderer = null
+})
+
 boot()