test(cctv): lock the still draw path and fit-aware dedupe

Drive drawProjectionFrame with a fake runtime and a recording canvas:
a 640x480 still draws at its fitted rectangle over the matte, the same
pixels at the same size skip the redraw, and the same pixels at a new
aspect redraw at the new fit. The last case fails on the pixel-only
signature; the first fails if drawImage stretches to the canvas again.
Expected rectangles now read the canvas size from policy.js.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

src/layers/cctv/frames.test.mjs

@@ -3,9 +3,25 @@
 // 1920x1080 projection canvas, instead of being stretched to fill it.
 import { test } from 'node:test';
 import assert from 'node:assert/strict';
-import { fitToProjection } from './frames.js';
+import { createFrames, fitToProjection } from './frames.js';
+import {
+  FRAME_SIGNATURE_W,
+  FRAME_SIGNATURE_H,
+  PROJECTION_CANVAS_WIDTH,
+  PROJECTION_CANVAS_HEIGHT,
+  PROJECTION_MATTE_COLOR,
+} from './policy.js';
 
-const FULL_CANVAS = { x: 0, y: 0, w: 1920, h: 1080 };
+// The expected rectangles below are written for a 1920x1080 canvas.
+assert.equal(PROJECTION_CANVAS_WIDTH, 1920);
+assert.equal(PROJECTION_CANVAS_HEIGHT, 1080);
+
+const FULL_CANVAS = {
+  x: 0,
+  y: 0,
+  w: PROJECTION_CANVAS_WIDTH,
+  h: PROJECTION_CANVAS_HEIGHT,
+};
 
 test('a 4:3 still is pillarboxed at full height', () => {
   assert.deepEqual(fitToProjection(640, 480), {
@@ -35,3 +51,91 @@ test('a missing or zero dimension falls back to the full canvas', () => {
   assert.deepEqual(fitToProjection(640, undefined), FULL_CANVAS);
   assert.deepEqual(fitToProjection(undefined, undefined), FULL_CANVAS);
 });
+
+// Draw path: the fit reaches drawImage, and the unchanged-frame skip keys on the
+// fitted size as well as the pixels (the 64x36 hash alone drops aspect).
+function stillHarness() {
+  const calls = [];
+  const ctx = {
+    fillStyle: null,
+    fillRect: (...rect) => calls.push(['fillRect', ctx.fillStyle, ...rect]),
+    clearRect: () => {},
+    drawImage: (_image, ...rect) => calls.push(['drawImage', ...rect]),
+  };
+  // Every frame downsamples to the same pixels, so only the size differs.
+  const pixels = new Uint8ClampedArray(
+    FRAME_SIGNATURE_W * FRAME_SIGNATURE_H * 4,
+  ).fill(7);
+  const runtime = {
+    mode: 'image',
+    ctx,
+    image: { naturalWidth: 0, naturalHeight: 0 },
+    imageReady: true,
+    // In flight, so refreshProjectionImage returns before touching image.src.
+    imageLoading: true,
+    imageStamp: 0,
+    drawnImageStamp: -1,
+    lastFrameSignature: null,
+    canvasStamp: 0,
+    signatureCtx: {
+      clearRect: () => {},
+      drawImage: () => {},
+      getImageData: () => ({ data: pixels }),
+    },
+  };
+  const record = { camera: { id: 'still' }, projection: runtime };
+  const { drawProjectionFrame } = createFrames({
+    state: { _healthById: new Map(), _activeCameraId: null },
+    services: {},
+    parts: {},
+    source: {},
+  });
+  const load = (width, height) => {
+    runtime.image = { naturalWidth: width, naturalHeight: height };
+    runtime.imageStamp += 1;
+    calls.length = 0;
+    drawProjectionFrame(record);
+    return calls.slice();
+  };
+  return { runtime, load };
+}
+
+test('a still is drawn into its fitted rectangle over a full matte', () => {
+  const { runtime, load } = stillHarness();
+  assert.deepEqual(load(640, 480), [
+    [
+      'fillRect',
+      PROJECTION_MATTE_COLOR,
+      0,
+      0,
+      PROJECTION_CANVAS_WIDTH,
+      PROJECTION_CANVAS_HEIGHT,
+    ],
+    ['drawImage', 240, 0, 1440, 1080],
+  ]);
+  assert.equal(runtime.canvasStamp, 1);
+});
+
+test('same pixels at the same size skip the redraw', () => {
+  const { runtime, load } = stillHarness();
+  load(640, 480);
+  assert.deepEqual(load(640, 480), []);
+  assert.equal(runtime.canvasStamp, 1);
+});
+
+test('same pixels at a new aspect redraw at the new fit', () => {
+  const { runtime, load } = stillHarness();
+  load(640, 480);
+  assert.deepEqual(load(1920, 1080), [
+    [
+      'fillRect',
+      PROJECTION_MATTE_COLOR,
+      0,
+      0,
+      PROJECTION_CANVAS_WIDTH,
+      PROJECTION_CANVAS_HEIGHT,
+    ],
+    ['drawImage', 0, 0, 1920, 1080],
+  ]);
+  assert.equal(runtime.canvasStamp, 2);
+});