feat(vom): fixture test

apps/extension/test-fixtures/rendered-surfaces/README.md

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+# Rendered Surface browser fixtures
+
+These pages exercise Canvas discovery through a real browser DOMSnapshot and AX tree. They are deliberately framework- and site-independent.
+
+## Serve
+
+From the repository root:
+
+```bash
+python3 -m http.server 4173 --bind 127.0.0.1 \
+  --directory apps/extension/test-fixtures/rendered-surfaces
+```
+
+Use an Agent Window large enough to keep the primary matrix visible:
+
+```bash
+bsk session start --width 1440 --height 1100
+bsk navigate http://127.0.0.1:4173/index.html --session <id>
+bsk observe --session <id>
+```
+
+Always stop the session after the run.
+
+## Pages
+
+### `index.html`
+
+Expected individual Surface labels:
+
+- `fixture-basic-large`
+- `fixture-tiny-8px`
+- `fixture-pointer-events-none`
+- `fixture-partial-ax`
+- `fixture-contained-outer`
+- `fixture-contained-inner`
+- `fixture-different-parent-a`
+- `fixture-different-parent-b`
+
+Expected one grouped Surface:
+
+- `fixture-layered-group`, with `layers=2`
+
+Expected absent:
+
+- `fixture-display-none`
+- `fixture-visibility-hidden`
+- `fixture-opacity-zero`
+- `fixture-parent-opacity-zero`
+- `fixture-hidden-attribute`
+- `fixture-inert-parent`
+- `fixture-aria-hidden-parent`
+- `fixture-zero-size`
+- `fixture-offscreen-right`
+- `fixture-fully-overflow-clipped`
+
+`fixture-partially-overflow-clipped` must remain present because part of it is visible. Its screenshot must contain only the browser's final composited view.
+
+### `unlabeled.html`
+
+This page contains eight Canvas elements but must render seven generic Surface markers because
+the two coincident layers form one group.
+
+- Every marker uses the stable fallback label `canvas visual surface`.
+- Exactly one marker has `layers=2`.
+- The two contained canvases remain separate markers.
+- `id`, `class`, `data-testid`, nearby prose, and fallback AX content never become a Surface label.
+- Blank `aria-label` and `title` values behave as no label.
+- Fallback AX content does not suppress the corresponding Surface.
+
+### `frames.html`
+
+Expected Surface labels:
+
+- `fixture-same-origin-frame`
+- `fixture-cross-origin-frame`
+- `fixture-nested-frame`
+
+The cross-origin frame uses `http://localhost:4173` while the parent uses `http://127.0.0.1:4173`. With Chromium site isolation this exercises the OOPIF path without an external service.
+
+### `viewport.html`
+
+Run with a `900x700` Agent Window.
+
+- `fixture-partial-viewport` is partly visible and must be represented.
+- `fixture-below-fold` is absent initially.
+- After scrolling it into view and observing again, `fixture-below-fold` must be represented with a fresh ref.
+
+### `dynamic.html`
+
+Use the normal DOM buttons and re-observe after each action:
+
+- Initial state: `fixture-dynamic` absent.
+- After **Insert canvas**: present.
+- After **Resize to zero**: absent.
+- After **Restore size**: present with a fresh ref.
+- After **Remove canvas**: absent.
+
+## Invariants
+
+- `snapshot` must not emit any of these Surface markers.
+- `observe` must emit only currently visible Canvas surfaces.
+- Existing DOM/AX controls remain readable alongside Surface markers.
+- Missing labels never prevent discovery; naming and discovery are independent.
+- A Surface ref allows `screenshot --ref` and rejects ordinary click/fill/hover/select.
+- No fixture URL, id, label, or layout constant may appear in production discovery code.

apps/extension/test-fixtures/rendered-surfaces/dynamic.html

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+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <title>Rendered Surface dynamic matrix</title>
+    <style>
+      html, body { margin: 0; font: 14px system-ui, sans-serif; }
+      body { padding: 16px; }
+      .controls { display: flex; gap: 8px; margin-bottom: 16px; }
+      button { padding: 8px 12px; }
+      canvas { display: block; width: 260px; height: 120px; background: #e8daef; border: 2px solid #7d3c98; }
+    </style>
+  </head>
+  <body>
+    <h1>Dynamic Canvas lifecycle</h1>
+    <div class="controls">
+      <button id="insert" type="button">Insert canvas</button>
+      <button id="zero" type="button">Resize to zero</button>
+      <button id="restore" type="button">Restore size</button>
+      <button id="remove" type="button">Remove canvas</button>
+    </div>
+    <div id="mount"></div>
+    <script>
+      const mount = document.querySelector("#mount");
+      const getCanvas = () => mount.querySelector("canvas");
+      document.querySelector("#insert").addEventListener("click", () => {
+        if (getCanvas()) return;
+        const canvas = document.createElement("canvas");
+        canvas.width = 260;
+        canvas.height = 120;
+        canvas.setAttribute("aria-label", "fixture-dynamic");
+        mount.append(canvas);
+      });
+      document.querySelector("#zero").addEventListener("click", () => {
+        const canvas = getCanvas();
+        if (canvas) canvas.style.cssText = "width:0;height:0;border:0";
+      });
+      document.querySelector("#restore").addEventListener("click", () => {
+        const canvas = getCanvas();
+        if (canvas) canvas.removeAttribute("style");
+      });
+      document.querySelector("#remove").addEventListener("click", () => getCanvas()?.remove());
+    </script>
+  </body>
+</html>

apps/extension/test-fixtures/rendered-surfaces/frame.html

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+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <style>
+      html, body { margin: 0; font: 14px system-ui, sans-serif; }
+      body { padding: 12px; background: #fdfefe; }
+      canvas { display: block; width: 220px; height: 90px; background: #d5f5e3; border: 2px solid #1e8449; }
+      iframe { width: 280px; height: 150px; margin-top: 10px; border: 2px solid #85929e; }
+    </style>
+  </head>
+  <body>
+    <canvas id="frame-canvas" width="220" height="90"></canvas>
+    <script>
+      const params = new URLSearchParams(location.search);
+      const canvas = document.querySelector("#frame-canvas");
+      if (params.get("canvas") === "0") canvas.remove();
+      else canvas.setAttribute("aria-label", params.get("label") || "fixture-frame-default");
+      if (params.get("nested") === "1") {
+        const iframe = document.createElement("iframe");
+        iframe.title = "nested fixture frame";
+        iframe.src = "frame.html?label=fixture-nested-frame";
+        document.body.append(iframe);
+      }
+    </script>
+  </body>
+</html>

apps/extension/test-fixtures/rendered-surfaces/frames.html

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+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <title>Rendered Surface frame matrix</title>
+    <style>
+      html, body { margin: 0; font: 14px system-ui, sans-serif; }
+      body { padding: 16px; }
+      .frames { display: grid; grid-template-columns: repeat(3, 320px); gap: 16px; }
+      iframe { width: 300px; height: 300px; border: 2px solid #5d6d7e; }
+    </style>
+  </head>
+  <body>
+    <h1>Frame matrix</h1>
+    <div class="frames">
+      <iframe title="same-origin fixture" src="frame.html?label=fixture-same-origin-frame"></iframe>
+      <iframe title="cross-origin fixture" src="http://localhost:4173/frame.html?label=fixture-cross-origin-frame"></iframe>
+      <iframe title="nested fixture" src="frame.html?canvas=0&nested=1"></iframe>
+    </div>
+  </body>
+</html>

apps/extension/test-fixtures/rendered-surfaces/index.html

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+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <title>Rendered Surface discovery matrix</title>
+    <style>
+      * { box-sizing: border-box; }
+      html, body { margin: 0; min-height: 100%; font: 14px/1.4 system-ui, sans-serif; }
+      body { padding: 16px; background: #f4f6f8; color: #17202a; }
+      h1 { margin: 0 0 12px; font-size: 20px; }
+      .matrix { display: grid; grid-template-columns: repeat(4, minmax(220px, 1fr)); gap: 12px; }
+      .case { min-height: 150px; padding: 10px; overflow: hidden; border: 1px solid #aeb6bf; border-radius: 6px; background: white; }
+      .case h2 { margin: 0 0 8px; font-size: 13px; }
+      canvas { display: block; background: #d6eaf8; border: 2px solid #2874a6; }
+      .stack { position: relative; width: 180px; height: 90px; }
+      .stack canvas { position: absolute; inset: 0; width: 180px; height: 90px; }
+      .stack canvas + canvas { background: rgb(244 208 63 / 45%); border-color: #b7950b; }
+      .contained { position: relative; width: 190px; height: 100px; }
+      .contained > canvas:first-child { width: 190px; height: 100px; }
+      .contained > canvas:last-child { position: absolute; left: 55px; top: 30px; width: 70px; height: 40px; background: #fadbd8; border-color: #c0392b; }
+      .same-place { position: relative; width: 180px; height: 90px; }
+      .same-place > div { position: absolute; inset: 0; }
+      .same-place canvas { width: 180px; height: 90px; }
+      .same-place > div:last-child canvas { border-color: #7d3c98; background: rgb(210 180 222 / 35%); }
+      .clip-box { width: 100px; height: 70px; overflow: hidden; border: 2px dashed #566573; }
+      .partially-clipped { width: 140px; height: 60px; transform: translateX(45px); }
+      .fully-clipped { width: 80px; height: 50px; transform: translateX(130px); }
+      .tiny { width: 8px; height: 8px; border-width: 1px; }
+    </style>
+  </head>
+  <body>
+    <h1>Rendered Surface discovery matrix</h1>
+    <main class="matrix">
+      <section class="case">
+        <h2>Visible named canvas</h2>
+        <canvas aria-label="fixture-basic-large" width="200" height="90"></canvas>
+      </section>
+
+      <section class="case">
+        <h2>Tiny canvas remains addressable</h2>
+        <canvas class="tiny" aria-label="fixture-tiny-8px" width="8" height="8"></canvas>
+      </section>
+
+      <section class="case">
+        <h2>Visible but pointer-events none</h2>
+        <canvas aria-label="fixture-pointer-events-none" width="180" height="80" style="pointer-events: none"></canvas>
+      </section>
+
+      <section class="case">
+        <h2>Partial AX/fallback content</h2>
+        <canvas aria-label="fixture-partial-ax" width="180" height="80">
+          <button type="button">Fallback button must not suppress the surface</button>
+        </canvas>
+      </section>
+
+      <section class="case">
+        <h2>Two real rendering layers</h2>
+        <div class="stack">
+          <canvas aria-label="fixture-layered-group" width="180" height="90"></canvas>
+          <canvas width="180" height="90"></canvas>
+        </div>
+      </section>
+
+      <section class="case">
+        <h2>Contained canvases are independent</h2>
+        <div class="contained">
+          <canvas aria-label="fixture-contained-outer" width="190" height="100"></canvas>
+          <canvas aria-label="fixture-contained-inner" width="70" height="40"></canvas>
+        </div>
+      </section>
+
+      <section class="case">
+        <h2>Same geometry, different parents</h2>
+        <div class="same-place">
+          <div><canvas aria-label="fixture-different-parent-a" width="180" height="90"></canvas></div>
+          <div><canvas aria-label="fixture-different-parent-b" width="180" height="90"></canvas></div>
+        </div>
+      </section>
+
+      <section class="case">
+        <h2>Partially overflow-clipped</h2>
+        <div class="clip-box">
+          <canvas class="partially-clipped" aria-label="fixture-partially-overflow-clipped" width="140" height="60"></canvas>
+        </div>
+      </section>
+
+      <section class="case">
+        <h2>Fully overflow-clipped</h2>
+        <div class="clip-box">
+          <canvas class="fully-clipped" aria-label="fixture-fully-overflow-clipped" width="80" height="50"></canvas>
+        </div>
+      </section>
+
+      <section class="case">
+        <h2>CSS-hidden variants</h2>
+        <canvas aria-label="fixture-display-none" width="80" height="40" style="display: none"></canvas>
+        <canvas aria-label="fixture-visibility-hidden" width="80" height="40" style="visibility: hidden"></canvas>
+        <canvas aria-label="fixture-opacity-zero" width="80" height="40" style="opacity: 0"></canvas>
+      </section>
+
+      <section class="case">
+        <h2>Hidden ancestor variants</h2>
+        <div style="opacity: 0"><canvas aria-label="fixture-parent-opacity-zero" width="80" height="40"></canvas></div>
+        <div hidden><canvas aria-label="fixture-hidden-attribute" width="80" height="40"></canvas></div>
+        <div inert><canvas aria-label="fixture-inert-parent" width="80" height="40"></canvas></div>
+        <div aria-hidden="true"><canvas aria-label="fixture-aria-hidden-parent" width="80" height="40"></canvas></div>
+      </section>
+
+      <section class="case">
+        <h2>Zero-size and offscreen</h2>
+        <canvas aria-label="fixture-zero-size" width="80" height="40" style="width: 0; height: 0; border: 0"></canvas>
+        <canvas aria-label="fixture-offscreen-right" width="80" height="40" style="position: fixed; left: 5000px; top: 0"></canvas>
+      </section>
+    </main>
+  </body>
+</html>
+

apps/extension/test-fixtures/rendered-surfaces/unlabeled.html

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+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <title>Unlabeled Rendered Surface matrix</title>
+    <style>
+      * { box-sizing: border-box; }
+      html, body { margin: 0; min-height: 100%; font: 14px/1.4 system-ui, sans-serif; }
+      body { padding: 16px; background: #f4f6f8; color: #17202a; }
+      h1 { margin: 0 0 12px; font-size: 20px; }
+      .matrix { display: grid; grid-template-columns: repeat(3, minmax(240px, 1fr)); gap: 12px; }
+      .case { min-height: 150px; padding: 10px; overflow: hidden; border: 1px solid #aeb6bf; border-radius: 6px; background: white; }
+      .case h2 { margin: 0 0 8px; font-size: 13px; }
+      .case p { margin: 0 0 8px; }
+      canvas { display: block; background: #d6eaf8; border: 2px solid #2874a6; }
+      .stack { position: relative; width: 180px; height: 90px; }
+      .stack canvas { position: absolute; inset: 0; width: 180px; height: 90px; }
+      .stack canvas + canvas { background: rgb(244 208 63 / 45%); border-color: #b7950b; }
+      .contained { position: relative; width: 190px; height: 100px; }
+      .contained > canvas:first-child { width: 190px; height: 100px; }
+      .contained > canvas:last-child { position: absolute; left: 55px; top: 30px; width: 70px; height: 40px; background: #fadbd8; border-color: #c0392b; }
+    </style>
+  </head>
+  <body>
+    <h1>Unlabeled Rendered Surface matrix</h1>
+    <main class="matrix">
+      <section class="case">
+        <h2>Only engineering attributes</h2>
+        <canvas id="must-not-be-a-label" class="must-not-be-a-label" data-testid="must-not-be-a-label" width="200" height="90"></canvas>
+      </section>
+
+      <section class="case">
+        <h2>Blank explicit names</h2>
+        <canvas aria-label="   " title="   " width="180" height="80"></canvas>
+      </section>
+
+      <section class="case">
+        <h2>Nearby prose is not a Canvas name</h2>
+        <p>must-not-be-inferred-as-a-surface-label</p>
+        <canvas width="180" height="80"></canvas>
+      </section>
+
+      <section class="case">
+        <h2>Fallback AX content does not name or suppress the Canvas</h2>
+        <canvas width="180" height="80">
+          <button type="button">Fallback control remains separate</button>
+        </canvas>
+      </section>
+
+      <section class="case">
+        <h2>Unnamed rendering layers still cluster</h2>
+        <div class="stack">
+          <canvas width="180" height="90"></canvas>
+          <canvas width="180" height="90"></canvas>
+        </div>
+      </section>
+
+      <section class="case">
+        <h2>Unnamed contained canvases stay independent</h2>
+        <div class="contained">
+          <canvas width="190" height="100"></canvas>
+          <canvas width="70" height="40"></canvas>
+        </div>
+      </section>
+    </main>
+  </body>
+</html>

apps/extension/test-fixtures/rendered-surfaces/viewport.html

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+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <title>Rendered Surface viewport matrix</title>
+    <style>
+      html, body { margin: 0; font: 14px system-ui, sans-serif; }
+      body { min-height: 1800px; padding: 16px; }
+      canvas { display: block; background: #fdebd0; border: 2px solid #ca6f1e; }
+      #partial { position: fixed; left: -70px; top: 120px; width: 180px; height: 100px; }
+      #below { position: absolute; left: 40px; top: 1350px; width: 240px; height: 120px; }
+    </style>
+  </head>
+  <body>
+    <h1>Viewport matrix</h1>
+    <p>The orange canvas on the left is intentionally clipped by the viewport.</p>
+    <canvas id="partial" aria-label="fixture-partial-viewport" width="180" height="100"></canvas>
+    <canvas id="below" aria-label="fixture-below-fold" width="240" height="120"></canvas>
+  </body>
+</html>
+