feat(viewer): fit camera to loaded model and add checked-in browser acceptance driver

- add three.js Box3/Camera bindings and bbox-driven camera framing
  (fov-fit with margin, recenters the model so group rotation orbits
  in place); refit on canvas resize instead of reverting to replay
  placeholder geometry
- expose window.SOMHAIRLES_VIEWER debug handle for numeric verification
- add tools/acceptance/e2e_acceptance.py: self-provisioning playwright
  driver (isolated port/artifact root, unique run ids) asserting framing,
  frozen-screenshot determinism, GLB hash equality, failure surfacing
- gitignore scratch/ and tools/acceptance/deps/; document the
  clean-checkout verification sequence (fable before build)

1 files changed, 43 insertions, 1 deletions

diff --git a/public/App.js b/public/App.js
index c5a5418..f953832 100644
--- a/public/App.js
+++ b/public/App.js
@@ -58,6 +58,8 @@ export let currentRunId = createAtom("");
 
 export let loadedStepPath = createAtom(undefined);
 
+export let displayedNode = createAtom(undefined);
+
 export let freezeRotation = createAtom(false);
 
 export function element(id) {
@@ -173,6 +175,7 @@ export function addMesh(view, frame) {
 
 export function renderFrame(frame) {
     selectedFrame(frame);
+    displayedNode(undefined);
     if (viewState() != null) {
         const view = viewState();
         view.Group.clear();
@@ -181,11 +184,46 @@ export function renderFrame(frame) {
     }
 }
 
+export function frameObject(view, node) {
+    const box = new THREE.Box3();
+    box.setFromObject(node);
+    if (!box.isEmpty()) {
+        const center = new THREE.Vector3();
+        const size = new THREE.Vector3();
+        box.getCenter(center);
+        box.getSize(size);
+        const radius = 0.5 * size.length();
+        if (radius > 1E-06) {
+            node.position.set(-center.x, -center.y, -center.z);
+            const camera = view.Camera;
+            const aspect = max(1, view.Canvas.clientWidth) / max(1, view.Canvas.clientHeight);
+            camera.aspect = aspect;
+            const fovY = (camera.fov * 3.141592653589793) / 180;
+            const limitingFov = min(fovY, 2 * Math.atan(Math.tan(fovY / 2) * aspect));
+            const distance = (1.28 * radius) / Math.sin(limitingFov / 2);
+            const norm = Math.sqrt(((0.62 * 0.62) + (0.45 * 0.45)) + (0.7 * 0.7));
+            camera.position.set((0.62 / norm) * distance, (0.45 / norm) * distance, (0.7 / norm) * distance);
+            camera.near = max(distance * 0.01, distance - (radius * 2.5));
+            camera.far = (distance + (radius * 4));
+            camera.lookAt(0, 0, 0);
+            camera.updateProjectionMatrix();
+        }
+    }
+}
+
 export function resizeView(view) {
     const width = max(1, view.Canvas.clientWidth);
     const height = max(1, view.Canvas.clientHeight);
     view.Renderer.setSize(width, height, false);
-    renderFrame(selectedFrame());
+    view.Camera.aspect = (width / height);
+    view.Camera.updateProjectionMatrix();
+    if (displayedNode() == null) {
+        renderFrame(selectedFrame());
+    }
+    else {
+        frameObject(view, displayedNode());
+        view.Renderer.render(view.Scene, view.Camera);
+    }
 }
 
 export function initializeView() {
@@ -213,6 +251,7 @@ export function initializeView() {
     const view = new ViewState(renderer, scene, camera, group, canvas);
     viewState(view);
     freezeRotation((new URLSearchParams(window.location.search).get("freeze")) === "1");
+    window.SOMHAIRLES_VIEWER = { camera: camera, scene: scene, group: group, canvas: canvas };
     renderFrame(selectedFrame());
     window.addEventListener("resize", (_arg) => {
         resizeView(view);
@@ -262,6 +301,9 @@ export function loadStepArtifact(view, stepPath) {
     loader.load(url, ((gltf) => {
         view.Group.clear();
         view.Group.add(gltf.scene);
+        displayedNode(gltf.scene);
+        frameObject(view, gltf.scene);
+        view.Renderer.render(view.Scene, view.Camera);
         setText("viewport-note", toText(printf("管线几何 · %s"))(stepPath));
     }), null, ((_arg) => {
         setText("viewport-note", toText(printf("管线几何加载失败 · %s"))(stepPath));