feat(viewer): stream live pipeline GLBs into the browser viewport

Protocol: RunSnapshot gains CompletedSteps (accumulated from checkpoint
artifact paths, reset on start) so the frontend can tell when real
pipeline geometry exists. New coordinator method StepArtifact plus
GET /api/artifacts/steps serves steps/*.glb while a run is active (any
lifecycle status), traversal-guarded and .glb-only, so stages appear
without waiting for run completion.

Frontend: GLTFLoader loads the latest completed step into the viewport
group as soon as its checkpoint lands over SSE; replay placeholder
frames render only while no step artifacts exist. ?freeze=1 query param
stops rotation for deterministic screenshot verification. Three.js r160
and GLTFLoader (with BufferGeometryUtils) are vendored under public/
vendor with an import map and a window.THREE shim, replacing the CDN
UMD script; the ~1.4MB vendored three.js files are third-party
dependencies (MIT), not project assets.

Tests: store accumulation of completed artifact paths; steps endpoint
serves GLB during an active run, rejects traversal, 404s missing files.

Verified: dotnet build Debug+Release clean, 42/42 tests pass, Fable
compile clean, release server smoke serves index/vendor/steps endpoint.

1 files changed, 59 insertions, 4 deletions

diff --git a/public/App.js b/public/App.js
index 262025a..c5a5418 100644
--- a/public/App.js
+++ b/public/App.js
@@ -1,7 +1,7 @@
 import { Record } from "./fable_modules/fable-library-js.4.24.0/Types.js";
 import { class_type, record_type, bool_type, string_type } from "./fable_modules/fable-library-js.4.24.0/Reflection.js";
 import { Replay_frames } from "./SomhairlesDream.Shared/Replay.js";
-import { createAtom } from "./fable_modules/fable-library-js.4.24.0/Util.js";
+import { equals, createAtom } from "./fable_modules/fable-library-js.4.24.0/Util.js";
 import { tryFind, item } from "./fable_modules/fable-library-js.4.24.0/Array.js";
 import { isNullOrWhiteSpace, printf, toText } from "./fable_modules/fable-library-js.4.24.0/String.js";
 import { MeshData_triangleIndices, MeshData_positionData } from "./SomhairlesDream.Shared/Domain.js";
@@ -52,6 +52,14 @@ export let replayIndex = createAtom(0);
 
 export let eventSource = createAtom(undefined);
 
+export let currentProjectId = createAtom("");
+
+export let currentRunId = createAtom("");
+
+export let loadedStepPath = createAtom(undefined);
+
+export let freezeRotation = createAtom(false);
+
 export function element(id) {
     return document.getElementById(id);
 }
@@ -204,12 +212,15 @@ export function initializeView() {
     scene.add(keyLight);
     const view = new ViewState(renderer, scene, camera, group, canvas);
     viewState(view);
+    freezeRotation((new URLSearchParams(window.location.search).get("freeze")) === "1");
     renderFrame(selectedFrame());
     window.addEventListener("resize", (_arg) => {
         resizeView(view);
     });
     const animate = (_arg_1) => {
-        group.rotation.y = (group.rotation.y + 0.003);
+        if (!freezeRotation()) {
+            group.rotation.y = (group.rotation.y + 0.003);
+        }
         renderer.render(scene, camera);
         requestAnimationFrame(animate);
     };
@@ -239,6 +250,24 @@ export function setManifestLink(payload) {
     }
 }
 
+export function loadStepArtifact(view, stepPath) {
+    loadedStepPath(stepPath);
+    const loader = new GLTFLoader();
+    const projectId = encodeURIComponent(currentProjectId());
+    const runId = encodeURIComponent(currentRunId());
+    let url;
+    const arg_2 = encodeURIComponent(stepPath);
+    url = toText(printf("/api/artifacts/steps?projectId=%s&runId=%s&path=%s"))(projectId)(runId)(arg_2);
+    setText("viewport-note", toText(printf("管线几何加载中 · %s"))(stepPath));
+    loader.load(url, ((gltf) => {
+        view.Group.clear();
+        view.Group.add(gltf.scene);
+        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));
+    }));
+}
+
 export function updateState(payload) {
     let arg, arg_3;
     setStatusClass(statusName(payload));
@@ -246,6 +275,8 @@ export function updateState(payload) {
     setText("run-message", ((payload.status === "failed") && !isNullOrWhiteSpace(payload.error)) ? payload.error : payload.message);
     setText("project-id", payload.projectId);
     setText("run-id", payload.runId);
+    currentProjectId(payload.projectId);
+    currentRunId(payload.runId);
     const currentVersion = max(0, payload.currentStepIndex + 1) | 0;
     setText("target-version", (arg = (payload.totalSteps | 0), toText(printf("V%02d"))(arg)));
     setText("current-version", toText(printf("V%02d"))(currentVersion));
@@ -255,8 +286,32 @@ export function updateState(payload) {
     setWidth("progress-fill", toText(printf("%.0f%%"))(progress));
     const frame = defaultArg(tryFind((candidate) => (candidate.Version === currentVersion), frames), selectedFrame());
     setManifestLink(payload);
-    showFrameMetadata(frame);
-    renderFrame(frame);
+    const completedSteps = (payload.completedSteps == null) ? [] : payload.completedSteps;
+    const matchValue = viewState();
+    if (matchValue == null) {
+        const steps_1 = completedSteps;
+        if (steps_1.length > 0) {
+            setText("mesh-label", item(steps_1.length - 1, steps_1));
+        }
+        else {
+            showFrameMetadata(frame);
+        }
+    }
+    else {
+        const view = matchValue;
+        const steps = completedSteps;
+        if (steps.length === 0) {
+            showFrameMetadata(frame);
+            renderFrame(frame);
+        }
+        else {
+            const latest = item(steps.length - 1, steps);
+            if (!equals(loadedStepPath(), latest)) {
+                loadStepArtifact(view, latest);
+            }
+            setText("mesh-label", latest);
+        }
+    }
 }
 
 export function updateStreamState(message) {