Add Chromium-only Blender WebEngine parity work

web/protocol/manifest.ts

@@ -0,0 +1,44 @@
+export interface WasmResource {
+  id: string;
+  fileName: string;
+  url: string;
+  sha256: string;
+  required: boolean;
+}
+
+export interface WebEngineManifest {
+  schemaVersion: number;
+  protocolVersion: number;
+  engineVersion: string;
+  engine: "mock" | "blender-wasm";
+  memory: {
+    initialPages: number;
+    maximumPages: number;
+    shared: boolean;
+  };
+  wasm: WasmResource[];
+}
+
+export async function loadWebEngineManifest(url = "/engine-manifest.json"): Promise<WebEngineManifest> {
+  const response = await fetch(url, { cache: "no-store" });
+  if (!response.ok) throw new Error(`Engine manifest request failed: ${response.status}`);
+  const manifest = await response.json() as Partial<WebEngineManifest>;
+  if (manifest.schemaVersion !== 1 || manifest.protocolVersion !== 1) {
+    throw new Error("Unsupported engine manifest version");
+  }
+  if (!manifest.engine || !manifest.memory || !Array.isArray(manifest.wasm)) {
+    throw new Error("Invalid engine manifest shape");
+  }
+  return manifest as WebEngineManifest;
+}
+
+export async function verifyWasmResource(resource: WasmResource): Promise<void> {
+  const response = await fetch(resource.url, { cache: "no-store" });
+  if (!response.ok) throw new Error(`WASM resource request failed: ${resource.id}`);
+  const bytes = await response.arrayBuffer();
+  const digest = await crypto.subtle.digest("SHA-256", bytes);
+  const actual = [...new Uint8Array(digest)].map((byte) => byte.toString(16).padStart(2, "0")).join("");
+  if (actual !== resource.sha256.toLowerCase()) {
+    throw new Error(`WASM resource hash mismatch: ${resource.id}`);
+  }
+}