fix(security): harden extension and engine trust

scripts/engine-payload-integrity.js

@@ -0,0 +1,45 @@
+import crypto from 'node:crypto';
+import fs from 'node:fs';
+import path from 'node:path';
+
+export function sha256(file) {
+  return crypto.createHash('sha256').update(fs.readFileSync(file)).digest('hex');
+}
+
+export function collectRegularFiles(root, options = {}) {
+  const ignoredNames = new Set(options.ignoredNames || []);
+  const files = [];
+
+  const walk = directory => {
+    for (const entry of fs.readdirSync(directory, { withFileTypes: true })) {
+      const file = path.join(directory, entry.name);
+      const relative = path.relative(root, file).split(path.sep).join('/');
+      if (ignoredNames.has(entry.name)) {
+        continue;
+      }
+      if (entry.isSymbolicLink()) {
+        throw new Error(`Unsupported symlink in engine payload: ${relative}`);
+      }
+      if (entry.isDirectory()) {
+        walk(file);
+      } else if (entry.isFile()) {
+        files.push(file);
+      } else {
+        throw new Error(`Unsupported filesystem entry in engine payload: ${relative}`);
+      }
+    }
+  };
+
+  walk(root);
+  return files.sort((left, right) => left.localeCompare(right));
+}
+
+export function treeDigest(root) {
+  const files = collectRegularFiles(root);
+  const digest = crypto.createHash('sha256');
+  for (const file of files) {
+    const relative = path.relative(root, file).split(path.sep).join('/');
+    digest.update(`${relative}\0${sha256(file)}\n`);
+  }
+  return { files: files.length, sha256: digest.digest('hex') };
+}