Add queryable capability contracts and checked GraphQL artifacts

src/capability-language/source-loader.ts

@@ -4,13 +4,20 @@ import { parseQx, validateQxImportPath, walkSyntax } from "./source.js";
 
 export const readQxSource = async (root: string, name: string) => {
   validateQxImportPath(name);
+  return readRepositorySource(root, name);
+};
+
+/** Refuse symlinks at every component, including the final source file. */
+export const readRepositorySource = async (root: string, name: string) => {
+  if (!/^(?:[A-Za-z0-9_-][A-Za-z0-9_.-]*\/)*[A-Za-z0-9_-][A-Za-z0-9_.-]*$/.test(name))
+    throw new Error(`Invalid repository-relative source path: ${name}`);
   let current = path.resolve(root);
   const segments = name.split("/");
   for (const [index, segment] of segments.entries()) {
     current = path.join(current, segment);
     const stat = await lstat(current);
     if (stat.isSymbolicLink() || (index === segments.length - 1 ? !stat.isFile() : !stat.isDirectory()))
-      throw new Error(`QX imports must be ordinary files beneath ordinary directories: ${name}`);
+      throw new Error(`Sources must be ordinary files beneath ordinary directories: ${name}`);
   }
   return readFile(current, "utf8");
 };