Generate typed QX bindings and add source editing tools

src/capability-language/scaffold.ts

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+import { lstat, open, rename, unlink } from "node:fs/promises";
+import path from "node:path";
+import { randomUUID } from "node:crypto";
+import { addWorkspaceImport } from "./source.js";
+import { readQxSource } from "./source-loader.js";
+import { compileWorkspaceRepository, type CapabilityRepositoryResolver } from "./assembly.js";
+
+export const planAtomScaffold = (workspace: string, name: string, id: string) => {
+  if (!/^[A-Z][A-Za-z0-9]*$/.test(name)) throw new Error("Atom name must be PascalCase");
+  if (!id.trim()) throw new Error("Atom ID must not be empty");
+  const fileName = `${name}.qx`;
+  return {
+    before: workspace,
+    workspace: addWorkspaceImport(workspace, fileName),
+    fileName,
+    fragment: `fragment {\n  atom ${name} id ${JSON.stringify(id)};\n}\n`,
+  };
+};
+
+/** Validate an in-memory proposal before creating files. Never replace a fragment. */
+export const scaffoldAtom = async (options: {
+  root: string; name: string; id: string; write: boolean; resolveResource: CapabilityRepositoryResolver;
+}) => {
+  const before = await readQxSource(options.root, "workspace.qx");
+  const plan = planAtomScaffold(before, options.name, options.id);
+  const fragmentPath = path.join(options.root, plan.fileName);
+  try {
+    await lstat(fragmentPath);
+    throw new Error(`Scaffold target already exists: ${plan.fileName}`);
+  } catch (error) {
+    if ((error as NodeJS.ErrnoException).code !== "ENOENT") throw error;
+  }
+  const observed = new Map<string, string>();
+  await compileWorkspaceRepository({ rootDirectory: options.root, resolveResource: options.resolveResource,
+    readSource: async (name) => {
+      if (name === "workspace.qx") return plan.workspace;
+      if (name === plan.fileName) return plan.fragment;
+      const text = await readQxSource(options.root, name);
+      observed.set(name, text);
+      return text;
+    } });
+  if (!options.write) return plan;
+  const workspacePath = path.join(options.root, "workspace.qx");
+  const temporary = path.join(options.root, `.qx-scaffold-${randomUUID()}.tmp`);
+  let createdFragment = false;
+  let createdTemporary = false;
+  try {
+    const fragment = await open(fragmentPath, "wx");
+    createdFragment = true;
+    try { await fragment.writeFile(plan.fragment); } finally { await fragment.close(); }
+    const file = await open(temporary, "wx", (await lstat(workspacePath)).mode);
+    createdTemporary = true;
+    try { await file.writeFile(plan.workspace); } finally { await file.close(); }
+    observed.set("workspace.qx", before);
+    for (const [name, text] of observed) {
+      if (await readQxSource(options.root, name) !== text) throw new Error(`QX source changed during scaffolding: ${name}`);
+    }
+    await rename(temporary, workspacePath);
+    createdTemporary = false;
+    createdFragment = false;
+  } finally {
+    if (createdTemporary) await unlink(temporary);
+    if (createdFragment) await unlink(fragmentPath);
+  }
+  return plan;
+};