chore: enforce scoped formatting and browser package boundaries

scripts/format.mjs

@@ -0,0 +1,101 @@
+import { readFile, writeFile, realpath, stat } from 'node:fs/promises';
+import path from 'node:path';
+import { fileURLToPath, pathToFileURL } from 'node:url';
+import * as prettier from 'prettier';
+
+/** Check or format the explicitly adopted files, without scanning other source. */
+export async function formatAdoptedFiles(root, mode) {
+  if (!['--check', '--write'].includes(mode)) {
+    throw new Error('Usage: node scripts/format.mjs --check|--write');
+  }
+  root = await realpath(root);
+  const scope = JSON.parse(
+    await readFile(path.join(root, 'scripts/format-scope.json'), 'utf8'),
+  );
+  if (
+    !Array.isArray(scope) ||
+    !scope.length ||
+    new Set(scope).size !== scope.length
+  ) {
+    throw new Error(
+      'Formatting scope must be a nonempty list of unique file paths',
+    );
+  }
+
+  // Validate the whole scope before any write, including resolved symlink paths.
+  const files = [];
+  for (const name of scope) {
+    if (
+      typeof name !== 'string' ||
+      !name ||
+      name.includes('\\') ||
+      path.isAbsolute(name) ||
+      name.split('/').includes('..')
+    ) {
+      throw new Error(
+        'Formatting scope entries must be paths inside the repository',
+      );
+    }
+    const file = path.join(root, name);
+    const relative = path.relative(root, await realpath(file));
+    if (
+      relative === '..' ||
+      relative.startsWith(`..${path.sep}`) ||
+      path.isAbsolute(relative) ||
+      !(await stat(file)).isFile()
+    ) {
+      throw new Error(
+        `Formatting scope must contain repository files: ${name}`,
+      );
+    }
+    const info = await prettier.getFileInfo(file, {
+      ignorePath: path.join(root, '.prettierignore'),
+    });
+    if (info.ignored || !info.inferredParser) {
+      throw new Error(
+        `Formatting scope contains an ignored or unsupported file: ${name}`,
+      );
+    }
+    const options = { ...(await prettier.resolveConfig(file)), filepath: file };
+    const source = await readFile(file, 'utf8');
+    files.push({
+      name,
+      file,
+      source,
+      formatted: await prettier.format(source, options),
+    });
+  }
+
+  const changed = files.filter(({ source, formatted }) => source !== formatted);
+  if (mode === '--write') {
+    for (const { file, formatted } of changed) await writeFile(file, formatted);
+  }
+  return { count: files.length, changed: changed.map(({ name }) => name) };
+}
+
+const invoked = process.argv[1]
+  ? pathToFileURL(path.resolve(process.argv[1])).href
+  : '';
+if (import.meta.url === invoked) {
+  try {
+    if (process.argv.length !== 3)
+      throw new Error('Usage: node scripts/format.mjs --check|--write');
+    const mode = process.argv[2];
+    const result = await formatAdoptedFiles(
+      fileURLToPath(new URL('../', import.meta.url)),
+      mode,
+    );
+    if (mode === '--check' && result.changed.length) {
+      for (const name of result.changed)
+        console.error(`Needs formatting: ${name}`);
+      process.exitCode = 1;
+    } else {
+      console.log(
+        `${mode === '--write' ? 'Formatted' : 'Checked'} ${result.count} adopted files.`,
+      );
+    }
+  } catch (error) {
+    console.error(error.message);
+    process.exitCode = 1;
+  }
+}