fix(create-void): validate Cloudflare-compatible project names

packages/create-void/src/args.ts

@@ -14,6 +14,21 @@ export function validateProjectName(value: string | undefined): string | undefin
   if (value !== undefined && value !== value.toLowerCase()) {
     return 'Project name must be lowercase';
   }
+  // The prompt uses an empty value to select its default project name.
+  if (!value) {
+    return undefined;
+  }
+  // Keep scaffold names usable as workers.dev DNS labels.
+  // https://developers.cloudflare.com/workers/configuration/routing/workers-dev/#limitations
+  if (value.length > 63) {
+    return 'Project name must be at most 63 characters';
+  }
+  if (/[^a-z0-9-]/.test(value)) {
+    return 'Project name must contain only lowercase letters, numbers, and dashes';
+  }
+  if (value.startsWith('-') || value.endsWith('-')) {
+    return 'Project name cannot start or end with a dash';
+  }
   return undefined;
 }
 

packages/create-void/test/unit/args.test.ts

@@ -21,6 +21,24 @@ describe('parseCreateArgs', () => {
     expect(() => parseCreateArgs([name])).toThrow('create-void: Project name must be lowercase');
   });
 
+  it.each([
+    'my_app',
+    'my.app',
+    'my app',
+    'nested/my-app',
+    'my-app-',
+    'a'.repeat(64),
+  ])('rejects invalid project names from the command line: %s', (name) => {
+    expect(() => parseCreateArgs([name])).toThrow('create-void: Project name');
+  });
+
+  it.each(['a', '0', 'my-app', 'my--app', 'app123', 'a'.repeat(63)])(
+    'accepts deployable project names from the command line: %s',
+    (name) => {
+      expect(parseCreateArgs([name])).toEqual({ appName: name, initArgs: [] });
+    },
+  );
+
   it('rejects arguments that are not plain flags or values', () => {
     expect(() => parseCreateArgs(['my-app', '--framework', 'react&calc'])).toThrow(
       "create-void: Unsupported argument 'react&calc'.",
@@ -33,8 +51,47 @@ describe('validateProjectName', () => {
     expect(validateProjectName(name)).toBe('Project name must be lowercase');
   });
 
-  it.each(['my-app', 'app123', 'nested/my-app', '.'])('accepts lowercase names: %s', (name) => {
-    expect(validateProjectName(name)).toBeUndefined();
+  it.each(['a', '0', 'my-app', 'my--app', 'app123', 'a'.repeat(63)])(
+    'accepts lowercase names: %s',
+    (name) => {
+      expect(validateProjectName(name)).toBeUndefined();
+    },
+  );
+
+  it.each([
+    'my_app',
+    'my.app',
+    'my app',
+    ' my-app',
+    'my-app ',
+    'my-app\n',
+    'my-app\t',
+    'my-app\u0000',
+    'café',
+    '项目',
+    'my😀app',
+    'nested/my-app',
+    'nested\\my-app',
+    '@scope/my-app',
+    '.',
+    '..',
+    '../my-app',
+    '/tmp/my-app',
+    'my&app',
+    'my;app',
+    'my$app',
+  ])('rejects characters outside the Cloudflare name alphabet: %j', (name) => {
+    expect(validateProjectName(name)).toBe(
+      'Project name must contain only lowercase letters, numbers, and dashes',
+    );
+  });
+
+  it.each(['-app', 'app-', '-', '--'])('rejects leading or trailing dashes: %s', (name) => {
+    expect(validateProjectName(name)).toBe('Project name cannot start or end with a dash');
+  });
+
+  it('rejects names longer than a workers.dev DNS label', () => {
+    expect(validateProjectName('a'.repeat(64))).toBe('Project name must be at most 63 characters');
   });
 
   it('allows the prompt default and rejects whitespace-only names', () => {