fix(transform,nuxt): use project rootDir for .domscribe/ artifacts in Nuxt

In Nuxt projects with a custom srcDir (e.g. srcDir: 'app/'), Vite's
config.root is set to the source directory. The Vite plugin used this as
the root for .domscribe/ artifacts, while the Nuxt module started the
relay with nuxt.options.rootDir. This split the .domscribe/ directory
across two locations, breaking relay/manifest coordination.

Add a rootDir option to VitePluginOptions that overrides config.root for
.domscribe/ path resolution. The Nuxt module passes nuxt.options.rootDir
so all components write to the same project-level .domscribe/ directory.

Author: Narrator

packages/domscribe-nuxt/src/module.spec.ts

@@ -342,6 +342,7 @@ describe('domscribeModule', () => {
           expect.objectContaining({
             debug: true,
             overlay: true,
+            rootDir: '/test/project',
             relay: { port: 3001, autoStart: false },
           }),
         );

packages/domscribe-nuxt/src/module.ts

@@ -113,6 +113,7 @@ export const domscribeModule = defineNuxtModule<DomscribeNuxtOptions>({
       () => {
         const plugin = domscribe({
           ...options,
+          rootDir: nuxt.options.rootDir,
           relay: { ...options.relay, autoStart: false },
         });
         // The Vite plugin defaults to `apply: 'serve'` (dev-only). During

packages/domscribe-transform/src/plugins/vite/types.ts

@@ -45,4 +45,13 @@ export interface VitePluginOptions {
    * @default true
    */
   overlay?: boolean | OverlayPluginOptions;
+
+  /**
+   * Override the root directory for `.domscribe/` artifacts (manifest,
+   * transform cache, relay lock).
+   *
+   * When omitted, defaults to Vite's `config.root`. Needed when the Vite
+   * root differs from the project root (e.g., Nuxt with a custom `srcDir`).
+   */
+  rootDir?: string;
 }

packages/domscribe-transform/src/plugins/vite/vite.plugin.spec.ts

@@ -317,6 +317,22 @@ describe('domscribe Vite plugin', () => {
       }).not.toThrow();
     });
 
+    it('should use rootDir option over config.root when provided', async () => {
+      // Arrange — Nuxt sets config.root to srcDir, but rootDir points to project root
+      const plugin = domscribe({ rootDir: '/project/root' });
+      const config = createMockResolvedConfig({ root: '/project/root/app' });
+
+      // Act
+      callHook(plugin.configResolved, {}, config);
+      await callHook(plugin.buildStart);
+
+      // Assert — ManifestWriter should be initialized with the project root
+      expect(mockWriterGetInstance).toHaveBeenCalledWith(
+        '/project/root',
+        expect.any(Object),
+      );
+    });
+
     it('should handle being called multiple times', () => {
       // Arrange
       const plugin = domscribe();

packages/domscribe-transform/src/plugins/vite/vite.plugin.ts

@@ -36,6 +36,7 @@ export function domscribe(options: VitePluginOptions = {}): Plugin {
     debug = false,
     relay: relayOptions = {},
     overlay: overlayOption = true,
+    rootDir,
   } = options;
   const filter = createFilter(include, exclude);
 
@@ -106,7 +107,7 @@ export function domscribe(options: VitePluginOptions = {}): Plugin {
     apply: 'serve', // Only run in development mode
 
     configResolved(config) {
-      rootContext = config.root;
+      rootContext = rootDir ?? config.root;
     },
 
     async buildStart() {