Temporary workaround for a problem with the NeoViewer component that has surfaced due to the recent upgrades of other dependencies.

See https://gitlab.ebrains.eu/data-services/neural-activity-resource/-/issues/1

Author: apdavison

apps/nar-v3/vite.config.js

@@ -3,7 +3,36 @@ import react from "@vitejs/plugin-react";
 
 // https://vitejs.dev/config/
 export default defineConfig({
-  plugins: [react()],
+  plugins: [
+    react(),
+    {
+      // Vite 8 / rolldown's CJS→ESM interop calls __toESM with isNodeMode=1,
+      // which ignores the __esModule flag and wraps the whole exports object as
+      // the default export. react-plotly.js sets exports.__esModule=true and
+      // exports.default=PlotComponent, but isNodeMode=1 causes Plot to resolve
+      // to {__esModule: true, default: PlotComponent} instead of PlotComponent.
+      //
+      // Fix: exclude neural-activity-visualizer-react from pre-bundling so Vite
+      // serves its ESM source directly (triggering this transform), then rewrite
+      // the import to extract .default explicitly before rolldown sees it.
+      name: "fix-react-plotly-interop",
+      enforce: "pre",
+      transform(code, id) {
+        if (
+          id.includes("neural-activity-visualizer-react") &&
+          code.includes('import Plot from "react-plotly.js"')
+        ) {
+          return {
+            code: code.replace(
+              'import Plot from "react-plotly.js"',
+              'import _reactPlotly from "react-plotly.js";\nconst Plot = _reactPlotly.default ?? _reactPlotly;'
+            ),
+            map: null,
+          };
+        }
+      },
+    },
+  ],
   server: {
     port: 3000,
     proxy: {
@@ -15,6 +44,14 @@ export default defineConfig({
       },
     },
   },
+  optimizeDeps: {
+    // Pre-bundle react-plotly.js so its CJS is converted to ESM before the
+    // browser sees it. neural-activity-visualizer-react is excluded so Vite
+    // serves it as raw ESM, which triggers the fix-react-plotly-interop plugin
+    // transform above (plugin transforms don't run on pre-bundled files).
+    include: ["react-plotly.js"],
+    exclude: ["neural-activity-visualizer-react"],
+  },
   build: {
     target: "esnext",
   },