Repo setup and build step configuration

plugins/manifest.ts

@@ -0,0 +1,46 @@
+import { PluginOption, ResolvedConfig } from "vite";
+import path from "path";
+import fs from "fs";
+import merge from "lodash.merge";
+
+export type ManifestMergerOptions = {
+  output: string;
+  files: string[];
+}
+
+function mergeManifests(inputs: string[]): string {
+  const parsed = inputs.map(v => JSON.parse(v));
+  const output = {};
+  const merged = merge(output, ...parsed);
+  return JSON.stringify(merged, null, 2);
+}
+
+export const manifestMerge = (options: ManifestMergerOptions): PluginOption[] => {
+  const inputFiles = options.files.map(v=>fs.readFileSync(v, 'utf8'));
+  let config: ResolvedConfig | null = null;
+  let distPath: string | null = null;
+
+  return [
+    {
+      name: 'manifest-merger',
+      configResolved(resolvedConfig) {
+        config = resolvedConfig
+        distPath = path.resolve(config.build.outDir)
+      },
+      closeBundle() {
+        if (!config || !distPath) return
+        if (config.command === 'serve') {
+          return
+        }
+
+        fs.writeFileSync(
+          path.join(distPath ?? "", options.output),
+          mergeManifests(inputFiles),
+          {
+            encoding: 'utf8',
+          }
+        )
+      }
+    },
+  ]
+}