add index.md demo

extensions/a/README.md

@@ -1 +1,3 @@
 # Hi
+
+README.md

extensions/a/index.md

@@ -0,0 +1,3 @@
+# Hi
+
+index.md

pages/api/info.ts

@@ -0,0 +1,35 @@
+// Next.js API route support: https://nextjs.org/docs/api-routes/introduction
+import type { NextApiRequest, NextApiResponse } from "next";
+import { resolve, join } from "path";
+import { readFileSync } from "fs";
+
+type Data = {
+  content: string;
+};
+
+type Error = {
+  error: string;
+};
+
+export default function handler(
+  req: NextApiRequest,
+  res: NextApiResponse<Data | Error>
+) {
+  if (req.method === "GET") {
+    const { slugs } = req.query;
+    const slug = typeof slugs === "string" ? slugs : slugs[0];
+
+    const templateDirectory = resolve(process.cwd(), "extensions");
+    const emailTemplate = readFileSync(
+      join(templateDirectory, slug, "index.md"),
+      "utf8"
+    );
+    return res.status(200).json({
+      content: emailTemplate,
+    });
+  } else {
+    return res.status(404).json({
+      error: "Not Support Method",
+    });
+  }
+}

vercel.json

@@ -2,6 +2,9 @@
   "functions": {
     "pages/api/contact.ts": {
       "includeFiles": "extensions/**/README.md"
+    },
+    "pages/api/info.ts": {
+      "includeFiles": "extensions/**/index.md"
     }
   }
 }