feat: Prepare Vercel deployment with serverless adapter

- Extract buildApp() from server.ts into app.ts for reuse
- Create api/index.ts as Vercel serverless function entry point
- Add vercel.json with rewrites (static assets + catch-all to API)
- Build script now copies static assets to public/ and templates to dist/
- Include src/templates/** in serverless function bundle
- Local dev and tests continue to work unchanged (60/60 passing)

https://claude.ai/code/session_01CvrcMDqfCKWV2hC3xpRbx3

jus-ia-start-kit/.gitignore

@@ -2,4 +2,5 @@ node_modules/
 dist/
 .env
 src/public/css/app.css
+/public/
 *.tsbuildinfo

jus-ia-start-kit/api/index.ts

@@ -0,0 +1,22 @@
+import type { IncomingMessage, ServerResponse } from "node:http";
+import { buildApp } from "../src/app.js";
+
+let appReady: ReturnType<typeof buildApp> | null = null;
+
+function getApp() {
+  if (!appReady) {
+    appReady = buildApp().then(async (app) => {
+      await app.ready();
+      return app;
+    });
+  }
+  return appReady;
+}
+
+export default async function handler(
+  req: IncomingMessage,
+  res: ServerResponse,
+) {
+  const app = await getApp();
+  app.server.emit("request", req, res);
+}

jus-ia-start-kit/package.json

@@ -7,9 +7,10 @@
     "dev": "concurrently \"npm run dev:server\" \"npm run dev:css\"",
     "dev:server": "tsx watch --env-file=.env src/server.ts",
     "dev:css": "npx @tailwindcss/cli -i src/styles/input.css -o src/public/css/app.css --watch",
-    "build": "npm run build:css && npm run build:server",
+    "build": "npm run build:css && npm run build:server && npm run build:assets",
     "build:server": "tsc",
     "build:css": "npx @tailwindcss/cli -i src/styles/input.css -o src/public/css/app.css --minify",
+    "build:assets": "cp -r src/public/* public/ 2>/dev/null; cp -r src/templates dist/templates",
     "start": "node --env-file=.env dist/server.js",
     "test": "vitest run",
     "test:watch": "vitest"

jus-ia-start-kit/src/app.ts

@@ -0,0 +1,56 @@
+import Fastify from "fastify";
+import fastifyView from "@fastify/view";
+import fastifyStatic from "@fastify/static";
+import fastifyFormbody from "@fastify/formbody";
+import nunjucks from "nunjucks";
+import { fileURLToPath } from "node:url";
+import { dirname, join } from "node:path";
+import { config } from "./config/index.js";
+import { homeRoutes } from "./routes/home.js";
+import { flowRoutes } from "./routes/flow.js";
+
+const __filename = fileURLToPath(import.meta.url);
+const __dirname = dirname(__filename);
+
+export async function buildApp() {
+  const app = Fastify({
+    logger: {
+      level: config.nodeEnv === "production" ? "info" : "debug",
+      transport:
+        config.nodeEnv === "development"
+          ? { target: "pino-pretty", options: { translateTime: "HH:MM:ss" } }
+          : undefined,
+    },
+  });
+
+  // Parse form body (application/x-www-form-urlencoded)
+  await app.register(fastifyFormbody);
+
+  // Serve static assets (local dev only — Vercel serves from public/)
+  await app.register(fastifyStatic, {
+    root: join(__dirname, "public"),
+    prefix: "/",
+  });
+
+  // Nunjucks template engine
+  nunjucks.configure(join(__dirname, "templates"), {
+    autoescape: true,
+    noCache: config.nodeEnv === "development",
+  });
+
+  await app.register(fastifyView, {
+    engine: { nunjucks },
+    templates: join(__dirname, "templates"),
+    options: {
+      onConfigure: (_env: nunjucks.Environment) => {
+        // Add any custom filters here
+      },
+    },
+  });
+
+  // Register routes
+  await app.register(homeRoutes);
+  await app.register(flowRoutes);
+
+  return app;
+}

jus-ia-start-kit/src/server.ts

@@ -1,57 +1,8 @@
-import Fastify from "fastify";
-import fastifyView from "@fastify/view";
-import fastifyStatic from "@fastify/static";
-import fastifyFormbody from "@fastify/formbody";
-import nunjucks from "nunjucks";
-import { fileURLToPath } from "node:url";
-import { dirname, join } from "node:path";
 import { config } from "./config/index.js";
-import { homeRoutes } from "./routes/home.js";
-import { flowRoutes } from "./routes/flow.js";
+import { buildApp } from "./app.js";
 
-const __filename = fileURLToPath(import.meta.url);
-const __dirname = dirname(__filename);
+const app = await buildApp();
 
-const app = Fastify({
-  logger: {
-    level: config.nodeEnv === "production" ? "info" : "debug",
-    transport:
-      config.nodeEnv === "development"
-        ? { target: "pino-pretty", options: { translateTime: "HH:MM:ss" } }
-        : undefined,
-  },
-});
-
-// Parse form body (application/x-www-form-urlencoded)
-await app.register(fastifyFormbody);
-
-// Serve static assets
-await app.register(fastifyStatic, {
-  root: join(__dirname, "public"),
-  prefix: "/",
-});
-
-// Nunjucks template engine
-const nunjucksEnv = nunjucks.configure(join(__dirname, "templates"), {
-  autoescape: true,
-  noCache: config.nodeEnv === "development",
-});
-
-await app.register(fastifyView, {
-  engine: { nunjucks },
-  templates: join(__dirname, "templates"),
-  options: {
-    onConfigure: (env: nunjucks.Environment) => {
-      // Add any custom filters here
-    },
-  },
-});
-
-// Register routes
-await app.register(homeRoutes);
-await app.register(flowRoutes);
-
-// Start server
 try {
   const address = await app.listen({ port: config.port, host: config.host });
   app.log.info(`Jus IA Start Kit running at ${address}`);

jus-ia-start-kit/vercel.json

@@ -0,0 +1,17 @@
+{
+  "$schema": "https://openapi.vercel.sh/vercel.json",
+  "buildCommand": "npm run build",
+  "outputDirectory": "public",
+  "functions": {
+    "api/index.ts": {
+      "includeFiles": "src/templates/**"
+    }
+  },
+  "rewrites": [
+    { "source": "/css/(.*)", "destination": "/css/$1" },
+    { "source": "/js/(.*)", "destination": "/js/$1" },
+    { "source": "/images/(.*)", "destination": "/images/$1" },
+    { "source": "/favicon.ico", "destination": "/favicon.ico" },
+    { "source": "/(.*)", "destination": "/api/index" }
+  ]
+}