fix(minting-service): bundle Vercel functions via Nx esbuild build (#133)

The prior `tsc --noEmit` buildCommand didn't emit any JS, so Vercel
would still try to compile `api/*.ts` directly at deploy time. That
path can't resolve `@cacheplane/db` or `@cacheplane/licensing` because
`libs/*` isn't in the root npm workspaces and the libs don't declare
`exports` entry points.

Switch to Nx-native build: a new `build` target runs esbuild over
every `api/*.ts`, inlining workspace deps via tsconfig paths and
emitting Vercel Build Output API v3 layout under `.vercel/output/`.
Each `.func` colocates a `package.json` pinning `commonjs` to override
the app's `"type": "module"`.

Co-authored-by: Claude Opus 4 <noreply@anthropic.com>

Author: blove

apps/minting-service/project.json

@@ -5,6 +5,14 @@
   "projectType": "application",
   "tags": ["scope:service", "type:app"],
   "targets": {
+    "build": {
+      "executor": "nx:run-commands",
+      "outputs": ["{projectRoot}/.vercel/output"],
+      "options": {
+        "command": "node scripts/build.mjs",
+        "cwd": "apps/minting-service"
+      }
+    },
     "lint": { "executor": "@nx/eslint:lint" },
     "test": {
       "executor": "@nx/vitest:test",

apps/minting-service/scripts/build.mjs

@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: PolyForm-Noncommercial-1.0.0
+/**
+ * Builds the minting-service API functions using Vercel Build Output API v3.
+ *
+ * - Bundles each `api/*.ts` into a self-contained CommonJS module via esbuild,
+ *   inlining workspace deps (@cacheplane/*) and npm deps alike so no install
+ *   step is required inside each function directory.
+ * - Writes to `.vercel/output/functions/api/<name>.func/` with the companion
+ *   `.vc-config.json` Vercel's Node runtime expects.
+ * - Writes `.vercel/output/config.json` at the top level so Vercel picks up
+ *   the Build Output API layout instead of scanning `api/` for TS sources.
+ *
+ * Run via `nx build minting-service`, which sets `cwd` to this app.
+ */
+import { build } from 'esbuild';
+import { mkdir, readdir, rm, writeFile } from 'node:fs/promises';
+import { basename, join, resolve } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const appRoot = resolve(fileURLToPath(import.meta.url), '..', '..');
+const apiDir = join(appRoot, 'api');
+const outputRoot = join(appRoot, '.vercel', 'output');
+const functionsRoot = join(outputRoot, 'functions', 'api');
+
+async function listEntries() {
+  const files = await readdir(apiDir);
+  return files
+    .filter((f) => f.endsWith('.ts') && !f.endsWith('.spec.ts') && !f.endsWith('.d.ts'))
+    .map((f) => join(apiDir, f));
+}
+
+async function buildEntry(entry) {
+  const name = basename(entry, '.ts');
+  const funcDir = join(functionsRoot, `${name}.func`);
+  await mkdir(funcDir, { recursive: true });
+
+  await build({
+    entryPoints: [entry],
+    outfile: join(funcDir, 'index.js'),
+    bundle: true,
+    platform: 'node',
+    target: 'node20',
+    format: 'cjs',
+    // Lets esbuild resolve `@cacheplane/*` via tsconfig paths and
+    // follows `extends` up to the workspace tsconfig.base.json.
+    tsconfig: join(appRoot, 'tsconfig.app.json'),
+    // @vercel/node provides these as ambient in the runtime environment.
+    external: ['@vercel/node'],
+    sourcemap: 'inline',
+    logLevel: 'info',
+  });
+
+  const vcConfig = {
+    runtime: 'nodejs20.x',
+    handler: 'index.js',
+    launcherType: 'Nodejs',
+    shouldAddHelpers: true,
+    maxDuration: 10,
+  };
+  await writeFile(join(funcDir, '.vc-config.json'), JSON.stringify(vcConfig, null, 2));
+
+  // The app's package.json declares `"type": "module"`, which would make Node
+  // load `index.js` as ESM. esbuild emits CJS, so drop a colocated package.json
+  // that pins `commonjs` inside each function directory.
+  await writeFile(
+    join(funcDir, 'package.json'),
+    JSON.stringify({ type: 'commonjs' }, null, 2),
+  );
+}
+
+async function main() {
+  await rm(outputRoot, { recursive: true, force: true });
+  await mkdir(functionsRoot, { recursive: true });
+
+  const entries = await listEntries();
+  if (entries.length === 0) {
+    throw new Error(`no api entries found in ${apiDir}`);
+  }
+
+  await Promise.all(entries.map(buildEntry));
+
+  // Minimal Build Output API v3 config — no custom routes needed;
+  // Vercel maps `functions/api/<name>.func/` to `/api/<name>` by convention.
+  await writeFile(
+    join(outputRoot, 'config.json'),
+    JSON.stringify({ version: 3 }, null, 2),
+  );
+
+  console.log(`\nbuilt ${entries.length} function(s) to ${outputRoot}`);
+}
+
+main().catch((err) => {
+  console.error(err);
+  process.exit(1);
+});

apps/minting-service/vercel.json

@@ -1,11 +1,5 @@
 {
   "installCommand": "cd ../.. && npm ci",
-  "buildCommand": "cd ../.. && npx tsc --noEmit -p apps/minting-service/tsconfig.app.json",
-  "framework": null,
-  "functions": {
-    "api/*.ts": {
-      "runtime": "nodejs20.x",
-      "maxDuration": 10
-    }
-  }
+  "buildCommand": "cd ../.. && npx nx build minting-service",
+  "framework": null
 }