Add post-build smoke test to catch CJS-in-ESM bundling errors

Imports each connector chunk from dist/ and verifies no "Dynamic require"
errors occur. This catches cases where tsup accidentally bundles CJS driver
internals into ESM chunks — the exact bug from #288 that unit/integration
tests miss because they run against TypeScript source, not bundled output.

Run with: pnpm test:build

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: tianzhou

package.json

@@ -30,7 +30,8 @@
     "test": "vitest run",
     "test:unit": "vitest run --project unit",
     "test:watch": "vitest",
-    "test:integration": "vitest run --project integration"
+    "test:integration": "vitest run --project integration",
+    "test:build": "node scripts/smoke-test-build.mjs"
   },
   "engines": {
     "node": ">=20"

scripts/smoke-test-build.mjs

@@ -0,0 +1,58 @@
+#!/usr/bin/env node
+
+// Post-build smoke test: verify that the bundled dist/ output can import
+// each connector module without "Dynamic require of X is not supported"
+// errors. This catches cases where tsup accidentally bundles CJS driver
+// internals into ESM chunks.
+//
+// Run: node scripts/smoke-test-build.mjs
+
+import { readdir } from "node:fs/promises";
+import { pathToFileURL } from "node:url";
+import { join } from "node:path";
+
+const distDir = join(import.meta.dirname, "..", "dist");
+
+// Find connector chunk files (e.g. postgres-B7YSSZMH.js, mysql-I35IQ2GH.js)
+const files = await readdir(distDir);
+const connectorFiles = files.filter(
+  (f) =>
+    f.endsWith(".js") &&
+    /^(postgres|mysql|mariadb|sqlite|sqlserver|demo-loader)-/.test(f)
+);
+
+if (connectorFiles.length === 0) {
+  console.error("No connector chunks found in dist/ — was the build run?");
+  process.exit(1);
+}
+
+let passed = 0;
+let failed = 0;
+
+for (const file of connectorFiles) {
+  const url = pathToFileURL(join(distDir, file)).href;
+  try {
+    await import(url);
+    console.log(`  OK  ${file}`);
+    passed++;
+  } catch (err) {
+    if (err.message?.includes("Dynamic require")) {
+      console.error(`  FAIL  ${file}: ${err.message.split("\n")[0]}`);
+      failed++;
+    } else if (err.code === "ERR_MODULE_NOT_FOUND") {
+      // Driver package not installed — expected in CI/minimal installs
+      console.log(`  SKIP  ${file} (driver not installed)`);
+      passed++;
+    } else {
+      // Other errors (e.g. missing config) are fine — we only care about
+      // bundling errors that happen at import time
+      console.log(`  OK  ${file} (runtime error ignored: ${err.message?.split("\n")[0]})`);
+      passed++;
+    }
+  }
+}
+
+console.log(`\n${passed} passed, ${failed} failed, ${connectorFiles.length} total`);
+if (failed > 0) {
+  process.exit(1);
+}