diff --git a/esbuild.config.mjs b/esbuild.config.mjs
index 3b66d35..d9729c7 100644
--- a/esbuild.config.mjs
+++ b/esbuild.config.mjs
@@ -1,7 +1,7 @@
 import esbuild from "esbuild";
 import process from "process";
 import { builtinModules } from "module";
-import { copyFileSync, mkdirSync } from "fs";
+import { copyFileSync, mkdirSync, readFileSync, writeFileSync } from "fs";
 
 const banner = `/*
 THIS IS A GENERATED/BUNDLED FILE BY ESBUILD
@@ -42,8 +42,26 @@ const context = await esbuild.context({
 if (prod) {
   await context.rebuild();
   mkdirSync("dist", { recursive: true });
-  copyFileSync("manifest.json", "dist/manifest.json");
+
+  // Generate build number: version+YYYYMMDDHHmm
+  const manifest = JSON.parse(readFileSync("manifest.json", "utf8"));
+  const now = new Date();
+  const buildStamp = [
+    now.getFullYear(),
+    String(now.getMonth() + 1).padStart(2, "0"),
+    String(now.getDate()).padStart(2, "0"),
+    String(now.getHours()).padStart(2, "0"),
+    String(now.getMinutes()).padStart(2, "0"),
+  ].join("");
+  const buildVersion = `${manifest.version}+${buildStamp}`;
+
+  // Write dist/manifest.json with build version
+  const distManifest = { ...manifest, version: buildVersion };
+  writeFileSync("dist/manifest.json", JSON.stringify(distManifest, null, 2) + "\n");
+
   copyFileSync("styles.css", "dist/styles.css");
+
+  console.log(`Build complete: ${buildVersion}`);
   process.exit(0);
 } else {
   await context.watch();