diff --git a/README.md b/README.md
index 9b6a11c..7a3d68a 100644
--- a/README.md
+++ b/README.md
@@ -83,6 +83,8 @@
 ```
 
 Панель и API на одном origin: `http://<host>:8081` (caddy: статика + `/api → server`).
+Для сборки zip-архивов расширения (страница /download) на сервере должен быть
+установлен `zip` (`apt install zip` и т.п.).
 Первый зарегистрированный через панель аккаунт — обычный пользователь;
 проекты создаёт каждый сам, публичные ссылки выдаются на проект и репорт.
 
diff --git a/deploy/Caddyfile b/deploy/Caddyfile
index b381455..5eccbdc 100644
--- a/deploy/Caddyfile
+++ b/deploy/Caddyfile
@@ -2,6 +2,11 @@
 	handle /api/* {
 		reverse_proxy server:8000
 	}
+	# extension zips: real files only — no SPA fallback, a missing zip is a 404
+	handle /ext/* {
+		root * /srv/web
+		file_server
+	}
 	handle {
 		root * /srv/web
 		try_files {path} /index.html
diff --git a/packages/extension/scripts/package.mjs b/packages/extension/scripts/package.mjs
index e520298..c2c34fd 100644
--- a/packages/extension/scripts/package.mjs
+++ b/packages/extension/scripts/package.mjs
@@ -1,7 +1,7 @@
 import { execSync } from "node:child_process";
 import { createRequire } from "node:module";
-import { mkdirSync, rmSync } from "node:fs";
-import { dirname, join } from "node:path";
+import { existsSync, mkdirSync, rmSync } from "node:fs";
+import { join } from "node:path";
 
 /**
  * Zips the built extension targets into the web panel's public dir so caddy
@@ -13,12 +13,22 @@
 const extDir = new URL("..", import.meta.url).pathname;
 const outDir = join(extDir, "..", "web", "public", "ext");
 
+if (execSync("command -v zip || true").toString().trim() === "") {
+  console.error("The `zip` CLI is not installed — install it (apt install zip / apk add zip / pacman -S zip) and re-run.");
+  process.exit(1);
+}
+
 mkdirSync(outDir, { recursive: true });
 for (const target of ["chrome", "firefox"]) {
+  const dist = join(extDir, "dist", target);
+  if (!existsSync(join(dist, "manifest.json"))) {
+    console.error(`${dist} has no manifest.json — run \`npm run build -w @ltt/extension\` first.`);
+    process.exit(1);
+  }
   const out = join(outDir, `bugtrail-${target}.zip`);
   rmSync(out, { force: true });
   // zip the directory contents (manifest at the archive root) so the unpacked
   // folder can be loaded directly via "Load unpacked"
-  execSync(`zip -qr ${JSON.stringify(out)} .`, { cwd: join(extDir, "dist", target), stdio: "inherit" });
+  execSync(`zip -qr ${JSON.stringify(out)} .`, { cwd: dist, stdio: "inherit" });
   console.log(`packaged bugtrail-${target} v${version} -> ${out}`);
 }
\ No newline at end of file