test(docker): cover browser install build arg

CHANGELOG.md

@@ -14,6 +14,7 @@ Docs: https://docs.openclaw.ai
 - Discord: allow reusable interactive components with `components.reusable=true` so buttons, selects, and forms can be used multiple times before expiring. Thanks @thewilloftheshadow.
 - Cron/Gateway: separate per-job webhook delivery (`delivery.mode = "webhook"`) from announce delivery, enforce valid HTTP(S) webhook URLs, and keep a temporary legacy `notify + cron.webhook` fallback for stored jobs. (#17901) Thanks @advaitpaliwal.
 - Discord: add per-button `allowedUsers` allowlist for interactive components to restrict who can click buttons. Thanks @thewilloftheshadow.
+- Docker: add optional `OPENCLAW_INSTALL_BROWSER` build arg to preinstall Chromium + Xvfb in the Docker image, avoiding runtime Playwright installs. (#18449)
 
 ### Fixes
 

src/dockerfile.test.ts

@@ -0,0 +1,23 @@
+import { readFile } from "node:fs/promises";
+import { join, resolve } from "node:path";
+import { fileURLToPath } from "node:url";
+import { describe, expect, it } from "vitest";
+
+const repoRoot = resolve(fileURLToPath(new URL(".", import.meta.url)), "..");
+const dockerfilePath = join(repoRoot, "Dockerfile");
+
+describe("Dockerfile", () => {
+  it("installs optional browser dependencies after pnpm install", async () => {
+    const dockerfile = await readFile(dockerfilePath, "utf8");
+    const installIndex = dockerfile.indexOf("RUN pnpm install --frozen-lockfile");
+    const browserArgIndex = dockerfile.indexOf("ARG OPENCLAW_INSTALL_BROWSER");
+
+    expect(installIndex).toBeGreaterThan(-1);
+    expect(browserArgIndex).toBeGreaterThan(-1);
+    expect(browserArgIndex).toBeGreaterThan(installIndex);
+    expect(dockerfile).toContain(
+      "node /app/node_modules/playwright-core/cli.js install --with-deps chromium",
+    );
+    expect(dockerfile).toContain("apt-get install -y --no-install-recommends xvfb");
+  });
+});