diff --git a/app/utils/public-profile-url.test.ts b/app/utils/public-profile-url.test.ts
new file mode 100644
index 0000000..6a46d35
--- /dev/null
+++ b/app/utils/public-profile-url.test.ts
@@ -0,0 +1,14 @@
+import { describe, expect, test } from "bun:test";
+import { buildPublicProfileAbsoluteUrl } from "./public-profile-url";
+
+describe("buildPublicProfileAbsoluteUrl", () => {
+  test("joins origin with /@slug path", () => {
+    expect(buildPublicProfileAbsoluteUrl("https://example.com", "my-slug")).toBe(
+      "https://example.com/@my-slug",
+    );
+  });
+
+  test("normalizes origin without trailing slash", () => {
+    expect(buildPublicProfileAbsoluteUrl("https://example.com/", "ab")).toBe("https://example.com/@ab");
+  });
+});
diff --git a/app/utils/public-profile-url.ts b/app/utils/public-profile-url.ts
new file mode 100644
index 0000000..7e961e9
--- /dev/null
+++ b/app/utils/public-profile-url.ts
@@ -0,0 +1,7 @@
+/**
+ * 与站内路由 `/@${publicSlug}` 对应的绝对 URL（用于复制到剪贴板）。
+ */
+export function buildPublicProfileAbsoluteUrl(origin: string, publicSlug: string): string {
+  const base = origin.replace(/\/+$/, "");
+  return new URL(`/@${publicSlug}`, `${base}/`).href;
+}