diff --git a/package.json b/package.json
index 93e8c8c..ff9ece9 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "tallynote",
-  "version": "1.1.10",
+  "version": "1.1.11",
   "private": true,
   "type": "module",
   "packageManager": "pnpm@9.0.6",
diff --git a/server/app.ts b/server/app.ts
index 3d9e27b..ce760ba 100644
--- a/server/app.ts
+++ b/server/app.ts
@@ -590,6 +590,13 @@ function conflict(database: DatabaseContext, id: string): never {
 }
 
 export async function buildApp(database: DatabaseContext, config: AppConfig) {
+  // Helmet's defaults include `upgrade-insecure-requests`, HSTS, COOP and
+  // Origin-Agent-Cluster. Those headers are appropriate for HTTPS, but an
+  // explicitly opted-in HTTP deployment must remain HTTP all the way through
+  // the asset graph; otherwise browsers upgrade `/assets/*` to HTTPS and the
+  // plain HTTP listener appears as a blank page. Keep the transport-sensitive
+  // headers protocol-aware while retaining the other hardening headers.
+  const secureOrigin = config.publicOrigin.startsWith("https:");
   const app = Fastify({
     logger: config.isProduction ? { level: "info", redact: ["req.headers.cookie", "req.headers.x-csrf-token", "password", "temporaryPassword"] } : false,
     // Fastify's runtime accepts a numeric hop count, while its v5 typings do
@@ -604,10 +611,10 @@ export async function buildApp(database: DatabaseContext, config: AppConfig) {
 
   await app.register(cookie);
   await app.register(helmet, {
-    ...(config.isLocalOrigin ? { hsts: false } : {}),
+    ...(!secureOrigin || config.isLocalOrigin ? { hsts: false } : {}),
     frameguard: { action: "deny" },
     referrerPolicy: { policy: "no-referrer" },
-    crossOriginOpenerPolicy: { policy: "same-origin" },
+    ...(secureOrigin ? { crossOriginOpenerPolicy: { policy: "same-origin" }, originAgentCluster: true } : { crossOriginOpenerPolicy: false, originAgentCluster: false }),
     crossOriginResourcePolicy: { policy: "same-origin" },
     contentSecurityPolicy: {
       directives: {
@@ -618,7 +625,7 @@ export async function buildApp(database: DatabaseContext, config: AppConfig) {
         "frame-ancestors": ["'none'"],
         "base-uri": ["'none'"],
         "form-action": ["'self'"],
-        ...(config.isLocalOrigin ? { "upgrade-insecure-requests": null } : {}),
+        ...(!secureOrigin ? { "upgrade-insecure-requests": null } : {}),
       },
     },
   });
diff --git a/tests/api.test.ts b/tests/api.test.ts
index 576c980..af10956 100644
--- a/tests/api.test.ts
+++ b/tests/api.test.ts
@@ -87,6 +87,48 @@ describe("TallyNote API", () => {
     expect(missing.json().error.requestId).toBeTruthy();
   });
 
+  it("显式允许的公网 HTTP 不会把静态资源升级到 HTTPS", async () => {
+    const publicHttpConfig = {
+      ...config,
+      publicOrigin: "http://192.0.2.10:3999",
+      isLocalOrigin: false,
+      allowInsecureHttp: true,
+      cookieSecure: false,
+    };
+    const publicHttpApp = await buildApp(database, publicHttpConfig);
+    try {
+      const response = await publicHttpApp.inject({ method: "GET", url: "/health" });
+      expect(response.statusCode).toBe(200);
+      expect(response.headers["content-security-policy"]).not.toContain("upgrade-insecure-requests");
+      expect(response.headers["strict-transport-security"]).toBeUndefined();
+      expect(response.headers["cross-origin-opener-policy"]).toBeUndefined();
+      expect(response.headers["origin-agent-cluster"]).toBeUndefined();
+    } finally {
+      await publicHttpApp.close();
+    }
+  });
+
+  it("HTTPS 仍保留传输安全响应头", async () => {
+    const secureConfig = {
+      ...config,
+      publicOrigin: "https://example.test:3999",
+      isLocalOrigin: false,
+      allowInsecureHttp: false,
+      cookieSecure: true,
+    };
+    const secureApp = await buildApp(database, secureConfig);
+    try {
+      const response = await secureApp.inject({ method: "GET", url: "/health" });
+      expect(response.statusCode).toBe(200);
+      expect(response.headers["content-security-policy"]).toContain("upgrade-insecure-requests");
+      expect(response.headers["strict-transport-security"]).toContain("max-age=");
+      expect(response.headers["cross-origin-opener-policy"]).toBe("same-origin");
+      expect(response.headers["origin-agent-cluster"]).toBe("?1");
+    } finally {
+      await secureApp.close();
+    }
+  });
+
   it("拒绝没有 Origin 的写请求", async () => {
     const response = await app.inject({ method: "POST", url: "/api/auth/login", payload: { username: "x", password: "x" } });
     expect(response.statusCode).toBe(403);