fix(gateway): avoid sync Control UI asset reads

vincentkoc · vincentkoc · commit af9bad9fe7f7 · 2026-06-02T10:53:31.000+02:00
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -45,6 +45,7 @@ Docs: https://docs.openclaw.ai
 
 ### Fixes
 
+- Control UI: serve static assets asynchronously after safe-open checks so large UI files do not block Gateway request handling.
 - Scripts/UI: forward direct wrapper SIGHUP shutdown to child processes so terminal hangups do not leave wrapped dev commands running.
 - Gateway: return the post-expiration pending-work revision from node drains so reconnecting nodes do not observe stale queue revisions after expired items are pruned.
 - Release/CI/E2E: keep temporary full-sync checkouts alive while slow Crabbox leases boot, so sparse worktree runs do not lose their sync source before file-list generation.
diff --git a/src/gateway/control-ui.http.test.ts b/src/gateway/control-ui.http.test.ts
@@ -1,4 +1,5 @@
 import { createHash } from "node:crypto";
+import fsSync from "node:fs";
 import fs from "node:fs/promises";
 import type { IncomingMessage } from "node:http";
 import os from "node:os";
@@ -1100,6 +1101,30 @@ describe("handleControlUiHttpRequest", () => {
     });
   });
 
+  it("serves static assets without synchronous file reads", async () => {
+    await withControlUiRoot({
+      fn: async (tmp) => {
+        await writeAssetFile(tmp, "actual.txt", "inside-ok\n");
+        const readFileSync = vi.spyOn(fsSync, "readFileSync").mockImplementation(() => {
+          throw new Error("readFileSync should not run on Control UI request path");
+        });
+        try {
+          const { res, end, handled } = await runControlUiRequest({
+            url: "/assets/actual.txt",
+            method: "GET",
+            rootPath: tmp,
+          });
+
+          expect(handled).toBe(true);
+          expect(res.statusCode).toBe(200);
+          expect(responseBody(end)).toBe("inside-ok\n");
+        } finally {
+          readFileSync.mockRestore();
+        }
+      },
+    });
+  });
+
   it("serves HEAD for in-root assets without writing a body", async () => {
     await withControlUiRoot({
       fn: async (tmp) => {
diff --git a/src/gateway/control-ui.ts b/src/gateway/control-ui.ts
@@ -754,6 +754,22 @@ function serveResolvedIndexHtml(res: ServerResponse, body: string) {
   res.end(body);
 }
 
+function readOpenedFile(fd: number): Promise<Buffer> {
+  return new Promise((resolve, reject) => {
+    fs.readFile(fd, (error, data) => {
+      if (error) {
+        reject(error);
+        return;
+      }
+      resolve(data);
+    });
+  });
+}
+
+async function readOpenedFileText(fd: number): Promise<string> {
+  return (await readOpenedFile(fd)).toString("utf8");
+}
+
 function isExpectedSafePathError(error: unknown): boolean {
   const code =
     typeof error === "object" && error !== null && "code" in error ? String(error.code) : "";
@@ -995,10 +1011,10 @@ export async function handleControlUiHttpRequest(
         return true;
       }
       if (path.basename(safeFile.path) === "index.html") {
-        serveResolvedIndexHtml(res, fs.readFileSync(safeFile.fd, "utf8"));
+        serveResolvedIndexHtml(res, await readOpenedFileText(safeFile.fd));
         return true;
       }
-      serveResolvedFile(res, safeFile.path, fs.readFileSync(safeFile.fd));
+      serveResolvedFile(res, safeFile.path, await readOpenedFile(safeFile.fd));
       return true;
     } finally {
       fs.closeSync(safeFile.fd);
@@ -1023,7 +1039,7 @@ export async function handleControlUiHttpRequest(
       if (respondHeadForFile(req, res, safeIndex.path)) {
         return true;
       }
-      serveResolvedIndexHtml(res, fs.readFileSync(safeIndex.fd, "utf8"));
+      serveResolvedIndexHtml(res, await readOpenedFileText(safeIndex.fd));
       return true;
     } finally {
       fs.closeSync(safeIndex.fd);
