fix(codex-supervisor): use truncateUtf16Safe for stderr tail truncation (#102590)

Pandah97 · steipete · web-flow · commit 4be6fa7413af · 2026-07-09T10:59:17.000+01:00
* fix(codex-supervisor): use truncateUtf16Safe for stderr tail truncation

StdioCodexJsonRpcConnection includes stderr output in the transport-closed
error message with a naive .slice(0, 1200) which can split surrogate pairs.
Replace with truncateUtf16Safe().

* test(codex-supervisor): cover UTF-16-safe stderr tails

---------

Co-authored-by: Peter Steinberger &lt;steipete@gmail.com&gt;
diff --git a/extensions/codex-supervisor/src/json-rpc-client.ts b/extensions/codex-supervisor/src/json-rpc-client.ts
@@ -8,6 +8,7 @@ import * as net from "node:net";
 import * as os from "node:os";
 import * as path from "node:path";
 import { isRecord } from "openclaw/plugin-sdk/string-coerce-runtime";
+import { truncateUtf16Safe } from "openclaw/plugin-sdk/text-utility-runtime";
 import WebSocket from "ws";
 import type { CodexJsonRpcConnection, CodexSupervisorEndpoint } from "./types.js";
 
@@ -199,7 +200,7 @@ class StdioCodexJsonRpcConnection extends BaseCodexJsonRpcConnection {
     this.proc.once("close", () =>
       this.fail(
         new Error(
-          `Codex app-server stdio transport closed. stderr_tail=${this.stderrTail.join("\n").slice(0, 1200)}`,
+          `Codex app-server stdio transport closed. stderr_tail=${truncateUtf16Safe(this.stderrTail.join("\n"), 1200)}`,
         ),
       ),
     );
diff --git a/extensions/codex-supervisor/src/supervisor.test.ts b/extensions/codex-supervisor/src/supervisor.test.ts
@@ -909,6 +909,31 @@ describe("connectCodexAppServerEndpoint", () => {
     await expect(waitForFile(marker)).resolves.toBe("closed");
   });
 
+  it("keeps stdio close errors UTF-16 safe at the stderr tail boundary", async () => {
+    const prefix = "x".repeat(1_199);
+    const script = `
+      process.stderr.write(${JSON.stringify(`${prefix}😀`)});
+      process.exit(0);
+    `;
+    let closeError: unknown;
+
+    try {
+      await connectCodexAppServerEndpoint({
+        id: "exits",
+        transport: "stdio-proxy",
+        command: process.execPath,
+        args: ["-e", script],
+      });
+    } catch (error) {
+      closeError = error;
+    }
+
+    expect(closeError).toBeInstanceOf(Error);
+    expect((closeError as Error).message).toBe(
+      `Codex app-server stdio transport closed. stderr_tail=${prefix}`,
+    );
+  });
+
   it("fails a cached stdio connection cleanly after the child exits", async () => {
     const script = `
       const readline = require("node:readline");
