Harden terminal streaming and worktree setup flow

packages/server/src/shared/binary-mux.test.ts

@@ -3,6 +3,7 @@ import {
   BinaryMuxChannel,
   TerminalBinaryFlags,
   TerminalBinaryMessageType,
+  asUint8Array,
   decodeBinaryMuxFrame,
   encodeBinaryMuxFrame,
 } from "./binary-mux.js";
@@ -40,4 +41,10 @@ describe("binary mux frame codec", () => {
     const tampered = encoded.slice(0, encoded.byteLength - 1);
     expect(decodeBinaryMuxFrame(tampered)).toBeNull();
   });
+
+  it("converts UTF-8 string payloads to bytes", () => {
+    const bytes = asUint8Array("hello");
+    expect(bytes).not.toBeNull();
+    expect(Array.from(bytes ?? [])).toEqual(Array.from(new TextEncoder().encode("hello")));
+  });
 });

packages/server/src/shared/binary-mux.ts

@@ -37,6 +37,19 @@ export interface BinaryMuxFrame {
 }
 
 export function asUint8Array(data: unknown): Uint8Array | null {
+  if (typeof data === "string") {
+    if (typeof TextEncoder !== "undefined") {
+      return new TextEncoder().encode(data);
+    }
+    if (typeof Buffer !== "undefined") {
+      return new Uint8Array(Buffer.from(data, "utf8"));
+    }
+    const out = new Uint8Array(data.length);
+    for (let i = 0; i < data.length; i += 1) {
+      out[i] = data.charCodeAt(i) & 0xff;
+    }
+    return out;
+  }
   if (data instanceof Uint8Array) {
     return data;
   }