fix(types): preserve array-buffer response bodies (#9092)

Validated in local merge-train (devbox-vm-06-dev002) @ combined-tip (FAST gates: typecheck/complexity/cognitive/changelog/vitest — only pre-existing audit.test.ts flake). Evidence: /home/diegosouzapw/dev/proxys/OmniRoute/.claude/worktrees/merge-train-20260805-222248-suite.log

open-sse/executors/duckduckgo-web.ts

@@ -1,3 +1,4 @@
+import { Buffer } from "node:buffer";
 import { generateKeyPairSync, randomUUID } from "node:crypto";
 import vm from "node:vm";
 import { solveDuckDuckGoChallenge, makeDuckDuckGoFeSignals } from "./duckduckgo-web/challenge.ts";
@@ -499,7 +500,7 @@ export class DuckDuckGoWebExecutor extends BaseExecutor {
         // Wrap the captured body as a Response so processResponse
         // (already a streaming/non-streaming transformer) can be
         // reused unchanged.
-        const upstreamResp = new Response(result.body, {
+        const upstreamResp = new Response(Buffer.from(result.body), {
           status: result.status,
           headers: {
             "Content-Type": result.contentType || "text/event-stream",

open-sse/executors/edgeTts.ts

@@ -58,7 +58,7 @@ export interface EdgeTtsSynthInput {
 }
 
 export interface EdgeTtsSynthResult {
-  audio: Buffer;
+  audio: Buffer<ArrayBuffer>;
   contentType: string;
 }
 
@@ -189,9 +189,7 @@ export function isTurnEndMessage(message: string): boolean {
  * ASCII headers, then the remaining bytes are audio data. Returns `null`
  * for a frame too short to contain a valid header-length prefix.
  */
-export function demuxAudioChunk(
-  frame: Buffer
-): { headers: string; audio: Buffer } | null {
+export function demuxAudioChunk(frame: Buffer): { headers: string; audio: Buffer } | null {
   if (!Buffer.isBuffer(frame) || frame.length < 2) return null;
   const headerLength = frame.readUInt16BE(0);
   if (2 + headerLength > frame.length) return null;

open-sse/executors/windsurf.ts

@@ -168,7 +168,7 @@ function encodeVarint(value: number): Uint8Array {
   return new Uint8Array(bytes);
 }
 
-function concatBytes(arrays: Uint8Array[]): Uint8Array {
+function concatBytes(arrays: Uint8Array[]): Uint8Array<ArrayBuffer> {
   const total = arrays.reduce((n, a) => n + a.length, 0);
   const out = new Uint8Array(total);
   let off = 0;
@@ -626,7 +626,8 @@ export class WindsurfExecutor extends BaseExecutor {
                 const { done, value } = await reader.read();
                 if (done) break;
                 if (!value) continue;
-                pending = pending.length === 0 ? value : concatBytes([pending, value]);
+                pending =
+                  pending.length === 0 ? Uint8Array.from(value) : concatBytes([pending, value]);
                 drainFrames();
               }
             } finally {

src/lib/skills/builtins.ts

@@ -148,7 +148,7 @@ async function readResponseText(response: Response, maxBytes: number) {
 function normalizeBody(body: unknown, headers?: Record<string, string>) {
   if (body === undefined || body === null) return undefined;
   if (typeof body === "string") return body;
-  if (body instanceof Uint8Array) return body;
+  if (body instanceof Uint8Array) return new Uint8Array(body);
   if (typeof body === "object") {
     if (headers && !Object.keys(headers).some((key) => key.toLowerCase() === "content-type")) {
       headers["Content-Type"] = "application/json";
@@ -388,14 +388,7 @@ export const builtinSkills: Record<string, SkillHandler> = {
   },
 
   web_fetch: async (input, context) => {
-    const {
-      url,
-      format,
-      depth,
-      wait_for_selector,
-      include_metadata,
-      provider,
-    } = input as {
+    const { url, format, depth, wait_for_selector, include_metadata, provider } = input as {
       url: string;
       format?: "markdown" | "html" | "links" | "screenshot";
       depth?: 0 | 1 | 2;