fix(openai-responses): normalize Copilot response item IDs (#69362) (thanks @Menci)

extensions/github-copilot/connection-bound-ids.ts

@@ -0,0 +1,51 @@
+import { createHash } from "node:crypto";
+
+// Copilot's OpenAI-compatible `/responses` endpoint can emit replay item IDs
+// that encode upstream connection state. Those IDs are rejected after the
+// connection changes, so normalize them at the provider boundary before send.
+
+function looksLikeConnectionBoundId(id: string): boolean {
+  if (id.length < 24) {
+    return false;
+  }
+  if (/^(?:rs|msg|fc)_[A-Za-z0-9_-]+$/.test(id)) {
+    return false;
+  }
+  if (!/^[A-Za-z0-9+/_-]+=*$/.test(id)) {
+    return false;
+  }
+  return Buffer.from(id, "base64").length >= 16;
+}
+
+function deriveReplacementId(type: string | undefined, originalId: string): string {
+  const prefix = type === "reasoning" ? "rs" : type === "function_call" ? "fc" : "msg";
+  const hex = createHash("sha256").update(originalId).digest("hex").slice(0, 16);
+  return `${prefix}_${hex}`;
+}
+
+type InputItem = Record<string, unknown> & { id?: unknown; type?: unknown };
+
+export function rewriteCopilotConnectionBoundResponseIds(input: unknown): boolean {
+  if (!Array.isArray(input)) {
+    return false;
+  }
+  let rewrote = false;
+  for (const item of input as InputItem[]) {
+    const id = item.id;
+    if (typeof id !== "string" || id.length === 0) {
+      continue;
+    }
+    if (looksLikeConnectionBoundId(id)) {
+      item.id = deriveReplacementId(typeof item.type === "string" ? item.type : undefined, id);
+      rewrote = true;
+    }
+  }
+  return rewrote;
+}
+
+export function rewriteCopilotResponsePayloadConnectionBoundIds(payload: unknown): boolean {
+  if (!payload || typeof payload !== "object") {
+    return false;
+  }
+  return rewriteCopilotConnectionBoundResponseIds((payload as { input?: unknown }).input);
+}