fix: drop unsafe copilot reasoning replay ids

Galin Iliev · Galin Iliev · commit 9a42f9e32fb8 · 2026-05-22T04:21:45.000Z
diff --git a/src/agents/openai-transport-stream.test.ts b/src/agents/openai-transport-stream.test.ts
@@ -2383,7 +2383,7 @@ describe("openai transport stream", () => {
     });
   });
 
-  it("preserves oversized Responses reasoning replay item ids for provider boundary sanitizers", () => {
+  it("drops oversized GitHub Copilot Responses reasoning replay items before send", () => {
     const model = {
       id: "gpt-5.5",
       name: "GPT-5.5",
@@ -2441,9 +2441,7 @@ describe("openai transport stream", () => {
       }>;
     };
 
-    const reasoningItem = params.input?.find((item) => item.type === "reasoning");
-    expect(reasoningItem?.id).toBe(longReasoningId);
-    expect(reasoningItem?.id?.length).toBeGreaterThan(64);
+    expect(params.input?.some((item) => item.type === "reasoning")).toBe(false);
   });
 
   it("strips encrypted reasoning replay when provenance does not match", () => {
diff --git a/src/agents/openai-transport-stream.ts b/src/agents/openai-transport-stream.ts
@@ -954,6 +954,14 @@ function normalizeResponsesReplayItemId(
   return `${prefix}_${shortHash(id)}`;
 }
 
+function isSafeResponsesReplayItemId(id: unknown): id is string {
+  return (
+    typeof id === "string" &&
+    id.length > 0 &&
+    id.length <= OPENAI_RESPONSES_REPLAY_ITEM_ID_MAX_LENGTH
+  );
+}
+
 function encodeTextSignatureV1(id: string, phase?: "commentary" | "final_answer"): string {
   return JSON.stringify({ v: 1, id, ...(phase ? { phase } : {}) });
 }
@@ -1105,6 +1113,12 @@ function convertResponsesMessages(
             if (!shouldReplayResponsesItemIds) {
               delete replayableReasoningItem.id;
             }
+            if (
+              model.provider === "github-copilot" &&
+              !isSafeResponsesReplayItemId(replayableReasoningItem.id)
+            ) {
+              continue;
+            }
             output.push(replayableReasoningItem as ResponseInputItem);
           }
         } else if (block.type === "text") {
