diff --git a/open-sse/translator/request/openai-responses/toResponses.ts b/open-sse/translator/request/openai-responses/toResponses.ts
index 857f5dbffe6..4171bdf0e24 100644
--- a/open-sse/translator/request/openai-responses/toResponses.ts
+++ b/open-sse/translator/request/openai-responses/toResponses.ts
@@ -308,7 +308,7 @@ export function openaiToOpenAIResponsesRequest(
     if (role === "tool") {
       input.push({
         type: "function_call_output",
-        call_id: clampCallId(toString(msg.tool_call_id)),
+        call_id: clampCallId(toString(msg.tool_call_id).trim()),
         output:
           typeof msg.content === "string"
             ? msg.content
@@ -328,7 +328,7 @@ export function openaiToOpenAIResponsesRequest(
     if (role === "function") {
       input.push({
         type: "function_call_output",
-        call_id: clampCallId(`call_${toString(msg.name)}`),
+        call_id: clampCallId(`call_${toString(msg.name).trim()}`),
         output: typeof msg.content === "string" ? msg.content : String(msg.content ?? ""),
         status: "completed",
       });
diff --git a/tests/unit/translator-request-openai-responses.test.ts b/tests/unit/translator-request-openai-responses.test.ts
index c88507b08f5..691534a1423 100644
--- a/tests/unit/translator-request-openai-responses.test.ts
+++ b/tests/unit/translator-request-openai-responses.test.ts
@@ -9,9 +9,8 @@ import assert from "node:assert/strict";
 // conversion in openai-responses.ts, hardened under #2893 to also catch
 // empty/missing call ids). These tests just pin that behavior down explicitly so a
 // future edit to that filter trips a red here.
-const { openaiResponsesToOpenAIRequest } = await import(
-  "../../open-sse/translator/request/openai-responses.ts"
-);
+const { openaiResponsesToOpenAIRequest, openaiToOpenAIResponsesRequest } =
+  await import("../../open-sse/translator/request/openai-responses.ts");
 
 type ChatMsg = { role: string; tool_call_id?: string; content?: unknown };
 
@@ -94,3 +93,38 @@ test("Responses -> OpenAI: mixed matched + orphan keeps only the matched output"
   assert.equal(toolMsgs.length, 1);
   assert.equal(toolMsgs[0].tool_call_id, "call_valid");
 });
+
+test("OpenAI -> Responses: whitespace-padded matching call ids stay paired (not orphan-dropped)", () => {
+  const result = openaiToOpenAIResponsesRequest(
+    "gpt-4o",
+    {
+      messages: [
+        { role: "user", content: "read the file" },
+        {
+          role: "assistant",
+          content: null,
+          tool_calls: [
+            { id: " call_1 ", type: "function", function: { name: "read_file", arguments: "{}" } },
+          ],
+        },
+        { role: "tool", tool_call_id: " call_1 ", content: "file contents" },
+      ],
+    },
+    false,
+    {}
+  ) as { input: Array<{ type?: string; call_id?: string }> };
+
+  const outputs = result.input.filter((i) => i.type === "function_call_output");
+  const call = result.input.find((i) => i.type === "function_call");
+  assert.ok(call, "a function_call is emitted");
+  assert.equal(
+    outputs.length,
+    1,
+    "the tool result must survive the orphaned-output filter despite padded ids"
+  );
+  assert.equal(
+    outputs[0].call_id,
+    call!.call_id,
+    "the function_call_output call_id must equal its paired function_call id"
+  );
+});