fix(responses): stop marking native collaboration calls as plaintext

open-sse/handlers/chatCore/nonStreamingClientTranslate.ts

@@ -182,7 +182,12 @@ export function translateNonStreamingClientResponse(
           item.namespace = identity.namespace;
           item.name = identity.name;
         }
-        Object.assign(item, plaintextCollaborationFields(item.namespace, item.name));
+        // #15088 - the empty marker means "this call was translated from
+        // plaintext Chat Completions". A native Responses body already carries
+        // the protocol's own encrypted_function_args (present or absent).
+        if (responsePayloadFormat !== FORMATS.OPENAI_RESPONSES) {
+          Object.assign(item, plaintextCollaborationFields(item.namespace, item.name));
+        }
       }
     }
   } else if (clientResponseFormat === FORMATS.OPENAI) {

open-sse/handlers/responseSanitizer.ts

@@ -888,12 +888,18 @@ function sanitizeResponsesOutputItem(item: unknown, index: number): JsonRecord |
 
   if (type === "function_call") {
     const callId = toString(itemRecord.call_id) || toString(itemRecord.id) || `call_${index}`;
+    const namespace = toString(itemRecord.namespace);
     return {
       id: toString(itemRecord.id) || `fc_${callId}`,
       type: "function_call",
       call_id: callId,
       name: toString(itemRecord.name) || "",
       arguments: stripZeroWidthToolArgumentJson(itemRecord.arguments),
+      ...(namespace ? { namespace } : {}),
+      ...(itemRecord.status !== undefined ? { status: itemRecord.status } : {}),
+      ...(itemRecord.encrypted_function_args !== undefined
+        ? { encrypted_function_args: itemRecord.encrypted_function_args }
+        : {}),
     };
   }
 

open-sse/utils/stream.ts

@@ -1787,18 +1787,18 @@ export function createSSEStream(options: StreamOptions = {}) {
                       parsed.response.output
                     );
                   }
-                  // #7936 — restore `namespace` + `name` fields on passthrough
-                  // Responses function_call items for downstream Codex clients.
-                  if (
-                    parsed.type === "response.output_item.added" ||
-                    parsed.type === "response.output_item.done" ||
-                    parsed.type === "response.completed"
-                  ) {
+                  // #7936 - restore `namespace` + `name` on passthrough Responses
+                  // function_call items. The restoration mutates `parsed`, so a
+                  // real change must be re-serialized; otherwise the client still
+                  // receives the flattened wire name.
+                  const responsesIdentityRestored =
+                    (parsed.type === "response.output_item.added" ||
+                      parsed.type === "response.output_item.done" ||
+                      parsed.type === "response.completed") &&
                     restoreResponsesPassthroughFunctionCallIdentity(
                       parsed as JsonRecord,
                       requestToolIdentityMap
                     );
-                  }
                   if (
                     parsed.type === "response.completed" &&
                     passthroughResponsesPendingFunctionCalls.size > 0
@@ -1843,7 +1843,8 @@ export function createSSEStream(options: StreamOptions = {}) {
                     textualToolCallBackfilled ||
                     responsesIdsNormalized ||
                     usageNormalized ||
-                    responsesCommentaryStrippedFromCompleted
+                    responsesCommentaryStrippedFromCompleted ||
+                    responsesIdentityRestored
                   ) {
                     output = `data: ${JSON.stringify(parsed)}\n\n`;
                     injectedUsage = true;