fix: finish review-driven single-source cleanup

src/server/transformers/openai/responses/conversion.test.ts

@@ -34,6 +34,47 @@ describe('responses conversion single source of truth', () => {
     expect(convertOpenAiBodyToResponsesBodyViaCompatibility).toBe(convertOpenAiBodyToResponsesBody);
     expect(sanitizeResponsesBodyForProxyViaCompatibility).toBe(sanitizeResponsesBodyForProxy);
   });
+
+  it('preserves extra properties when normalizing role-only message items', () => {
+    expect(normalizeResponsesInputForCompatibility([
+      {
+        role: 'assistant',
+        content: 'done',
+        id: 'msg_1',
+        status: 'completed',
+      },
+    ])).toEqual([
+      {
+        type: 'message',
+        role: 'assistant',
+        content: [{ type: 'output_text', text: 'done' }],
+        id: 'msg_1',
+        status: 'completed',
+      },
+    ]);
+  });
+
+  it('filters whitespace-only string entries from normalized responses input arrays', () => {
+    expect(normalizeResponsesInputForCompatibility([
+      'hello',
+      '   ',
+      {
+        role: 'user',
+        content: 'world',
+      },
+    ])).toEqual([
+      {
+        type: 'message',
+        role: 'user',
+        content: [{ type: 'input_text', text: 'hello' }],
+      },
+      {
+        type: 'message',
+        role: 'user',
+        content: [{ type: 'input_text', text: 'world' }],
+      },
+    ]);
+  });
 });
 
 describe('sanitizeResponsesBodyForProxy', () => {

src/server/transformers/openai/responses/normalization.ts

@@ -136,6 +136,7 @@ export function normalizeResponsesMessageItem(item: Record<string, unknown>): Re
 
   if (asTrimmedString(item.role)) {
     return {
+      ...item,
       type: 'message',
       role,
       content: normalizedContent,
@@ -158,13 +159,13 @@ export function normalizeResponsesInputForCompatibility(input: unknown): unknown
   }
 
   if (Array.isArray(input)) {
-    return input.map((item) => {
+    return input.flatMap((item) => {
       if (typeof item === 'string') {
         const normalized = item.trim();
-        return normalized ? toResponsesInputMessageFromText(normalized) : item;
+        return normalized ? [toResponsesInputMessageFromText(normalized)] : [];
       }
-      if (!isRecord(item)) return item;
-      return normalizeResponsesMessageItem(item);
+      if (!isRecord(item)) return [item];
+      return [normalizeResponsesMessageItem(item)];
     });
   }