feat: show request payload size

tests/test_payload.py

@@ -126,6 +126,7 @@ class CodexRetryGatewayTUITests(unittest.TestCase):
             "input_tokens": 1200,
             "output_tokens": 340,
             "cached_tokens": 128,
+            "request_body_bytes": 0,
             "response_bytes_received": 363800,
             "response_stream": True,
             "stream_chunk_count": 587,
@@ -137,11 +138,44 @@ class CodexRetryGatewayTUITests(unittest.TestCase):
         }
         compact = mod.request_row_cells(row, {"id": 18, "thread": 18, "path": 22, "model": 16, "usage": 24, "note": 22})
         wide = mod.request_row_cells(row, {"id": 36, "thread": 36, "path": 40, "model": 24, "usage": 72, "note": 48})
+        self.assertEqual(compact[9], "0B")
+        self.assertEqual(wide[9], "0B")
         self.assertLess(len(compact[1]), len(wide[1]))
         self.assertLess(len(compact[2]), len(wide[2]))
         self.assertLess(len(compact[5]), len(wide[5]))
         self.assertLess(len(compact[8]), len(wide[8]))
-        self.assertLess(len(compact[14]), len(wide[14]))
+        self.assertLess(len(compact[15]), len(wide[15]))
+
+    def test_request_row_cells_show_request_bytes(self) -> None:
+        mod = load_module()
+        row = {
+            "seq": 1,
+            "request_id": "req_1",
+            "response_id": "resp_1",
+            "thread_id": "thread_1",
+            "started_at": "2026-06-30T12:00:00Z",
+            "status_code": 200,
+            "path": "/responses",
+            "model": "gpt-5",
+            "requested_model": "",
+            "forwarded_model": "",
+            "reasoning_tokens": 7,
+            "input_tokens": 20,
+            "output_tokens": 10,
+            "cached_tokens": 5,
+            "request_body_bytes": 1536,
+            "response_bytes_received": 4096,
+            "response_stream": True,
+            "stream_chunk_count": 4,
+            "first_response_delay_ms": 1200,
+            "duration_ms": 3400,
+            "upstream_attempt_count": 1,
+            "error": "",
+            "finished_at": "2026-06-30T12:00:03Z",
+        }
+        cells = mod.request_row_cells(row)
+        self.assertEqual(cells[9], "1.5KB")
+        self.assertEqual(cells[10], "4.1KB")
 
     def test_request_rows_read_usage_from_nested_usage_object(self) -> None:
         mod = load_module()