diff --git a/tools/code_execution_rpc.py b/tools/code_execution_rpc.py
index a3191a27d8..eae6ccc6d8 100644
--- a/tools/code_execution_rpc.py
+++ b/tools/code_execution_rpc.py
@@ -109,14 +109,11 @@ def _rpc_server_loop(server_sock: socket.socket, task_id: str, tool_call_log: li
                 except (json.JSONDecodeError, UnicodeDecodeError) as exc:
                     resp = tool_error(f"Invalid RPC request: {exc}")
                 else:
-                    if not _rpc_token_ok(request, rpc_token):
-                        resp = tool_error("Unauthorized RPC request")
-                    else:
-                        resp = _handle_rpc_request(
-                            request, allowed_tools=allowed_tools, tool_call_counter=tool_call_counter,
-                            max_tool_calls=max_tool_calls, dispatch=dispatch, tool_call_log=tool_call_log,
-                            call_start=call_start, where="sandbox",
-                        )
+                    resp = _handle_rpc_request(
+                        request, allowed_tools=allowed_tools, tool_call_counter=tool_call_counter,
+                        max_tool_calls=max_tool_calls, dispatch=dispatch, tool_call_log=tool_call_log,
+                        call_start=call_start, where="sandbox",
+                    ) if _rpc_token_ok(request, rpc_token) else tool_error("Unauthorized RPC request")
                 conn.sendall((resp + "\n").encode())
     except socket.timeout:
         logger.debug("RPC listener socket timeout")
@@ -146,10 +143,8 @@ def _rpc_poll_loop(env, rpc_dir: str, task_id: str, tool_call_log: list, tool_ca
             if not output:
                 stop_event.wait(poll_interval)
                 continue
-            req_files = sorted(
-                f for f in (line.strip() for line in output.split("\n"))
-                if f and not f.endswith(".tmp") and "/req_" in f
-            )
+            req_files = sorted(f for f in (line.strip() for line in output.split("\n"))
+                               if f and not f.endswith(".tmp") and "/req_" in f)
             for req_file in req_files:
                 if stop_event.is_set():
                     break
diff --git a/tools/code_kernel.py b/tools/code_kernel.py
index 14f13cd822..4bf80d5947 100644
--- a/tools/code_kernel.py
+++ b/tools/code_kernel.py
@@ -202,11 +202,10 @@ class _BoundedBuffer:
         self.total = 0
 
     def append(self, data: bytes, cap: int) -> None:
-        if self.total >= cap:
-            return
-        keep = data[: cap - self.total]
-        self.chunks.append(keep)
-        self.total += len(keep)
+        keep = data[: max(0, cap - self.total)]
+        if keep:
+            self.chunks.append(keep)
+            self.total += len(keep)
 
     def drain(self) -> str:
         chunks, self.chunks, self.total = self.chunks, [], 0
@@ -414,10 +413,7 @@ def _stdout_reader(kernel: SessionKernel) -> None:
 def _stderr_reader(kernel: SessionKernel) -> None:
     from tools.code_execution_tool import MAX_STDERR_BYTES
     assert kernel.proc is not None and kernel.proc.stderr is not None
-    while True:
-        chunk = kernel.proc.stderr.read1(4096)
-        if not chunk:
-            return
+    while chunk := kernel.proc.stderr.read1(4096):
         kernel.stderr.append(chunk, MAX_STDERR_BYTES)