From e7e12495859df5abc89bc9e4614cb07148493199 Mon Sep 17 00:00:00 2001
From: "zhangxiaoyu.york" <zhangxiaoyu.york@bytedance.com>
Date: Fri, 10 Apr 2026 12:13:58 +0800
Subject: [PATCH] fix(agent): avoid truncate_text name shadowing

Rename the boolean flag in _sanitize_persisted_blocks and alias the imported helper so session persistence cannot crash with TypeError when truncation is enabled.
---
 nanobot/agent/loop.py                 | 12 +++++------
 tests/test_truncate_text_shadowing.py | 31 +++++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 6 deletions(-)
 create mode 100644 tests/test_truncate_text_shadowing.py

diff --git a/nanobot/agent/loop.py b/nanobot/agent/loop.py
index 16a086fdb..bc83cc77c 100644
--- a/nanobot/agent/loop.py
+++ b/nanobot/agent/loop.py
@@ -33,7 +33,7 @@ from nanobot.bus.queue import MessageBus
 from nanobot.config.schema import AgentDefaults
 from nanobot.providers.base import LLMProvider
 from nanobot.session.manager import Session, SessionManager
-from nanobot.utils.helpers import image_placeholder_text, truncate_text
+from nanobot.utils.helpers import image_placeholder_text, truncate_text as truncate_text_fn
 from nanobot.utils.runtime import EMPTY_FINAL_RESPONSE_MESSAGE
 
 if TYPE_CHECKING:
@@ -590,7 +590,7 @@ class AgentLoop:
         self,
         content: list[dict[str, Any]],
         *,
-        truncate_text: bool = False,
+        should_truncate_text: bool = False,
         drop_runtime: bool = False,
     ) -> list[dict[str, Any]]:
         """Strip volatile multimodal payloads before writing session history."""
@@ -618,8 +618,8 @@ class AgentLoop:
 
             if block.get("type") == "text" and isinstance(block.get("text"), str):
                 text = block["text"]
-                if truncate_text and len(text) > self.max_tool_result_chars:
-                    text = truncate_text(text, self.max_tool_result_chars)
+                if should_truncate_text and len(text) > self.max_tool_result_chars:
+                    text = truncate_text_fn(text, self.max_tool_result_chars)
                 filtered.append({**block, "text": text})
                 continue
 
@@ -637,9 +637,9 @@ class AgentLoop:
                 continue  # skip empty assistant messages — they poison session context
             if role == "tool":
                 if isinstance(content, str) and len(content) > self.max_tool_result_chars:
-                    entry["content"] = truncate_text(content, self.max_tool_result_chars)
+                    entry["content"] = truncate_text_fn(content, self.max_tool_result_chars)
                 elif isinstance(content, list):
-                    filtered = self._sanitize_persisted_blocks(content, truncate_text=True)
+                    filtered = self._sanitize_persisted_blocks(content, should_truncate_text=True)
                     if not filtered:
                         continue
                     entry["content"] = filtered
diff --git a/tests/test_truncate_text_shadowing.py b/tests/test_truncate_text_shadowing.py
new file mode 100644
index 000000000..11132b511
--- /dev/null
+++ b/tests/test_truncate_text_shadowing.py
@@ -0,0 +1,31 @@
+import inspect
+from types import SimpleNamespace
+
+
+def test_sanitize_persisted_blocks_truncate_text_shadowing_regression() -> None:
+    """Regression: avoid bool param shadowing imported truncate_text.
+
+    Buggy behavior (historical):
+    - loop.py imports `truncate_text` from helpers
+    - `_sanitize_persisted_blocks(..., truncate_text: bool=...)` uses same name
+    - when called with `truncate_text=True`, function body executes `truncate_text(text, ...)`
+      which resolves to bool and raises `TypeError: 'bool' object is not callable`.
+
+    This test asserts the fixed API exists and truncation works without raising.
+    """
+
+    from nanobot.agent.loop import AgentLoop
+
+    sig = inspect.signature(AgentLoop._sanitize_persisted_blocks)
+    assert "should_truncate_text" in sig.parameters
+    assert "truncate_text" not in sig.parameters
+
+    dummy = SimpleNamespace(max_tool_result_chars=5)
+    content = [{"type": "text", "text": "0123456789"}]
+
+    out = AgentLoop._sanitize_persisted_blocks(dummy, content, should_truncate_text=True)
+    assert isinstance(out, list)
+    assert out and out[0]["type"] == "text"
+    assert isinstance(out[0]["text"], str)
+    assert out[0]["text"] != content[0]["text"]
+