fix(tools): scope file state by session

Made-with: Cursor

tests/tools/test_read_enhancements.py

@@ -127,6 +127,36 @@ class TestReadDedupSessionIsolation:
         )
         assert "line 0" in second
 
+    @pytest.mark.asyncio
+    async def test_shared_loop_tool_uses_bound_session_state(self, tmp_path):
+        f = tmp_path / "shared.txt"
+        f.write_text("\n".join(f"line {i}" for i in range(10)), encoding="utf-8")
+
+        # AgentLoop registers one shared ReadFileTool instance. The session
+        # boundary is the task-local FileStates binding, not the tool object.
+        shared_tool = ReadFileTool(workspace=tmp_path)
+        session_a = file_state.FileStates()
+        session_b = file_state.FileStates()
+
+        token = file_state.bind_file_states(session_a)
+        try:
+            first = await shared_tool.execute(path=str(f))
+            repeat = await shared_tool.execute(path=str(f))
+        finally:
+            file_state.reset_file_states(token)
+
+        assert "line 0" in first
+        assert "unchanged" in repeat.lower()
+
+        token = file_state.bind_file_states(session_b)
+        try:
+            second_session_read = await shared_tool.execute(path=str(f))
+        finally:
+            file_state.reset_file_states(token)
+
+        assert "unchanged" not in second_session_read.lower()
+        assert "line 0" in second_session_read
+
 
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