Reject colliding PythonInterpreter mounts

Amp-Thread-ID: https://ampcode.com/threads/T-019fcce1-bc8b-753e-886f-9b77c0ccb376
Co-authored-by: Isaac Miller <isaac@cmpnd.ai>

Author: ampagent

dspy/primitives/python_interpreter.py

@@ -267,6 +267,13 @@ def __init__(
 
         self.enable_read_paths = enable_read_paths or []
         self.enable_write_paths = enable_write_paths or []
+        mounts = {
+            _canonicalize_path(path): os.path.basename(os.fspath(path))
+            for path in [*self.enable_read_paths, *self.enable_write_paths]
+            if path
+        }
+        if len(mounts) != len(set(mounts.values())):
+            raise CodeInterpreterError("Mounted files must have unique basenames inside the sandbox.")
         self.enable_env_vars = enable_env_vars or []
         self.enable_network_access = enable_network_access or []
         self.sync_files = sync_files

tests/primitives/test_python_interpreter.py

@@ -413,6 +413,22 @@ def test_custom_deno_command_is_unchanged():
     assert interpreter.deno_command is not command
 
 
+def test_rejects_mounts_with_the_same_guest_basename(tmp_path):
+    first = tmp_path / "first" / "shared.txt"
+    second = tmp_path / "second" / "shared.txt"
+    first.parent.mkdir()
+    second.parent.mkdir()
+
+    with pytest.raises(CodeInterpreterError, match="unique basenames"):
+        PythonInterpreter(deno_command=["deno"], enable_read_paths=[first], enable_write_paths=[second])
+
+
+def test_allows_same_canonical_file_as_read_and_write_mount(tmp_path):
+    path = tmp_path / "shared.txt"
+
+    PythonInterpreter(deno_command=["deno"], enable_read_paths=[path], enable_write_paths=[path])
+
+
 def test_custom_deno_command_preserves_environment(monkeypatch):
     monkeypatch.setenv("DENO_NO_PACKAGE_JSON", "0")
     captured = {}