Persistence

Correctness fixes in Checkpoint save, load, and range.

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save truncates the good file before dumping

open(path, "wb") wiped the previous checkpoint, then dill.dump ran. A pickle/TypeError mid-write left a truncated file. raise_errors=False still raised TypeError / EOFError because those are not dill.PickleError.

Fix. Dump to a sibling *.tmp and os.replace onto file_path only after a successful dump. Load and save also catch EOFError and TypeError. A failed dump leaves the previous file loadable.

Validator. tests/test_controllers/test_checkpoint.py::TestCheckpoint::test_failed_save_leaves_previous_checkpoint_loadable

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load overwrites constructor file_path, raise_errors, and make_dir

load rebound self.__dict__ from the pickle, including the original absolute path and error-handling flags. Opening a copied checkpoint with a new dir_path still wrote later saves to the old location.

Fix. Stash file_path, raise_errors, and make_dir before the rebind, then restore those constructor fields (including on error).

Validator. tests/test_controllers/test_checkpoint.py::TestCheckpoint::test_load_keeps_constructor_path_and_raise_errors

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Mid-loop save_freq = -1 turns saving on

The enabled/disabled switch was tested once before the first yield. Setting save_freq = -1 inside the enabled loop made elapsed >= -1.0 always true, so every remaining generation saved. The reverse switch (enable after starting disabled) did nothing.

Fix. range decides whether to save inside the loop from the current save_freq (-1 means skip).

Validator. tests/test_controllers/test_checkpoint.py::TestCheckpoint::test_save_freq_can_be_disabled_during_range