[BUG] Fix MCTS.run() docstring and add __repr__ for inspectability

- Fix run() docstring: document all 3 return dict keys (candidate,
  sequence, score) instead of just 2
- Fix verbose param description: uses logger.debug, not print
- Add __repr__ showing depth, n_iterations, n_states, experiment
- Add 3 new tests for return dict keys and repr

Author: Vaishnav88sk

pyaptamer/mcts/_algorithm.py

@@ -70,6 +70,7 @@ class MCTS(BaseObject):
     >>> experiment = AptamerEvalAptaTrans(target, model, device, prot_words)
     >>> mcts = MCTS(depth=5, n_iterations=2, experiment=experiment)
     >>> candidate = mcts.run(verbose=False)
+    >>> candidate["candidate"]  # the reconstructed aptamer string  # doctest: +SKIP
     """
 
     def __init__(
@@ -112,6 +113,14 @@ def __init__(
         self.base = ""
         self.candidate = ""
 
+    def __repr__(self) -> str:
+        """Return a human-readable representation of the MCTS configuration."""
+        return (
+            f"MCTS(depth={self.depth}, n_iterations={self.n_iterations}, "
+            f"n_states={len(self.states)}, "
+            f"experiment={self.experiment.__class__.__name__ if self.experiment else None})"
+        )
+
     def _reset(self) -> None:
         """Reset the MCTS algorithm to its initial state."""
         self.root = TreeNode(
@@ -281,18 +290,24 @@ def _find_best_subsequence(self) -> str:
     def run(self, verbose: bool = True) -> dict:
         """
         Perform a full recommendation run consisting of `self.n_iterations` rounds of
-        (selection -> expansion -> simulation -> backpropagation)
+        (selection -> expansion -> simulation -> backpropagation).
 
         Parameters
         ----------
         verbose : bool, optional, default=True
-            Whether to print progress information.
+            Whether to log progress information via ``logger.debug``.
+            Messages are only emitted when the logger level is ``DEBUG``.
 
         Returns
         -------
         dict
-            Dictionary containing the final candidate sequence (`candidate`) and its
-            score (`score`).
+            A dictionary with the following keys:
+
+            - ``"candidate"`` (*str*) — The reconstructed aptamer sequence.
+            - ``"sequence"`` (*str*) — The raw encoded sequence with direction
+              markers (underscores), before reconstruction.
+            - ``"score"`` (*float*) — The score of the candidate as evaluated
+              by ``self.experiment``.
         """
         self._reset()
 

pyaptamer/mcts/tests/test_mcts.py

@@ -360,3 +360,28 @@ def test_run_verbose(self, mcts):
         # length of sequence should be 2 * 5 (i.e., 2 * 5) as it still contains
         # the underscores
         assert len(candidate["sequence"]) == 10
+
+    def test_run_return_dict_keys(self, mcts):
+        """Verify that run() returns exactly the three documented keys."""
+        result = mcts.run(verbose=False)
+        assert set(result.keys()) == {"candidate", "sequence", "score"}
+        assert isinstance(result["candidate"], str)
+        assert isinstance(result["sequence"], str)
+
+    def test_repr(self):
+        """Verify __repr__ includes configuration details."""
+        mcts = MCTS(depth=10, n_iterations=500)
+        r = repr(mcts)
+        assert "MCTS(" in r
+        assert "depth=10" in r
+        assert "n_iterations=500" in r
+        assert "n_states=8" in r
+        assert "experiment=None" in r
+
+    def test_repr_with_experiment(self, mcts):
+        """Verify __repr__ shows experiment class name."""
+        r = repr(mcts)
+        assert "MCTS(" in r
+        assert "experiment=" in r
+        assert "None" not in r
+