test(eval): cover running marker with no attempt directory

CodeRabbit review on #436: pin the crash window where cell.json records
a running attempt but no attempt-NNN directory exists yet, so resume
allocates the next number instead of reusing it.

Author: solomonneas

tests/test_model_trials.py

@@ -91,6 +91,12 @@ def test_attempt_number_does_not_reuse_deleted_highest_attempt(tmp_path):
     assert model_trials._attempt_number(tmp_path) == 4
 
 
+def test_attempt_number_counts_running_marker_without_attempt_dir(tmp_path):
+    # Crash window: cell.json was written as running before attempt-001 existed.
+    (tmp_path / "cell.json").write_text(json.dumps({"state": "running", "attempt": 1}))
+    assert model_trials._attempt_number(tmp_path) == 2
+
+
 def test_expand_cells_is_stable_and_conditions_change_identity():
     first = model_trials.expand_cells(_manifest(), _roster())
     second = model_trials.expand_cells(_manifest(), _roster())