Address Copilot review: drop unused cache, validate --runs, tighten type assert

- Remove unused group_vote_matrices dict (comment 3)
- Validate --runs >= 1 in benchmark script (comment 4)
- Tighten correlation type check to exact `float` (comment 5)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: jucor

delphi/polismath/conversation/conversation.py

@@ -793,17 +793,15 @@ def _compute_participant_info_optimized(self, vote_matrix: pd.DataFrame, group_c
 
         # OPTIMIZATION 3: Precompute group vote matrices and average votes
 
-        # Precompute group vote matrices and their valid comment masks
-        group_vote_matrices = {}
+        # Precompute group average votes and valid comment masks
         group_avg_votes = {}
         group_valid_masks = {}
-        
+
         for group_id, member_indices in group_member_indices.items():
             if len(member_indices) >= 3:  # Only calculate for groups with enough members
                 # Extract the group vote matrix
                 group_vote_matrix = matrix_values[member_indices, :]
-                group_vote_matrices[group_id] = group_vote_matrix
-                
+
                 # Calculate average votes per comment for this group
                 group_avg_votes[group_id] = np.mean(group_vote_matrix, axis=0)
 

delphi/scripts/benchmark_participant_info.py

@@ -211,9 +211,12 @@ def main():
     parser = argparse.ArgumentParser(description="Benchmark participant info: old loop vs vectorized")
     parser.add_argument('--include-local', action='store_true', help="Include private datasets")
     parser.add_argument('--datasets', type=str, default=None, help="Comma-separated dataset names")
-    parser.add_argument('--runs', type=int, default=3, help="Number of runs per implementation")
+    parser.add_argument('--runs', type=int, default=3, help="Number of runs per implementation (>=1)")
     args = parser.parse_args()
 
+    if args.runs < 1:
+        parser.error("--runs must be a positive integer (got %d)" % args.runs)
+
     all_datasets = discover_datasets(include_local=args.include_local)
     valid = [name for name, info in all_datasets.items() if info.is_valid]
 

delphi/tests/test_participant_info.py

@@ -546,7 +546,7 @@ def test_stats_value_types(self):
             assert type(s["n_pass"]) is int
             assert type(s["n_votes"]) is int
             for gid, corr in s["group_correlations"].items():
-                assert isinstance(corr, (float, np.floating)), (
+                assert type(corr) is float, (
                     f"corr for pid={pid}, gid={gid} is {type(corr)}"
                 )