Fix mass extraction + db close order + nan handling

- Journal now extracts p173 mass expression and writes _temp_mass.txt
- history.get_study_summary() called before history.close()
- Optuna nan rejection: fallback to INFEASIBLE_MASS penalty
- pyNastran warning 'nx 2512 not supported' is harmless (reads fine)

optimization_engine/nx/solve_simulation.py

@@ -1170,6 +1170,31 @@ def solve_simple_workflow(
         f"[JOURNAL] Solve completed: {numsolved} solved, {numfailed} failed, {numskipped} skipped"
     )
 
+    # Extract mass from geometry part expression (p173) and write to temp file
+    try:
+        mass_value = None
+        # Find geometry part (Beam.prt)
+        for part in theSession.Parts:
+            part_type = type(part).__name__
+            if "fem" not in part_type.lower() and "sim" not in part_type.lower():
+                # This is the geometry part — look for mass expression
+                for expr in part.Expressions:
+                    if expr.Name == "p173":
+                        mass_value = expr.Value
+                        print(f"[JOURNAL] Mass expression p173 = {mass_value}")
+                        break
+                break
+
+        if mass_value is not None:
+            mass_file = os.path.join(working_dir, "_temp_mass.txt")
+            with open(mass_file, "w") as f:
+                f.write(f"p173={mass_value}\n")
+            print(f"[JOURNAL] Wrote mass to {mass_file}")
+        else:
+            print(f"[JOURNAL] WARNING: Could not find mass expression p173")
+    except Exception as e:
+        print(f"[JOURNAL] WARNING: Mass extraction failed: {e}")
+
     # Save all
     try:
         anyPartsModified, partSaveStatus = theSession.Parts.SaveAll()

projects/hydrotech-beam/studies/01_doe_landscape/run_doe.py

@@ -255,6 +255,12 @@ def evaluate_trial(
         )
         history.export_csv()  # Live update CSV after each trial
 
+    # Optuna rejects nan — use INFEASIBLE_MASS as fallback
+    import math
+    if math.isnan(nx_result.mass):
+        logger.warning("Trial %d: mass is NaN (extraction failed), using penalty value", trial_num)
+        return INFEASIBLE_MASS
+
     return nx_result.mass
 
 
@@ -542,10 +548,10 @@ def run_study(args: argparse.Namespace) -> None:
     # Cleanup
     solver.close()
 
-    # Final history export + summary
-    history.close()
+    # Final history summary (before close!)
     hist_summary = history.get_study_summary(study_name)
     logger.info("History DB: %d total records across all studies", hist_summary["total"])
+    history.close()
 
 
 def _progress_callback(study: optuna.Study, trial: optuna.trial.FrozenTrial) -> None: