fix: mass extraction NaN in Hydrotech Beam DOE — two bugs

Bug 1 — Journal (solve_simulation.py simple workflow):
  Expression lookup for p173 fails silently for derived/measurement
  expressions, so _temp_mass.txt was never written. Added MeasureManager
  fallback via extract_part_mass() (already used in assembly workflow).

Bug 2 — Extractor (extract_mass_from_expression.py):
  Journal writes 'p173=<value>' format but extractor tried float() on
  the whole content including 'p173='. Added key=value parsing.

Defense in depth — nx_interface.py:
  Added stdout parsing fallback: if _temp_mass.txt still missing, parse
  mass from journal output captured via solver.py stdout passthrough.

Files changed:
  - optimization_engine/nx/solve_simulation.py — MeasureManager fallback
  - optimization_engine/extractors/extract_mass_from_expression.py — key=value parse
  - optimization_engine/nx/solver.py — include stdout in result dict
  - projects/hydrotech-beam/studies/01_doe_landscape/nx_interface.py — stdout fallback

Tags: hydrotech-beam, mass-extraction

optimization_engine/extractors/extract_mass_from_expression.py

@@ -42,13 +42,19 @@ def extract_mass_from_expression(prt_file: Path, expression_name: str = "p173")
     # Read mass from file
     try:
         with open(mass_file, 'r') as f:
-            mass_kg = float(f.read().strip())
+            content = f.read().strip()
+
+        # Handle key=value format (e.g., "p173=1185.767")
+        if '=' in content:
+            content = content.split('=', 1)[1]
+
+        mass_kg = float(content)
 
         print(f"[OK] Mass from {expression_name}: {mass_kg:.6f} kg ({mass_kg * 1000:.2f} g)")
         return mass_kg
 
     except ValueError as e:
-        raise ValueError(f"Could not parse mass from {mass_file}: {e}")
+        raise ValueError(f"Could not parse mass from {mass_file} (content: {content!r}): {e}")
     except Exception as e:
         raise RuntimeError(f"Failed to read mass file: {e}")
 

optimization_engine/nx/solve_simulation.py

@@ -1170,28 +1170,49 @@ 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
+    # Extract mass and write to _temp_mass.txt
+    # Strategy: try expression lookup first, fall back to MeasureManager
     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
 
+        # Attempt 1: Read mass from expression p173 on geometry part
+        try:
+            for part in theSession.Parts:
+                part_type = type(part).__name__
+                if "fem" not in part_type.lower() and "sim" not in part_type.lower():
+                    for expr in part.Expressions:
+                        if expr.Name == "p173":
+                            mass_value = expr.Value
+                            print(f"[JOURNAL] Mass expression p173 = {mass_value}")
+                            break
+                    break
+        except Exception as expr_err:
+            print(f"[JOURNAL] Expression lookup failed: {expr_err}")
+
+        # Attempt 2: Use MeasureManager (more reliable for derived/measurement expressions)
+        if mass_value is None:
+            print(f"[JOURNAL] Expression p173 not found, using MeasureManager fallback...")
+            geom_part = None
+            for part in theSession.Parts:
+                part_type = type(part).__name__
+                if "fem" not in part_type.lower() and "sim" not in part_type.lower():
+                    geom_part = part
+                    break
+            if geom_part is not None:
+                try:
+                    mass_value = extract_part_mass(theSession, geom_part, working_dir)
+                    print(f"[JOURNAL] MeasureManager mass = {mass_value}")
+                except Exception as mm_err:
+                    print(f"[JOURNAL] MeasureManager failed: {mm_err}")
+
+        # Write mass file (extract_part_mass may have already written it, but ensure consistency)
         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")
+            print(f"[JOURNAL] WARNING: Could not extract mass via expression or MeasureManager")
     except Exception as e:
         print(f"[JOURNAL] WARNING: Mass extraction failed: {e}")
 

optimization_engine/nx/solver.py

@@ -605,7 +605,8 @@ sys.argv = ['', {argv_str}]  # Set argv for the main function
                 'elapsed_time': elapsed_time,
                 'errors': errors,
                 'return_code': result.returncode,
-                'solution_name': solution_name
+                'solution_name': solution_name,
+                'stdout': result.stdout if self.use_journal else '',
             }
 
         except subprocess.TimeoutExpired: