fix: generic mass extraction in solve_simulation.py (beam + bracket)

- Extract mass RIGHT AFTER geometry rebuild while part is work part
- Replace unreliable p173 expression lookup with MeasureManager
- Skip re-extraction if mass already captured during rebuild
- Relax displacement constraint to 20mm (DEC-HB-012, CEO approved)

Root cause: journal hardcoded M1_Blank for bracket, failed silently on Beam.prt
Fix by: NX Expert + Manager diagnosis

projects/hydrotech-beam/CONTEXT.md

@@ -20,7 +20,7 @@ Minimize beam mass while meeting displacement and stress constraints. Single-obj
 | hole_span | `p6` (→ `Pattern_p9`) | 4,000 | TBD | mm | Potential (G15) | Total span for hole distribution |
 
 ## Constraints
-- Max tip displacement: ≤ 10 mm
+- Max tip displacement: ≤ 20 mm (relaxed from 10mm — CEO approved 2026-02-13, dummy case)
 - Max von Mises stress: ≤ ~130 MPa (steel, conservative — Gap G9)
 - Mass tracked via NX expression **`p173`** (`body_property147.mass` [kg])
 

projects/hydrotech-beam/DECISIONS.md

@@ -79,6 +79,13 @@ Numbered decision log. Check here before proposing anything that contradicts a p
 - **Rationale:** Optuna DB is study-scoped and can be cleaned/reset. History DB provides permanent record across studies, enabling cross-study learning, debugging, and auditability. Append-only means no data loss.
 - **Status:** Approved — implemented and tested
 
+## DEC-HB-012: Relax displacement constraint to 20mm
+- **Date:** 2026-02-13
+- **By:** CEO
+- **Decision:** Relax max tip displacement constraint from 10 mm to 20 mm. Stress constraint unchanged (≤ 130 MPa).
+- **Rationale:** Hydrotech Beam is a dummy/proving case — goal is to validate the full optimization pipeline end-to-end, not achieve a real engineering target. 10mm was unreachable in the current design space (baseline 19.6mm, 0/51 DOE trials feasible). 20mm makes feasibility achievable.
+- **Status:** Approved
+
 ## DEC-HB-011: Git-only development workflow (Syncthing paused)
 - **Date:** 2026-02-11
 - **By:** CEO