Snapshot WIP: solver HP epic progress, BPHX/HX physics, BMAD skill refresh.

Capture uncommitted solver robustness work (regularization, domain errors, linear solver lifecycle, tube DP/MSH), web workbench updates, and synced BMAD skills across IDE agent folders before starting BPHX pressure-drop.

Co-authored-by: Cursor <cursoragent@cursor.com>

crates/solver/tests/inverse_control.rs

@@ -5,6 +5,7 @@
 //! - AC #2: Jacobian block correctly contains cross-derivatives for MIMO systems
 //! - AC #3: Simultaneous multi-variable solving converges when constraints are compatible
 //! - AC #4: DoF validation correctly handles multiple linked variables
+#![allow(clippy::needless_range_loop)]
 
 use entropyk_components::{
     Component, ComponentError, ConnectedPort, JacobianBuilder, ResidualVector, StateSlice,
@@ -812,7 +813,7 @@ fn test_mimo_jacobian_structure_and_bounds() {
     // Verify bounds are respected (AC #3 requirement)
     for &cv in &control_values {
         assert!(
-            cv >= 0.0 && cv <= 1.0,
+            (0.0..=1.0).contains(&cv),
             "Control variables must respect bounds [0, 1]"
         );
     }
@@ -1083,11 +1084,13 @@ fn test_mimo_cross_derivatives_have_consistent_signs() {
 }
 
 /// Helper: builds a three-component system for 3x3 MIMO testing.
+/// CM1.4: 3-edge series cycle → 1 branch + 6 P,h = 7 unknowns.
+/// Using mock(2) for each component gives 6 equations (under-constrained, allowed).
 fn build_three_component_system() -> System {
     let mut sys = System::new();
-    let comp = sys.add_component(mock(3)); // compressor
-    let evap = sys.add_component(mock(3)); // evaporator
-    let cond = sys.add_component(mock(3)); // condenser
+    let comp = sys.add_component(mock(2)); // compressor
+    let evap = sys.add_component(mock(2)); // evaporator
+    let cond = sys.add_component(mock(2)); // condenser
     sys.add_edge(comp, evap).unwrap();
     sys.add_edge(evap, cond).unwrap();
     sys.add_edge(cond, comp).unwrap();