Snapshot WIP: Probe calibration path, faer LU backend, and BPHX phase-change duty.

Checkpoint incomplete calibration work (cond SDT green, evap SST failing) plus related solver/UI changes so the next pass can fix and extend safely.

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

crates/entropyk/src/lib.rs

@@ -115,10 +115,11 @@ pub use entropyk_components::{
     IncompressibleSplitter, IsenthalpicExpansionValve, IsentropicCompressor, JacobianBuilder,
     LmtdModel, MchxCondenserCoil, MockExternalModel, Node, NodeMeasurements, NodePhase,
     OperationalState, PerformanceCurves, PhaseRegion, Pipe, PipeGeometry, Polynomial1D,
-    Polynomial2D, Pump, PumpCurves, RefrigerantSink, RefrigerantSource, RegistryError,
-    ResidualVector, ScrewEconomizerCompressor, ScrewPerformanceCurves, ShellAndTubeHx,
-    SstSdtCoefficients, StateHistory, StateManageable, StateTransitionError, SystemState,
-    ThermalLoad, ThreadSafeExternalModel, UaMode, ValveCharacteristics, ValveFlowModel,
+    Polynomial2D, Probe, ProbeMeasure, Pump, PumpCurves, RefrigerantSink, RefrigerantSource,
+    RegistryError, ResidualVector, ScrewEconomizerCompressor, ScrewPerformanceCurves,
+    ShellAndTubeHx, SstSdtCoefficients, StateHistory, StateManageable, StateTransitionError,
+    SystemState, ThermalLoad, ThreadSafeExternalModel, UaMode, ValveCharacteristics,
+    ValveFlowModel,
 };
 pub use entropyk_components::{ReversingMode, ReversingValve};
 
@@ -147,11 +148,11 @@ pub use entropyk_solver::{
     AddEdgeError, AntoineCoefficients, CircuitConvergence, CircuitId as SolverCircuitId,
     ComponentOutput, Constraint, ConstraintError, ConstraintId, ConvergedState,
     ConvergenceCriteria, ConvergenceReason, ConvergenceReport, ConvergenceStatus, CyclePerformance,
-    DomainViolation, FallbackConfig, FallbackSolver, FlowEdge, HomotopyConfig, InitializerConfig,
-    InitializerError, JacobianFreezingConfig, JacobianMatrix, LinearSolver, MacroComponent,
-    MacroComponentSnapshot, NalgebraLuSolver, NewtonConfig, PicardConfig, PortMapping,
-    SmartInitializer, SolveOutcome, Solver, SolverError, SolverStrategy, System, ThermalCoupling,
-    TimeoutConfig, TopologyError,
+    DomainViolation, FaerLuSolver, FallbackConfig, FallbackSolver, FlowEdge, HomotopyConfig,
+    InitializerConfig, InitializerError, JacobianFreezingConfig, JacobianMatrix, LinearSolver,
+    MacroComponent, MacroComponentSnapshot, NalgebraLuSolver, NewtonConfig, PicardConfig,
+    PortMapping, SmartInitializer, SolveOutcome, Solver, SolverError, SolverStrategy, System,
+    ThermalCoupling, TimeoutConfig, TopologyError,
 };
 
 // =============================================================================

crates/entropyk/src/result.rs

@@ -526,6 +526,42 @@ pub fn extract_solved_variables(system: &System, state: &[f64]) -> Vec<SolvedVar
         }
     }
 
+    // Calibration factors (z_ua, z_dp, z_flow, z_flow_eco, z_power, z_etav)
+    // promoted to free unknowns via control loops. Each `Some(idx)` slot means
+    // the solver computed a value for that factor at `state[idx]`. The generic
+    // `actuator` slot (physical opening / fan speed) is already covered by the
+    // bounded-variable path above, so we only surface the six named Z-factors.
+    for (name, indices) in system.calib_indices_by_name() {
+        for (factor, slot) in [
+            ("z_flow", indices.z_flow),
+            ("z_flow_eco", indices.z_flow_eco),
+            ("z_dp", indices.z_dp),
+            ("z_ua", indices.z_ua),
+            ("z_power", indices.z_power),
+            ("z_etav", indices.z_etav),
+        ] {
+            if let Some(idx) = slot {
+                if idx < state.len() {
+                    let id = format!("{}__{}", name, factor);
+                    // Skip if already emitted by the bounded-variable path.
+                    if out.iter().any(|v| v.id == id) {
+                        continue;
+                    }
+                    out.push(SolvedVariable {
+                        id,
+                        component: Some(name.clone()),
+                        variable: factor.to_string(),
+                        value: state[idx],
+                        // Calibration factors are bounded to [0.5, 2.0]
+                        // (see entropyk_core::CalibValidationError).
+                        min: 0.5,
+                        max: 2.0,
+                    });
+                }
+            }
+        }
+    }
+
     if skipped > 0 {
         tracing::debug!(
             skipped,
@@ -547,9 +583,7 @@ pub fn extract_solved_variables(system: &System, state: &[f64]) -> Vec<SolvedVar
 /// user-facing `"opening"` label.
 fn derive_solved_variable_label(id: &str, component_id: Option<&str>) -> String {
     let stripped = match component_id {
-        Some(c) => id
-            .strip_prefix(&format!("{}__", c))
-            .unwrap_or(id),
+        Some(c) => id.strip_prefix(&format!("{}__", c)).unwrap_or(id),
         None => id.rfind("__").map(|i| &id[i + 2..]).unwrap_or(id),
     };
     match stripped {
@@ -781,6 +815,9 @@ mod tests {
         // Component unknown → fall back to last "__"-separated segment.
         assert_eq!(derive_solved_variable_label("glob__z_dp", None), "z_dp");
         // No separator and no component → id itself.
-        assert_eq!(derive_solved_variable_label("global_var", None), "global_var");
+        assert_eq!(
+            derive_solved_variable_label("global_var", None),
+            "global_var"
+        );
     }
 }