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>

docs/components/reversing-valve.md

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+# ReversingValve / FourWayValve
+
+Config types: `"ReversingValve"`, `"FourWayValve"`  
+Source: reversing valve module
+
+---
+
+## EN
+
+### Purpose & model
+
+4-way reversing valve for heat-pump mode swap (heating ↔ cooling). Routes compressor discharge/suction between indoor and outdoor exchangers according to `mode` (or boolean heat/cool).
+
+Ideal model: port permutation with negligible ΔP/Δh; real models may add leakage or pressure drop.
+
+### Residuals
+
+Port coupling residuals matching the selected flow graph for the active mode.
+
+### Ports
+
+Four refrigerant ports (naming depends on implementation: e.g. compressor discharge/suction, indoor, outdoor).
+
+### JSON (main)
+
+| Key | Meaning | Default |
+|-----|---------|---------|
+| `mode` / `reversing_mode` | heat / cool | – |
+
+### Calibration
+
+Usually none; treat as topology switch.
+
+---
+
+## FR
+
+### But
+
+**Vanne 4 voies** pour inverser le cycle PAC.
+
+### JSON
+
+Mode chaud / froid. Voir EN.