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/free-cooling-exchanger.md

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+# FreeCoolingExchanger
+
+Config types: `"FreeCoolingExchanger"`, `"FreeCooling"`  
+Source: free-cooling HX module
+
+---
+
+## EN
+
+### Purpose & model
+
+Free-cooling heat exchanger between two liquid loops (e.g. tower water ↔ chilled water) without vapor-compression. Effectiveness–NTU or UA·LMTD between two single-phase streams.
+
+```
+Q = ε · C_min · (T_hot,in − T_cold,in)
+```
+
+### Residuals
+
+Two-stream energy balances + optional ΔP per leg.
+
+### Ports
+
+Hot and cold in/out (4-port).
+
+### Calibration
+
+`z_ua` default **1.0**.
+
+### JSON
+
+UA, fluids, optional secondary stream params — see CLI arm.
+
+---
+
+## FR
+
+### But
+
+Échangeur de **free-cooling** (liquide–liquide), sans cycle frigo.
+
+### Calibration
+
+Z_UA = 1 par défaut.