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>

.agents/skills/bmad-agent-tech-writer/explain-concept.md

@@ -0,0 +1,20 @@
+---
+name: explain-concept
+description: Create clear technical explanations with examples
+menu-code: EC
+---
+
+# Explain Concept
+
+Create a clear technical explanation with examples and diagrams for a complex concept.
+
+## Process
+
+1. **Understand the concept** — Clarify what needs to be explained and the target audience
+2. **Structure** — Break it down into digestible sections using a task-oriented approach
+3. **Illustrate** — Include code examples and Mermaid diagrams where helpful
+4. **Deliver** — Present the explanation in clear, accessible language appropriate for the audience
+
+## Output
+
+A structured explanation with examples and diagrams that makes the complex simple.