Shared theory

Cross-engine electromagnetics and conventions. Per-engine theory and architecture live under that engine in the docs nav (package READMEs, gates, phase archives).

Topic	Where
Framework contracts	Architecture
Q, mode volume, coupling, AD	pages under this section
Quan–Lončar v1	Engine
Design23 v1	Engine
Majumdar lab	Engine

Scientific scope

Analytical and FDTD values are never silently substituted for one another. Each engine documents its trust boundaries and validation status.