unicode-math breaks amscd

[mbertucci47]

If unicode-math is loaded, amscd diagrams are not output correctly though there is no error. Here's an example from amsldoc.

\documentclass{article}

\usepackage{amsmath}
\usepackage{amscd}
%\usepackage{unicode-math}

\DeclareMathOperator{\End}{End}

\begin{document}

\[\begin{CD}
S^{\mathcal{W}_\Lambda}\otimes T @>j>> T\\
@VVV @VV{\End P}V\\
(S\otimes T)/I @= (Z\otimes T)/J
\end{CD}\]

\end{document}

Without unicode-math

With unicode-math

[mbertucci47]

See also https://tex.stackexchange.com/q/566473/208544

[eg9]

amscd globally makes @ math active, but this is nullified by unicode-math.

On the other hand, the math code assignment is important only inside amscd, so a fix is to do

\AddToHook{env/CD/begin}{\mathcode`@="8000\relax}

Example

\documentclass{article}

\usepackage{amsmath}
\usepackage{amscd}
\usepackage{unicode-math}

\DeclareMathOperator{\End}{End}

\AddToHook{env/CD/begin}{\mathcode`@="8000\relax}

\begin{document}

\[\begin{CD}
S^{\mathcal{W}_\Lambda}\otimes T @>j>> T\\
@VVV @VV{\End P}V\\
(S\otimes T)/I @= (Z\otimes T)/J
\end{CD}\]

\end{document}