.amxd Container Format and Conversion

.amxd files are NOT just renamed .maxpat files. They are an IFF-style binary container with a 36-byte mixed-endian header, the patcher JSON NUL-terminated, then a dlst/dire dependency trailer.

The format is undocumented by Cycling '74; everything here is reverse-engineered from Max-exported devices, the shakfu/py2max Python library, and Ableton's official maxdevtools/maxdiff/amxd_textconv.py parser.

1. Byte layout (Max-native canonical form)