diff --git a/AGENTS.md b/AGENTS.md
index a512ba0..01fbd5e 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -63,7 +63,13 @@ The project contains:
 ## Build System
 
 CMake is configured with `LANGUAGES NONE` and invokes `rustc` through three
-custom commands:
+custom commands. CMake 4.4's experimental native Rust support
+(`CMAKE_EXPERIMENTAL_RUST`) was evaluated and rejected: it compiles each
+source file as its own crate, so multi-module crates break; it links Rust
+libraries into executables as native `.lib` inputs instead of `--extern`;
+and it has no `proc-macro` crate type. Keep the direct `rustc` commands.
+
+The three custom commands are:
 
 1. Compile `macros/src/lib.rs` as a host procedural macro.
 2. Compile `src/lib.rs` and its modules to `librslibc.rlib`.