docs: add and clean up AI-generated rustdoc comments (grok-4.5)

src/core/build/language/mod.rs

@@ -15,21 +15,29 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
+/// Core module for language support in the DCR build system.
+/// Defines the Language trait and helper functions to register and lookup languages.
 pub mod asm;
 pub mod c;
 pub mod cxx;
 pub mod llvm_ir;
 
+/// Trait representing a supported programming language.
+/// Each implementation must specify its unique identifier, list of supported file extensions,
+/// and a method to determine if a given token matches the language.
 pub trait Language {
     fn id(&self) -> &'static str;
     fn extensions(&self) -> &'static [&'static str];
     fn matches_token(&self, token: &str) -> bool;
 }
 
+/// Returns a fixed-size array containing static references to all supported language types.
 pub fn languages() -> [&'static dyn Language; 4] {
     [&c::C, &cxx::Cxx, &asm::Asm, &llvm_ir::LlvmIr]
 }
 
+/// Looks up the language implementation that matches the given token by checking each language's
+/// matches_token method. Returns the first match or None if no language matches.
 pub fn language_for_token(token: &str) -> Option<&'static dyn Language> {
     languages().into_iter().find(|l| l.matches_token(token))
 }
@@ -38,6 +46,7 @@ pub fn language_for_token(token: &str) -> Option<&'static dyn Language> {
 mod tests {
     use super::*;
 
+    /// Ensures that input tokens are resolved to the correct language IDs.
     #[test]
     fn tokens_resolve_to_languages() {
         assert_eq!(language_for_token("c").unwrap().id(), "c");
@@ -48,6 +57,7 @@ mod tests {
         assert!(language_for_token("rust").is_none());
     }
 
+    /// Ensures that each language reports the expected set of file extensions.
     #[test]
     fn languages_expose_expected_extensions() {
         assert_eq!(c::C.extensions(), &["c"]);