Minor refactors

src/engine/Atom.zig

@@ -2,8 +2,13 @@ const std = @import("std");
 
 const ctx = @import("../AppContext.zig");
 
+/// Interned string ID. A string can be converted to a stable integer constant,
+/// called an *atom*. The value of an atom for a given string is guaranteed to
+/// be stable throughout a program's runtime, but not across different runs.
+/// There can be no more than 2¹⁶ atoms.
 pub const Atom = enum(u16) {
-    // VOLATILE Synchronize explicit values with `Atoms.init` implementation.
+    // VOLATILE When modifying the list of explicitly defined atoms (i.e. any
+    // explicit enum value), we need to update `Atoms.init` implementation.
 
     /// Atom representing an empty string, i.e. `""`.
     empty,