fix(stdlib/S2.1b): namespace-qualified parameterized heads [additive]

src/ir/resolver.zig

@@ -752,10 +752,38 @@ const ResolvePass = struct {
     /// in scope is symbolic (not an author); a name with no user author (builtins
     /// like `Vector`, undeclared) or only non-head authors is omitted.
     fn classifyHead(self: *ResolvePass, node: *const ast.Node, name: []const u8, is_raw: bool, ctx: Ctx) void {
+        if (std.mem.indexOfScalar(u8, name, '.')) |first_dot| {
+            const set = self.collectQualifiedHeadAuthors(name, first_dot, ctx.source) orelse return;
+            self.classifyHeadSet(node, set);
+            return;
+        }
+
         if (!is_raw and lookupGeneric(ctx.scope, name) != null) return;
         const set = self.res.collectVisibleAuthors(name, ctx.source, .user_bare_flat);
         if (set.distinctCount() == 0) return;
 
+        self.classifyHeadSet(node, set);
+    }
+
+    /// `alias.Member(args)` reaches this pass as one `parameterized_type_expr`
+    /// named `alias.Member`. Split like the old lowering path: alias before the
+    /// first dot, member after the last dot, then collect from the namespace
+    /// target's own declarations only.
+    fn collectQualifiedHeadAuthors(self: *ResolvePass, name: []const u8, first_dot: usize, from: []const u8) ?AuthorSet {
+        const alias = name[0..first_dot];
+        const last_dot = std.mem.lastIndexOfScalar(u8, name, '.') orelse first_dot;
+        const member = name[last_dot + 1 ..];
+        if (alias.len == 0 or member.len == 0) return null;
+
+        const edges = self.res.index.namespace_edges orelse return null;
+        const aliases = edges.get(from) orelse return null;
+        const target = aliases.get(alias) orelse return null;
+        const set = self.res.collectNamespaceAuthors(target, member);
+        if (set.distinctCount() == 0) return null;
+        return set;
+    }
+
+    fn classifyHeadSet(self: *ResolvePass, node: *const ast.Node, set: AuthorSet) void {
         var gs = false;
         var tf = false;
         var pr = false;