diff --git a/src/ir/resolver.test.zig b/src/ir/resolver.test.zig
index 3e18a55..bc2f9e8 100644
--- a/src/ir/resolver.test.zig
+++ b/src/ir/resolver.test.zig
@@ -342,6 +342,26 @@ fn findFn(root: *const ast.Node, name: []const u8) ?*const ast.Node {
     return null;
 }
 
+fn findDecl(root: *const ast.Node, name: []const u8, comptime kind: std.meta.Tag(ast.Node.Data)) ?*const ast.Node {
+    for (root.data.root.decls) |d| {
+        if (std.meta.activeTag(d.data) != kind) continue;
+        const dn = d.data.declName() orelse continue;
+        if (std.mem.eql(u8, dn, name)) return d;
+    }
+    return null;
+}
+
+fn expectTypeRefOwnTag(
+    rp: *const resolver.ResolvedProgram,
+    node: *const ast.Node,
+    expected: std.meta.Tag(resolver.RawDeclRef),
+) !void {
+    const ref = rp.type_refs.get(node) orelse return error.MissingTypeRef;
+    try std.testing.expect(ref == .authors);
+    try std.testing.expect(ref.authors.own != null);
+    try std.testing.expectEqual(expected, std.meta.activeTag(ref.authors.own.?.raw));
+}
+
 // The pass populates the three bare-name domains over REAL Phase A facts: a type
 // reference (own struct author), a value/const reference (own const), and a
 // callable head (flat-imported author). It keys every entry by NODE IDENTITY, and
@@ -462,3 +482,56 @@ test "resolver: resolve — bare-name domains populated, keyed by node, symbolic
     try std.testing.expectEqual(@as(u32, 0), rp.struct_const_refs.count());
     try std.testing.expectEqual(@as(u32, 0), rp.ufcs_refs.count());
 }
+
+test "resolver: resolve — generic constraints and named error sets are type refs" {
+    var arena = std.heap.ArenaAllocator.init(std.testing.allocator);
+    defer arena.deinit();
+    const alloc = arena.allocator();
+    const io = testIo();
+
+    var tmp = std.testing.tmpDir(.{});
+    defer tmp.cleanup();
+
+    try tmp.dir.writeFile(io, .{ .sub_path = "main.sx", .data =
+        \\Alias :: struct { x: s64 }
+        \\ParseErr :: error { Bad }
+        \\Box :: struct($N: Alias) { value: Alias }
+        \\Constrained :: protocol(T: Alias) { get :: () -> T; }
+        \\take :: ($N: Alias) -> s64 { return 0; }
+        \\fail :: () -> !ParseErr { raise error.Bad; }
+        \\main :: () -> s32 { return 0; }
+        \\
+    });
+
+    var dirbuf: [4096]u8 = undefined;
+    const absdir = dirbuf[0..try tmp.dir.realPath(io, &dirbuf)];
+    const main_path = try std.fmt.allocPrint(alloc, "{s}/main.sx", .{absdir});
+
+    var prog = try buildResolved(alloc, io, absdir, main_path);
+
+    var idx = ProgramIndex.init(alloc);
+    defer idx.deinit();
+    idx.module_decls = &prog.decls;
+    idx.flat_import_graph = &prog.flat_import_graph;
+    idx.import_graph = &prog.import_graph;
+
+    var rp = resolver.resolve(prog.root, &idx, main_path, alloc);
+    defer rp.deinit();
+
+    const alias_tag = std.meta.Tag(resolver.RawDeclRef).struct_decl;
+    const error_tag = std.meta.Tag(resolver.RawDeclRef).error_set_decl;
+
+    const box = findDecl(prog.root, "Box", .struct_decl) orelse return error.MissingStruct;
+    try expectTypeRefOwnTag(&rp, box.data.struct_decl.type_params[0].constraint, alias_tag);
+
+    const constrained = findDecl(prog.root, "Constrained", .protocol_decl) orelse return error.MissingProtocol;
+    try expectTypeRefOwnTag(&rp, constrained.data.protocol_decl.type_params[0].constraint, alias_tag);
+
+    const take = findFn(prog.root, "take") orelse return error.MissingFn;
+    try expectTypeRefOwnTag(&rp, take.data.fn_decl.type_params[0].constraint, alias_tag);
+
+    const fail = findFn(prog.root, "fail") orelse return error.MissingFn;
+    const err_ty = fail.data.fn_decl.return_type orelse return error.NoReturnType;
+    try std.testing.expect(err_ty.data == .error_type_expr);
+    try expectTypeRefOwnTag(&rp, err_ty, error_tag);
+}
diff --git a/src/ir/resolver.zig b/src/ir/resolver.zig
index 7040ffe..f936682 100644
--- a/src/ir/resolver.zig
+++ b/src/ir/resolver.zig
@@ -392,6 +392,7 @@ const ResolvePass = struct {
             .fn_decl => |*fd| {
                 var frame = Frame{ .params = fd.type_params, .owner = node, .parent = here.scope };
                 const inner = Ctx{ .source = here.source, .scope = &frame };
+                self.visitTypeParamConstraints(fd.type_params, inner);
                 for (fd.params) |p| {
                     self.visit(p.type_expr, inner);
                     if (p.default_expr) |d| self.visit(d, inner);
@@ -402,6 +403,7 @@ const ResolvePass = struct {
             .lambda => |*l| {
                 var frame = Frame{ .params = l.type_params, .owner = node, .parent = here.scope };
                 const inner = Ctx{ .source = here.source, .scope = &frame };
+                self.visitTypeParamConstraints(l.type_params, inner);
                 for (l.params) |p| {
                     self.visit(p.type_expr, inner);
                     if (p.default_expr) |d| self.visit(d, inner);
@@ -412,6 +414,7 @@ const ResolvePass = struct {
             .struct_decl => |*sd| {
                 var frame = Frame{ .params = sd.type_params, .owner = node, .parent = here.scope };
                 const inner = Ctx{ .source = here.source, .scope = &frame };
+                self.visitTypeParamConstraints(sd.type_params, inner);
                 self.visitAll(sd.field_types, inner);
                 self.visitAllOpt(sd.field_defaults, inner);
                 self.visitAll(sd.methods, inner);
@@ -420,6 +423,7 @@ const ResolvePass = struct {
             .protocol_decl => |*pd| {
                 var frame = Frame{ .params = pd.type_params, .owner = node, .parent = here.scope };
                 const inner = Ctx{ .source = here.source, .scope = &frame };
+                self.visitTypeParamConstraints(pd.type_params, inner);
                 for (pd.methods) |m| {
                     self.visitAll(m.params, inner);
                     if (m.return_type) |rt| self.visit(rt, inner);
@@ -429,6 +433,7 @@ const ResolvePass = struct {
             .impl_block => |*ib| {
                 var frame = Frame{ .params = ib.target_type_params, .owner = node, .parent = here.scope };
                 const inner = Ctx{ .source = here.source, .scope = &frame };
+                self.visitTypeParamConstraints(ib.target_type_params, inner);
                 if (ib.target_type_expr) |tt| self.visit(tt, inner);
                 self.visitAll(ib.protocol_type_args, inner);
                 self.visitAll(ib.methods, inner);
@@ -466,6 +471,9 @@ const ResolvePass = struct {
             },
             .pack_index_type_expr => |*p| self.recordPack(&self.out.type_refs, node, p.pack_name, p.index, here.scope),
             .comptime_pack_ref => |*p| self.recordPack(&self.out.value_refs, node, p.pack_name, null, here.scope),
+            .error_type_expr => |*e| {
+                if (e.name) |name| self.recordAuthors(&self.out.type_refs, node, name, here.source);
+            },
             .parameterized_type_expr => |*p| {
                 // the head (generic-struct / type-fn / protocol) is S2.1b; the
                 // type args are ordinary references, collected now.
@@ -625,7 +633,6 @@ const ResolvePass = struct {
             .import_decl,
             .namespace_decl,
             .error_set_decl,
-            .error_type_expr,
             .foreign_expr,
             .library_decl,
             .framework_decl,
@@ -643,6 +650,10 @@ const ResolvePass = struct {
         for (nodes) |n| if (n) |nn| self.visit(nn, ctx);
     }
 
+    fn visitTypeParamConstraints(self: *ResolvePass, params: []const ast.StructTypeParam, ctx: Ctx) void {
+        for (params) |p| self.visit(p.constraint, ctx);
+    }
+
     /// A type-position reference: a generic param in scope → symbolic template ref;
     /// otherwise a user type, collected RAW. Builtins / undeclared names collect to
     /// an empty set and are simply not recorded.
@@ -676,16 +687,29 @@ const ResolvePass = struct {
     fn recordAuthors(self: *ResolvePass, table: *NodeRefTable, node: *const ast.Node, name: []const u8, from: []const u8) void {
         const set = self.res.collectVisibleAuthors(name, from, .user_bare_flat);
         if (set.distinctCount() == 0) return;
-        table.put(node, .{ .authors = set }) catch @panic("resolve: OOM");
+        self.replaceRef(table, node, .{ .authors = set });
     }
 
     fn recordTemplate(self: *ResolvePass, table: *NodeRefTable, node: *const ast.Node, m: GenericMatch) void {
-        table.put(node, .{ .template = self.internTemplate(m) }) catch @panic("resolve: OOM");
+        self.replaceRef(table, node, .{ .template = self.internTemplate(m) });
     }
 
     fn recordPack(self: *ResolvePass, table: *NodeRefTable, node: *const ast.Node, name: []const u8, index: ?u32, scope: ?*const Frame) void {
         const m = lookupGeneric(scope, name) orelse return;
-        table.put(node, .{ .pack = .{ .id = self.internPack(m), .index = index } }) catch @panic("resolve: OOM");
+        self.replaceRef(table, node, .{ .pack = .{ .id = self.internPack(m), .index = index } });
+    }
+
+    fn replaceRef(self: *ResolvePass, table: *NodeRefTable, node: *const ast.Node, ref: ResolvedRef) void {
+        const entry = table.getOrPut(node) catch @panic("resolve: OOM");
+        if (entry.found_existing) self.releaseRef(entry.value_ptr.*);
+        entry.value_ptr.* = ref;
+    }
+
+    fn releaseRef(self: *ResolvePass, ref: ResolvedRef) void {
+        switch (ref) {
+            .authors => |a| if (a.flat.len > 0) self.out.alloc.free(a.flat),
+            .template, .pack => {},
+        }
     }
 
     fn internTemplate(self: *ResolvePass, m: GenericMatch) TemplateParamId {