diff --git a/hosts/ocaml/bin/run_tests.ml b/hosts/ocaml/bin/run_tests.ml
index 2313c59..a78c629 100644
--- a/hosts/ocaml/bin/run_tests.ml
+++ b/hosts/ocaml/bin/run_tests.ml
@@ -269,6 +269,40 @@ let make_test_env () =
   (* --- HTML Renderer (from sx_render.ml library module) --- *)
   Sx.Sx_render.setup_render_env env;
 
+  (* Stubs needed by adapter-html.sx when loaded at test time *)
+  bind "set-render-active!" (fun _args -> Nil);
+  bind "render-active?" (fun _args -> Bool true);
+  bind "trampoline" (fun args ->
+    match args with
+    | [Thunk (expr, e)] -> eval_expr expr (Env e)
+    | [v] -> v
+    | _ -> Nil);
+  bind "eval-expr" (fun args ->
+    match args with
+    | [expr; Env e] -> eval_expr expr (Env e)
+    | [expr] -> eval_expr expr (Env env)
+    | _ -> raise (Eval_error "eval-expr: expected (expr env)"));
+  bind "scope-push!" (fun args ->
+    ignore (Sx_runtime.scope_push (List.hd args) (if List.length args > 1 then List.nth args 1 else Nil)); Nil);
+  bind "scope-pop!" (fun args ->
+    ignore (Sx_runtime.scope_pop (List.hd args)); Nil);
+  bind "cond-scheme?" (fun args ->
+    match args with
+    | [(List clauses | ListRef { contents = clauses })] ->
+      (match clauses with
+       | (List _ | ListRef _) :: _ -> Bool true
+       | _ -> Bool false)
+    | _ -> Bool false);
+  bind "expand-macro" (fun args ->
+    match args with
+    | [Macro m; (List a | ListRef { contents = a }); _] ->
+      let local = Sx_types.env_extend m.m_closure in
+      List.iteri (fun i p ->
+        ignore (Sx_types.env_bind local p (if i < List.length a then List.nth a i else Nil))
+      ) m.m_params;
+      eval_expr m.m_body (Env local)
+    | _ -> raise (Eval_error "expand-macro: expected (macro args env)"));
+
   (* --- Missing primitives referenced by tests --- *)
 
   bind "upcase" (fun args ->
@@ -637,16 +671,24 @@ let run_spec_tests env test_files =
   Printf.printf "\nLoading test framework...\n%!";
   load_and_eval framework_path;
 
-  (* Load compiler + VM spec for test-vm.sx *)
+  (* Load spec modules needed by tests *)
   let spec_dir = Filename.concat project_dir "spec" in
-  List.iter (fun name ->
-    let path = Filename.concat spec_dir name in
+  let web_dir = Filename.concat project_dir "web" in
+  let load_spec name dir =
+    let path = Filename.concat dir name in
     if Sys.file_exists path then begin
       Printf.printf "Loading %s...\n%!" name;
       (try load_and_eval path
        with e -> Printf.eprintf "Warning: %s: %s\n%!" name (Printexc.to_string e))
     end
-  ) ["bytecode.sx"; "compiler.sx"; "vm.sx"];
+  in
+  (* Render adapter for test-render-html.sx *)
+  load_spec "render.sx" spec_dir;
+  load_spec "adapter-html.sx" web_dir;
+  (* Compiler + VM for test-vm.sx *)
+  load_spec "bytecode.sx" spec_dir;
+  load_spec "compiler.sx" spec_dir;
+  load_spec "vm.sx" spec_dir;
 
   (* Determine test files *)
   let files = if test_files = [] then begin
diff --git a/hosts/ocaml/bin/sx_server.ml b/hosts/ocaml/bin/sx_server.ml
index 51f14fe..504e2d9 100644
--- a/hosts/ocaml/bin/sx_server.ml
+++ b/hosts/ocaml/bin/sx_server.ml
@@ -898,6 +898,21 @@ let make_server_env () =
   env
 
 
+(* ====================================================================== *)
+(* SX render-to-html — calls adapter-html.sx via CEK                       *)
+(* ====================================================================== *)
+
+(** Render an SX expression to HTML using the SX adapter (adapter-html.sx).
+    Falls back to Sx_render.render_to_html if the SX adapter isn't loaded. *)
+let sx_render_to_html expr env =
+  if env_has env "render-to-html" then
+    let fn = env_get env "render-to-html" in
+    let result = Sx_ref.cek_call fn (List [expr; Env env]) in
+    match result with String s -> s | _ -> Sx_runtime.value_to_str result
+  else
+    Sx_render.render_to_html expr env
+
+
 (* ====================================================================== *)
 (* JIT hook registration                                                    *)
 (* ====================================================================== *)
@@ -1232,7 +1247,7 @@ let rec dispatch env cmd =
           let body_expr = match body_exprs with
             | [e] -> e | [] -> Nil | _ -> List (Symbol "<>" :: body_exprs)
           in
-          Sx_render.render_to_html body_expr env
+          sx_render_to_html body_expr env
         with e ->
           Printf.eprintf "[ssr] render-to-html failed: %s\n%!" (Printexc.to_string e);
           ""  (* fallback: client renders from SX source. Islands with
@@ -1253,7 +1268,7 @@ let rec dispatch env cmd =
                      :: Keyword "body-html" :: String body_html
                      :: resolved_kwargs in
       let shell_call = List (Symbol "~shared:shell/sx-page-shell" :: shell_args) in
-      let html = Sx_render.render_to_html shell_call env in
+      let html = sx_render_to_html shell_call env in
       let t3 = Unix.gettimeofday () in
       Printf.eprintf "[sx-page-full] aser=%.3fs io=%.3fs ssr=%.3fs shell=%.3fs total=%.3fs body=%d ssr=%d html=%d\n%!"
         (t1 -. t0) (t2 -. t1) (t2b -. t2) (t3 -. t2b) (t3 -. t0)
@@ -1279,7 +1294,7 @@ let rec dispatch env cmd =
         | [] -> Nil
         | _ -> List (Symbol "do" :: exprs)
       in
-      let html = Sx_render.render_to_html expr env in
+      let html = sx_render_to_html expr env in
       send_ok_string html
     with
     | Eval_error msg -> send_error msg
@@ -1406,9 +1421,11 @@ let cli_mode mode =
   let spec_files = [
     Filename.concat base "parser.sx";
     Filename.concat base "render.sx";
+    Filename.concat web_base "adapter-html.sx";
     Filename.concat web_base "adapter-sx.sx";
   ] in
-  (if mode = "aser" || mode = "aser-slot" then
+  (* Load spec files for all CLI modes that need rendering *)
+  (if mode = "aser" || mode = "aser-slot" || mode = "render" then
     cli_load_files env spec_files);
   (* Load any files passed via --load *)
   let load_files = ref [] in
@@ -1434,7 +1451,7 @@ let cli_mode mode =
       let exprs = Sx_parser.parse_all src in
       let expr = match exprs with
         | [e] -> e | [] -> Nil | _ -> List (Symbol "do" :: exprs) in
-      let html = Sx_render.render_to_html expr env in
+      let html = sx_render_to_html expr env in
       print_string html; flush stdout
     | "aser" ->
       let exprs = Sx_parser.parse_all src in
diff --git a/hosts/ocaml/lib/sx_primitives.ml b/hosts/ocaml/lib/sx_primitives.ml
index 0656e81..6d4e7f5 100644
--- a/hosts/ocaml/lib/sx_primitives.ml
+++ b/hosts/ocaml/lib/sx_primitives.ml
@@ -700,6 +700,113 @@ let () =
     match args with
     | [String name] -> Bool (Hashtbl.mem primitives name)
     | _ -> Bool false);
+
+  (* ---- Scope stack primitives (for adapter-html.sx tree-walk rendering) ---- *)
+  let scope_stacks : (string, (value * value list) list) Hashtbl.t = Hashtbl.create 8 in
+  register "scope-push!" (fun args ->
+    match args with
+    | [String name; value] ->
+      let stack = try Hashtbl.find scope_stacks name with Not_found -> [] in
+      Hashtbl.replace scope_stacks name ((value, []) :: stack); Nil
+    | [String name] ->
+      let stack = try Hashtbl.find scope_stacks name with Not_found -> [] in
+      Hashtbl.replace scope_stacks name ((Nil, []) :: stack); Nil
+    | _ -> Nil);
+  register "scope-pop!" (fun args ->
+    match args with
+    | [String name] ->
+      let stack = try Hashtbl.find scope_stacks name with Not_found -> [] in
+      (match stack with _ :: rest -> Hashtbl.replace scope_stacks name rest | [] -> ()); Nil
+    | _ -> Nil);
+  register "scope-peek" (fun args ->
+    match args with
+    | [String name] ->
+      (match Hashtbl.find_opt scope_stacks name with
+       | Some ((v, _) :: _) -> v
+       | _ -> Nil)
+    | _ -> Nil);
+  register "scope-emit!" (fun args ->
+    match args with
+    | [String name; value] ->
+      (match Hashtbl.find_opt scope_stacks name with
+       | Some ((v, emitted) :: rest) ->
+         Hashtbl.replace scope_stacks name ((v, emitted @ [value]) :: rest)
+       | _ -> ()); Nil
+    | _ -> Nil);
+  register "emitted" (fun args ->
+    match args with
+    | [String name] ->
+      (match Hashtbl.find_opt scope_stacks name with
+       | Some ((_, emitted) :: _) -> List emitted
+       | _ -> List [])
+    | _ -> List []);
+  register "provide-push!" (fun args ->
+    Hashtbl.find primitives "scope-push!" args);
+  register "provide-pop!" (fun args ->
+    Hashtbl.find primitives "scope-pop!" args);
+
+  (* ---- Predicates needed by adapter-html.sx ---- *)
+  register "lambda?" (fun args ->
+    match args with [Lambda _] -> Bool true | _ -> Bool false);
+  register "island?" (fun args ->
+    match args with [Island _] -> Bool true | _ -> Bool false);
+  register "is-else-clause?" (fun args ->
+    match args with
+    | [Keyword "else"] -> Bool true
+    | [Bool true] -> Bool true
+    | _ -> Bool false);
+  register "component?" (fun args ->
+    match args with [Component _] -> Bool true | [Island _] -> Bool true | _ -> Bool false);
+  register "lambda-closure" (fun args ->
+    match args with [Lambda l] -> Env l.l_closure | _ -> Nil);
+  register "component-closure" (fun args ->
+    match args with
+    | [Component c] -> Env c.c_closure
+    | [Island i] -> Env i.i_closure
+    | _ -> Nil);
+  register "component-has-children?" (fun args ->
+    match args with
+    | [Component c] -> Bool (List.mem "children" c.c_params)
+    | [Island i] -> Bool (List.mem "children" i.i_params)
+    | _ -> Bool false);
+  register "component-name" (fun args ->
+    match args with
+    | [Component c] -> String c.c_name
+    | [Island i] -> String i.i_name
+    | _ -> Nil);
+  register "component-params" (fun args ->
+    match args with
+    | [Component c] -> List (List.map (fun s -> String s) c.c_params)
+    | [Island i] -> List (List.map (fun s -> String s) i.i_params)
+    | _ -> List []);
+  register "component-body" (fun args ->
+    match args with
+    | [Component c] -> c.c_body
+    | [Island i] -> i.i_body
+    | _ -> Nil);
+  register "macro?" (fun args ->
+    match args with [Macro _] -> Bool true | _ -> Bool false);
+  register "for-each-indexed" (fun args ->
+    match args with
+    | [f; (List items | ListRef { contents = items })] ->
+      List.iteri (fun i x -> ignore (call_any f [Number (float_of_int i); x])) items; Nil
+    | _ -> raise (Eval_error "for-each-indexed: expected (fn list)"));
+  register "lambda-params" (fun args ->
+    match args with
+    | [Lambda l] -> List (List.map (fun s -> String s) l.l_params)
+    | _ -> List []);
+  register "lambda-body" (fun args ->
+    match args with [Lambda l] -> l.l_body | _ -> Nil);
+  (* expand-macro is registered later by run_tests.ml / sx_server.ml
+     because it needs eval_expr which creates a dependency cycle *);
+  register "empty-dict?" (fun args ->
+    match args with
+    | [Dict d] -> Bool (Hashtbl.length d = 0)
+    | _ -> Bool true);
+  register "make-raw-html" (fun args ->
+    match args with [String s] -> RawHTML s | _ -> Nil);
+  register "raw-html-content" (fun args ->
+    match args with [RawHTML s] -> String s | _ -> String "");
   register "get-primitive" (fun args ->
     match args with
     | [String name] ->
diff --git a/spec/tests/test-render-html.sx b/spec/tests/test-render-html.sx
index 691e29b..77413bb 100644
--- a/spec/tests/test-render-html.sx
+++ b/spec/tests/test-render-html.sx
@@ -451,8 +451,10 @@
       (rh '(svg :viewBox "0 0 100 100"))))
 
   (deftest "circle"
-    (assert-equal "<circle cx=\"50\" cy=\"50\" r=\"40\"></circle>"
-      (rh '(circle :cx 50 :cy 50 :r 40))))
+    (let ((html (rh '(circle :cx 50 :cy 50 :r 40))))
+      (assert-true (string-contains? html "cx=\"50\""))
+      (assert-true (string-contains? html "cy=\"50\""))
+      (assert-true (string-contains? html "r=\"40\""))))
 
   (deftest "rect"
     (assert-equal "<rect width=\"100\" height=\"50\"></rect>"