Wire adapter-html.sx into OCaml server, replacing hand-written renderer

sx_server.ml: sx_render_to_html() calls the SX adapter-html.sx render-to-html
via CEK eval, falling back to Sx_render.render_to_html if adapter not loaded.
CLI --render mode now loads render.sx + adapter-html.sx.

sx_primitives.ml: Added ~25 primitives needed by adapter-html.sx:
  scope-push!/pop!/peek/emit!, emitted, provide-push!/pop! (hashtable stack),
  lambda?/island?/component?/macro?, component-closure/name/params/body/
  has-children?, lambda-closure/params/body, is-else-clause?, for-each-indexed,
  empty-dict?, make-raw-html, raw-html-content

run_tests.ml: Loads render.sx + adapter-html.sx for test-render-html.sx.
Registers trampoline, eval-expr, scope stubs, expand-macro, cond-scheme?.

Status: 1105/1114 OCaml tests pass. 8 remaining failures are env-merge
edge cases in render-lambda-html/component-children/island rendering —
same adapter code works in JS (143/143).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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] ->