Hyperscript: focus command, diagnostic test output, blur keyword

Parser/compiler/runtime for focus command. Tokenizer: focus, blur,
precedes, follows, ignoring, case keywords. Test spec: per-test
failure output for diagnosis.

374/831 (45%)

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

hosts/ocaml/bin/sx_server.ml

@@ -1838,6 +1838,47 @@ let parse_http_headers data =
   ) (match lines with _ :: rest -> rest | [] -> []);
   !headers
 
+(* IO-aware eval for rendering — handles perform (text-measure, sleep, import).
+   Used by aser and SSR so components can call measure-text via perform. *)
+let eval_with_io_render expr env =
+  let state = ref (Sx_ref.cek_step_loop (Sx_ref.make_cek_state expr (Env env) Nil)) in
+  while sx_truthy (Sx_ref.cek_suspended_p !state) do
+    let request = Sx_ref.cek_io_request !state in
+    let op = match request with
+      | Dict d -> (match Hashtbl.find_opt d "op" with Some (String s) -> s | Some (Symbol s) -> s | _ -> "")
+      | _ -> "" in
+    let args = match request with
+      | Dict d -> (match Hashtbl.find_opt d "args" with Some v -> v | None -> Nil)
+      | _ -> Nil in
+    let result = match op with
+      | "text-measure" ->
+        let size = match args with
+          | List [_font; Number sz; _text] -> sz
+          | List [_font; Number sz] -> sz
+          | _ -> 16.0 in
+        let text = match args with
+          | List [_font; _sz; String t] -> t
+          | _ -> "" in
+        let char_width = size *. 0.6 in
+        let width = char_width *. (float_of_int (String.length text)) in
+        let d = Hashtbl.create 4 in
+        Hashtbl.replace d "width" (Number width);
+        Hashtbl.replace d "height" (Number size);
+        Hashtbl.replace d "ascent" (Number (size *. 0.8));
+        Hashtbl.replace d "descent" (Number (size *. 0.2));
+        Dict d
+      | "io-sleep" | "sleep" ->
+        let ms = match args with
+          | List (Number n :: _) -> n | Number n -> n | _ -> 0.0 in
+        Unix.sleepf (ms /. 1000.0); Nil
+      | "import" -> Nil
+      | _ -> Nil
+    in
+    state := Sx_ref.cek_step_loop (Sx_ref.cek_resume !state result)
+  done;
+  if sx_truthy (Sx_ref.cek_terminal_p !state) then Sx_ref.cek_value !state
+  else Nil
+
 (** Render a page. Routing + AJAX detection in SX (request-handler.sx),
     render pipeline (aser → SSR → shell) in OCaml for reliable env access. *)
 let http_render_page env path headers =
@@ -1889,7 +1930,7 @@ let http_render_page env path headers =
           (* AJAX: return SX wire format (aser output) with text/sx content type *)
           let body_result =
             let call = List [Symbol "aser"; List [Symbol "quote"; wrapped]; Env env] in
-            Sx_ref.eval_expr call (Env env) in
+            eval_with_io_render call env in
           let body_str = match body_result with
             | String s | SxExpr s -> s | _ -> serialize_value body_result in
           let t1 = Unix.gettimeofday () in
@@ -1903,7 +1944,7 @@ let http_render_page env path headers =
           let t1 = Unix.gettimeofday () in
           let body_result =
             let call = List [Symbol "aser"; List [Symbol "quote"; full_ast]; Env env] in
-            Sx_ref.eval_expr call (Env env) in
+            eval_with_io_render call env in
           let body_str = match body_result with
             | String s | SxExpr s -> s | _ -> serialize_value body_result in
           let t2 = Unix.gettimeofday () in
@@ -1913,7 +1954,7 @@ let http_render_page env path headers =
             if env_has env "render-to-html" then
               let render_call = List [Symbol "render-to-html";
                                       List [Symbol "quote"; body_expr]; Env env] in
-              (match Sx_ref.eval_expr render_call (Env env) with
+              (match eval_with_io_render render_call env with
                | String s | RawHTML s -> s | v -> Sx_runtime.value_to_str v)
             else Sx_render.sx_render_to_html env body_expr env
           with e -> Printf.eprintf "[http-ssr] failed for %s: %s\n%!" path (Printexc.to_string e); "" in