sx-http: header island working, stepper partial, CSSX source included

Include cssx.sx source in component-defs for client CSSX runtime.
Island placeholders now contain SX call expression for client hydration.
escape_sx_string only escapes </script, not all </ sequences.
serialize_value: no (list) wrapper, matching Python serialize() exactly.

Homepage: header renders (<sx>, tagline, copyright), stepper shows
raw SX (cssx/tw not expanding client-side). Geography fully rendered
including island hydration.

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

hosts/ocaml/bin/sx_server.ml

@@ -34,8 +34,10 @@ let escape_sx_string s =
     | '\n' -> Buffer.add_string buf "\\n"
     | '\r' -> Buffer.add_string buf "\\r"
     | '\t' -> Buffer.add_string buf "\\t"
-    | '<' when i + 1 < len && s.[i + 1] = '/' ->
-      (* Escape </ as <\\/ to prevent HTML parser matching </script> *)
+    | '<' when i + 7 < len && s.[i + 1] = '/' &&
+               (s.[i + 2] = 's' || s.[i + 2] = 'S') &&
+               String.lowercase_ascii (String.sub s (i + 2) 6) = "script" ->
+      (* Escape </script as <\\/script to prevent HTML parser closing the tag *)
       Buffer.add_string buf "<\\\\/"
     | c    -> Buffer.add_char buf c
   done;
@@ -1515,6 +1517,15 @@ let http_render_page env path =
       | String s | SxExpr s -> s
       | _ -> serialize_value body_result
     in
+    (* Debug: dump aser for homepage *)
+    if path = "/sx/" then begin
+      try
+        let oc = open_out "/tmp/sx-aser-home.txt" in
+        output_string oc body_str;
+        close_out oc;
+        Printf.eprintf "[debug] Wrote aser for %s: %d bytes\n%!" path (String.length body_str)
+      with _ -> ()
+    end;
     let t2 = Unix.gettimeofday () in
     (* Phase 2: SSR — render to HTML using streaming buffer renderer.
        Writes directly to buffer, no intermediate string allocations. *)
@@ -1525,7 +1536,7 @@ let http_render_page env path =
           | [e] -> e | [] -> Nil | _ -> List (Symbol "<>" :: body_exprs) in
         let buf = Buffer.create 65536 in
         (try Sx_render.render_to_buffer buf body_expr env
-         with e -> Printf.eprintf "[http-ssr] partial: %s\n%!" (Printexc.to_string e));
+         with e -> Printf.eprintf "[http-ssr] partial for %s: %s\n%!" path (Printexc.to_string e));
         Buffer.contents buf
       with e ->
         Printf.eprintf "[http-ssr] failed: %s\n%!" (Printexc.to_string e); ""
@@ -1631,8 +1642,7 @@ let read_css_file path =
 let http_inject_shell_statics env static_dir sx_sxc =
   (* Component definitions for client *)
   let buf = Buffer.create 65536 in
-  Hashtbl.iter (fun sym v ->
-    let name = Sx_types.unintern sym in
+  Hashtbl.iter (fun _sym v ->
     match v with
     | Component c ->
       let ps = String.concat " " (
@@ -1646,24 +1656,24 @@ let http_inject_shell_statics env static_dir sx_sxc =
         (if i.i_has_children then ["&rest"; "children"] else [])) in
       Buffer.add_string buf (Printf.sprintf "(defisland ~%s (%s) %s)\n"
         i.i_name ps (serialize_value i.i_body))
-    | Lambda l when l.l_name <> None ->
-      (* Named lambdas — client needs utility functions like cssx-process-token *)
-      let fn_name = match l.l_name with Some n -> n | None -> name in
-      let ps = String.concat " " l.l_params in
-      Buffer.add_string buf (Printf.sprintf "(define %s (fn (%s) %s))\n"
-        fn_name ps (serialize_value l.l_body))
-    | Macro m ->
-      let ps = String.concat " " m.m_params in
-      let mname = match m.m_name with Some n -> n | None -> name in
-      Buffer.add_string buf (Printf.sprintf "(defmacro %s (%s) %s)\n"
-        mname ps (serialize_value m.m_body))
-    | Dict _ | Number _ | String _ | Bool _ | List _ | ListRef _ ->
-      (* Named values (dicts, lists, constants) — client needs CSSX config etc. *)
-      if String.length name > 0 && name.[0] <> '_' && name.[0] <> '*' then
-        Buffer.add_string buf (Printf.sprintf "(define %s %s)\n"
-          name (serialize_value v))
     | _ -> ()
   ) env.bindings;
+  (* Prepend client library source files — these define functions that
+     island components need at runtime (CSSX, signals, etc.).
+     Read directly from .sx files, same as Quart's _CLIENT_LIBRARY_SOURCES. *)
+  let project_dir = try Sys.getenv "SX_PROJECT_DIR" with Not_found ->
+    Filename.dirname (Filename.dirname static_dir) in
+  let templates_dir = project_dir ^ "/shared/sx/templates" in
+  let client_libs = [
+    templates_dir ^ "/cssx.sx";
+  ] in
+  List.iter (fun path ->
+    if Sys.file_exists path then begin
+      let src = In_channel.with_open_text path In_channel.input_all in
+      Buffer.add_string buf src;
+      Buffer.add_char buf '\n'
+    end
+  ) client_libs;
   let raw_defs = Buffer.contents buf in
   (* Component-defs are inlined in <script type="text/sx">.
      The escape_sx_string function handles </ → <\\/ inside string

hosts/ocaml/lib/sx_render.ml

@@ -258,8 +258,12 @@ and render_list_to_html head args env =
        | Component c when c.c_affinity = "client" -> ""  (* skip client-only *)
        | Component _ -> render_component v args env
        | Island _i ->
-         (* Islands are client-rendered — emit placeholder for hydration *)
-         Printf.sprintf "<span data-sx-island=\"%s\"></span>" _i.i_name
+         let call_sx = "(" ^ String.concat " " (List.map (fun v ->
+           match v with
+           | Symbol s -> s | Keyword k -> ":" ^ k | String s -> "\"" ^ s ^ "\""
+           | _ -> Sx_runtime.value_to_str v
+         ) (Symbol name :: args)) ^ ")" in
+         Printf.sprintf "<span data-sx-island=\"%s\">%s</span>" _i.i_name call_sx
        | Macro m ->
          let expanded = expand_macro m args env in
          do_render_to_html expanded env
@@ -501,10 +505,15 @@ and render_list_buf buf head args env =
        | Component c when c.c_affinity = "client" -> ()
        | Component _ -> render_component_buf buf v args env
        | Island _i ->
-         (* Islands are client-rendered — emit placeholder for hydration.
-            SSR of island bodies is unreliable (client-only symbols like
-            signals, DOM refs) and can cascade errors. *)
-         Buffer.add_string buf (Printf.sprintf "<span data-sx-island=\"%s\"></span>" _i.i_name)
+         (* Islands are client-rendered — emit placeholder with SX call
+            expression so the client can hydrate from source. *)
+         let call_sx = "(" ^ String.concat " " (List.map (fun v ->
+           match v with
+           | Symbol s -> s | Keyword k -> ":" ^ k | String s -> "\"" ^ s ^ "\""
+           | _ -> Sx_runtime.value_to_str v
+         ) (Symbol name :: args)) ^ ")" in
+         Buffer.add_string buf (Printf.sprintf "<span data-sx-island=\"%s\">%s</span>"
+           _i.i_name call_sx)
        | Macro m ->
          let expanded = expand_macro m args env in
          render_to_buf buf expanded env