Page helpers in pure SX: 3 OCaml primitives + SX data + SX helpers

Add pretty-print, read-file, env-list-typed primitives to OCaml kernel.
Convert Python reference data (attrs, headers, events, primitives) to SX
data files. Implement page helpers (component-source, handler-source,
read-spec-file, reference-data, etc.) as pure SX functions.

The helper dispatcher in HTTP mode looks up named functions in the env
and calls them directly, replacing the Python IO bridge path.

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

hosts/ocaml/bin/sx_server.ml

@@ -1907,33 +1907,116 @@ let http_load_files env files =
   ) files;
   rebind_host_extensions env
 
+(* Pretty printer — AST value → formatted SX source string *)
+let pp_atom = Sx_types.inspect
+
+let rec est_width = function
+  | Nil -> 3 | Bool true -> 4 | Bool false -> 5
+  | Number n -> String.length (if Float.is_integer n then string_of_int (int_of_float n) else Printf.sprintf "%g" n)
+  | String s -> String.length s + 2
+  | Symbol s -> String.length s
+  | Keyword k -> String.length k + 1
+  | SxExpr s -> String.length s + 2
+  | List items | ListRef { contents = items } ->
+    2 + List.fold_left (fun acc x -> acc + est_width x + 1) 0 items
+  | _ -> 10
+
+let pretty_print_value ?(max_width=80) v =
+  let buf = Buffer.create 4096 in
+  let rec pp indent v =
+    match v with
+    | List items | ListRef { contents = items } when items <> [] ->
+      if est_width v <= max_width - indent then
+        Buffer.add_string buf (pp_atom v)
+      else begin
+        Buffer.add_char buf '(';
+        let head = List.hd items in
+        Buffer.add_string buf (pp_atom head);
+        let child_indent = indent + 2 in
+        let rest = List.tl items in
+        let rec emit = function
+          | [] -> ()
+          | Keyword k :: v :: rest ->
+            Buffer.add_char buf '\n';
+            Buffer.add_string buf (String.make child_indent ' ');
+            Buffer.add_char buf ':';
+            Buffer.add_string buf k;
+            Buffer.add_char buf ' ';
+            pp child_indent v;
+            emit rest
+          | item :: rest ->
+            Buffer.add_char buf '\n';
+            Buffer.add_string buf (String.make child_indent ' ');
+            pp child_indent item;
+            emit rest
+        in
+        emit rest;
+        Buffer.add_char buf ')'
+      end
+    | _ -> Buffer.add_string buf (pp_atom v)
+  in
+  pp 0 v;
+  Buffer.contents buf
+
 let http_setup_page_helpers env =
-  (* Page helpers that Python normally provides. Minimal stubs for HTTP mode.
-     These return empty/nil so pages render without hanging. *)
   let bind name fn = ignore (env_bind env name (NativeFn (name, fn))) in
-  (* highlight — passthrough without syntax coloring *)
-  bind "highlight" (fun args ->
+
+  (* Primitive 1: pretty-print — AST → formatted SX source *)
+  bind "pretty-print" (fun args ->
     match args with
-    | String code :: _ ->
-      let escaped = escape_sx_string code in
-      SxExpr (Printf.sprintf "(pre :class \"text-sm overflow-x-auto\" (code \"%s\"))" escaped)
-    | _ -> Nil);
-  (* Stub all Python page helpers with nil/empty returns *)
+    | [v] -> String (pretty_print_value v)
+    | _ -> raise (Eval_error "pretty-print: expected 1 argument"));
+
+  (* Primitive 2: read-file — path → string contents or nil *)
+  bind "read-file" (fun args ->
+    match args with
+    | [String path] ->
+      (try
+        let ic = open_in path in
+        let n = in_channel_length ic in
+        let s = Bytes.create n in
+        really_input ic s 0 n;
+        close_in ic;
+        String (Bytes.to_string s)
+      with _ -> Nil)
+    | _ -> raise (Eval_error "read-file: expected string path"));
+
+  (* Primitive 3: env-list-typed — list all bindings of a given type *)
+  bind "env-list-typed" (fun args ->
+    match args with
+    | [String type_name] ->
+      let matches = ref [] in
+      Hashtbl.iter (fun id v ->
+        let matches_type = match type_name, v with
+          | "component", Component _ -> true
+          | "island", Island _ -> true
+          | "lambda", Lambda _ -> true
+          | "macro", Macro _ -> true
+          | "native", NativeFn _ -> true
+          | _ -> false
+        in
+        if matches_type then
+          matches := String (Sx_types.unintern id) :: !matches
+      ) env.bindings;
+      List (List.sort compare !matches)
+    | _ -> raise (Eval_error "env-list-typed: expected type name string"));
+
+  (* helper dispatcher — looks up named function in env, calls it directly.
+     In coroutine mode this goes through the Python IO bridge.
+     In HTTP mode we dispatch locally to functions defined by SX helpers. *)
+  bind "helper" (fun args ->
+    match args with
+    | String name :: rest ->
+      (try
+        let fn = env_get env name in
+        Sx_ref.cek_call fn (List rest)
+      with Eval_error _ ->
+        Printf.eprintf "[helper] not found: %s\n%!" name;
+        Nil)
+    | _ -> raise (Eval_error "helper: expected (helper \"name\" ...args)"));
+
+  (* Stub remaining demo/action helpers that need real IO *)
   let stub name = bind name (fun _args -> Nil) in
-  let stub_s name = bind name (fun _args -> String "") in
-  stub_s "component-source";
-  stub_s "handler-source";
-  stub "primitives-data";
-  stub "special-forms-data";
-  stub "reference-data";
-  stub "attr-detail-data";
-  stub "header-detail-data";
-  stub "event-detail-data";
-  stub_s "read-spec-file";
-  stub "bootstrapper-data";
-  stub "bundle-analyzer-data";
-  stub "routing-analyzer-data";
-  stub "data-test-data";
   stub "run-spec-tests";
   stub "run-modular-tests";
   stub "streaming-demo-data";
@@ -1942,9 +2025,7 @@ let http_setup_page_helpers env =
   stub "action:add-demo-item";
   stub "offline-demo-data";
   stub "prove-data";
-  stub "page-helpers-demo-data";
-  stub "spec-explorer-data";
-  stub "spec-explorer-data-by-slug"
+  stub "page-helpers-demo-data"
 
 let http_mode port =
   let env = make_server_env () in
@@ -1972,6 +2053,11 @@ let http_mode port =
     let dev_path = project_dir ^ "/sx/sx" in
     if Sys.file_exists (docker_path ^ "/page-functions.sx") then docker_path
     else dev_path in
+  (* Expose project paths to SX helpers *)
+  ignore (env_bind env "_project-dir" (String project_dir));
+  ignore (env_bind env "_spec-dir" (String spec_base));
+  ignore (env_bind env "_lib-dir" (String lib_base));
+  ignore (env_bind env "_web-dir" (String web_base));
   let t0 = Unix.gettimeofday () in
   (* Core spec + adapters.
      Skip: primitives.sx (declarative metadata — all prims native in OCaml),