Fix defhandler: native special form in make_server_env

defhandler was only available via web-forms.sx which had load
dependencies that failed. Now registered as a native special form
in make_server_env, works in both coroutine and HTTP modes.

Key fix: custom special forms receive [List args; Env eval_env],
not flat args. The handler is now bound in the eval env, not the
make_server_env closure env.

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

hosts/ocaml/bin/sx_server.ml

@@ -692,6 +692,37 @@ let make_server_env () =
   setup_io_bridges env;
   setup_html_tags env;
   setup_io_env env;
+  (* defhandler — native special form. Called by CEK as (handler [raw-args; Env eval-env]).
+     Registers handler as handler:name in the eval env. *)
+  ignore (Sx_ref.register_special_form (String "defhandler") (NativeFn ("defhandler", fun sf_args ->
+    (* Custom special forms receive [List args; Env eval_env] *)
+    let raw_args, eval_env = match sf_args with
+      | [List a; Env e] | [ListRef { contents = a }; Env e] -> (a, e)
+      | _ -> ([], env) in
+    match raw_args with
+    | name_sym :: rest ->
+      let name = match name_sym with Symbol s -> s | String s -> s | _ -> Sx_types.inspect name_sym in
+      let rec parse_opts acc = function
+        | Keyword k :: v :: rest -> Hashtbl.replace acc k v; parse_opts acc rest
+        | rest -> (acc, rest) in
+      let opts = Hashtbl.create 4 in
+      let (_, remaining) = parse_opts opts rest in
+      let params, body = match remaining with
+        | List p :: b :: _ -> (p, b) | List p :: [] -> (p, Nil) | _ -> ([], Nil) in
+      let hdef = Hashtbl.create 8 in
+      Hashtbl.replace hdef "__type" (String "handler");
+      Hashtbl.replace hdef "name" (String name);
+      Hashtbl.replace hdef "params" (List params);
+      Hashtbl.replace hdef "body" body;
+      Hashtbl.replace hdef "closure" (Env eval_env);
+      Hashtbl.replace hdef "method" (match Hashtbl.find_opt opts "method" with
+        | Some (Keyword m) -> String m | Some v -> v | None -> String "get");
+      Hashtbl.replace hdef "path" (match Hashtbl.find_opt opts "path" with Some v -> v | None -> Nil);
+      Hashtbl.replace hdef "csrf" (match Hashtbl.find_opt opts "csrf" with Some v -> v | None -> Bool true);
+      Hashtbl.replace hdef "returns" (match Hashtbl.find_opt opts "returns" with Some v -> v | None -> String "element");
+      ignore (env_bind eval_env ("handler:" ^ name) (Dict hdef));
+      Dict hdef
+    | _ -> Nil)));
   (* Initialize trampoline ref so HO primitives (map, filter, etc.)
      can call SX lambdas. Must be done here because Sx_ref is only
      available at the binary level, not in the library. *)
@@ -1840,7 +1871,48 @@ let http_setup_declarative_stubs env =
   noop "define-primitive";
   noop "deftype";
   noop "defeffect";
-  noop "define-page-helper"
+  noop "define-page-helper";
+  (* defhandler — register as native special form so it works without web-forms.sx.
+     Parses the handler args and stores as handler:name in the env. *)
+  ignore (Sx_ref.register_special_form (String "defhandler") (NativeFn ("defhandler", fun args ->
+    match args with
+    | name_sym :: rest ->
+      let name = match name_sym with Symbol s -> s | String s -> s | _ -> Sx_types.inspect name_sym in
+      (* Parse keyword opts and find params/body *)
+      let rec parse_opts acc = function
+        | Keyword k :: v :: rest -> Hashtbl.replace acc k v; parse_opts acc rest
+        | rest -> (acc, rest)
+      in
+      let opts = Hashtbl.create 4 in
+      let (_, remaining) = parse_opts opts rest in
+      let params, body = match remaining with
+        | List p :: b :: _ -> (p, b)
+        | List p :: [] -> (p, Nil)
+        | _ -> ([], Nil)
+      in
+      let hdef = Hashtbl.create 8 in
+      Hashtbl.replace hdef "__type" (String "handler");
+      Hashtbl.replace hdef "name" (String name);
+      Hashtbl.replace hdef "params" (List params);
+      Hashtbl.replace hdef "body" body;
+      Hashtbl.replace hdef "closure" (Env env);
+      Hashtbl.replace hdef "method" (match Hashtbl.find_opt opts "method" with
+        | Some (Keyword m) -> String m | Some v -> v | None -> String "get");
+      Hashtbl.replace hdef "path" (match Hashtbl.find_opt opts "path" with
+        | Some v -> v | None -> Nil);
+      Hashtbl.replace hdef "csrf" (match Hashtbl.find_opt opts "csrf" with
+        | Some v -> v | None -> Bool true);
+      Hashtbl.replace hdef "returns" (match Hashtbl.find_opt opts "returns" with
+        | Some v -> v | None -> String "element");
+      let handler_key = "handler:" ^ name in
+      ignore (env_bind env handler_key (Dict hdef));
+      Dict hdef
+    | _ -> Nil)));
+  (* Also stub defquery/defaction/defrelation/defstyle as no-ops *)
+  noop "defquery";
+  noop "defaction";
+  noop "defrelation";
+  noop "defstyle"
 
 let http_setup_platform_constructors env =
   (* Platform constructor functions expected by evaluator.sx.