diff --git a/hosts/ocaml/browser/sx-platform.js b/hosts/ocaml/browser/sx-platform.js
index 64817559..02c210d4 100644
--- a/hosts/ocaml/browser/sx-platform.js
+++ b/hosts/ocaml/browser/sx-platform.js
@@ -57,6 +57,7 @@
     var obj = args[0], method = args[1];
     var callArgs = [];
     for (var i = 2; i < args.length; i++) callArgs.push(args[i]);
+    if (method === "addEventListener") console.log("[host-call] addEventListener args:", callArgs.map(a => typeof a === "function" ? "fn:" + (a.__host_callback ? "HOST_CB" : "other") : typeof a));
     if (obj == null) {
       // Global function call
       var fn = typeof globalThis !== "undefined" ? globalThis[method] : window[method];
@@ -157,12 +158,16 @@
     if (typeof fn === "function") return fn;
     // SX callable (has __sx_handle) — wrap as JS function
     if (fn && fn.__sx_handle !== undefined) {
-      return function() {
+      var wrappedFn = function() {
         var a = Array.prototype.slice.call(arguments);
+        console.log("[host-callback] FIRED handle=" + fn.__sx_handle);
         var r = K.callFn(fn, a);
+        console.log("[host-callback] callFn returned suspended=" + !!(r && r.suspended));
         if (window._driveAsync) window._driveAsync(r);
         return r;
       };
+      wrappedFn.__host_callback = true;
+      return wrappedFn;
     }
     return function() {};
   });
diff --git a/hosts/ocaml/browser/sx_browser.ml b/hosts/ocaml/browser/sx_browser.ml
index c4ddcab9..3263a785 100644
--- a/hosts/ocaml/browser/sx_browser.ml
+++ b/hosts/ocaml/browser/sx_browser.ml
@@ -91,7 +91,9 @@ let rec value_to_js (v : value) : Js.Unsafe.any =
   | Dict d ->
     (* Check for __host_handle — return original JS object *)
     (match Hashtbl.find_opt d "__host_handle" with
-     | Some (Number n) -> host_get_js (int_of_float n)
+     | Some (Number n) ->
+       Printf.eprintf "[value_to_js] Dict→host_get_js handle=%d\n%!" (int_of_float n);
+       host_get_js (int_of_float n)
      | _ ->
        let obj = Js.Unsafe.obj [||] in
        Js.Unsafe.set obj (Js.string "_type") (Js.string "dict");
@@ -168,7 +170,10 @@ and js_to_value (js : Js.Unsafe.any) : value =
     | "string" -> String (Js.to_string (Js.Unsafe.coerce js))
     | "function" ->
       let h = Js.Unsafe.get js (Js.string "__sx_handle") in
-      if not (Js.Unsafe.equals h Js.undefined) then
+      let has_host_cb = Js.to_bool (Js.Unsafe.coerce (Js.Unsafe.get js (Js.string "__host_callback"))) in
+      if has_host_cb then
+        Printf.eprintf "[js_to_value] fn has __host_callback! Storing as host obj\n%!";
+      if not (Js.Unsafe.equals h Js.undefined) && not has_host_cb then
         get_handle (Js.float_of_number (Js.Unsafe.coerce h) |> int_of_float)
       else
         (* Plain JS function — store as host object so value_to_js
@@ -176,6 +181,7 @@ and js_to_value (js : Js.Unsafe.any) : value =
            This preserves wrappers like _driveAsync that host-callback
            attaches for IO suspension handling. *)
         let id = host_put js in
+        Printf.eprintf "[js_to_value] plain JS fn → host_object id=%d\n%!" id;
         let d = Hashtbl.create 2 in
         Hashtbl.replace d "__host_handle" (Number (float_of_int id));
         Dict d