Add register-special-form!, collect!, random-int, try-rerender-page

- register-special-form!: guards defhandler/defisland from SX override
- collect!/collected/clear-collected!: scope accumulator primitives
- random-int: deterministic stub (returns lo)
- try-rerender-page: no-op stub for offline tests
- defpage now works via forms.sx (needs make-page-def — separate issue)

1702 → 1710 passing tests.

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

hosts/ocaml/bin/run_tests.ml

@@ -430,6 +430,31 @@ let make_test_env () =
     | [state] -> Sx_ref.cek_run state
     | _ -> Nil);
   bind "now-ms" (fun _args -> Number 1000.0);
+  bind "random-int" (fun args -> match args with [Number lo; _] -> Number lo | _ -> Number 0.0);
+  bind "try-rerender-page" (fun _args -> Nil);
+  bind "collect!" (fun args ->
+    match args with
+    | [String name; value] ->
+      let stack = try Hashtbl.find _scope_stacks name with Not_found -> [] in
+      (match stack with
+       | List items :: rest ->
+         if List.mem value items then Nil
+         else (Hashtbl.replace _scope_stacks name (List (items @ [value]) :: rest); Nil)
+       | _ ->
+         Hashtbl.replace _scope_stacks name (List [value] :: stack); Nil)
+    | _ -> Nil);
+  bind "collected" (fun args ->
+    match args with
+    | [String name] ->
+      let stack = try Hashtbl.find _scope_stacks name with Not_found -> [] in
+      (match stack with List items :: _ -> List items | _ -> List [])
+    | _ -> List []);
+  bind "clear-collected!" (fun args ->
+    match args with
+    | [String name] ->
+      let stack = try Hashtbl.find _scope_stacks name with Not_found -> [] in
+      (match stack with _ :: rest -> Hashtbl.replace _scope_stacks name (List [] :: rest) | [] -> ()); Nil
+    | _ -> Nil);
   bind "regex-find-all" (fun args ->
     (* Stub: supports simple ~name pattern for component scanning *)
     match args with
@@ -492,6 +517,13 @@ let make_test_env () =
   (* Declarative type/effect forms — no-ops at runtime *)
   bind "deftype" (fun _args -> Nil);
   bind "defeffect" (fun _args -> Nil);
+  bind "register-special-form!" (fun args ->
+    match args with
+    | [String name; fn_val] ->
+      (* Don't let SX modules override OCaml-registered defhandler/defisland *)
+      if name = "defhandler" || name = "defisland" then Nil
+      else (ignore (Sx_ref.register_special_form (String name) fn_val); Nil)
+    | _ -> Nil);
 
   (* defhandler — register handler as handler:name in eval env.
      Mirrors sx_server.ml's defhandler special form. *)