spec: promises — delay/force/delay-force/make-promise/promise?

25 tests pass on OCaml (4357 total) and JS. Promise represented as
mutable dict {:_promise true :forced :thunk :value}; delay-force
adds :_iterative for chain-following semantics.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

hosts/ocaml/bin/run_tests.ml

@@ -1141,6 +1141,26 @@ let make_test_env () =
       Sx_ref.cek_call consumer (List spread)
     | _ -> raise (Eval_error "call-with-values: expected 2 args"));
 
+  bind "promise?" (fun args ->
+    match args with
+    | [v] -> Bool (Sx_ref.is_promise v)
+    | _ -> Bool false);
+
+  bind "make-promise" (fun args ->
+    match args with
+    | [v] ->
+      let d = Hashtbl.create 4 in
+      Hashtbl.replace d "_promise" (Bool true);
+      Hashtbl.replace d "forced" (Bool true);
+      Hashtbl.replace d "value" v;
+      Dict d
+    | _ -> Nil);
+
+  bind "force" (fun args ->
+    match args with
+    | [p] -> Sx_ref.force_promise p
+    | _ -> Nil);
+
   env
 
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