diff --git a/src/proto_alpha/bin_sc_rollup_node/inbox.ml b/src/proto_alpha/bin_sc_rollup_node/inbox.ml
index 6c587b8809922ed6da1f82db234ba02187121847..9c99c15c109074ff6625fbfa221eb5c4dd0c54af 100644
--- a/src/proto_alpha/bin_sc_rollup_node/inbox.ml
+++ b/src/proto_alpha/bin_sc_rollup_node/inbox.ml
@@ -70,39 +70,58 @@ module State = struct
   let set_message_tree = Store.MessageTrees.set
 end
 
-(* FIXME: https://gitlab.com/tezos/tezos/-/issues/3199
-   For the moment, the rollup node ignores L1 to L2 messages.
-*)
-let get_messages l1_ctxt head rollup =
+let get_messages Node_context.{l1_ctxt; rollup_address; _} head =
   let open Lwt_result_syntax in
   let* block = Layer1.fetch_tezos_block l1_ctxt head in
   let apply (type kind) accu ~source:_ (operation : kind manager_operation)
       _result =
+    let open Result_syntax in
+    let+ accu = accu in
     match operation with
-    | Sc_rollup_add_messages {rollup = rollup'; messages}
-      when Sc_rollup.Address.(rollup' = rollup) ->
+    | Sc_rollup_add_messages {rollup; messages}
+      when Sc_rollup.Address.(rollup = rollup_address) ->
+        let messages =
+          List.map
+            (fun message -> Store.Inbox.Message.External message)
+            messages
+        in
         List.rev_append messages accu
     | _ -> accu
   in
-  let apply_internal (type kind) accu ~source:_
-      (_operation : kind Apply_internal_results.internal_operation_contents)
-      (_result :
+  let apply_internal (type kind) accu ~source
+      (operation : kind Apply_internal_results.internal_operation)
+      (result :
         kind Apply_internal_results.successful_internal_operation_result) =
-    accu
+    let open Result_syntax in
+    let* accu = accu in
+    match (operation, result) with
+    | ( {
+          operation = Transaction {destination = Sc_rollup rollup; parameters; _};
+          source = Originated sender;
+          _;
+        },
+        ITransaction_result (Transaction_to_sc_rollup_result _) )
+      when Sc_rollup.Address.(rollup = rollup_address) ->
+        let+ payload =
+          Environment.wrap_tzresult @@ Script_repr.force_decode parameters
+        in
+        let message = Store.Inbox.Message.{payload; sender; source} in
+        Store.Inbox.Message.Internal message :: accu
+    | _ -> return accu
   in
-  let messages =
+  let*? messages =
     Layer1_services.(
       process_applied_manager_operations
-        []
+        (Ok [])
         block.operations
         {apply; apply_internal})
   in
   return (List.rev messages)
 
-let process_head Node_context.({l1_ctxt; rollup_address; _} as node_ctxt) store
-    Layer1.(Head {level; hash = head_hash} as head) =
+let process_head node_ctxt store Layer1.(Head {level; hash = head_hash} as head)
+    =
   let open Lwt_result_syntax in
-  let*! res = get_messages l1_ctxt head_hash rollup_address in
+  let*! res = get_messages node_ctxt head_hash in
   match res with
   | Error e -> head_processing_failure e
   | Ok [] -> return_unit
@@ -124,12 +143,7 @@ let process_head Node_context.({l1_ctxt; rollup_address; _} as node_ctxt) store
       @@ let*! history = State.history_of_hash store predecessor in
          let*! messages_tree = State.find_message_tree store predecessor in
          let*? level = Raw_level.of_int32 level in
-         let*? messages =
-           List.map_e
-             (fun message ->
-               Sc_rollup.Inbox.Message.(serialize @@ External message))
-             messages
-         in
+         let*? messages = List.map_e Store.Inbox.Message.serialize messages in
          let* messages_tree, history, inbox =
            Store.Inbox.add_messages
              store
diff --git a/src/proto_alpha/bin_sc_rollup_node/interpreter.ml b/src/proto_alpha/bin_sc_rollup_node/interpreter.ml
index 38c15746e6a667a27c5bd4f6e7a3602f93193968..093a3c34b00ba4341615460b0c6eabdc1b84bad9 100644
--- a/src/proto_alpha/bin_sc_rollup_node/interpreter.ml
+++ b/src/proto_alpha/bin_sc_rollup_node/interpreter.ml
@@ -98,10 +98,7 @@ module Make (PVM : Pvm.S) : S = struct
           let*! messages = Store.Messages.get store hash in
           let* state =
             List.fold_left_i_es
-              (fun message_counter state external_message ->
-                let message =
-                  Sc_rollup.Inbox.Message.External external_message
-                in
+              (fun message_counter state message ->
                 let*? payload =
                   Environment.wrap_tzresult
                     (Sc_rollup.Inbox.Message.serialize message)
diff --git a/src/proto_alpha/bin_sc_rollup_node/layer1_services.ml b/src/proto_alpha/bin_sc_rollup_node/layer1_services.ml
index 6dcd12d01413d6bc42086278211cfdf2f93efc49..922c75ab8afe2fa7c645e133f587f132e6e78d14 100644
--- a/src/proto_alpha/bin_sc_rollup_node/layer1_services.ml
+++ b/src/proto_alpha/bin_sc_rollup_node/layer1_services.ml
@@ -40,7 +40,7 @@ type 'accu operation_processor = {
     'kind.
     'accu ->
     source:public_key_hash ->
-    'kind Apply_internal_results.internal_operation_contents ->
+    'kind Apply_internal_results.internal_operation ->
     'kind Apply_internal_results.successful_internal_operation_result ->
     'accu;
 }
@@ -78,7 +78,7 @@ let process_applied_manager_operations operations accu f =
   and on_applied_internal_operations accu source internal_operation_results =
     let open Apply_internal_results in
     List.fold_left
-      (fun accu (Internal_operation_result ({operation; _}, result)) ->
+      (fun accu (Internal_operation_result (operation, result)) ->
         match result with
         | Applied result -> f.apply_internal accu ~source operation result
         | _ -> accu)
diff --git a/src/proto_alpha/bin_sc_rollup_node/layer1_services.mli b/src/proto_alpha/bin_sc_rollup_node/layer1_services.mli
index f6e5a10afecf985545ec24e125ebe4c0d0b9c174..669cacbe849526c151a95863d803106f72cd3d38 100644
--- a/src/proto_alpha/bin_sc_rollup_node/layer1_services.mli
+++ b/src/proto_alpha/bin_sc_rollup_node/layer1_services.mli
@@ -39,7 +39,7 @@ type 'accu operation_processor = {
     'kind.
     'accu ->
     source:public_key_hash ->
-    'kind Apply_internal_results.internal_operation_contents ->
+    'kind Apply_internal_results.internal_operation ->
     'kind Apply_internal_results.successful_internal_operation_result ->
     'accu;
 }
@@ -48,4 +48,4 @@ type 'accu operation_processor = {
     folds over the list of [operations] applying [operator] to
     transform [accu] along the way. *)
 val process_applied_manager_operations :
-  'a -> operation trace trace -> 'a operation_processor -> 'a
+  'a -> operation list list -> 'a operation_processor -> 'a
diff --git a/src/proto_alpha/bin_sc_rollup_node/store.ml b/src/proto_alpha/bin_sc_rollup_node/store.ml
index 7ec698f4a6395eec7089827031d9c5281a77f473..d465aee1983e73f7606f4f61913a242bc2d5578e 100644
--- a/src/proto_alpha/bin_sc_rollup_node/store.ml
+++ b/src/proto_alpha/bin_sc_rollup_node/store.ml
@@ -23,7 +23,8 @@
 (*                                                                           *)
 (*****************************************************************************)
 
-open Protocol.Alpha_context
+open Protocol
+open Alpha_context
 module Maker = Irmin_pack_unix.Maker (Tezos_context_encoding.Context.Conf)
 
 module IStore = struct
@@ -410,14 +411,10 @@ module Messages = Make_append_only_map (struct
 
   let string_of_key = Block_hash.to_b58check
 
-  (* FIXME: https://gitlab.com/tezos/tezos/-/issues/3199
-     For the moment, the rollup node ignores L1 to L2 messages.
-     When internal messages will also be considered, the following
-     should probably be changed into [Sc_rollup.Inbox.message list].
-  *)
-  type value = string list
+  type value = Inbox.Message.t list
 
-  let value_encoding = Data_encoding.(list string)
+  let value_encoding =
+    Data_encoding.(list @@ dynamic_size Inbox.Message.encoding)
 end)
 
 (** Inbox state for each block *)
diff --git a/src/proto_alpha/lib_protocol/alpha_context.mli b/src/proto_alpha/lib_protocol/alpha_context.mli
index b4aa6f4b162c8d7d834e8a6572340316c0fbd9cb..7235ef6faae84eb2d32f281c5ab24dbe5109f71a 100644
--- a/src/proto_alpha/lib_protocol/alpha_context.mli
+++ b/src/proto_alpha/lib_protocol/alpha_context.mli
@@ -2787,6 +2787,8 @@ module Sc_rollup : sig
 
       type serialized = private string
 
+      val encoding : t Data_encoding.t
+
       val unsafe_of_string : string -> serialized
 
       val serialize : t -> serialized tzresult
diff --git a/src/proto_alpha/lib_protocol/sc_rollup_arith.ml b/src/proto_alpha/lib_protocol/sc_rollup_arith.ml
index fe11af685a2c286fc02e9ded5e18419d811494f3..6df3ffac0caa966c1bf39562c713a6403a554c9c 100644
--- a/src/proto_alpha/lib_protocol/sc_rollup_arith.ml
+++ b/src/proto_alpha/lib_protocol/sc_rollup_arith.ml
@@ -837,15 +837,24 @@ module Make (Context : P) :
 
   let set_input_monadic {PS.inbox_level; message_counter; payload} =
     let open Monad.Syntax in
-    match Sc_rollup_inbox_message_repr.deserialize payload with
-    | Ok (External payload) ->
+    let payload =
+      match Sc_rollup_inbox_message_repr.deserialize payload with
+      | Error _ -> None
+      | Ok (External payload) -> Some payload
+      | Ok (Internal {payload; _}) -> (
+          match Micheline.root payload with
+          | String (_, payload) -> Some payload
+          | _ -> None)
+    in
+    match payload with
+    | Some payload ->
         let* boot_sector = Boot_sector.get in
         let msg = boot_sector ^ payload in
         let* () = CurrentLevel.set inbox_level in
         let* () = MessageCounter.set (Some message_counter) in
         let* () = NextMessage.set (Some msg) in
         return ()
-    | Error _ | Ok (Internal _) ->
+    | None ->
         let* () = CurrentLevel.set inbox_level in
         let* () = MessageCounter.set (Some message_counter) in
         let* () = Status.set WaitingForInputMessage in
diff --git a/src/proto_alpha/lib_protocol/sc_rollup_inbox_message_repr.mli b/src/proto_alpha/lib_protocol/sc_rollup_inbox_message_repr.mli
index 987b57e60b0a6d12aa8ad2c8c25a4a8ad2257fa8..7611afd6220ae770e956dd157f8dbd89a4abce12 100644
--- a/src/proto_alpha/lib_protocol/sc_rollup_inbox_message_repr.mli
+++ b/src/proto_alpha/lib_protocol/sc_rollup_inbox_message_repr.mli
@@ -63,6 +63,9 @@ type t = Internal of internal_inbox_message | External of string
 
 type serialized = private string
 
+(** Encoding for messages from Layer 1 to Layer 2 *)
+val encoding : t Data_encoding.t
+
 (** [serialize msg] encodes the inbox message [msg] in binary format. *)
 val serialize : t -> serialized tzresult
 
diff --git a/tezt/tests/contracts/proto_alpha/sc_rollup_forward.tz b/tezt/tests/contracts/proto_alpha/sc_rollup_forward.tz
new file mode 100644
index 0000000000000000000000000000000000000000..22789dbc3e169adcf7e458b843b505b2761ed75f
--- /dev/null
+++ b/tezt/tests/contracts/proto_alpha/sc_rollup_forward.tz
@@ -0,0 +1,12 @@
+parameter (pair address string) ;
+storage unit ;
+code { UNPAIR ;
+       DIP { NIL operation };
+       UNPAIR ;
+       CONTRACT string ;
+       ASSERT_SOME;
+       SWAP;
+       DIP { PUSH mutez 0 };
+       TRANSFER_TOKENS;
+       CONS;
+       PAIR; }
\ No newline at end of file
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- configuration of a smart contract optimistic rollup node.out b/tezt/tests/expected/sc_rollup.ml/Alpha- configuration of a smart contract optimistic rollup node.out
index 84c2be78f6289f388d664a1c3be011bab9953d96..de9331f43ea1e5e18063768d58431e77507341f1 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- configuration of a smart contract optimistic rollup node.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- configuration of a smart contract optimistic rollup node.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- consecutive commitments.out b/tezt/tests/expected/sc_rollup.ml/Alpha- consecutive commitments.out
index 53b1f4bce04a009a65d83bed9515086b69a32a66..c9116db63b8654f0d2feb9444d9fecd43809059a 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- consecutive commitments.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- consecutive commitments.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- ensure boot sector is used.out b/tezt/tests/expected/sc_rollup.ml/Alpha- ensure boot sector is used.out
index 1221615d6f31e06f43ab76d040696ab206d8e602..8b48c5f5d81550573ea9ceff07ab01fa780104db 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- ensure boot sector is used.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- ensure boot sector is used.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with '10 10 10 + +' --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with '10 10 10 + +' --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6626 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000626
       payload fees(the block proposer) ....... +ꜩ0.000626
-    Originate smart contract rollup of kind arith and type unit with boot sector '10 10 10 + +'
+    Originate smart contract rollup of kind arith and type string with boot sector '10 10 10 + +'
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6626 bytes
@@ -75,7 +75,7 @@ This sequence of operations was run:
 ./tezos-sc-rollup-client-alpha rpc get /global/state_hash
 "scs11h9A7VAzxxEkEW6ufnfbPnu717o4mc6hagzqvPLhLvHcXyRQVA"
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with 31 --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with 31 --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6616 bytes added (will add 20 for safety)
@@ -95,7 +95,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000616
       payload fees(the block proposer) ....... +ꜩ0.000616
-    Originate smart contract rollup of kind arith and type unit with boot sector '31'
+    Originate smart contract rollup of kind arith and type string with boot sector '31'
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6616 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- get genesis info of a sc rollup.out b/tezt/tests/expected/sc_rollup.ml/Alpha- get genesis info of a sc rollup.out
index 84c2be78f6289f388d664a1c3be011bab9953d96..de9331f43ea1e5e18063768d58431e77507341f1 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- get genesis info of a sc rollup.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- get genesis info of a sc rollup.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- get last cemented commitment hash and inbox level of a sc rollup.out b/tezt/tests/expected/sc_rollup.ml/Alpha- get last cemented commitment hash and inbox level of a sc rollup.out
index 84c2be78f6289f388d664a1c3be011bab9953d96..de9331f43ea1e5e18063768d58431e77507341f1 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- get last cemented commitment hash and inbox level of a sc rollup.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- get last cemented commitment hash and inbox level of a sc rollup.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- getting a smart-contract rollup address through the client.out b/tezt/tests/expected/sc_rollup.ml/Alpha- getting a smart-contract rollup address through the client.out
index 84c2be78f6289f388d664a1c3be011bab9953d96..de9331f43ea1e5e18063768d58431e77507341f1 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- getting a smart-contract rollup address through the client.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- getting a smart-contract rollup address through the client.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- list originated rollups.out b/tezt/tests/expected/sc_rollup.ml/Alpha- list originated rollups.out
index fa66c2b7a71399d306c471f8d321d44462ad9071..dec06cb9fe3b7f6ef36cc5dbf3e26e5d03b0d351 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- list originated rollups.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- list originated rollups.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
@@ -30,7 +30,7 @@ This sequence of operations was run:
         storage fees ........................... +ꜩ1.6535
 
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -50,7 +50,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
@@ -61,7 +61,7 @@ This sequence of operations was run:
         storage fees ........................... +ꜩ1.6535
 
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -81,7 +81,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
@@ -92,7 +92,7 @@ This sequence of operations was run:
         storage fees ........................... +ꜩ1.6535
 
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -112,7 +112,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
@@ -123,7 +123,7 @@ This sequence of operations was run:
         storage fees ........................... +ꜩ1.6535
 
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -143,7 +143,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
@@ -154,7 +154,7 @@ This sequence of operations was run:
         storage fees ........................... +ꜩ1.6535
 
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -174,7 +174,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
@@ -185,7 +185,7 @@ This sequence of operations was run:
         storage fees ........................... +ꜩ1.6535
 
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -205,7 +205,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
@@ -216,7 +216,7 @@ This sequence of operations was run:
         storage fees ........................... +ꜩ1.6535
 
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -236,7 +236,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
@@ -247,7 +247,7 @@ This sequence of operations was run:
         storage fees ........................... +ꜩ1.6535
 
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -267,7 +267,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
@@ -278,7 +278,7 @@ This sequence of operations was run:
         storage fees ........................... +ꜩ1.6535
 
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -298,7 +298,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- node advances PVM state with internal messages.out b/tezt/tests/expected/sc_rollup.ml/Alpha- node advances PVM state with internal messages.out
new file mode 100644
index 0000000000000000000000000000000000000000..4a842d17f5f71abc7e744928088c22cf3a77e0b1
--- /dev/null
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- node advances PVM state with internal messages.out	
@@ -0,0 +1,185 @@
+
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
+Node is bootstrapped.
+Estimated gas: 2509.092 units (will add 100 for safety)
+Estimated storage: 6614 bytes added (will add 20 for safety)
+Operation successfully injected in the node.
+Operation hash is '[OPERATION_HASH]'
+NOT waiting for the operation to be included.
+Use command
+  tezos-client wait for [OPERATION_HASH] to be included --confirmations 1 --branch [BLOCK_HASH]
+and/or an external block explorer to make sure that it has been included.
+This sequence of operations was run:
+  Manager signed operations:
+    From: [PUBLIC_KEY_HASH]
+    Fee to the baker: ꜩ0.000614
+    Expected counter: 1
+    Gas limit: 2610
+    Storage limit: 6634 bytes
+    Balance updates:
+      [PUBLIC_KEY_HASH] ... -ꜩ0.000614
+      payload fees(the block proposer) ....... +ꜩ0.000614
+    Originate smart contract rollup of kind arith and type string with boot sector ''
+      This smart contract rollup origination was successfully applied
+      Consumed gas: 2509.092
+      Storage size: 6614 bytes
+      Address: [SC_ROLLUP_HASH]
+      Genesis commitment hash: [SC_ROLLUP_COMMITMENT_HASH]
+      Balance updates:
+        [PUBLIC_KEY_HASH] ... -ꜩ1.6535
+        storage fees ........................... +ꜩ1.6535
+
+
+./tezos-client rpc get '/chains/main/blocks/head/context/sc_rollup/[SC_ROLLUP_HASH]/genesis_info'
+{ "level": 2,
+  "commitment_hash": "[SC_ROLLUP_COMMITMENT_HASH]" }
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs139rUcWoTB9MbNUEaWYn5RswKF7G2uENnRPq7Q9ByQRMahtB2NA"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"0"
+
+./tezos-sc-rollup-client-alpha get state value for vars/value
+"\000\000\000\007"
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs139EB5Ny4fma7o6nS9mGauvHFbwpfvsJijBU4tNjEr9QZ8ZJWQd"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"19"
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs139EB5Ny4fma7o6nS9mGauvHFbwpfvsJijBU4tNjEr9QZ8ZJWQd"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"19"
+
+./tezos-sc-rollup-client-alpha get state value for vars/value
+"\000\000\000\n"
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs12UMx1ykNkh7mGwph7oc47aPAYSZfSdx6E6gqHdNuD3fWoY5z7V"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"37"
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs12UMx1ykNkh7mGwph7oc47aPAYSZfSdx6E6gqHdNuD3fWoY5z7V"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"37"
+
+./tezos-sc-rollup-client-alpha get state value for vars/value
+"\000\000\000\r"
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs12ssnuPLi7HmVNDsZmAn38HQHQ3Yy7M8iqxALseKWEZjhetGdQj"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"56"
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs12ssnuPLi7HmVNDsZmAn38HQHQ3Yy7M8iqxALseKWEZjhetGdQj"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"56"
+
+./tezos-sc-rollup-client-alpha get state value for vars/value
+"\000\000\000\016"
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs11bU88Xg7RJhWwcd6xjATkP9KxurEXizBzGm99Y7f1AuwHSwMFr"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"75"
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs11bU88Xg7RJhWwcd6xjATkP9KxurEXizBzGm99Y7f1AuwHSwMFr"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"75"
+
+./tezos-sc-rollup-client-alpha get state value for vars/value
+"\000\000\000\019"
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs11deEDoFvXGQjSLah1h2N13p1PJTVQNqm1qxaSHUhX9HnZGK3wZ"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"94"
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs11deEDoFvXGQjSLah1h2N13p1PJTVQNqm1qxaSHUhX9HnZGK3wZ"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"94"
+
+./tezos-sc-rollup-client-alpha get state value for vars/value
+"\000\000\000\022"
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs13DumkywYF7EtycrHEqToSzBFnYBvJeTA2XUZySvttgXzWWP14d"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"113"
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs13DumkywYF7EtycrHEqToSzBFnYBvJeTA2XUZySvttgXzWWP14d"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"113"
+
+./tezos-sc-rollup-client-alpha get state value for vars/value
+"\000\000\000\025"
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs13RfGYbA1saxvGJMLCySU3tja9MNaqG4CRiWofbCuFiwNofAFCt"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"132"
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs13RfGYbA1saxvGJMLCySU3tja9MNaqG4CRiWofbCuFiwNofAFCt"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"132"
+
+./tezos-sc-rollup-client-alpha get state value for vars/value
+"\000\000\000\028"
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs11vJrzpmNeM3aydKLFC8LN2qzEiLPDW1hYUAWb9aFXKyveoZHGM"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"151"
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs11vJrzpmNeM3aydKLFC8LN2qzEiLPDW1hYUAWb9aFXKyveoZHGM"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"151"
+
+./tezos-sc-rollup-client-alpha get state value for vars/value
+"\000\000\000\031"
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs11daEh8MqwPhDawd8n5frMeRhoASh46rnJYNvFz2eSWiVeUfYwS"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"170"
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs11daEh8MqwPhDawd8n5frMeRhoASh46rnJYNvFz2eSWiVeUfYwS"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"170"
+
+./tezos-sc-rollup-client-alpha get state value for vars/value
+"\000\000\000\""
+
+./tezos-sc-rollup-client-alpha rpc get /global/state_hash
+"scs12P2MF8NUnH7BrSuRCuSjpBcYpL3ZGJwwm6N3WYkBxvbbwGhdtz"
+
+./tezos-sc-rollup-client-alpha rpc get /global/total_ticks
+"190"
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- node advances PVM state with messages.out b/tezt/tests/expected/sc_rollup.ml/Alpha- node advances PVM state with messages.out
index f100b69f970bc47c7626fdd8dacc53b77bbdfc81..6acafae0a4daa6da1cf68475b4c20f4ee289977b 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- node advances PVM state with messages.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- node advances PVM state with messages.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- node boots into the initial state.out b/tezt/tests/expected/sc_rollup.ml/Alpha- node boots into the initial state.out
index 77e1fedd0efc594c08dc889b1745c34d00868c8f..13564d8816a0a6ef7d4cd8b94e390508d8c0aa3a 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- node boots into the initial state.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- node boots into the initial state.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (commitm.out b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (commitm.out
index 521d45d24c569d3a7c8d18effe6c5fbb3cb9c698..58a2928ed662322914ff769494b8fa6bfc5bb0be 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (commitm.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (commitm.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (first_p.out b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (first_p.out
index 97123c74b8867447a34d694a0668f9d562c5b4c4..97ff8a99a1052d3ed66006ff00a587a2a5df5f3d 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (first_p.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (first_p.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (handles.out b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (handles.out
index a1d68e90b5ab47068e6fa2b913d604e9728039db..f62b3c5b741ad27289f0783d24e759d78ad5f3e9 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (handles.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (handles.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (message.out b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (message.out
index a43f2ad94eae4db39ac8bafeab4af1626c1df155..d25ce26b35643a530c0b4d58b7676f541dcab083 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (message.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (message.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (no_comm.out b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (no_comm.out
index 18695bb7f3bce050dba92913e8b8412916317127..e9640807e794dec29d5aadc70ef44caa53127426 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (no_comm.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (no_comm.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (node_us.out b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (node_us.out
index 925fe7c72e47e41deabcc765068c7db08204fb82..b20cc1155cb07624ac91d538b7a213651d1255ee 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (node_us.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (node_us.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (non_fin.out b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (non_fin.out
index 1fbe5d1cfbe1c7d0fa87dd45843324d080d947cd..cba6a64c700ce054a90c8e63be385d05824f0258 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (non_fin.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct handling of commitments in the rollup node (non_fin.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct maintenance of inbox in the rollup node (basic).out b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct maintenance of inbox in the rollup node (basic).out
index 31462e9d15420221d77f38f965bf4228e63de43c..c388500287a6022ebeba989cc7cae48b69ef3fac 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct maintenance of inbox in the rollup node (basic).out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct maintenance of inbox in the rollup node (basic).out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct maintenance of inbox in the rollup node (handles_ch.out b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct maintenance of inbox in the rollup node (handles_ch.out
index 679799b3f2df08f7c84f90cb796ab749593319dd..baee5739d0e569a2e047b33f2b78f1ded9bd30df 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct maintenance of inbox in the rollup node (handles_ch.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct maintenance of inbox in the rollup node (handles_ch.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct maintenance of inbox in the rollup node (stops).out b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct maintenance of inbox in the rollup node (stops).out
index 30b726333f4bba25b4582102f3cb7fbf7fe06768..3170d2c2a6858e4dafeaa42b780139a062303091 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct maintenance of inbox in the rollup node (stops).out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct maintenance of inbox in the rollup node (stops).out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- originate with boot sector.out b/tezt/tests/expected/sc_rollup.ml/Alpha- originate with boot sector.out
index eea1e76a3d1967218dd4508ac020b20e5ad317a3..bc4abe91fc0d630e26a0b7198944099696c1083e 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- originate with boot sector.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- originate with boot sector.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with '10 10 10 + +' --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with '10 10 10 + +' --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6626 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000626
       payload fees(the block proposer) ....... +ꜩ0.000626
-    Originate smart contract rollup of kind arith and type unit with boot sector '10 10 10 + +'
+    Originate smart contract rollup of kind arith and type string with boot sector '10 10 10 + +'
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6626 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- origination of a SCORU executes without error.out b/tezt/tests/expected/sc_rollup.ml/Alpha- origination of a SCORU executes without error.out
index 84c2be78f6289f388d664a1c3be011bab9953d96..de9331f43ea1e5e18063768d58431e77507341f1 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- origination of a SCORU executes without error.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- origination of a SCORU executes without error.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- pushing messages in the inbox - check inbox size.out b/tezt/tests/expected/sc_rollup.ml/Alpha- pushing messages in the inbox - check inbox size.out
index 63fb8c7e49022c83452cd48493add9f6bb7d4b17..f5cacfba21b8424c9b9ab1937e255ceba8a16252 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- pushing messages in the inbox - check inbox size.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- pushing messages in the inbox - check inbox size.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- pushing messages in the inbox - current messages hash.out b/tezt/tests/expected/sc_rollup.ml/Alpha- pushing messages in the inbox - current messages hash.out
index d09b3b1c5699e14b8d956ef020f9025238aaa9a6..28bd204f8482172b8735d6a5f74fff70c12fc60c 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- pushing messages in the inbox - current messages hash.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- pushing messages in the inbox - current messages hash.out	
@@ -1,5 +1,5 @@
 
-./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type unit booting with  --burn-cap 9999999
+./tezos-client --wait none originate sc rollup from '[PUBLIC_KEY_HASH]' of kind arith of type string booting with  --burn-cap 9999999
 Node is bootstrapped.
 Estimated gas: 2509.092 units (will add 100 for safety)
 Estimated storage: 6614 bytes added (will add 20 for safety)
@@ -19,7 +19,7 @@ This sequence of operations was run:
     Balance updates:
       [PUBLIC_KEY_HASH] ... -ꜩ0.000614
       payload fees(the block proposer) ....... +ꜩ0.000614
-    Originate smart contract rollup of kind arith and type unit with boot sector ''
+    Originate smart contract rollup of kind arith and type string with boot sector ''
       This smart contract rollup origination was successfully applied
       Consumed gas: 2509.092
       Storage size: 6614 bytes
diff --git a/tezt/tests/sc_rollup.ml b/tezt/tests/sc_rollup.ml
index a15007f5d26c59354d7cfacc6281cb87e6d6201a..88eb31b37057135a1bc28525e051a74689e908a6 100644
--- a/tezt/tests/sc_rollup.ml
+++ b/tezt/tests/sc_rollup.ml
@@ -153,7 +153,7 @@ let with_fresh_rollup f tezos_node tezos_client bootstrap1_key =
       ~src:bootstrap1_key
       ~kind:"arith"
       ~boot_sector:""
-      ~parameters_ty:"unit"
+      ~parameters_ty:"string"
       tezos_client
   in
   let sc_rollup_node =
@@ -263,7 +263,7 @@ let test_origination =
           ~burn_cap:Tez.(of_int 9999999)
           ~src:bootstrap1_key
           ~kind:"arith"
-          ~parameters_ty:"unit"
+          ~parameters_ty:"string"
           ~boot_sector:""
           client
       in
@@ -282,7 +282,7 @@ let with_fresh_rollup ?(boot_sector = "") f tezos_node tezos_client
       ~burn_cap:Tez.(of_int 9999999)
       ~src:bootstrap1_key
       ~kind:"arith"
-      ~parameters_ty:"unit"
+      ~parameters_ty:"string"
       ~boot_sector
       tezos_client
   in
@@ -923,8 +923,8 @@ let test_rollup_node_boots_into_initial_state =
    When the rollup node receives messages, we like to see evidence that the PVM
    has advanced.
 *)
-let test_rollup_node_advances_pvm_state =
-  let go client sc_rollup sc_rollup_node =
+let test_rollup_node_advances_pvm_state protocols =
+  let go ~internal client sc_rollup sc_rollup_node =
     let* genesis_info =
       RPC.Client.call ~hooks client @@ RPC.Sc_rollup.get_genesis_info sc_rollup
     in
@@ -937,17 +937,48 @@ let test_rollup_node_advances_pvm_state =
     Check.(level = init_level)
       Check.int
       ~error_msg:"Current level has moved past origination level (%L = %R)" ;
-
+    let* level, forwarder =
+      if not internal then return (level, None)
+      else
+        (* Originate forwarder contract to send internal messages to rollup *)
+        let* contract_id =
+          Client.originate_contract
+            ~alias:"rollup_deposit"
+            ~amount:Tez.zero
+            ~src:Constant.bootstrap1.alias
+            ~prg:"file:./tezt/tests/contracts/proto_alpha/sc_rollup_forward.tz"
+            ~init:"Unit"
+            ~burn_cap:Tez.(of_int 1)
+            client
+        in
+        let* () = Client.bake_for_and_wait client in
+        Log.info
+          "The forwarder %s contract was successfully originated"
+          contract_id ;
+        return (level + 1, Some contract_id)
+    in
     let test_message i =
       let* prev_state_hash =
         Sc_rollup_client.state_hash ~hooks sc_rollup_client
       in
       let* prev_ticks = Sc_rollup_client.total_ticks ~hooks sc_rollup_client in
+      let message = sf "%d %d + value" i ((i + 2) * 2) in
       let* () =
-        send_message
-          client
-          sc_rollup
-          (Printf.sprintf "[\"%d %d + value\"]" i ((i + 2) * 2))
+        match forwarder with
+        | None ->
+            (* External message *)
+            send_message client sc_rollup (sf "[%S]" message)
+        | Some forwarder ->
+            (* Internal message through forwarder *)
+            let* () =
+              Client.transfer
+                client
+                ~amount:Tez.zero
+                ~giver:Constant.bootstrap1.alias
+                ~receiver:forwarder
+                ~arg:(sf "Pair %S %S" sc_rollup message)
+            in
+            Client.bake_for_and_wait client
       in
       let* _ = Sc_rollup_node.wait_for_level sc_rollup_node (level + i) in
       let* encoded_value =
@@ -990,10 +1021,24 @@ let test_rollup_node_advances_pvm_state =
     (fun protocol ->
       setup ~protocol @@ fun node client ->
       with_fresh_rollup
-        (fun sc_rollup sc_rollup_node _filename ->
-          go client sc_rollup sc_rollup_node)
+        (fun sc_rollup_address sc_rollup_node _filename ->
+          go ~internal:false client sc_rollup_address sc_rollup_node)
+        node
+        client)
+    protocols ;
+
+  regression_test
+    ~__FILE__
+    ~tags:["run"; "node"; "internal"]
+    "node advances PVM state with internal messages"
+    (fun protocol ->
+      setup ~protocol @@ fun node client ->
+      with_fresh_rollup
+        (fun sc_rollup_address sc_rollup_node _filename ->
+          go ~internal:true client sc_rollup_address sc_rollup_node)
         node
         client)
+    protocols
 
 (* Ensure that commitments are stored and published properly.
    ----------------------------------------------------------
@@ -1887,7 +1932,7 @@ let test_consecutive_commitments =
           ~burn_cap:Tez.(of_int 9999999)
           ~src:bootstrap1_key
           ~kind:"arith"
-          ~parameters_ty:"unit"
+          ~parameters_ty:"string"
           ~boot_sector:""
           client
       in