diff --git a/sidekick-base.opam b/sidekick-base.opam
index 9ba376f3..cf87e388 100644
--- a/sidekick-base.opam
+++ b/sidekick-base.opam
@@ -17,7 +17,7 @@ depends: [
   "ocaml" { >= "4.04" }
   "sidekick" { = version }
   "zarith" { >= "1.8" } # constraint for infix ops
-  "bare_encoding"
+  "bare_encoding" {dev}
   "alcotest" {with-test}
   "qcheck" {with-test & >= "0.16" }
   "odoc" {with-doc}
diff --git a/src/base/Sidekick_base.ml b/src/base/Sidekick_base.ml
index 58565d79..1aa32bd7 100644
--- a/src/base/Sidekick_base.ml
+++ b/src/base/Sidekick_base.ml
@@ -35,5 +35,7 @@ module Solver_arg = Solver_arg
 module Lit = Lit
 module Proof_stub = Proof_stub
 
+module Proof_ser = Proof_ser
+
 (* re-export *)
 module IArray = IArray
diff --git a/src/base/dune b/src/base/dune
index 629f4c13..6007589d 100644
--- a/src/base/dune
+++ b/src/base/dune
@@ -5,11 +5,12 @@
  (libraries containers sidekick.core sidekick.util sidekick.lit
             sidekick.arith-lra sidekick.th-bool-static sidekick.th-data
             sidekick.zarith
-            bare_encoding zarith)
+            zarith)
  (flags :standard -w -32 -open Sidekick_util))
 
 (rule
   (targets proof_ser.ml)
   (deps proof_ser.bare)
-  (action (run bare-codegen %{deps} -o %{targets})))
+  (mode promote) ; not required in releases
+  (action (run bare-codegen --standalone %{deps} -o %{targets})))
 
diff --git a/src/base/proof_ser.ml b/src/base/proof_ser.ml
new file mode 100644
index 00000000..2f2feb89
--- /dev/null
+++ b/src/base/proof_ser.ml
@@ -0,0 +1,434 @@
+[@@@ocaml.warning "-26-27"]
+
+(* embedded runtime library *)
+module Bare = struct
+  
+module String_map = Map.Make(String)
+
+let spf = Printf.sprintf
+
+module Decode = struct
+  exception Error of string
+
+  type t = {
+    bs: bytes;
+    mutable off: int;
+  }
+
+  type 'a dec = t -> 'a
+
+  let fail_ e = raise (Error e)
+  let fail_eof_ what =
+    fail_ (spf "unexpected end of input, expected %s" what)
+
+  let uint (self:t) : int64 =
+    let rec loop () =
+      if self.off >= Bytes.length self.bs then fail_eof_ "uint";
+      let c = Char.code (Bytes.get self.bs self.off) in
+      self.off <- 1 + self.off; (* consume *)
+      if c land 0b1000_0000 <> 0 then (
+        let rest = loop() in
+        let c = Int64.of_int (c land 0b0111_1111) in
+        Int64.(logor (shift_left rest 7) c)
+      ) else (
+        Int64.of_int c (* done *)
+      )
+    in
+    loop()
+
+  let int (self:t) : int64 =
+    let open Int64 in
+    let i = uint self in
+    let sign_bit = logand 0b1L i in (* true if negative *)
+    let sign = equal sign_bit 0L in
+    let res =
+      if sign then (
+        shift_right_logical i 1
+      ) else (
+        (* put sign back *)
+        logor (shift_left 1L 63) (shift_right_logical (lognot i) 1)
+      )
+    in
+    res
+
+  let u8 self : char =
+    let x = Bytes.get self.bs self.off in
+    self.off <- self.off + 1;
+    x
+  let i8 = u8
+
+  let u16 self =
+    let x = Bytes.get_int16_le self.bs self.off in
+    self.off <- self.off + 2;
+    x
+  let i16 = u16
+
+  let u32 self =
+    let x = Bytes.get_int32_le self.bs self.off in
+    self.off <- self.off + 4;
+    x
+  let i32 = u32
+
+  let u64 self =
+    let i = Bytes.get_int64_le self.bs self.off in
+    self.off <- 8 + self.off;
+    i
+  let i64 = u64
+
+  let bool self : bool =
+    let c = Bytes.get self.bs self.off in
+    self.off <- 1 + self.off;
+    Char.code c <> 0
+
+  let f32 (self:t) : float =
+    let i = i32 self in
+    Int32.float_of_bits i
+
+  let f64 (self:t) : float =
+    let i = i64 self in
+    Int64.float_of_bits i
+
+  let data_of ~size self : bytes =
+    let s = Bytes.sub self.bs self.off size in
+    self.off <- self.off + size;
+    s
+
+  let data self : bytes =
+    let size = uint self in
+    if Int64.compare size (Int64.of_int Sys.max_string_length) > 0 then
+      fail_ "string too large";
+    let size = Int64.to_int size in (* fits, because of previous test *)
+    data_of ~size self
+
+  let string self : string =
+    Bytes.unsafe_to_string (data self)
+
+  let[@inline] optional dec self : _ option =
+    let c = u8 self in
+    if Char.code c = 0 then None else Some (dec self)
+end
+
+module Encode = struct
+  type t = Buffer.t
+
+  let of_buffer buf : t = buf
+
+  type 'a enc = t -> 'a -> unit
+
+  (* no need to check for overflow below *)
+  external unsafe_chr : int -> char = "%identity"
+
+  let uint (self:t) (i:int64) : unit =
+    let module I = Int64 in
+    let i = ref i in
+    let continue = ref true in
+    while !continue do
+      let j = I.logand 0b0111_1111L !i in
+      if !i = j then (
+        continue := false;
+        let j = I.to_int j in
+        Buffer.add_char self (unsafe_chr j)
+      ) else (
+        (* set bit 8 to [1] *)
+        let lsb = I.to_int (I.logor 0b1000_0000L j) in
+        let lsb = (unsafe_chr lsb) in
+        Buffer.add_char self lsb;
+        i := I.shift_right_logical !i 7;
+      )
+    done
+
+  let[@inline] int (self:t) i =
+    let open Int64 in
+    let ui = logxor (shift_left i 1) (shift_right i 63) in
+    uint self ui
+
+  let u8 self x = Buffer.add_char self x
+  let i8 = u8
+  let u16 self x = Buffer.add_int16_le self x
+  let i16 = u16
+  let u32 self x = Buffer.add_int32_le self x
+  let i32 = u32
+  let u64 self x = Buffer.add_int64_le self x
+  let i64 = u64
+
+  let bool self x = Buffer.add_char self (if x then Char.chr 1 else Char.chr 0)
+
+  let f64 (self:t) x = Buffer.add_int64_le self (Int64.bits_of_float x)
+
+  let data_of ~size self x =
+    if size <> Bytes.length x then failwith "invalid length for Encode.data_of";
+    Buffer.add_bytes self x
+
+  let data self x =
+    uint self (Int64.of_int (Bytes.length x));
+    Buffer.add_bytes self x
+
+  let string self x = data self (Bytes.unsafe_of_string x)
+
+  let[@inline] optional enc self x : unit =
+    match x with
+    | None -> u8 self (Char.chr 0)
+    | Some x ->
+      u8 self (Char.chr 1);
+      enc self x
+end
+
+let to_string (e:'a Encode.enc) (x:'a) =
+  let buf = Buffer.create 32 in
+  e buf x;
+  Buffer.contents buf
+
+let of_bytes_exn ?(off=0) dec bs =
+  let i = {Decode.bs; off} in
+  dec i
+
+let of_bytes ?off dec bs =
+  try Ok (of_bytes_exn ?off dec bs)
+  with Decode.Error e -> Error e
+
+let of_string_exn dec s = of_bytes_exn dec (Bytes.unsafe_of_string s)
+let of_string dec s = of_bytes dec (Bytes.unsafe_of_string s)
+
+
+(*$inject
+  let to_s f x =
+    let buf = Buffer.create 32 in
+    let out = Encode.of_buffer buf in
+    f out x;
+    Buffer.contents buf
+
+  let of_s f x =
+    let i = {Decode.off=0; bs=Bytes.unsafe_of_string x} in
+    f i
+*)
+
+(*$= & ~printer:Int64.to_string
+  37L (of_s Decode.uint (to_s Encode.uint 37L))
+  42L (of_s Decode.uint (to_s Encode.uint 42L))
+  0L (of_s Decode.uint (to_s Encode.uint 0L))
+  105542252L (of_s Decode.uint (to_s Encode.uint 105542252L))
+  Int64.max_int (of_s Decode.uint (to_s Encode.uint Int64.max_int))
+*)
+
+(*$= & ~printer:Int64.to_string
+  37L (of_s Decode.int (to_s Encode.int 37L))
+  42L (of_s Decode.int (to_s Encode.int 42L))
+  0L (of_s Decode.int (to_s Encode.int 0L))
+  105542252L (of_s Decode.int (to_s Encode.int 105542252L))
+  Int64.max_int (of_s Decode.int (to_s Encode.int Int64.max_int))
+  Int64.min_int (of_s Decode.int (to_s Encode.int Int64.min_int))
+  (-1209433446454112432L) (of_s Decode.int (to_s Encode.int (-1209433446454112432L)))
+  (-3112855215860398414L) (of_s Decode.int (to_s Encode.int (-3112855215860398414L)))
+*)
+
+(*$=
+  1 (let s = to_s Encode.int (-1209433446454112432L) in 0x1 land (Char.code s.[0]))
+*)
+
+(*$Q
+  Q.(int64) (fun s -> \
+    s = (of_s Decode.uint (to_s Encode.uint s)))
+*)
+
+(*$Q
+  Q.(int64) (fun s -> \
+    s = (of_s Decode.int (to_s Encode.int s)))
+*)
+
+(* TODO: some tests with qtest *)
+
+end
+
+module ProofID = struct
+  type t = int64
+  
+  (** @raise Bare.Decode.Error in case of error. *)
+  let decode (dec: Bare.Decode.t) : t =
+    Bare.Decode.int dec
+  
+  let encode (enc: Bare.Encode.t) (self: t) : unit =
+    Bare.Encode.int enc self
+  
+end
+
+module Lit = struct
+  type t = int64
+  
+  (** @raise Bare.Decode.Error in case of error. *)
+  let decode (dec: Bare.Decode.t) : t =
+    Bare.Decode.int dec
+  
+  let encode (enc: Bare.Encode.t) (self: t) : unit =
+    Bare.Encode.int enc self
+  
+end
+
+module ExprID = struct
+  type t = int64
+  
+  (** @raise Bare.Decode.Error in case of error. *)
+  let decode (dec: Bare.Decode.t) : t =
+    Bare.Decode.int dec
+  
+  let encode (enc: Bare.Encode.t) (self: t) : unit =
+    Bare.Encode.int enc self
+  
+end
+
+module Clause = struct
+  type t = {
+    lits: Lit.t array;
+  }
+  
+  (** @raise Bare.Decode.Error in case of error. *)
+  let decode (dec: Bare.Decode.t) : t =
+    let lits =
+      (let len = Bare.Decode.uint dec in
+       if len>Int64.of_int Sys.max_array_length then raise (Bare.Decode.Error"array too big");
+       Array.init (Int64.to_int len) (fun _ -> Lit.decode dec)) in
+    {lits; }
+  
+  let encode (enc: Bare.Encode.t) (self: t) : unit =
+    begin
+      (let arr = self.lits in
+       Bare.Encode.uint enc (Int64.of_int (Array.length arr));
+       Array.iter (fun xi -> Lit.encode enc xi) arr);
+    end
+  
+end
+
+module Step_rup = struct
+  type t = {
+    res: Clause.t;
+    steps: ProofID.t array;
+  }
+  
+  (** @raise Bare.Decode.Error in case of error. *)
+  let decode (dec: Bare.Decode.t) : t =
+    let res = Clause.decode dec in
+    let steps =
+      (let len = Bare.Decode.uint dec in
+       if len>Int64.of_int Sys.max_array_length then raise (Bare.Decode.Error"array too big");
+       Array.init (Int64.to_int len) (fun _ -> ProofID.decode dec)) in
+    {res; steps; }
+  
+  let encode (enc: Bare.Encode.t) (self: t) : unit =
+    begin
+      Clause.encode enc self.res;
+      (let arr = self.steps in
+       Bare.Encode.uint enc (Int64.of_int (Array.length arr));
+       Array.iter (fun xi -> ProofID.encode enc xi) arr);
+    end
+  
+end
+
+module Step_bridge_lit_expr = struct
+  type t = {
+    lit: Lit.t;
+    expr: ExprID.t;
+  }
+  
+  (** @raise Bare.Decode.Error in case of error. *)
+  let decode (dec: Bare.Decode.t) : t =
+    let lit = Lit.decode dec in let expr = ExprID.decode dec in {lit; expr; }
+  
+  let encode (enc: Bare.Encode.t) (self: t) : unit =
+    begin Lit.encode enc self.lit; ExprID.encode enc self.expr; end
+  
+end
+
+module Step_cc = struct
+  type t = {
+    eqns: ExprID.t array;
+  }
+  
+  (** @raise Bare.Decode.Error in case of error. *)
+  let decode (dec: Bare.Decode.t) : t =
+    let eqns =
+      (let len = Bare.Decode.uint dec in
+       if len>Int64.of_int Sys.max_array_length then raise (Bare.Decode.Error"array too big");
+       Array.init (Int64.to_int len) (fun _ -> ExprID.decode dec)) in
+    {eqns; }
+  
+  let encode (enc: Bare.Encode.t) (self: t) : unit =
+    begin
+      (let arr = self.eqns in
+       Bare.Encode.uint enc (Int64.of_int (Array.length arr));
+       Array.iter (fun xi -> ExprID.encode enc xi) arr);
+    end
+  
+end
+
+module Step_preprocess = struct
+  type t = {
+    t: ExprID.t;
+    u: ExprID.t;
+    using: ProofID.t;
+  }
+  
+  (** @raise Bare.Decode.Error in case of error. *)
+  let decode (dec: Bare.Decode.t) : t =
+    let t = ExprID.decode dec in
+    let u = ExprID.decode dec in
+    let using = ProofID.decode dec in
+    {t; u; using; }
+  
+  let encode (enc: Bare.Encode.t) (self: t) : unit =
+    begin
+      ExprID.encode enc self.t;
+      ExprID.encode enc self.u;
+      ProofID.encode enc self.using;
+    end
+  
+end
+
+module Step_view = struct
+  type t =
+    | Step_rup of Step_rup.t
+    | Step_bridge_lit_expr of Step_bridge_lit_expr.t
+    | Step_cc of Step_cc.t
+    
+  
+  (** @raise Bare.Decode.Error in case of error. *)
+  let decode (dec: Bare.Decode.t) : t =
+    let tag = Bare.Decode.uint dec in
+    match tag with
+    | 0L -> Step_rup (Step_rup.decode dec)
+    | 1L -> Step_bridge_lit_expr (Step_bridge_lit_expr.decode dec)
+    | 2L -> Step_cc (Step_cc.decode dec)
+    | _ -> raise (Bare.Decode.Error(Printf.sprintf "unknown union tag Step_view.t: %Ld" tag))
+    
+  
+  let encode (enc: Bare.Encode.t) (self: t) : unit =
+    match self with
+    | Step_rup x ->
+      Bare.Encode.uint enc 0L;
+      Step_rup.encode enc x
+    | Step_bridge_lit_expr x ->
+      Bare.Encode.uint enc 1L;
+      Step_bridge_lit_expr.encode enc x
+    | Step_cc x ->
+      Bare.Encode.uint enc 2L;
+      Step_cc.encode enc x
+    
+    
+end
+
+module Step = struct
+  type t = {
+    id: ProofID.t;
+    view: Step_view.t;
+  }
+  
+  (** @raise Bare.Decode.Error in case of error. *)
+  let decode (dec: Bare.Decode.t) : t =
+    let id = ProofID.decode dec in
+    let view = Step_view.decode dec in
+    {id; view; }
+  
+  let encode (enc: Bare.Encode.t) (self: t) : unit =
+    begin ProofID.encode enc self.id; Step_view.encode enc self.view; end
+  
+end
+
+