diff --git a/src/amount.ml b/src/amount.ml
index 3caeaf68..7ff74514 100644
--- a/src/amount.ml
+++ b/src/amount.ml
@@ -1,8 +1,4 @@
-(* TODO
-   have a currency agnostic amount_lib.ml
-   and specialize amount.ml to Config.currency??
-
-   have safe amount arithmetic *)
+(* TODO implement operations on amounts *)
 open Syntax
 
 type sign =
diff --git a/src/api.ml b/src/api.ml
index 062ca181..2a6ea9cc 100644
--- a/src/api.ml
+++ b/src/api.ml
@@ -85,9 +85,6 @@ module Bytes64 = struct
       ~decode:of_octets Caqti_type.octets
 end
 
-(* TODO error response
-   - use GANA error codes
-     https://git.gnunet.org/gana.git/tree/gnu-taler-error-codes/registry.rec *)
 module ErrorDetail = struct
   type t = {
     code: int;
diff --git a/src/crypto.ml b/src/crypto.ml
index 5402e12b..5c480085 100644
--- a/src/crypto.ml
+++ b/src/crypto.ml
@@ -60,7 +60,7 @@ module Binary_format_rsa = struct
     let* arr = z_array_of_octets ~nb:2 s in
     match arr with
     | [| n; e |] ->
-        let+ pub = Mirage_crypto_pk.Rsa.pub ~n ~e |> unwrap_err_msg in
+        let+ pub = Mirage_crypto_pk.Rsa.pub ~n ~e |> unwrap_msg in
         pub
     | _ -> assert false
 
@@ -74,7 +74,7 @@ module Binary_format_rsa = struct
     match arr with
     | [| e; d; n; p; q; dp; dq; q' |] ->
         let+ priv =
-          Mirage_crypto_pk.Rsa.priv ~e ~d ~n ~p ~q ~dp ~dq ~q' |> unwrap_err_msg
+          Mirage_crypto_pk.Rsa.priv ~e ~d ~n ~p ~q ~dp ~dq ~q' |> unwrap_msg
         in
         priv
     | _ -> assert false
diff --git a/src/headers.ml b/src/headers.ml
index fd6ebfc7..6d4a64f7 100644
--- a/src/headers.ml
+++ b/src/headers.ml
@@ -6,7 +6,8 @@ let accept_header_value =
 let avail_languages_header_value =
   Fmt.str "%a" (Fmt.array ~sep:(Fmt.any ", ") Fmt.string) Assets.Language.arr
 
-(* TODO Cohttp raises on invalid *)
+(* TODO better headers_lib
+   Cohttp raises on invalid *)
 let select_mimetype headers =
   let opt = Vif.Headers.get headers "accept" in
   Cohttp.Accept.media_ranges opt
diff --git a/src/keys.ml b/src/keys.ml
index 6ad2a4f6..66b48442 100644
--- a/src/keys.ml
+++ b/src/keys.ml
@@ -1,7 +1,6 @@
 open Syntax
 open Crypto
 
-(* TODO better error type *)
 type 'a result = ('a, string) Result.t
 
 module type S = sig
@@ -33,8 +32,8 @@ module Make (Conn : Pg.CONN) : S = struct
 
   let conn = (module Conn : Pg.CONN)
 
-  (* TODO
-     error "key not found", either:
+  (* TODO better error
+     can only be "key not found", either:
        - we tried to sign with a key that is not ours
        - key was revoked
        - bad keyring state *)
@@ -49,8 +48,8 @@ module Make (Conn : Pg.CONN) : S = struct
     | Ok v -> v
 
   (* - *)
-  let find_signkey pub = Pg.find_signkey conn pub |> unwrap_err_caqti
-  let find_denomination h_pub = Pg.find_denom conn h_pub |> unwrap_err_caqti
+  let find_signkey pub = Pg.find_signkey conn pub |> unwrap_caqti
+  let find_denomination h_pub = Pg.find_denom conn h_pub |> unwrap_caqti
 
   let warn_key_state =
     let first = ref true in
@@ -65,7 +64,7 @@ module Make (Conn : Pg.CONN) : S = struct
 
   let signkeys () : Signkey.t list result =
     let now = Timestamp.of_ptime @@ Ptime_clock.now () in
-    let+ l = Pg.get_signkeys conn ~now |> unwrap_err_caqti in
+    let+ l = Pg.get_signkeys conn ~now |> unwrap_caqti in
     let missing_l, l =
       List.partition
         (fun sk -> Option.is_none @@ Sm_eddsa.find_key sk.Signkey.pub)
@@ -79,7 +78,7 @@ module Make (Conn : Pg.CONN) : S = struct
         l
 
   let denominations () =
-    let+ l = Pg.get_denominations conn () |> unwrap_err_caqti in
+    let+ l = Pg.get_denominations conn () |> unwrap_caqti in
     let missing_l, l =
       List.partition
         (fun dn -> Option.is_none @@ Sm_rsa.find_key dn.Denomination.h_pub)
@@ -201,7 +200,7 @@ module Make (Conn : Pg.CONN) : S = struct
   let make_future_keys_response () =
     let now = Timestamp.of_ptime @@ Ptime_clock.now () in
     (* get keys from database to filter out keys already certified *)
-    let* sk_db_l = Pg.get_signkeys conn ~now |> unwrap_err_caqti in
+    let* sk_db_l = Pg.get_signkeys conn ~now |> unwrap_caqti in
     let sk_ht = Hashtbl.create 0xff in
     List.iter (fun sk -> Hashtbl.replace sk_ht sk.Signkey.pub ()) sk_db_l;
     let future_signkeys =
@@ -209,7 +208,7 @@ module Make (Conn : Pg.CONN) : S = struct
       |> List.filter (fun (pub, _) -> not @@ Hashtbl.mem sk_ht pub)
       |> List.map make_future_sk
     in
-    let* dn_db_l = Pg.get_denominations conn () |> unwrap_err_caqti in
+    let* dn_db_l = Pg.get_denominations conn () |> unwrap_caqti in
     let dn_ht = Hashtbl.create 0xff in
     List.iter (fun dn -> Hashtbl.replace dn_ht dn.Denomination.h_pub ()) dn_db_l;
     let future_denoms =
@@ -303,7 +302,7 @@ module Make (Conn : Pg.CONN) : S = struct
             (* rebuild it *)
             let future_sk = make_future_sk (pub, (t1, t2)) in
             let sk = sk_of_future_sk future_sk master_sig in
-            let+ () = Pg.insert_signkey conn sk |> unwrap_err_caqti in
+            let+ () = Pg.insert_signkey conn sk |> unwrap_caqti in
             Logs.info (fun m ->
                 m "certified signkey `%s`" (EddsaPublicKey.to_b32 sk.pub));
             ())
@@ -321,7 +320,7 @@ module Make (Conn : Pg.CONN) : S = struct
         | None ->
             let future_dn = make_future_dn (h_pub, (section_name, pub, t1)) in
             let dn = dn_of_future_dn future_dn h_pub master_sig in
-            let+ () = Pg.insert_denom conn dn |> unwrap_err_caqti in
+            let+ () = Pg.insert_denom conn dn |> unwrap_caqti in
             Logs.info (fun m ->
                 m "certified denomination `%s`"
                   (DenominationHash.to_b32 dn.h_pub));
@@ -332,7 +331,7 @@ module Make (Conn : Pg.CONN) : S = struct
     let* _sk = Option.to_result ~none:"signkey not found" opt in
     let* () = Sm_eddsa.revoke pub in
     let+ () =
-      Pg.insert_signkey_revocation conn pub revoked_sig |> unwrap_err_caqti
+      Pg.insert_signkey_revocation conn pub revoked_sig |> unwrap_caqti
     in
     Logs.info (fun m -> m "revoked signkey `%s`" (EddsaPublicKey.to_b32 pub));
     ()
@@ -343,7 +342,7 @@ module Make (Conn : Pg.CONN) : S = struct
     let* () = Sm_rsa.revoke dn.h_pub in
     let+ () =
       Pg.insert_denomination_revocation conn dn.h_pub revoked_sig
-      |> unwrap_err_caqti
+      |> unwrap_caqti
     in
     Logs.info (fun m ->
         m "revoked denomination `%s`" (DenominationHash.to_b32 h_pub));
diff --git a/src/mte_info.ml b/src/mte_info.ml
index a57d7682..60c5bf59 100644
--- a/src/mte_info.ml
+++ b/src/mte_info.ml
@@ -41,13 +41,11 @@ let mk_keys ~db_conn (module Keys : Keys.S) ~last_issue_date =
   let stefan_lin = Config.stefan_lin in
   (* type of the asset. "fiat", "crypto", "regional" or "stock". *)
   let asset_type = "fiat" in
-  let* accounts = Pg.get_wire_accounts db_conn () |> unwrap_err_caqti in
+  let* accounts = Pg.get_wire_accounts db_conn () |> unwrap_caqti in
   let* wire_fees =
     (* wire_methods? *)
     let wire_method = "x-taler-bank" in
-    let+ wire_fees =
-      Pg.get_wire_fees db_conn ~wire_method |> unwrap_err_caqti
-    in
+    let+ wire_fees = Pg.get_wire_fees db_conn ~wire_method |> unwrap_caqti in
     String_map.singleton wire_method wire_fees
   in
   let wads = [] in
@@ -111,7 +109,7 @@ let mk_keys ~db_conn (module Keys : Keys.S) ~last_issue_date =
 
   let recoup = (* /recoup *) [] in
   let* global_fees =
-    Pg.get_global_fees db_conn ~start_date:Timestamp.zero |> unwrap_err_caqti
+    Pg.get_global_fees db_conn ~start_date:Timestamp.zero |> unwrap_caqti
   in
   let* auditors =
     (* /auditors/$AUDITOR_PUB/$H_DENOM_PUB *)
diff --git a/src/mte_management.ml b/src/mte_management.ml
index a5c45e55..d289678f 100644
--- a/src/mte_management.ml
+++ b/src/mte_management.ml
@@ -33,7 +33,7 @@ module Keys_post = struct
     Logs.info (fun m -> m "POST /management/keys/");
     let keys = Vif.Server.device Devices.keys server in
     let res =
-      let* v = Vif.Request.of_json req |> unwrap_err_msg in
+      let* v = Vif.Request.of_json req |> unwrap_msg in
       let* () = verify keys v in
       let* () = do_ keys v in
       Ok ()
@@ -59,7 +59,7 @@ module Denom_revoke = struct
     let keys = Vif.Server.device Devices.keys server in
     let res =
       let* h_denom_pub = Crypto.DenominationHash.of_b32 h_denom_pub in
-      let* v = Vif.Request.of_json req |> unwrap_err_msg in
+      let* v = Vif.Request.of_json req |> unwrap_msg in
       let* () = verify keys h_denom_pub v in
       let* () = do_ keys h_denom_pub v in
       Ok ()
@@ -85,7 +85,7 @@ module Signkey_revoke = struct
     let keys = Vif.Server.device Devices.keys server in
     let res =
       let* exchange_pub = Crypto.EddsaPublicKey.of_b32 exchange_pub in
-      let* v = Vif.Request.of_json req |> unwrap_err_msg in
+      let* v = Vif.Request.of_json req |> unwrap_msg in
       let* () = verify keys exchange_pub v in
       let* () = do_ keys exchange_pub v in
       Ok ()
@@ -114,18 +114,18 @@ module Auditors = struct
   let do_ ~db_conn v =
     let auditor_pub = v.AuditorSetupMessage.auditor_pub in
     let validity_start = v.AuditorSetupMessage.validity_start in
-    let* opt = Pg.find_auditor db_conn auditor_pub |> unwrap_err_caqti in
+    let* opt = Pg.find_auditor db_conn auditor_pub |> unwrap_caqti in
     match opt with
     | None ->
         let auditor = Auditor.of_setup_message v in
-        let+ () = Pg.update_auditor db_conn auditor |> unwrap_err_caqti in
+        let+ () = Pg.update_auditor db_conn auditor |> unwrap_caqti in
         Logs.info (fun m -> m "enabled auditor");
         ()
     | Some auditor ->
         if Timestamp.compare validity_start auditor.last_change <= 0 then
           Error "replay detected on enable-auditor"
         else
-          let+ () = Pg.update_auditor db_conn auditor |> unwrap_err_caqti in
+          let+ () = Pg.update_auditor db_conn auditor |> unwrap_caqti in
           Logs.info (fun m -> m "updated auditor");
           ()
 
@@ -136,7 +136,7 @@ module Auditors = struct
     let keys = Vif.Server.device Devices.keys server in
     let db_conn = Vif.Server.device Devices.db_connection server in
     let res =
-      let* v = Vif.Request.of_json req |> unwrap_err_msg in
+      let* v = Vif.Request.of_json req |> unwrap_msg in
       let* () = verify keys v in
       let* () = do_ ~db_conn v in
       Ok ()
@@ -153,7 +153,7 @@ module Auditors_disable = struct
 
   let do_ ~db_conn auditor_pub
       AuditorTeardownMessage.{ master_sig= _; validity_end } =
-    let* opt = Pg.find_auditor db_conn auditor_pub |> unwrap_err_caqti in
+    let* opt = Pg.find_auditor db_conn auditor_pub |> unwrap_caqti in
     match opt with
     | None -> Error "auditor not found"
     | Some auditor -> (
@@ -168,7 +168,7 @@ module Auditors_disable = struct
               let auditor =
                 { auditor with last_change= validity_end; is_active= false }
               in
-              let+ () = Pg.update_auditor db_conn auditor |> unwrap_err_caqti in
+              let+ () = Pg.update_auditor db_conn auditor |> unwrap_caqti in
               Logs.info (fun m ->
                   m "revoked auditor `%s`"
                     (Crypto.EddsaPublicKey.to_b32 auditor_pub));
@@ -182,7 +182,7 @@ module Auditors_disable = struct
     let db_conn = Vif.Server.device Devices.db_connection server in
     let res =
       let* auditor_pub = Crypto.EddsaPublicKey.of_b32 auditor_pub in
-      let* v = Vif.Request.of_json req |> unwrap_err_msg in
+      let* v = Vif.Request.of_json req |> unwrap_msg in
       let* () = verify keys auditor_pub v in
       let* () = do_ ~db_conn auditor_pub v in
       Ok ()
@@ -215,11 +215,11 @@ module Wire_fee = struct
     let* wire_fees =
       Pg.get_wire_fees_by_time db_conn ~wire_method:v.wire_method
         ~start_date:v.fee_start ~end_date:v.fee_end
-      |> unwrap_err_caqti
+      |> unwrap_caqti
     in
     match wire_fees with
     | [] ->
-        let+ () = Pg.insert_wire_fee db_conn v |> unwrap_err_caqti in
+        let+ () = Pg.insert_wire_fee db_conn v |> unwrap_caqti in
         Logs.info (fun m -> m "added wire fee");
         ()
     | [ vv ] -> (
@@ -241,7 +241,7 @@ module Wire_fee = struct
     let keys = Vif.Server.device Devices.keys server in
     let db_conn = Vif.Server.device Devices.db_connection server in
     let res =
-      let* v = Vif.Request.of_json req |> unwrap_err_msg in
+      let* v = Vif.Request.of_json req |> unwrap_msg in
       let* () = verify keys v in
       let* () = do_ ~db_conn v in
       Ok ()
@@ -256,12 +256,11 @@ module Global_fees = struct
     let* global_fees =
       let start_date = v.GlobalFees.start_date in
       let end_date = v.GlobalFees.end_date in
-      Pg.get_global_fees_by_time db_conn ~start_date ~end_date
-      |> unwrap_err_caqti
+      Pg.get_global_fees_by_time db_conn ~start_date ~end_date |> unwrap_caqti
     in
     match global_fees with
     | [] ->
-        let+ () = Pg.insert_global_fees db_conn v |> unwrap_err_caqti in
+        let+ () = Pg.insert_global_fees db_conn v |> unwrap_caqti in
         Logs.info (fun m -> m "added global fees");
         ()
     | [ vv ] -> (
@@ -287,7 +286,7 @@ module Global_fees = struct
     Logs.info (fun m -> m "POST /management/global-fees/");
     let db_conn = Vif.Server.device Devices.db_connection server in
     let res =
-      let* v = Vif.Request.of_json req |> unwrap_err_msg in
+      let* v = Vif.Request.of_json req |> unwrap_msg in
       let* () = verify v in
       let* () = do_ ~db_conn v in
       Ok ()
@@ -362,7 +361,7 @@ module Wire = struct
           bank_label;
           priority;
         } =
-    let* opt = Pg.find_wire db_conn ~payto_uri |> unwrap_err_caqti in
+    let* opt = Pg.find_wire db_conn ~payto_uri |> unwrap_caqti in
     match opt with
     | None ->
         let wire =
@@ -380,7 +379,7 @@ module Wire = struct
         let+ () =
           Pg.update_wire db_conn ~is_active:true ~last_change:validity_start
             wire
-          |> unwrap_err_caqti
+          |> unwrap_caqti
         in
         Logs.info (fun m -> m "added wire method");
         ()
@@ -391,7 +390,7 @@ module Wire = struct
           let+ () =
             Pg.update_wire db_conn ~is_active:true ~last_change:validity_start
               wire
-            |> unwrap_err_caqti
+            |> unwrap_caqti
           in
           Logs.info (fun m -> m "updated wire method");
           ()
@@ -403,7 +402,7 @@ module Wire = struct
     let keys = Vif.Server.device Devices.keys server in
     let db_conn = Vif.Server.device Devices.db_connection server in
     let res =
-      let* v = Vif.Request.of_json req |> unwrap_err_msg in
+      let* v = Vif.Request.of_json req |> unwrap_msg in
       let* () = verify keys v in
       let* () = do_ ~db_conn v in
       Ok ()
@@ -420,7 +419,7 @@ module Wire_disable = struct
 
   let do_ ~db_conn
       WireTeardownMessage.{ payto_uri; master_sig_del= _; validity_end } =
-    let* opt = Pg.find_wire db_conn ~payto_uri |> unwrap_err_caqti in
+    let* opt = Pg.find_wire db_conn ~payto_uri |> unwrap_caqti in
     match opt with
     | None -> Error "wire not found"
     | Some (wire, _is_active, last_change) ->
@@ -430,7 +429,7 @@ module Wire_disable = struct
           let+ () =
             Pg.update_wire db_conn ~is_active:false ~last_change:validity_end
               wire
-            |> unwrap_err_caqti
+            |> unwrap_caqti
           in
           Logs.info (fun m -> m "disabled wire method");
           ()
@@ -442,7 +441,7 @@ module Wire_disable = struct
     let keys = Vif.Server.device Devices.keys server in
     let db_conn = Vif.Server.device Devices.db_connection server in
     let res =
-      let* v = Vif.Request.of_json req |> unwrap_err_msg in
+      let* v = Vif.Request.of_json req |> unwrap_msg in
       let* () = verify keys v in
       let* () = do_ ~db_conn v in
       Ok ()
@@ -473,15 +472,14 @@ module Drain = struct
 
   let do_ ~db_conn v =
     let* opt =
-      Pg.find_drain_profit db_conn v.DrainProfitsMessage.wtid
-      |> unwrap_err_caqti
+      Pg.find_drain_profit db_conn v.DrainProfitsMessage.wtid |> unwrap_caqti
     in
     match opt with
     | Some _ ->
         Logs.info (fun m -> m "drain profit message already added to database");
         Ok ()
     | None ->
-        let+ () = Pg.insert_drain_profit db_conn v |> unwrap_err_caqti in
+        let+ () = Pg.insert_drain_profit db_conn v |> unwrap_caqti in
         Logs.info (fun m -> m "added drain profit message to database");
         ()
 
@@ -492,7 +490,7 @@ module Drain = struct
     let keys = Vif.Server.device Devices.keys server in
     let db_conn = Vif.Server.device Devices.db_connection server in
     let res =
-      let* v = Vif.Request.of_json req |> unwrap_err_msg in
+      let* v = Vif.Request.of_json req |> unwrap_msg in
       let* () = verify keys v in
       let* () = do_ ~db_conn v in
       Ok ()
@@ -522,7 +520,7 @@ module AmlOfficer = struct
       }
 
   let do_ ~db_conn v =
-    let+ _last_change = Pg.insert_aml_officer db_conn v |> unwrap_err_caqti in
+    let+ _last_change = Pg.insert_aml_officer db_conn v |> unwrap_caqti in
     ()
 
   let jsont = AmlOfficerSetup.jsont
@@ -532,7 +530,7 @@ module AmlOfficer = struct
     let keys = Vif.Server.device Devices.keys server in
     let db_conn = Vif.Server.device Devices.db_connection server in
     let res =
-      let* v = Vif.Request.of_json req |> unwrap_err_msg in
+      let* v = Vif.Request.of_json req |> unwrap_msg in
       let* () = verify keys v in
       let* () = do_ ~db_conn v in
       Ok ()
@@ -564,7 +562,7 @@ module Partners = struct
       }
 
   let do_ ~db_conn v =
-    let+ () = Pg.insert_partner db_conn v |> unwrap_err_caqti in
+    let+ () = Pg.insert_partner db_conn v |> unwrap_caqti in
     ()
 
   let jsont = ExchangePartnerSetupRequest.jsont
@@ -574,7 +572,7 @@ module Partners = struct
     let keys = Vif.Server.device Devices.keys server in
     let db_conn = Vif.Server.device Devices.db_connection server in
     let res =
-      let* v = Vif.Request.of_json req |> unwrap_err_msg in
+      let* v = Vif.Request.of_json req |> unwrap_msg in
       let* () = verify keys v in
       let* () = do_ ~db_conn v in
       Ok ()
diff --git a/src/pg.ml b/src/pg.ml
index eb4c789e..39b29992 100644
--- a/src/pg.ml
+++ b/src/pg.ml
@@ -1,11 +1,6 @@
 (* TODO
-   can we avoid amount tuple boilerplate?
-   clean up caqti error type
-
    transaction
-
-   GNU Taler use of db-events?
-   it seems caqti/pgx does not support it *)
+   GNU Taler use of db-events? it seems caqti/pgx does not support it *)
 
 module type CONN = Caqti_miou.CONNECTION
 
@@ -162,7 +157,7 @@ let get_auditor_keys =
   in
   fun (module Conn : CONN) ->
     let open Syntax in
-    let* l = Conn.collect_list req () |> unwrap_err_caqti in
+    let* l = Conn.collect_list req () |> unwrap_caqti in
     let ht = Hashtbl.create 0xff in
     List.iter
       (fun (pub, url, name, denom_pub_h, auditor_sig) ->
diff --git a/src/respond.ml b/src/respond.ml
index 17f67039..a7780c36 100644
--- a/src/respond.ml
+++ b/src/respond.ml
@@ -1,6 +1,3 @@
-(* TODO response
-   use ErrorDetail *)
-
 let encode_error_detail err =
   match Api.(encode ErrorDetail.jsont err) with
   | Error e -> Fmt.failwith "json encoding error on `ErrorDetail`: %s." e
diff --git a/src/secmod_eddsa.ml b/src/secmod_eddsa.ml
index 6cf9ac1e..12d1041e 100644
--- a/src/secmod_eddsa.ml
+++ b/src/secmod_eddsa.ml
@@ -46,13 +46,13 @@ let key_fpath k =
 
 let read_key fpath =
   Log.debug (fun m -> m "reading key file `%a`" Fpath.pp fpath);
-  let* data = Bos.OS.File.read fpath |> unwrap_err_msg in
+  let* data = Bos.OS.File.read fpath |> unwrap_msg in
   EddsaPrivateKey.of_octets data
 
 let write_eddsa fpath priv =
   Log.debug (fun m -> m "writing key file `%a`" Fpath.pp fpath);
   let data = EddsaPrivateKey.to_octets priv in
-  Bos.OS.File.write fpath data |> unwrap_err_msg
+  Bos.OS.File.write fpath data |> unwrap_msg
 
 let write_key k = write_eddsa (key_fpath k) k.priv
 
@@ -66,16 +66,14 @@ let delete_file fpath =
         Fpath.pp fpath
   in
   Log.debug (fun m -> m "delete key file `%a`" Fpath.pp fpath);
-  let+ () = Bos.OS.File.delete ~must_exist:true fpath |> unwrap_err_msg in
+  let+ () = Bos.OS.File.delete ~must_exist:true fpath |> unwrap_msg in
   ()
 
 let get_key_dir_contents dir =
-  let* dir = Fpath.of_string dir |> unwrap_err_msg in
-  let* b = Bos.OS.Dir.create ~mode:0o700 dir |> unwrap_err_msg in
+  let* dir = Fpath.of_string dir |> unwrap_msg in
+  let* b = Bos.OS.Dir.create ~mode:0o700 dir |> unwrap_msg in
   if b then Log.info (fun m -> m "created directory `%a`" Fpath.pp dir);
-  let+ l =
-    Bos.OS.Dir.contents ~dotfiles:false ~rel:false dir |> unwrap_err_msg
-  in
+  let+ l = Bos.OS.Dir.contents ~dotfiles:false ~rel:false dir |> unwrap_msg in
   List.map Fpath.normalize l
 
 (* -- *)
@@ -103,7 +101,7 @@ let split_in_periodes ~start ~end_ =
   in
   go acc start end_
 
-(* TODO do not exceed lookahead (probably more important...) *)
+(* TODO do not exceed lookahead *)
 (* try to not generate keys with validity start in the past *)
 let gen_additional_keys_until_lookahead ~now l =
   let start =
@@ -118,11 +116,10 @@ let gen_additional_keys_until_lookahead ~now l =
     let new_keys = List.map (fun (t1, t2) -> gen_key t1 t2) periodes in
     new_keys
 
-(* TODO config *)
 let sm_key_fpath =
   Result.get_ok
   @@
-  let+ fpath = Fpath.of_string Cfg.sm_priv_key |> unwrap_err_msg in
+  let+ fpath = Fpath.of_string Cfg.sm_priv_key |> unwrap_msg in
   Fpath.normalize fpath
 
 (* we load sm_key separately
@@ -221,5 +218,5 @@ end
   - more checks
   - sign: check timestamps before signing
   - schedule tasks
-  - !lock
+  - ! use lock
 *)
diff --git a/src/secmod_rsa.ml b/src/secmod_rsa.ml
index 698c8de4..edc70476 100644
--- a/src/secmod_rsa.ml
+++ b/src/secmod_rsa.ml
@@ -80,22 +80,22 @@ let key_fpath k =
 
 let read_eddsa fpath =
   Log.debug (fun m -> m "reading key file `%a`" Fpath.pp fpath);
-  let* data = Bos.OS.File.read fpath |> unwrap_err_msg in
+  let* data = Bos.OS.File.read fpath |> unwrap_msg in
   EddsaPrivateKey.of_octets data
 
 let read_rsa fpath =
   Log.debug (fun m -> m "reading key file `%a`" Fpath.pp fpath);
-  let* data = Bos.OS.File.read fpath |> unwrap_err_msg in
+  let* data = Bos.OS.File.read fpath |> unwrap_msg in
   RsaPrivateKey.of_octets data
 
 let write_eddsa fpath priv =
   Log.debug (fun m -> m "writing key file `%a`" Fpath.pp fpath);
   let data = EddsaPrivateKey.to_octets priv in
-  Bos.OS.File.write fpath data |> unwrap_err_msg
+  Bos.OS.File.write fpath data |> unwrap_msg
 
 let write_rsa fpath priv =
   let data = RsaPrivateKey.to_octets priv in
-  Bos.OS.File.write fpath data |> unwrap_err_msg
+  Bos.OS.File.write fpath data |> unwrap_msg
 
 let write_key k = write_rsa (key_fpath k) k.priv
 
@@ -109,14 +109,14 @@ let delete_file fpath =
         Fpath.pp fpath
   in
   Log.debug (fun m -> m "delete key file `%a`" Fpath.pp fpath);
-  let+ () = Bos.OS.File.delete ~must_exist:true fpath |> unwrap_err_msg in
+  let+ () = Bos.OS.File.delete ~must_exist:true fpath |> unwrap_msg in
   ()
 
 let get_key_dir_contents dir_fpath =
-  let* b = Bos.OS.Dir.create ~mode:0o700 dir_fpath |> unwrap_err_msg in
+  let* b = Bos.OS.Dir.create ~mode:0o700 dir_fpath |> unwrap_msg in
   if b then Log.info (fun m -> m "created directory `%a`" Fpath.pp dir_fpath);
   let+ l =
-    Bos.OS.Dir.contents ~dotfiles:false ~rel:false dir_fpath |> unwrap_err_msg
+    Bos.OS.Dir.contents ~dotfiles:false ~rel:false dir_fpath |> unwrap_msg
   in
   List.map Fpath.normalize l
 
@@ -168,7 +168,7 @@ let gen_additional_keys_until_lookahead ~now ~section_name l =
 let sm_key_fpath =
   Result.get_ok
   @@
-  let+ fpath = Fpath.of_string Cfg.sm_priv_key |> unwrap_err_msg in
+  let+ fpath = Fpath.of_string Cfg.sm_priv_key |> unwrap_msg in
   Fpath.normalize fpath
 
 (* we load sm_key separately
diff --git a/src/syntax.ml b/src/syntax.ml
index 7db544ca..5b4937bc 100644
--- a/src/syntax.ml
+++ b/src/syntax.ml
@@ -1,10 +1,13 @@
 let ( let* ) o f = match o with Ok v -> f v | Error _ as e -> e
 let ( let+ ) o f = match o with Ok v -> Ok (f v) | Error _ as e -> e
 
-(* TODO use polymorphic variant for errors *)
-let unwrap_err_msg o = match o with Error (`Msg e) -> Error e | Ok v -> Ok v
+(* TODO better errors
+   use polymorphic variant for errors
+   use GANA error codes:
+     https://git.gnunet.org/gana.git/tree/gnu-taler-error-codes/registry.rec *)
+let unwrap_msg o = match o with Error (`Msg e) -> Error e | Ok v -> Ok v
 
-let unwrap_err_caqti o =
+let unwrap_caqti o =
   match o with Error err -> Fmt.error "%a" Caqti_error.pp err | Ok v -> Ok v
 
 let list_iter f l =
diff --git a/src/time.mli b/src/time.mli
index ca3322c4..7955f822 100644
--- a/src/time.mli
+++ b/src/time.mli
@@ -50,7 +50,6 @@ module Timestamp : sig
   val of_absolute : TimeAbsolute.t -> t
   val of_ptime : Ptime.t -> t
 
-  (* TODO add pp *)
   (* - *)
   val bin : t Bin.t
   val caqti : t Caqti_type.t
diff --git a/test/management.sh b/test/management.sh
index af0d57a6..1a13d8bf 100755
--- a/test/management.sh
+++ b/test/management.sh
@@ -10,6 +10,8 @@ auditor_pub="A17JXR3E6J4CXDPYT7S1H25PGJ3ABS26TQ38654QCX0TB59RPMF0"
 master_key="./default/master_offline_private_key"
 zero_kudos="KUDOS:0.0"
 
+# TODO launch mte.exe and kill it a then end with its PID
+
 offline_tool() {
    dune exec offline -- "$@" > /dev/null
 }
diff --git a/test/test.ml b/test/test.ml
index b2462f9b..53de5106 100644
--- a/test/test.ml
+++ b/test/test.ml
@@ -34,8 +34,6 @@ let () =
   check Timestamp.jsont {|{"t_s": "never"}|};
   check_bad Timestamp.jsont {|{"t_s": "123456780"}|};
   check_bad Timestamp.jsont {|{"t_s": "agagou"}|};
-
-  (* TODO CS not implemented *)
   check_bad DenominationKey.jsont
     {|{"cipher": "CS", "age_mask": 18, "cs_pub": "ouhagag"}|};
   ()
diff --git a/test/validate_response.ml b/test/validate_response.ml
index dda024b0..77a3c718 100644
--- a/test/validate_response.ml
+++ b/test/validate_response.ml
@@ -12,8 +12,8 @@ let keys content =
     else Fmt.error "version incompatible"
   in
 
-  (* TODO validate ExchangeWireAccount
-     need hash over json *)
+  (* TODO json hash
+     validate wire *)
   let* () =
     let open AggregateTransferFee in
     v.wire_fees
@@ -52,7 +52,7 @@ let keys content =
     match opt with
     | None -> Fmt.error "exchange_pub is not in signkeys list"
     | Some _sk ->
-        (* TODO add a --now option?
+        (* todo add a --now option if we want to validate timestamps
         let now = Timestamp.of_ptime (Ptime_clock.now ()) in
         if Signkey.is_valid_at ~timestamp:now sk then Ok ()
         else Fmt.error "exchange_pub is not valid at the current time"
@@ -129,7 +129,7 @@ let keys_cmd =
   @@
   let+ input = input in
   let* content =
-    Result.bind (Fpath.of_string input) Bos.OS.File.read |> unwrap_err_msg
+    Result.bind (Fpath.of_string input) Bos.OS.File.read |> unwrap_msg
   in
   keys content
 
diff --git a/tools/offline_impl.ml b/tools/offline_impl.ml
index b327b99f..d3ab9e41 100644
--- a/tools/offline_impl.ml
+++ b/tools/offline_impl.ml
@@ -145,10 +145,10 @@ end
 
 (* -- *)
 
-let read_file fname = Bos.OS.File.read (Fpath.v fname) |> unwrap_err_msg
+let read_file fname = Bos.OS.File.read (Fpath.v fname) |> unwrap_msg
 
 let write_file fname content =
-  Bos.OS.File.write (Fpath.v fname) content |> unwrap_err_msg
+  Bos.OS.File.write (Fpath.v fname) content |> unwrap_msg
 
 let read_master_key_file filename =
   let* master_key = read_file filename in
@@ -167,7 +167,7 @@ let download ~output ~url =
       % "-X"
       % "GET"
       % url)
-  |> unwrap_err_msg
+  |> unwrap_msg
 
 let upload ~input ~url =
   let open Bos in
@@ -185,7 +185,7 @@ let upload ~input ~url =
       % "--data"
       % ("@" ^ input)
       % url)
-  |> unwrap_err_msg
+  |> unwrap_msg
 
 let setup ~output ~output_pubkey =
   Mirage_crypto_rng_unix.use_default ();