diff --git a/src/ide/why3_js.ml b/src/ide/why3_js.ml
index c0140b1a6bc589f88808e5b3c3790b4650034766..e5736be6ea883604bc1f754ce0ff7dfcdf28accf 100644
--- a/src/ide/why3_js.ml
+++ b/src/ide/why3_js.ml
@@ -561,7 +561,7 @@ let interpNotif (n: notification) =
       | Query_Error (_nid, s) ->
         PE.error_print_msg
           (Format.asprintf "Query error on selected node: \"%s\"" s)
-      | Query_Info (nid, s) -> PE.error_print_msg s
+      | Query_Info (_nid, s) -> PE.error_print_msg s
       | Help s -> PE.error_print_msg s
       | Information s -> PE.error_print_msg s
       | Error s ->
@@ -579,6 +579,7 @@ let interpNotif (n: notification) =
   | Node_change (nid, up) ->
     begin
       match up with
+      | Obsolete _ -> assert false (* TODO *)
       | Proved true -> TaskList.update_status `Valid (string_of_int nid)
       | Proved false -> TaskList.update_status `Unknown (string_of_int nid)
       | Proof_status_change (c, _obsolete, _rl) ->
diff --git a/src/session/controller_itp.ml b/src/session/controller_itp.ml
index 34c8bff34179fac517f4c328785c49bb140a7707..d718c6cb61551251dd640c8d720f6df8f03fd303 100644
--- a/src/session/controller_itp.ml
+++ b/src/session/controller_itp.ml
@@ -551,8 +551,7 @@ let run_timeout_handler () =
 
 let schedule_proof_attempt_r c id pr ~limit ~callback =
   let panid =
-    graft_proof_attempt c.controller_session id pr
-      ~timelimit:limit.Call_provers.limit_time
+    graft_proof_attempt c.controller_session id pr ~limit
   in
   Queue.add (c,id,pr,limit,callback panid) scheduled_proof_attempts;
   callback panid Scheduled;
@@ -812,7 +811,8 @@ let replay_print fmt (lr: (proofNodeID * Whyconf.prover * Call_provers.resource_
   in
   Format.fprintf fmt "%a@." (Pp.print_list Pp.newline pp_elem) lr
 
-let replay ~remove_obsolete ~use_steps c ~callback ~notification ~final_callback =
+let replay ?(obsolete_only=true) ?(use_steps=false)
+           c ~callback ~notification ~final_callback =
 
   let craft_report count s r id pr limits pa =
     match s with
@@ -834,15 +834,6 @@ let replay ~remove_obsolete ~use_steps c ~callback ~notification ~final_callback
        r := (id, pr, limits, Prover_not_installed) :: !r;
   in
 
-  let update_uninstalled c remove_obsolete id s pr =
-    match s with
-    | Uninstalled _ ->
-        if remove_obsolete then
-          remove_proof_attempt c.controller_session id pr
-        else
-          ()
-    | _ -> () in
-
   (* === replay === *)
   let session = c.controller_session in
   let count = ref 0 in
@@ -851,26 +842,28 @@ let replay ~remove_obsolete ~use_steps c ~callback ~notification ~final_callback
   (* TODO count the number of node in a more efficient way *)
   (* Counting the number of proof_attempt to print report only once *)
   Session_itp.session_iter_proof_attempt
-    (fun _ _ -> incr count) session;
+    (fun _ pa -> if pa.proof_obsolete || not obsolete_only then incr count) session;
 
   (* Replaying function *)
   let replay_pa id pa =
-    let parid = pa.parent in
-    let pr = pa.prover in
-    (* If use_steps, we give only steps as a limit *)
-    let limit =
-      if use_steps then
-        Call_provers.{empty_limit with limit_steps = pa.limit.limit_steps}
-      else
-        Call_provers.{ pa.limit with limit_steps = empty_limit.limit_steps }
-    in
-    replay_proof_attempt c pr limit parid id
-      ~callback:(fun id s ->
-        craft_report count s report parid pr limit pa;
-        update_uninstalled c remove_obsolete parid s pr;
-        callback id s;
-        if !count = 0 then final_callback !report)
-      ~notification in
+    if pa.proof_obsolete || not obsolete_only then
+      begin
+        let parid = pa.parent in
+        let pr = pa.prover in
+        (* If use_steps, we give only steps as a limit *)
+        let limit =
+          if use_steps then
+            Call_provers.{empty_limit with limit_steps = pa.limit.limit_steps}
+          else
+            Call_provers.{ pa.limit with limit_steps = empty_limit.limit_steps }
+        in
+        replay_proof_attempt c pr limit parid id
+                             ~callback:(fun id s ->
+                                        craft_report count s report parid pr limit pa;
+                                        callback id s;
+                                        if !count = 0 then final_callback !report)
+                             ~notification
+      end in
 
   (* Calling replay on all the proof_attempts of the session *)
   Session_itp.session_iter_proof_attempt replay_pa session
diff --git a/src/session/controller_itp.mli b/src/session/controller_itp.mli
index 6fa3a2d43ad82df0bd4b6ae335d494d1b9f7ed0a..e0c241f04cb8ab09b513bf0dd7713561b2b6bc35 100644
--- a/src/session/controller_itp.mli
+++ b/src/session/controller_itp.mli
@@ -250,10 +250,8 @@ val replay_print:
         unit
 
 val replay:
-    remove_obsolete:bool ->
-    (** If true, removes obsolete attempt in all cases. Otherwise keep it in
-        some cases: for example when prover is not installed *)
-    use_steps:bool -> (** Replay use recorded number of proof steps if true *)
+    ?obsolete_only:bool ->
+    ?use_steps:bool ->
     controller ->
     callback:(proofAttemptID -> proof_attempt_status -> unit) ->
     notification:(any -> bool -> unit) ->
@@ -261,11 +259,24 @@ val replay:
       ((proofNodeID * Whyconf.prover * Call_provers.resource_limit * report) list
             -> unit) ->
     unit
-(** This function reruns all the proofs of the session, and reports for all
-    proofs the current result and new one (does change the session state and if
-    remove_obsolete is true also remove obsolete proofs that could not be
-    replayed). When finished, call the callback with the reports which are
-    4-uples [(goalID, prover, limits, report)] *)
+(** This function reruns all the proofs of the session, and produces a report
+    comparing the results with the former ones.
+
+    The proofs are replayed asynchronously, and the states of these proofs are
+    notified via [callback] similarly as for [schedule_proof_attempt].
+
+    The session state is changed, all changes are notified via the
+    callback [notification]
+
+    When finished, call the callback [final_callback] with the report,
+a list of 4-uples [(goalID, prover, limits, report)]
+
+    When obsolete_only is set, only obsolete proofs are replayed (default)
+
+    When use_steps is set, replay use the recorded number of proof
+    steps (not set by default)
+
+ *)
 
 
 end
diff --git a/src/session/itp_server.ml b/src/session/itp_server.ml
index d1a32ff87cd1eaa9451128ed283120a24576932d..77328b854904636a55566006547db8b8b343a5d1 100644
--- a/src/session/itp_server.ml
+++ b/src/session/itp_server.ml
@@ -938,7 +938,7 @@ let () =
     let final_callback lr =
       P.notify (Message (Replay_Info (Pp.string_of C.replay_print lr))) in
     (* TODO make replay print *)
-    C.replay ~use_steps:false ~remove_obsolete:false d.cont
+    C.replay ~use_steps:false ~obsolete_only:true d.cont
              ~callback ~notification:notify_change_proved ~final_callback
 
   (* ---------------- Mark obsolete ------------------ *)
diff --git a/src/session/server_utils.ml b/src/session/server_utils.ml
index d9dea5136f4041ec192b1fe330171905660818f2..a04658b67cfbaab70a5b47ab66262c33c740be65 100644
--- a/src/session/server_utils.ml
+++ b/src/session/server_utils.ml
@@ -199,17 +199,17 @@ let parse_prover_name config name args :
       if (List.length args > 2) then None else
       match args with
       | [] ->
-        let default_limit = Call_provers.{limit_time = Whyconf.timelimit main;
-                                          limit_mem = Whyconf.memlimit main;
-                                          limit_steps = 0} in
+        let default_limit = Call_provers.{empty_limit with
+                                          limit_time = Whyconf.timelimit main;
+                                          limit_mem = Whyconf.memlimit main} in
           Some (prover_config, default_limit)
       | [timeout] -> Some (prover_config,
                            Call_provers.{empty_limit with
                                          limit_time = int_of_string timeout})
       | [timeout; oom ] ->
-        Some (prover_config, Call_provers.{limit_time = int_of_string timeout;
-                                           limit_mem = int_of_string oom;
-                                           limit_steps = 0})
+        Some (prover_config, Call_provers.{empty_limit with
+                                           limit_time = int_of_string timeout;
+                                           limit_mem = int_of_string oom})
       | _ -> None
     end
 
diff --git a/src/session/session_itp.ml b/src/session/session_itp.ml
index 8e2c7de3413da003276d50c578b4e62166ebf773..0858cb4bb18e5aceb4044e053965581a3a06679e 100644
--- a/src/session/session_itp.ml
+++ b/src/session/session_itp.ml
@@ -515,10 +515,7 @@ let add_proof_attempt session prover limit state obsolete edit parentID =
   id
 
 let graft_proof_attempt (s : session) (id : proofNodeID) (pr : Whyconf.prover)
-    ~timelimit =
-  let limit = { Call_provers.limit_time  = timelimit;
-                Call_provers.limit_mem   = 0;
-                Call_provers.limit_steps = -1; } in
+    ~limit =
   add_proof_attempt s pr limit None false None id
 
 
diff --git a/src/session/session_itp.mli b/src/session/session_itp.mli
index 3d044ff98cf9587fe894110af79691d65c6d06e7..3495e7fa454f495dbef4889dba8c0e47e2aec3f7 100644
--- a/src/session/session_itp.mli
+++ b/src/session/session_itp.mli
@@ -129,11 +129,11 @@ val merge_file_section :
     theory *)
 
 val graft_proof_attempt : session -> proofNodeID -> Whyconf.prover ->
-  timelimit:int -> proofAttemptID
-(** [graft_proof_attempt s id pr t] adds a proof attempt with prover
-    [pr] and timelimit [t] in the session [s] as a child of the task
+  limit:Call_provers.resource_limit -> proofAttemptID
+(** [graft_proof_attempt s id pr l] adds a proof attempt with prover
+    [pr] and limits [l] in the session [s] as a child of the task
     [id]. If there already a proof attempt with the same prover, it
-    updates it with the new timelimit. It returns the id of the
+    updates it with the limits. It returns the id of the
     generated proof attempt. *)
 
 val update_proof_attempt : session -> proofNodeID -> Whyconf.prover ->