diff --git a/src/lib/time/timevalue.hpp b/src/lib/time/timevalue.hpp
index 6de086b50..b036c9d18 100644
--- a/src/lib/time/timevalue.hpp
+++ b/src/lib/time/timevalue.hpp
@@ -194,6 +194,9 @@ namespace time {
       /** @internal diagnostics */
       operator std::string ()  const;
       
+      /** @return is in-domain, not a boundary value */
+      bool isRegular()  const;
+      
       // Supporting totally_ordered
       friend bool operator<  (TimeValue const& t1, TimeValue const& t2)  { return t1.t_ <  t2.t_; }
       friend bool operator<  (TimeValue const& t1, gavl_time_t t2)       { return t1.t_ <  t2   ; }
@@ -768,6 +771,13 @@ namespace time {
                                                 : TimeSpan{start, extension};
   }
   
+  inline bool
+  TimeValue::isRegular()  const
+  {
+    return Time::MIN < *this
+       and *this < Time::MAX;
+  }
+  
   
   inline
   TimeVar::TimeVar (FSecs const& fractionalSeconds)
diff --git a/tests/vault/gear/activity-detector-test.cpp b/tests/vault/gear/activity-detector-test.cpp
index f74d42d35..6e19d6411 100644
--- a/tests/vault/gear/activity-detector-test.cpp
+++ b/tests/vault/gear/activity-detector-test.cpp
@@ -262,10 +262,16 @@ namespace test {
           Activity& probe = detector.buildActivationProbe (someID);
           CHECK (probe.is (Activity::HOOK));
           
+          CHECK (not detector.wasInvoked (probe));
+          
           Time realTime = RealClock::now();
           probe.activate (realTime, detector.executionCtx);
           
           CHECK (detector.verifyInvocation(someID).timeArg(realTime));
+          
+          // Probe instance recalls last invocation "now" argument
+          CHECK (realTime == detector.invokeTime (probe));
+          CHECK (detector.wasInvoked (probe));
         }
       
       
diff --git a/tests/vault/gear/activity-detector.hpp b/tests/vault/gear/activity-detector.hpp
index 98398a896..259e40f2f 100644
--- a/tests/vault/gear/activity-detector.hpp
+++ b/tests/vault/gear/activity-detector.hpp
@@ -345,16 +345,18 @@ namespace test {
        */
       class ActivityProbe
         : public Activity
-        , activity::Hook
+        , public activity::Hook
         {
           Logger log_;
-          
+          TimeVar invoked_{Time::ANYTIME};
+
           activity::Proc
           activation ( Activity& thisHook
                      , Time now
                      , void* executionCtx)  override
           {
             REQUIRE (thisHook.is (Activity::HOOK));
+            invoked_ = now;
             if (data_.callback.arg == 0)
               {// no adapted target; just record this activation
                 log_(util::toString(now) + " ⧐ ");
@@ -375,6 +377,7 @@ namespace test {
                      , void* executionCtx)  override
           {
             REQUIRE (thisHook.is (Activity::HOOK));
+            invoked_ = now;
             if (data_.callback.arg == 0)
               {// no adapted target; just record this notification
                 log_(util::toString(now) + " --notify-↯• ");
@@ -412,6 +415,19 @@ namespace test {
             {
               return diagnostic();
             }
+          
+          
+          static Time
+          lastInvoked (Activity const* act)
+            {
+              if (act and act->verb_ == HOOK)
+                {
+                  ActivityProbe* probe = dynamic_cast<ActivityProbe*> (act->data_.callback.hook); 
+                  if (probe)
+                    return probe->invoked_;
+                }
+              return Time::NEVER;
+            }
         };
       
       
@@ -543,6 +559,12 @@ namespace test {
         }
       
       
+      Time invokeTime (Activity const* hook) { return ActivityProbe::lastInvoked (hook); }
+      bool wasInvoked (Activity const* hook) { return invokeTime(hook).isRegular(); }
+      Time invokeTime (Activity const& hook) { return invokeTime (&hook); }
+      bool wasInvoked (Activity const& hook) { return wasInvoked (&hook); }
+      
+      
       struct FakeExecutionCtx;
       using SIG_post = activity::Proc(Time, Activity*, FakeExecutionCtx&);
       using SIG_work = void(Time, size_t);
diff --git a/tests/vault/gear/scheduler-service-test.cpp b/tests/vault/gear/scheduler-service-test.cpp
index d46674b28..43e3a484b 100644
--- a/tests/vault/gear/scheduler-service-test.cpp
+++ b/tests/vault/gear/scheduler-service-test.cpp
@@ -30,6 +30,7 @@
 #include "vault/gear/scheduler.hpp"
 #include "lib/time/timevalue.hpp"
 #include "lib/format-cout.hpp"
+#include "lib/test/diagnostic-output.hpp"///////////////TODO
 //#include "lib/util.hpp"
 
 //#include <utility>
@@ -106,6 +107,14 @@ namespace test {
           cout << detector.showLog()<<endl; // HINT: use this for investigation...
           CHECK (detector.verifyInvocation("testProbe"));
           ////////////////////////////////////////////////////////////////////////////////////TODO need a way to get the actual time passed to the Probe
+SHOW_EXPR(now)
+SHOW_EXPR(detector.invokeTime(probe))
+
+          auto wasClose = [](TimeValue a, TimeValue b)
+                            {
+                              return Duration{Offset{a,b}} < Duration{FSecs{1,2000}}; // 500µs are considered "close"
+                            };
+          CHECK (wasClose (now, detector.invokeTime (probe)));
         }
       
       
diff --git a/wiki/thinkPad.ichthyo.mm b/wiki/thinkPad.ichthyo.mm
index b839f412a..dabec0da9 100644
--- a/wiki/thinkPad.ichthyo.mm
+++ b/wiki/thinkPad.ichthyo.mm
@@ -88132,11 +88132,39 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
 <icon BUILTIN="pencil"/>
 <node CREATED="1698243387222" ID="ID_1151484757" MODIFIED="1698243397453" TEXT="und zwar direkten Aufruf, ohne WorkForce"/>
 <node CREATED="1698243399946" ID="ID_525069730" MODIFIED="1698243412341" TEXT="es kann zu Sleeps kommen"/>
-<node CREATED="1698243426549" ID="ID_1975979569" MODIFIED="1698243431240" TEXT="das bedeutet: Zeitmessung"/>
+<node CREATED="1698243426549" ID="ID_1975979569" MODIFIED="1698243431240" TEXT="das bedeutet: Zeitmessung">
+<node CREATED="1698269582160" ID="ID_211702790" MODIFIED="1698269611010" TEXT="und Pr&#xfc;fen unscharfer Zeitabst&#xe4;nde">
+<icon BUILTIN="messagebox_warning"/>
+<node CREATED="1698269686974" ID="ID_586911111" MODIFIED="1698269697257" TEXT="wie viel Genauigkeit kann man da &#xfc;berhaupt erwarten?"/>
+<node CREATED="1698269698148" ID="ID_220147663" MODIFIED="1698269740149" TEXT="RealClock::wasRecently  setzt 1ms an">
+<richcontent TYPE="NOTE"><html>
+  <head>
+    
+  </head>
+  <body>
+    <p>
+      ...und das erscheint ad&#228;quat f&#252;r moderne Maschinen
+    </p>
+  </body>
+</html>
+</richcontent>
+</node>
+<node BACKGROUND_COLOR="#eef0c5" COLOR="#990000" CREATED="1698269741040" ID="ID_868809913" MODIFIED="1698269752607" TEXT="verusche mal mein Gl&#xfc;ck mit 500&#xb5;s">
+<icon BUILTIN="pencil"/>
+</node>
+</node>
+<node CREATED="1698269618101" ID="ID_561925985" MODIFIED="1698269648550" TEXT="...das macht diesen Test ziemlich fragw&#xfc;rdig">
+<icon BUILTIN="broken-line"/>
+</node>
+<node BACKGROUND_COLOR="#fdfdcf" COLOR="#ff0000" CREATED="1698269656739" ID="ID_851832685" MODIFIED="1698269684671" TEXT="mu&#xdf; auf sehr deutliche Zeitungerschiede abzielen">
+<icon BUILTIN="yes"/>
+</node>
+</node>
 <node BACKGROUND_COLOR="#f0d5c5" COLOR="#990033" CREATED="1698243664309" ID="ID_654541946" MODIFIED="1698243687277" TEXT="was kann man sinnvollerweise pr&#xfc;fen?">
 <icon BUILTIN="help"/>
 <node CREATED="1698243697817" ID="ID_83311166" MODIFIED="1698243708627" TEXT="eine eingespiele Activity wird aufgerufen"/>
-<node CREATED="1698243756225" ID="ID_489965107" MODIFIED="1698243775440" TEXT="was f&#xe4;llig ist, wird sofort aufgerufen"/>
+<node CREATED="1698243756225" ID="ID_489965107" MODIFIED="1698268874810" TEXT="was f&#xe4;llig ist, wird direkt vom post() aufgerufen"/>
+<node CREATED="1698243756225" ID="ID_831882516" MODIFIED="1698268923359" TEXT="was f&#xe4;llig wurde, wird unverz&#xf6;gert aufgerufen"/>
 <node CREATED="1698243881573" ID="ID_1520192624" MODIFIED="1698243892539" TEXT="es wird genau eine scheduled Activity aufgerufen"/>
 <node CREATED="1698243927930" ID="ID_1326757783" MODIFIED="1698243935709" TEXT="die Zeit wird in etwa eingehalten"/>
 <node CREATED="1698243794737" ID="ID_1290805695" MODIFIED="1698243800463" TEXT="das Delay-Regime">
@@ -88163,8 +88191,8 @@ Date:&#160;&#160;&#160;Thu Apr 20 18:53:17 2023 +0200<br/>
 <icon BUILTIN="info"/>
 </node>
 </node>
-<node BACKGROUND_COLOR="#eee5c3" COLOR="#990000" CREATED="1698246249997" ID="ID_221908219" MODIFIED="1698246271187" TEXT="mu&#xdf; mir die now-Zeit in ActivityProbe speichern">
-<icon BUILTIN="flag-yellow"/>
+<node COLOR="#338800" CREATED="1698246249997" ID="ID_221908219" MODIFIED="1698269566601" TEXT="mu&#xdf; mir die now-Zeit in ActivityProbe speichern">
+<icon BUILTIN="button_ok"/>
 <node CREATED="1698246275186" ID="ID_389803917" MODIFIED="1698246286348" TEXT="bei jedem Aufruf im Objekt speichern"/>
 <node CREATED="1698246286912" ID="ID_1611070007" MODIFIED="1698246292046" TEXT="Zugriffs-Funktion schaffen"/>
 </node>