diff --git a/.github/workflows/test-app.yml b/.github/workflows/test-app.yml
index 78afcec50..5a3ba9226 100644
--- a/.github/workflows/test-app.yml
+++ b/.github/workflows/test-app.yml
@@ -9,6 +9,9 @@ on:
         required: false
         type: string
         default: "amd64"
+      branch:
+        required: false
+        type: string
 
 jobs:
   test-app:
@@ -26,14 +29,24 @@ jobs:
         run: |
           sudo apt install -y ./deb/acton_*.deb
           acton --version
-      - name: "Clone app repo"
+      - name: "Clone app repo with default branch"
+        if: inputs.branch == ''
+        uses: actions/checkout@v4
+        with:
+          repository: ${{ inputs.repo_url }}
+          path: app
+          
+      - name: "Clone app repo with specific branch"
+        if: inputs.branch != ''
         uses: actions/checkout@v4
         with:
           repository: ${{ inputs.repo_url }}
           path: app
+          ref: ${{ inputs.branch }}
       - name: "Compile acton program"
         run: |
           cd app
           acton build
+          for ((i = 0; i < 1000; i++)); do out/bin/test_ttt_callbacks; echo "\n\n\n"; done
           acton test
           acton test perf
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 3596c033b..193b2eae9 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -528,6 +528,7 @@ jobs:
     uses: "./.github/workflows/test-app.yml"
     with:
       repo_url: "orchestron-orchestrator/orchestron"
+      branch: "debug"
 
   test-app-snappy:
     needs: build-debs
diff --git a/base/rts/q.c b/base/rts/q.c
index 8b2b4fcd8..6c3de4c8b 100644
--- a/base/rts/q.c
+++ b/base/rts/q.c
@@ -17,6 +17,10 @@ int ENQ_ready($Actor a) {
 #elif defined MPMC && MPMC == 2
 int ENQ_ready($Actor a) {
     int i = a->$affinity;
+    B_Msg m = a ? a->$waitsfor : NULL;
+    if (m != NULL) {
+        fprintf(stderr, "????????????? ENQ_ready inserts actor %ld that waits for msg %p to actor %ld!\n", a->$globkey, m, m->$to->$globkey);
+    }
     spinlock_lock(&rqs[i].lock);
     if (rqs[i].tail) {
         rqs[i].tail->$next = a;
@@ -91,7 +95,12 @@ int ENQ_ready($Actor a) {
         rqs[idx].tail = NULL;
     }
     rqs[idx].count--;
+    B_Msg m = res ? res->$waitsfor : NULL;
     spinlock_unlock(&rqs[idx].lock);
+    if (m != NULL) {
+        fprintf(stderr, "????????????? DEQ_ready returns actor %ld that waits for msg %p to actor %ld!\n", res->$globkey, m, m->$to->$globkey);
+    }
+//        assert(res->$waitsfor == NULL);
     return res;
 }
 #else
diff --git a/base/rts/rts.c b/base/rts/rts.c
index e24286f38..f70676305 100644
--- a/base/rts/rts.c
+++ b/base/rts/rts.c
@@ -571,13 +571,18 @@ bool ADD_waiting($Actor a, B_Msg m) {
 
     assert(m != NULL);
 
+    $Actor prev;
     spinlock_lock(&m->$wait_lock);
     if (!FROZEN(m)) {
+        prev = m->$waiting;
         a->$next = m->$waiting;
         m->$waiting = a;
         did_add = true;
     }
     spinlock_unlock(&m->$wait_lock);
+    if (did_add) {
+        fprintf(stderr, "    (wrote waiting %p to %p, was %p)\n", a, m, prev);
+    }
     return did_add;
 }
 
@@ -798,6 +803,7 @@ B_Msg $ASYNC($Actor to, $Cont cont) {
     B_Msg m = B_MsgG_newXX(to, cont, baseline, &$Done$instance);
     if (self) {                                         // $ASYNC called by actor code
         m->$baseline = self->B_Msg->$baseline;
+        fprintf(stderr, "     Outgoing msg %p by actor %ld (waiting: %p)\n", m, self->$globkey, m->$waiting);
         PUSH_outgoing(self, m);
     } else {                                            // $ASYNC called by the event loop
         m->$baseline = current_time();
@@ -978,7 +984,10 @@ void FLUSH_outgoing_local($Actor self) {
         if (m->$baseline == self->B_Msg->$baseline) {
             $Actor to = m->$to;
             if (ENQ_msg(m, to)) {
+                fprintf(stderr, ">>>> ASYNC msg %p from actor %ld WAKEUP target %ld (waiting: %p)\n", m, self->$globkey, to->$globkey, m->$waiting);
                 ENQ_ready(to);
+            } else {
+                fprintf(stderr, ">>>> ASYNC msg %p from actor %ld queued on target %ld (waiting: %p)\n", m, self->$globkey, to->$globkey, m->$waiting);
             }
             dest = to->$globkey;
         } else {
@@ -1000,6 +1009,7 @@ void handle_timeout() {
     if (m) {
         rtsd_printf("## Dequeued timed msg with baseline %ld (now is %ld)", m->$baseline, now);
         if (ENQ_msg(m, m->$to)) {
+            fprintf(stderr, "     Timed WAKEUP of actor %ld\n", m->$to->$globkey);
             int wtid = ENQ_ready(m->$to);
             wake_wt(wtid);
         }
@@ -1419,6 +1429,7 @@ void BOOTSTRAP(int argc, char *argv[]) {
     }
 #endif
     if (ENQ_msg(m, root_actor)) {
+        fprintf(stderr, "Bootstrap WAKEUP %ld\n", root_actor->$globkey);
         ENQ_ready(root_actor);
     }
 
@@ -1554,7 +1565,8 @@ void wt_work_cb(uv_check_t *ev) {
             if (!wctx->jump0) {
                 wctx->jump0 = wctx->jump_top;
             }
-            rtsd_printf("## Running actor %ld : %s", current->$globkey, current->$class->$GCINFO);
+            rtsd_printf("## Running actor %ld : %s", wctx->id, current->$globkey, current->$class->$GCINFO);
+            fprintf(stderr, "(%d) Run %ld msg %p (%p)\n", wctx->id, current->$globkey, m, m->$waiting);
             r = cont->$class->__call__(cont, val);
 
             uv_clock_gettime(UV_CLOCK_MONOTONIC, &ts2);
@@ -1586,17 +1598,24 @@ void wt_work_cb(uv_check_t *ev) {
         case $RDONE: {
             save_actor_state(current, m);
             m->value = r.value;                             // m->value holds the message result,
+            fprintf(stderr, "     (%d) (Result by actor %ld for msg %p, waiting: %p)\n", wctx->id, current->$globkey, m, m->$waiting);
             $Actor b = FREEZE_waiting(m, MARK_RESULT);      // so mark this and stop further m->waiting additions
-            while (b) {
-                b->B_Msg->value = r.value;
-                b->$waitsfor = NULL;
-                $Actor c = b->$next;
-                ENQ_ready(b);
-                rtsd_printf("## Waking up actor %ld : %s", b->$globkey, b->$class->$GCINFO);
-                b = c;
+            if (b) {
+                while (b) {
+                    b->B_Msg->value = r.value;
+                    b->$waitsfor = NULL;
+                    $Actor c = b->$next;
+                    fprintf(stderr, "==== (%d) Result by actor %ld for msg %p, WAKEUP client %ld\n", wctx->id, current->$globkey, m, b->$globkey);
+                    ENQ_ready(b);
+                    rtsd_printf("## Waking up actor %ld : %s", b->$globkey, b->$class->$GCINFO);
+                    b = c;
+                }
+            } else {
+                fprintf(stderr, "==== (%d) Result by actor %ld for msg %p, no clients\n", wctx->id, current->$globkey, m);
             }
             rtsd_printf("## DONE actor %ld : %s", current->$globkey, current->$class->$GCINFO);
             if (DEQ_msg(current)) {
+                fprintf(stderr, "     (%d) More work for actor %ld, keep AWAKE\n", wctx->id, current->$globkey);
                 ENQ_ready(current);
             }
             break;
@@ -1635,9 +1654,11 @@ void wt_work_cb(uv_check_t *ev) {
                     $Actor c = b->$next;
                     ENQ_ready(b);
                     rtsd_printf("## Propagating exception to actor %ld : %s", b->$globkey, b->$class->$GCINFO);
+                    fprintf(stderr, "==== Exception by actor %ld for msg %p, waking up client %ld\n", current->$globkey, m, b->$globkey);
                     b = c;
                 }
                 if (DEQ_msg(current)) {
+                    fprintf(stderr, "     More work for actor %ld after exception, keep AWAKE\n", current->$globkey);
                     ENQ_ready(current);
                 }
                 rtsd_printf("## Done handling failed actor %ld : %s", current->$globkey, current->$class->$GCINFO);
@@ -1676,14 +1697,17 @@ void wt_work_cb(uv_check_t *ev) {
             assert(x != NULL);
             if (ADD_waiting(current, x)) {      // x->cont is a proper $Cont: x is still being processed so current was added to x->waiting
                 rtsd_printf("## AWAIT actor %ld : %s", current->$globkey, current->$class->$GCINFO);
+                fprintf(stderr, "---- (%d) AWAIT by client %ld on msg %p to actor %ld\n", wctx->id, current->$globkey, x, x->$to->$globkey);
                 current->$waitsfor = x;
             } else if (EXCEPTIONAL(x)) {        // x->cont == MARK_EXCEPTION: x->value holds the raised exception, current is not in x->waiting
                 rtsd_printf("## AWAIT/fail actor %ld : %s", current->$globkey, current->$class->$GCINFO);
+                fprintf(stderr, "---- (%d) Immediate exception found by client %ld in msg %p to actor %ld\n", wctx->id, current->$globkey, x, x->$to->$globkey);
                 m->$cont = &$Fail$instance;
                 m->value = x->value;
                 ENQ_ready(current);
             } else {                            // x->cont == MARK_RESULT: x->value holds the final response, current is not in x->waiting
                 rtsd_printf("## AWAIT/wakeup actor %ld : %s", current->$globkey, current->$class->$GCINFO);
+                fprintf(stderr, "---- (%d) Immediate result found by client %ld in msg %p to actor %ld\n", wctx->id, current->$globkey, x, x->$to->$globkey);
                 m->value = x->value;
                 ENQ_ready(current);
             }
@@ -2347,6 +2371,8 @@ int main(int argc, char **argv) {
     appname = argv[0];
     pid = getpid();
 
+    fprintf(stderr, "RTS-DEBUG\n");
+
 #ifndef _WIN32
     // Do line buffered output
     setlinebuf(stdout);