diff --git a/.github/workflows/pr-test.yaml b/.github/workflows/pr-test.yaml
index 6f192a76..6d094a95 100644
--- a/.github/workflows/pr-test.yaml
+++ b/.github/workflows/pr-test.yaml
@@ -11,6 +11,12 @@ on:
 permissions:
   contents: read
 
+# Only one validation run at a time on the self-hosted runner to prevent
+# resource contention (GPU, Docker, disk) that causes flaky test failures.
+concurrency:
+  group: pr-validation-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
 jobs:
   validate-swarm:
     runs-on: self-hosted
@@ -36,6 +42,16 @@ jobs:
           docker run --rm -v "$GITHUB_WORKSPACE":/ws alpine sh -c \
             'find /ws -mindepth 1 -maxdepth 1 -not -name ".git" -exec chown -R '"$(id -u):$(id -g)"' {} + 2>/dev/null || true'
 
+      - name: Reclaim disk space (prune stale Docker resources)
+        run: |
+          echo "Disk usage before cleanup:"
+          df -h / | tail -1
+          # Remove stopped containers, dangling images, and build cache older
+          # than 24 h to prevent "no space left on device" failures.
+          docker system prune -f --filter "until=24h" || true
+          echo "Disk usage after cleanup:"
+          df -h / | tail -1
+
       - name: Checkout repository (with submodules)
         uses: actions/checkout@v4
         with:
diff --git a/application/jobs/_shared/custom/models/challenge/1DivideAndConquer/model.py b/application/jobs/_shared/custom/models/challenge/1DivideAndConquer/model.py
index 1d73c33a..b51cd084 100644
--- a/application/jobs/_shared/custom/models/challenge/1DivideAndConquer/model.py
+++ b/application/jobs/_shared/custom/models/challenge/1DivideAndConquer/model.py
@@ -405,8 +405,11 @@ def map_key(unet_key):
                 print("No matching encoder weights found.")
             return self
 
-def create_model(num_classes: int = 3, n_input_channels = 1, spatial_dims=3, pretrained_path=None) -> BasicClassifier:
-    model = ResidualEncoderClsLightning(in_ch=n_input_channels, out_ch=num_classes, spatial_dims=spatial_dims)
+def create_model(num_classes: int = 3, n_input_channels = 1, spatial_dims=3, pretrained_path=None, loss_kwargs=None) -> BasicClassifier:
+    model = ResidualEncoderClsLightning(
+        in_ch=n_input_channels, out_ch=num_classes, spatial_dims=spatial_dims,
+        loss_kwargs=loss_kwargs if loss_kwargs is not None else {},
+    )
     if pretrained_path:
         model.load_pretrained_unet_encoder(pretrained_path, verbose=True)
     return model
diff --git a/application/jobs/_shared/custom/models/challenge/2bcnaim/swinunetr.py b/application/jobs/_shared/custom/models/challenge/2bcnaim/swinunetr.py
index 9032665c..f6475975 100644
--- a/application/jobs/_shared/custom/models/challenge/2bcnaim/swinunetr.py
+++ b/application/jobs/_shared/custom/models/challenge/2bcnaim/swinunetr.py
@@ -1150,7 +1150,10 @@ def forward(self, x):
         return cls_output # seg_output, cls_output, hidden_states
     
 
-def create_model(img_size: int, num_classes: int = 3, n_input_channels = 1, spatial_dims=3) -> BasicClassifier:
+def create_model(img_size: int, num_classes: int = 3, n_input_channels = 1, spatial_dims=3, loss_kwargs=None) -> BasicClassifier:
     model = SwinUNETRMultiTask(img_size=img_size, in_channels=n_input_channels, out_seg_channels=2, out_cls_classes=num_classes, spatial_dims=spatial_dims)
-    wrapped_model = ModelWrapper(backbone=model, in_ch=n_input_channels, num_classes=num_classes)
+    wrapped_model = ModelWrapper(
+        backbone=model, in_ch=n_input_channels, num_classes=num_classes,
+        loss_kwargs=loss_kwargs if loss_kwargs is not None else {},
+    )
     return wrapped_model
diff --git a/application/jobs/_shared/custom/models/challenge/4abmil/model.py b/application/jobs/_shared/custom/models/challenge/4abmil/model.py
index a430eba5..34441445 100644
--- a/application/jobs/_shared/custom/models/challenge/4abmil/model.py
+++ b/application/jobs/_shared/custom/models/challenge/4abmil/model.py
@@ -215,14 +215,17 @@ def forward(self, volume: torch.Tensor):
         return out #A.squeeze(-1)  # logits, attention weights
     
 
-def create_model(model_type = "swin", n_input_channels: int = 3, num_classes: int = 3) -> BasicClassifier:
-    
+def create_model(model_type = "swin", n_input_channels: int = 3, num_classes: int = 3, loss_kwargs=None) -> BasicClassifier:
+
     #config = pd.read_csv(config_path, skip_blank_lines=True, na_values=['NaN']).iloc[0]
     if model_type =="swin_cross":
         model = CrossModalAttentionABMIL_Swin(num_classes=num_classes)
     else:
         model = ABMIL_Swin(num_classes=num_classes)
 
-    wrapped_model = ModelWrapper(backbone=model, in_ch=n_input_channels, num_classes=num_classes)
+    wrapped_model = ModelWrapper(
+        backbone=model, in_ch=n_input_channels, num_classes=num_classes,
+        loss_kwargs=loss_kwargs if loss_kwargs is not None else {},
+    )
 
     return wrapped_model
diff --git a/application/jobs/_shared/custom/models/challenge/5pimed/model.py b/application/jobs/_shared/custom/models/challenge/5pimed/model.py
index f286200a..ddf859ea 100644
--- a/application/jobs/_shared/custom/models/challenge/5pimed/model.py
+++ b/application/jobs/_shared/custom/models/challenge/5pimed/model.py
@@ -55,7 +55,10 @@ def forward(self, x: torch.Tensor) -> torch.Tensor:
         return self.net(x)
     
 
-def create_model(model_name: str, num_classes: int = 3, n_input_channels = 1, spatial_dims = 3, norm: str = "batch") -> nn.Module:
+def create_model(model_name: str, num_classes: int = 3, n_input_channels = 1, spatial_dims = 3, norm: str = "batch", loss_kwargs=None) -> nn.Module:
     model = Resnet(model_name=model_name, num_classes=num_classes, norm=norm)
-    wrapped_model = ModelWrapper(backbone=model, in_ch=n_input_channels, num_classes=num_classes)
+    wrapped_model = ModelWrapper(
+        backbone=model, in_ch=n_input_channels, num_classes=num_classes,
+        loss_kwargs=loss_kwargs if loss_kwargs is not None else {},
+    )
     return wrapped_model
diff --git a/application/jobs/_shared/custom/models/models_config.py b/application/jobs/_shared/custom/models/models_config.py
index 40a08741..e42b0461 100644
--- a/application/jobs/_shared/custom/models/models_config.py
+++ b/application/jobs/_shared/custom/models/models_config.py
@@ -199,11 +199,30 @@ def create_model(logger=None, model_name: str = None, num_classes: int = 3,
         
         if "pretrained_path" in persistor_args:
             rel_path = persistor_args["pretrained_path"].rstrip(".")
-            persistor_args["pretrained_path"] = os.path.join(
+            # Primary: look relative to the model's challenge directory
+            primary_path = os.path.join(
                 base_dir, "challenge", team_name, rel_path
             )
+            # Fallback: Docker image stores weights at /MediSwarm/pretrained_weights/
+            # to avoid bloating NVFlare job transfers (see _cacheAndCopyPretrainedModelWeights.sh)
+            fallback_path = os.path.join("/MediSwarm/pretrained_weights", rel_path)
+            if os.path.isfile(primary_path):
+                persistor_args["pretrained_path"] = primary_path
+            elif os.path.isfile(fallback_path):
+                persistor_args["pretrained_path"] = fallback_path
+                logger.info(f'Using fallback pretrained weights from Docker image: {fallback_path}')
+            else:
+                persistor_args["pretrained_path"] = primary_path  # let it fail with original path
             logger.info(f'__________ model path is : {persistor_args["pretrained_path"]}')
 
+        # Forward loss_kwargs (e.g. class weights) so the challenge model
+        # registers the same buffers as the server-side persistor model.
+        # Without this, _class_weight may appear as a buffer on one side
+        # but not the other, causing state_dict mismatches during
+        # federated aggregation.
+        if loss_kwargs:
+            persistor_args["loss_kwargs"] = loss_kwargs
+
         factory_fn = getattr(module, func_name)
         logger.info(f"Now access {persistor_args} from module {module}")
         return factory_fn(**persistor_args)
diff --git a/deploy_and_test.sh b/deploy_and_test.sh
index dfb73b04..0d4a14f8 100755
--- a/deploy_and_test.sh
+++ b/deploy_and_test.sh
@@ -244,9 +244,16 @@ cmd_start_server() {
 }
 
 cmd_start_clients() {
+    local model_name="${1:-}"
     step "Starting NVFlare clients on remote sites"
     check_dependencies
 
+    local model_flag=""
+    if [[ -n "$model_name" ]]; then
+        model_flag="--model_name '$model_name'"
+        info "Using MODEL_NAME=$model_name"
+    fi
+
     for site in "${SITES[@]}"; do
         local site_name host deploy_dir datadir scratchdir gpu
         site_name=$(site_var "$site" SITE_NAME)
@@ -264,7 +271,7 @@ cmd_start_clients() {
              export SITE_NAME='$site_name' && \
              export DATADIR='$datadir' && \
              export SCRATCHDIR='$scratchdir' && \
-             ./docker.sh --data_dir '$datadir' --scratch_dir '$scratchdir' --GPU '$gpu' --start_client"
+             ./docker.sh --data_dir '$datadir' --scratch_dir '$scratchdir' --GPU '$gpu' $model_flag --start_client"
 
         ok "  Client started on $site_name"
     done
@@ -272,6 +279,20 @@ cmd_start_clients() {
     ok "All clients started"
 }
 
+# Map job directory names to the MODEL_NAME env var expected by the model factory.
+job_to_model_name() {
+    local job="$1"
+    case "$job" in
+        challenge_1DivideAndConquer)   echo "1DivideAndConquer" ;;
+        challenge_2BCN_AIM)            echo "2BCN_AIM" ;;
+        challenge_3agaldran)           echo "3agaldran" ;;
+        challenge_4abmil)              echo "4LME_ABMIL" ;;
+        challenge_5pimed)              echo "5Pimed" ;;
+        ODELIA_ternary_classification) echo "MST" ;;
+        *)                             echo "MST" ;;
+    esac
+}
+
 cmd_submit() {
     local job_name="${1:-$DEFAULT_JOB}"
     step "Submitting job: $job_name"
@@ -426,15 +447,17 @@ cmd_stop() {
 
 cmd_all() {
     local job_name="${1:-$DEFAULT_JOB}"
+    local model_name
+    model_name=$(job_to_model_name "$job_name")
     step "Full deployment pipeline"
-    info "Job: $job_name"
+    info "Job: $job_name (MODEL_NAME=$model_name)"
     echo ""
 
     cmd_build
     cmd_push
     cmd_deploy
     cmd_start_server
-    cmd_start_clients
+    cmd_start_clients "$model_name"
 
     info "Waiting 15s for clients to register with server..."
     sleep 15
@@ -484,7 +507,7 @@ case "$COMMAND" in
     push)           cmd_push ;;
     deploy)         cmd_deploy ;;
     start-server)   cmd_start_server ;;
-    start-clients)  cmd_start_clients ;;
+    start-clients)  cmd_start_clients "${1:-}" ;;
     submit)         cmd_submit "${1:-}" ;;
     status)         cmd_status ;;
     logs)           cmd_logs "${1:-}" ;;
diff --git a/docker_config/Dockerfile_ODELIA b/docker_config/Dockerfile_ODELIA
index 26cef726..24d753d1 100644
--- a/docker_config/Dockerfile_ODELIA
+++ b/docker_config/Dockerfile_ODELIA
@@ -277,6 +277,14 @@ COPY ./torch_home_cache /torch_home
 
 # Copy the source code for local training and deploying to the swarm
 COPY ./MediSwarm /MediSwarm
+# Replace symlinks with actual copies so NVFlare's os.walk()-based job signing
+# and zip utilities can traverse all directories (os.walk does not follow symlinks)
+RUN find /MediSwarm -type l | while read link; do \
+        target=$(readlink -f "$link") && \
+        rm "$link" && \
+        if [ -d "$target" ]; then cp -r "$target" "$link"; \
+        elif [ -f "$target" ]; then cp "$target" "$link"; fi; \
+    done
 RUN mkdir -p /fl_admin/transfer && ln -s /MediSwarm /fl_admin/transfer/MediSwarm
 
 # allow creating home directory for local user inside container if needed
diff --git a/docker_config/Dockerfile_STAMP b/docker_config/Dockerfile_STAMP
index ea676aff..9cbb8a3d 100644
--- a/docker_config/Dockerfile_STAMP
+++ b/docker_config/Dockerfile_STAMP
@@ -36,6 +36,8 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     git \
     libgl1-mesa-glx \
     libglib2.0-0 \
+    zip \
+    unzip \
     && rm -rf /var/lib/apt/lists/*
 
 # ---------------------------------------------------------------------------
diff --git a/scripts/ci/runIntegrationTests.sh b/scripts/ci/runIntegrationTests.sh
index 102cbd1c..8785164f 100755
--- a/scripts/ci/runIntegrationTests.sh
+++ b/scripts/ci/runIntegrationTests.sh
@@ -527,15 +527,33 @@ verify_wrong_certificates_are_rejected () {
 
 
 run_dummy_training_in_swarm () {
-    echo "[Run] Dummy training in swarm (result will be checked after 2 minutes) ..."
+    echo "[Run] Dummy training in swarm (polling for completion, up to 5 minutes) ..."
 
     cd "$PROJECT_DIR"/prod_00
     cd admin@test.odelia/startup
     expect -f "$CWD"/tests/integration_tests/_submitDummyTraining.exp
     docker kill odelia_swarm_admin_$CONTAINER_VERSION_SUFFIX
-    sleep 120
     cd "$CWD"
 
+    # Poll for completion instead of a fixed sleep.  The server log will
+    # contain "Server runner finished." once all rounds are done.  We check
+    # every 10 seconds for up to 5 minutes (30 iterations).
+    local server_log="$PROJECT_DIR/prod_00/localhost/startup/nohup.out"
+    local max_attempts=30
+    local attempt=0
+    echo "  Waiting for swarm training to finish (checking every 10s, max ${max_attempts}0s) ..."
+    while [ $attempt -lt $max_attempts ]; do
+        if [ -f "$server_log" ] && grep -q 'Server runner finished\.' "$server_log" 2>/dev/null; then
+            echo "  ✅ Server runner finished detected after $((attempt * 10))s"
+            break
+        fi
+        attempt=$((attempt + 1))
+        sleep 10
+    done
+    if [ $attempt -eq $max_attempts ]; then
+        echo "  ⚠️  Timed out after ${max_attempts}0s waiting for swarm completion — proceeding to assertions"
+    fi
+
     # check for expected output in server log (clients joined, job ID assigned, 5 rounds, start of round logged, finished training logged)
     cd "$PROJECT_DIR"/prod_00/localhost/startup
     CONSOLE_OUTPUT=nohup.out
@@ -634,15 +652,33 @@ run_3dcnn_local_training () {
 
 
 run_3dcnn_training_in_swarm () {
-    echo "[Run] 3DCNN training in swarm (result will be checked after 60 minutes) ..."
+    echo "[Run] 3DCNN training in swarm (polling for completion, up to 60 minutes) ..."
 
     cd "$PROJECT_DIR"/prod_00
     cd admin@test.odelia/startup
     expect -f "$CWD"/tests/integration_tests/_submit3DCNNTraining.exp
     docker kill odelia_swarm_admin_$CONTAINER_VERSION_SUFFIX
-    sleep 3600
     cd "$CWD"
 
+    # Poll for completion instead of a fixed sleep.  The server log will
+    # contain "Server runner finished." once all rounds are done.  We check
+    # every 30 seconds for up to 60 minutes (120 iterations).
+    local server_log="$PROJECT_DIR/prod_00/localhost/startup/nohup.out"
+    local max_attempts=120
+    local attempt=0
+    echo "  Waiting for 3DCNN swarm training to finish (checking every 30s, max 60min) ..."
+    while [ $attempt -lt $max_attempts ]; do
+        if [ -f "$server_log" ] && grep -q 'Server runner finished\.' "$server_log" 2>/dev/null; then
+            echo "  ✅ Server runner finished detected after $((attempt * 30))s"
+            break
+        fi
+        attempt=$((attempt + 1))
+        sleep 30
+    done
+    if [ $attempt -eq $max_attempts ]; then
+        echo "  ⚠️  Timed out after 60min waiting for 3DCNN swarm completion — proceeding to assertions"
+    fi
+
     # check for expected output in server log (clients joined, job ID assigned, 20 rounds)
     cd "$PROJECT_DIR"/prod_00/localhost/startup
     CONSOLE_OUTPUT=nohup.out