--- a/superdsm.xml	Mon Mar 02 14:53:09 2026 +0000
+++ b/superdsm.xml	Mon Mar 02 16:36:05 2026 +0000
@@ -3,8 +3,9 @@
     <macros>
         <import>creators.xml</import>
         <import>tests.xml</import>
+        <import>validators.xml</import>
         <token name="@TOOL_VERSION@">0.2.0</token>
-        <token name="@VERSION_SUFFIX@">3</token>
+        <token name="@VERSION_SUFFIX@">4</token>
     </macros>
     <creator>
         <expand macro="creators/bmcv"/>
@@ -53,7 +54,7 @@
         <requirement type="package" version="2024.12.30">imagecodecs</requirement>
 
     </requirements>
-    <command detect_errors="aggressive">
+    <command detect_errors="exit_code">
     <![CDATA[
     python '$__tool_directory__/run-superdsm.py'
     '${dataset}'
@@ -125,9 +126,18 @@
         -->
         <environment_variable name="MKL_DEBUG_CPU_TYPE">5</environment_variable>
 
+        <!--
+        Suppress warning that Ray Dashboard is not installed:
+        -->
+        <environment_variable name="RAY_DISABLE_IMPORT_WARNING">1</environment_variable>
+
     </environment_variables>
     <inputs>
-        <param name="dataset" type="data" format="tiff,png" label="Dataset" />
+        <param name="dataset" type="data" format="tiff,png" label="Dataset">
+            <expand macro="validators/is_single_channel"/>
+            <expand macro="validators/is_single_frame"/>
+            <expand macro="validators/is_2d"/>
+        </param>
         <param argument="--global_energy_minimization_pruning" type="select" label="Graph pruning for global energy minimization" help="Exact graph pruning corresponds to the original algorithm, which provably yields globally optimal results. Robust graph pruning is more greedy and has a provably bounded approximation error. Depending on the data, this can be significantly faster than exact graph pruning, without degrading the segmentation or cluster splitting performance.">
             <option value="exact">Exact graph pruning (Kostrykin and Rohr, TPAMI 2023)</option>
             <option value="isbi24" selected="true">Robust graph pruning (Kostrykin and Rohr, ISBI 2024)</option>

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/validators.xml	Mon Mar 02 16:36:05 2026 +0000
@@ -0,0 +1,55 @@
+<macros>
+
+    <!-- Macros for validation of inputs -->
+
+    <xml name="validators/is_single_channel">
+        <!--
+        The OME-Zarr datatype in Galaxy is currently not derived from the Image datatype, and it does
+        hence not inherit the metadata fields like `channels`. To cope with that, we allow all datasets
+        except those where we *know* that they are *not* single-channel.
+        -->
+        <validator type="expression" message="Dataset is a multi-channel image"
+            ><![CDATA[getattr(value.metadata, "channels", None) in (None, '') or int(value.metadata.channels) < 2]]></validator>
+    </xml>
+
+    <xml name="validators/is_single_frame">
+        <!--
+        The OME-Zarr datatype in Galaxy is currently not derived from the Image datatype, and it does
+        hence not inherit the metadata fields like `frames`. To cope with that, we allow all datasets
+        except those where we *know* that they are *not* single-frame.
+        -->
+        <validator type="expression" message="Dataset is a multi-frame image"
+            ><![CDATA[getattr(value.metadata, "frames", None) in (None, '') or int(value.metadata.frames) < 2]]></validator>
+    </xml>
+
+    <xml name="validators/is_2d">
+        <!--
+        The OME-Zarr datatype in Galaxy is currently not derived from the Image datatype, and it does
+        hence not inherit the metadata fields like `depth`. To cope with that, we allow all datasets
+        except those where we *know* that they are *not* 2-D.
+        -->
+        <validator type="expression" message="Dataset is a 3-D image"
+            ><![CDATA[getattr(value.metadata, "depth", None) in (None, '') or int(value.metadata.depth) < 2]]></validator>
+    </xml>
+
+    <xml name="validators/is_3d">
+        <!--
+        The OME-Zarr datatype in Galaxy is currently not derived from the Image datatype, and it does
+        hence not inherit the metadata fields like `depth`. To cope with that, we allow all datasets
+        except those where we *know* that they are *not* 3-D.
+        -->
+        <validator type="expression" message="Dataset is a 2-D image"
+            ><![CDATA[getattr(value.metadata, "depth", None) in (None, '') or int(value.metadata.depth) >= 2]]></validator>
+    </xml>
+
+    <xml name="validators/is_binary">
+        <!--
+        The OME-Zarr datatype in Galaxy is currently not derived from the Image datatype, and it does
+        hence not inherit the metadata fields like `num_unique_values`. To cope with that, we allow all
+        datasets except those where we *know* that they are *not* binary.
+        -->
+        <validator type="expression" message="Dataset is not a binary image"
+            ><![CDATA[getattr(value.metadata, "num_unique_values", None) in (None, '') or int(value.metadata.num_unique_values) <= 2]]></validator>
+    </xml>
+
+</macros>