fix: reject file edge labels that have more than one source node

concore_cli/commands/validate.py

@@ -64,6 +64,8 @@ def _classify_message(message, bucket_name):
         return {"error_type": "missing_edge_source"}
     if message.startswith("Edge references non-existent target node:"):
         return {"error_type": "missing_edge_target"}
+    if message.startswith("Edge label '") and "has more than one source" in message:
+        return {"error_type": "edge_label_multiple_sources"}
     if message == "Workflow contains cycles (expected for control loops)":
         return {"error_type": "cycle_detected"}
     if message.startswith("Invalid port number:"):
@@ -292,6 +294,7 @@ def finalize():
         edge_label_regex = re.compile(r"0x([a-fA-F0-9]+)_(\S+)")
         zmq_edges = 0
         file_edges = 0
+        label_sources = {}
 
         for edge in edges:
             try:
@@ -300,13 +303,25 @@ def finalize():
                     label_tag = edge.find("EdgeLabel")
 
                 if label_tag and label_tag.text:
-                    if edge_label_regex.match(label_tag.text.strip()):
+                    edge_label = label_tag.text.strip()
+                    if edge_label_regex.match(edge_label):
                         zmq_edges += 1
                     else:
                         file_edges += 1
+                        label_sources.setdefault(edge_label, set()).add(
+                            edge.get("source")
+                        )
             except Exception:
                 pass
 
+        # mkconcore mounts a file edge for its first source only
+        for edge_label, sources in label_sources.items():
+            if len(sources) > 1:
+                errors.append(
+                    f"Edge label '{edge_label}' has more than one source node: "
+                    f"{', '.join(sorted(sources))}"
+                )
+
         if zmq_edges > 0:
             info.append(f"ZMQ-based edges: {zmq_edges}")
         if file_edges > 0:

mkconcore.py

@@ -382,8 +382,17 @@ def cleanup_script_files():
                     #Validate edge labels
                     safe_name(edge_label, f"Edge label '{edge_label}'")
 
+                    source_label = nodes_dict[edge['source']]
                     if edge_label not in edges_dict:
-                        edges_dict[edge_label] = [nodes_dict[edge['source']], []]
+                        edges_dict[edge_label] = [source_label, []]
+                    elif edges_dict[edge_label][0] != source_label:
+                        # an edge label is one volume with a single writer, a second
+                        # source would get no out mount and its writes would be lost
+                        logging.error(
+                            f"Edge label '{raw_label}' has more than one source node: "
+                            f"{edges_dict[edge_label][0]} and {source_label}"
+                        )
+                        sys.exit(1)
                     edges_dict[edge_label][1].append(nodes_dict[edge['target']])
     except (IndexError, AttributeError, KeyError):
         logging.debug('An edge with no valid properties or missing node encountered and ignored')

tests/test_cli.py

@@ -136,6 +136,39 @@ def test_build_command_missing_source(self):
             )
             self.assertNotEqual(result.exit_code, 0)
 
+    def test_build_command_rejects_edge_label_with_multiple_sources(self):
+        with self.runner.isolated_filesystem(temp_dir=self.temp_dir):
+            Path("src").mkdir()
+            for name in ["a.py", "b.py", "c.py"]:
+                Path("src", name).write_text("import concore\n")
+            Path("workflow.graphml").write_text(
+                '<graphml xmlns:y="http://www.yworks.com/xml/graphml">\n'
+                '<graph id="G" edgedefault="directed">\n'
+                '<node id="n0"><data key="d0"><y:NodeLabel>A:a.py</y:NodeLabel></data></node>\n'
+                '<node id="n1"><data key="d0"><y:NodeLabel>B:b.py</y:NodeLabel></data></node>\n'
+                '<node id="n2"><data key="d0"><y:NodeLabel>C:c.py</y:NodeLabel></data></node>\n'
+                '<edge source="n0" target="n2"><data key="d1"><y:EdgeLabel>shared</y:EdgeLabel></data></edge>\n'
+                '<edge source="n1" target="n2"><data key="d1"><y:EdgeLabel>shared</y:EdgeLabel></data></edge>\n'
+                "</graph>\n"
+                "</graphml>\n"
+            )
+
+            result = self.runner.invoke(
+                cli,
+                [
+                    "build",
+                    "workflow.graphml",
+                    "--source",
+                    "src",
+                    "--output",
+                    "out",
+                    "--type",
+                    "posix",
+                ],
+            )
+            self.assertNotEqual(result.exit_code, 0)
+            self.assertIn("Edge label 'shared' has more than one source", result.output)
+
     def test_build_command_from_project_dir(self):
         with self.runner.isolated_filesystem(temp_dir=self.temp_dir):
             result = self.runner.invoke(cli, ["init", "test-project"])

tests/test_graph.py

@@ -1,3 +1,4 @@
+import json
 import unittest
 import tempfile
 import shutil
@@ -188,6 +189,39 @@ def test_validate_with_existing_source_file(self):
 
         self.assertIn("Validation passed", result.output)
 
+    def test_validate_edge_label_with_multiple_sources(self):
+        content = """
+        <graphml xmlns:y="http://www.yworks.com/xml/graphml">
+            <graph id="G" edgedefault="directed">
+                <node id="n0">
+                    <data key="d0"><y:NodeLabel>A:a.py</y:NodeLabel></data>
+                </node>
+                <node id="n1">
+                    <data key="d0"><y:NodeLabel>B:b.py</y:NodeLabel></data>
+                </node>
+                <node id="n2">
+                    <data key="d0"><y:NodeLabel>C:c.py</y:NodeLabel></data>
+                </node>
+                <edge source="n0" target="n2">
+                    <data key="d1"><y:EdgeLabel>shared</y:EdgeLabel></data>
+                </edge>
+                <edge source="n1" target="n2">
+                    <data key="d1"><y:EdgeLabel>shared</y:EdgeLabel></data>
+                </edge>
+            </graph>
+        </graphml>
+        """
+        filepath = self.create_graph_file("shared_label.graphml", content)
+
+        result = self.runner.invoke(cli, ["validate", filepath])
+
+        self.assertNotEqual(result.exit_code, 0)
+        self.assertIn("Edge label 'shared' has more than one source", result.output)
+
+        result = self.runner.invoke(cli, ["validate", filepath, "--format", "json"])
+        error_types = [e["error_type"] for e in json.loads(result.output)["errors"]]
+        self.assertIn("edge_label_multiple_sources", error_types)
+
     def test_validate_zmq_port_conflict(self):
         content = """
         <graphml xmlns:y="http://www.yworks.com/xml/graphml">