feat: add datasource and definition graph contracts

webui/tests/definition-graph.test.ts

@@ -0,0 +1,68 @@
+import {
+  createDefinitionGraphNode,
+  definitionConnectionError,
+  type DefinitionGraph,
+  type DefinitionGraphNodeType
+} from "../src/definitionGraph";
+
+const library: DefinitionGraphNodeType[] = [
+  {
+    type: "start",
+    category: "control",
+    category_label: "Control",
+    label: "Start",
+    description: "Start",
+    icon: "play",
+    input_ports: [],
+    output_ports: [
+      { id: "output", label: "Output", required: true, multiple: false, minimum_connections: 1 }
+    ],
+    config_fields: [],
+    default_config: { mode: "manual" }
+  },
+  {
+    type: "end",
+    category: "control",
+    category_label: "Control",
+    label: "End",
+    description: "End",
+    icon: "circle-stop",
+    input_ports: [
+      { id: "input", label: "Input", required: true, multiple: false, minimum_connections: 1 }
+    ],
+    output_ports: [],
+    config_fields: [],
+    default_config: {}
+  }
+];
+
+const graph: DefinitionGraph = {
+  schema_version: 1,
+  nodes: [
+    { id: "start", type: "start", label: "Start", position: { x: 0, y: 0 }, config: {} },
+    { id: "end", type: "end", label: "End", position: { x: 100, y: 0 }, config: {} }
+  ],
+  edges: []
+};
+
+if (definitionConnectionError(
+  graph,
+  library,
+  { source: "start", target: "end" }
+) !== null) {
+  throw new Error("Expected a valid library-driven connection.");
+}
+
+graph.edges.push({ id: "edge", source: "start", target: "end" });
+if (!definitionConnectionError(
+  graph,
+  library,
+  { source: "start", target: "end" }
+)) {
+  throw new Error("Expected duplicate connection validation.");
+}
+
+const created = createDefinitionGraphNode("start", { x: 40, y: 50 }, library);
+if (created.config.mode !== "manual" || created.position.x !== 40) {
+  throw new Error("Expected node creation to clone library defaults.");
+}