feat(frontend): remove an operator property when its field is cleared

frontend/src/app/workspace/service/workflow-graph/model/workflow-graph.spec.ts

@@ -199,6 +199,20 @@ describe("WorkflowGraph", () => {
     expect(operator.operatorProperties).toEqual(testProperty);
   });
 
+  // The property panel clears a field by sending the properties without it, so a
+  // key left out has to be dropped here. Retaining it leaves the operator running
+  // on a value the user removed and the panel no longer shows.
+  it("should drop a property the new object leaves out", () => {
+    workflowGraph.addOperator(mockScanPredicate);
+    workflowGraph.setOperatorProperty(mockScanPredicate.operatorID, { tableName: "testTable", limit: 5 });
+
+    workflowGraph.setOperatorProperty(mockScanPredicate.operatorID, { tableName: "testTable" });
+
+    expect(workflowGraph.getOperator(mockScanPredicate.operatorID).operatorProperties).toEqual({
+      tableName: "testTable",
+    });
+  });
+
   it("should throw an error when trying to set the property of an nonexist operator", () => {
     expect(() => {
       const testProperty = { tableName: "testTable" };

frontend/src/app/workspace/types/shared-editing.interface.spec.ts

@@ -142,7 +142,7 @@ describe("updateYTypeFromObject", () => {
     expect(originalText.toJSON()).toBe("world");
   });
 
-  it("adds new object keys but leaves keys absent from the new object in place", () => {
+  it("adds new object keys and removes the ones the new object no longer carries", () => {
     const doc = new Y.Doc();
     const yMap = attach(doc, "m", createYTypeFromObject({ keep: 1, drop: 2 }));
 
@@ -153,8 +153,21 @@ describe("updateYTypeFromObject", () => {
     // A key present only in the new object is added.
     expect(asMap.has("add")).toBe(true);
     expect(asMap.get("add")).toBe(3);
-    // A key omitted from the new object is retained (an undefined new value never deletes).
-    expect(asMap.get("drop")).toBe(2);
+    // A key the new object has dropped is deleted rather than left behind. Clearing
+    // an operator property is exactly this: the editor sends the properties without
+    // it, and anything retained here is a value the user removed and can no longer see.
+    expect(asMap.has("drop")).toBe(false);
+  });
+
+  it("keeps a key whose new value is explicitly undefined", () => {
+    const doc = new Y.Doc();
+    const yMap = attach(doc, "m", createYTypeFromObject({ a: 1 }));
+
+    updateYTypeFromObject(yMap, { a: undefined } as any);
+
+    // Carrying the key with an undefined value is not the same as dropping it, and
+    // only the latter means removal.
+    expect((yMap as unknown as Y.Map<any>).get("a")).toBe(1);
   });
 
   it("appends new items to a Y.Array in place", () => {

frontend/src/app/workspace/types/shared-editing.interface.ts

@@ -246,11 +246,21 @@ export function updateYTypeFromObject<T extends object>(oldYObj: YType<T>, newOb
     const keySet = new Set([...Object.keys(oldObj), ...Object.keys(newObj)]);
     keySet.forEach((k: string) => {
       const newValue = newObj[k as keyof T] as any;
-      if (!_.isEqual(oldObj[k as keyof T], newValue)) {
-        if (!updateYTypeFromObject(oldYObjAsYMap.get(k), newValue)) {
-          if (newValue !== undefined) {
-            oldYObjAsYMap.set(k, createYTypeFromObject(newValue));
-          }
+      if (_.isEqual(oldObj[k as keyof T], newValue)) {
+        return;
+      }
+      // A key the new object does not carry is one the caller removed, and deleting
+      // it is the only way that removal can reach the shared type: the update below
+      // changes a value or adds one, and for a key that is simply gone it did
+      // neither, leaving the old value in place. `in` rather than an undefined check,
+      // so a key explicitly carrying undefined still takes the path below.
+      if (!(k in newObj)) {
+        oldYObjAsYMap.delete(k);
+        return;
+      }
+      if (!updateYTypeFromObject(oldYObjAsYMap.get(k), newValue)) {
+        if (newValue !== undefined) {
+          oldYObjAsYMap.set(k, createYTypeFromObject(newValue));
         }
       }
     });