Fix atomic markdown mention deletion

Co-Authored-By: Paperclip <noreply@paperclip.ing>

ui/src/lib/mention-deletion.test.ts

@@ -0,0 +1,86 @@
+import { describe, expect, it } from "vitest";
+import { $createLinkNode, LinkNode } from "@lexical/link";
+import { buildAgentMentionHref } from "@paperclipai/shared";
+import {
+  createEditor,
+  $createParagraphNode,
+  $createTextNode,
+  $getRoot,
+  $getSelection,
+  $isRangeSelection,
+} from "lexical";
+import { deleteSelectedMentionChip } from "./mention-deletion";
+
+function createTestEditor() {
+  return createEditor({
+    namespace: "mention-deletion-test",
+    nodes: [LinkNode],
+    onError(error: Error) {
+      throw error;
+    },
+  });
+}
+
+describe("mention deletion", () => {
+  it("removes the full mention when backspacing from inside the chip", () => {
+    const editor = createTestEditor();
+
+    editor.update(() => {
+      const root = $getRoot();
+      const paragraph = $createParagraphNode();
+      const before = $createTextNode("Hello ");
+      const mention = $createLinkNode(buildAgentMentionHref("agent-123", "code"));
+      const mentionText = $createTextNode("@QA");
+      const after = $createTextNode(" world");
+
+      mention.append(mentionText);
+      paragraph.append(before, mention, after);
+      root.append(paragraph);
+
+      mentionText.selectEnd();
+
+      expect(deleteSelectedMentionChip("backward")).toBe(true);
+      expect(root.getTextContent()).toBe("Hello  world");
+
+      const selection = $getSelection();
+      expect($isRangeSelection(selection)).toBe(true);
+      if (!$isRangeSelection(selection)) {
+        throw new Error("Expected range selection after backward mention deletion");
+      }
+      expect(selection.isCollapsed()).toBe(true);
+      expect(selection.anchor.getNode().is(before)).toBe(true);
+      expect(selection.anchor.offset).toBe(before.getTextContentSize());
+    });
+  });
+
+  it("removes the full mention when deleting forward from adjacent text", () => {
+    const editor = createTestEditor();
+
+    editor.update(() => {
+      const root = $getRoot();
+      const paragraph = $createParagraphNode();
+      const before = $createTextNode("Hello ");
+      const mention = $createLinkNode(buildAgentMentionHref("agent-123", "code"));
+      const mentionText = $createTextNode("@QA");
+      const after = $createTextNode(" world");
+
+      mention.append(mentionText);
+      paragraph.append(before, mention, after);
+      root.append(paragraph);
+
+      before.selectEnd();
+
+      expect(deleteSelectedMentionChip("forward")).toBe(true);
+      expect(root.getTextContent()).toBe("Hello  world");
+
+      const selection = $getSelection();
+      expect($isRangeSelection(selection)).toBe(true);
+      if (!$isRangeSelection(selection)) {
+        throw new Error("Expected range selection after forward mention deletion");
+      }
+      expect(selection.isCollapsed()).toBe(true);
+      expect(selection.anchor.getNode().is(after)).toBe(true);
+      expect(selection.anchor.offset).toBe(0);
+    });
+  });
+});