feat: what is new since my last visit, and turning a comment into a ticket

Opening a ticket notes the visit and answers the one before (issue_visits),
so the page marks others' comments and changes since. A comment can become
a ticket of its own, as a subtask or linked; it remembers where it went.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

libs/api/tracker/domain/src/lib/comment/comment.ts

@@ -7,6 +7,7 @@ import {
 import { CommentAddedEvent } from '../events/comment-added.event';
 import { CommentDecisionMarkedEvent } from '../events/comment-decision-marked.event';
 import { CommentThreadResolvedEvent } from '../events/comment-thread-resolved.event';
+import { CommentTurnedIntoIssueEvent } from '../events/comment-turned-into-issue.event';
 import {
   CommentPollClosedEvent,
   CommentPollVotedEvent,
@@ -82,6 +83,8 @@ export class Comment extends VersionedAggregateRoot implements CommentProps {
   public pollVotes: Record<string, number> = {};
   public pollClosed = false;
   public pollWinner: number | null = null;
+  /** Tickets made from it, oldest first. */
+  public spawned: { id: string; key: string }[] = [];
   public deleted = false;
   public createdAt!: string;
   public editedAt: string | null = null;
@@ -277,10 +280,32 @@ export class Comment extends VersionedAggregateRoot implements CommentProps {
     this.resolved = event.resolved;
   }
 
+  onCommentTurnedIntoIssueEvent(event: CommentTurnedIntoIssueEvent): void {
+    this.spawned = event.spawned;
+  }
+
   onCommentDeletedEvent(): void {
     this.deleted = true;
   }
 
+  /**
+   * Notes a ticket made from it (its text became the ticket's description).
+   * Who may create it is the caller's check.
+   */
+  turnedInto(actorId: string, issue: { id: string; key: string }): void {
+    this.assertAlive();
+    if (this.spawned.some((s) => s.id === issue.id)) return;
+    this.apply(
+      new CommentTurnedIntoIssueEvent(
+        actorId,
+        this.id,
+        this.projectId,
+        this.issueId,
+        [...this.spawned, issue],
+      ),
+    );
+  }
+
   private assertAlive(): void {
     if (this.deleted) throw new BusinessRuleError('Comment was deleted');
   }