feat: quick polls in comments that end in a decision

«📊 Añadir una encuesta» adds 2 to 6 options to a new comment. Members,
viewers too, vote by clicking an option (one vote each, which they can
change or take back) and see each option's votes as a bar. Whoever
started it, or an admin, closes it with «Cerrar y decidir»: the most
voted wins (none on a tie) and a «Decidido: …» reply marked as a
decision shows above the ticket. Events of the comment (voted, closed).

API: addComment(…, poll), votePoll, closePoll, Comment.poll;
POST /api/comments/{id}/poll/vote and …/poll/close. MCP: add_comment
poll, vote_poll, close_poll.

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

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

@@ -7,6 +7,10 @@ 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 {
+  CommentPollClosedEvent,
+  CommentPollVotedEvent,
+} from '../events/comment-poll.events';
 import { CommentDeletedEvent } from '../events/comment-deleted.event';
 import { CommentEditedEvent } from '../events/comment-edited.event';
 import { CommentReactedEvent } from '../events/comment-reacted.event';
@@ -30,6 +34,32 @@ export interface CommentProps {
   deleted: boolean;
   createdAt: string;
   editedAt: string | null;
+  /** A quick poll's options (2–6); absent without one. */
+  poll?: string[] | null;
+}
+
+export const MIN_POLL_OPTIONS = 2;
+export const MAX_POLL_OPTIONS = 6;
+const MAX_POLL_OPTION = 80;
+
+/** A poll's options, trimmed: 2 to 6, different, short. */
+export function validPoll(options: string[]): string[] {
+  const clean = options
+    .map((o) => o.replace(/\s+/g, ' ').trim())
+    .filter(Boolean);
+  assertThat(
+    clean.length >= MIN_POLL_OPTIONS && clean.length <= MAX_POLL_OPTIONS,
+    `A poll takes ${MIN_POLL_OPTIONS} to ${MAX_POLL_OPTIONS} options`,
+  );
+  assertThat(
+    clean.every((o) => o.length <= MAX_POLL_OPTION),
+    `A poll option takes ${MAX_POLL_OPTION} characters at most`,
+  );
+  assertThat(
+    new Set(clean.map((o) => o.toLowerCase())).size === clean.length,
+    'Poll options must be different',
+  );
+  return clean;
 }
 
 const MAX_BODY = 20_000;
@@ -47,6 +77,11 @@ export class Comment extends VersionedAggregateRoot implements CommentProps {
   public decision = false;
   /** A top-level comment whose conversation was settled. */
   public resolved = false;
+  /** A quick poll: its options, who voted what, and whether it closed. */
+  public poll: string[] | null = null;
+  public pollVotes: Record<string, number> = {};
+  public pollClosed = false;
+  public pollWinner: number | null = null;
   public deleted = false;
   public createdAt!: string;
   public editedAt: string | null = null;
@@ -139,6 +174,63 @@ export class Comment extends VersionedAggregateRoot implements CommentProps {
     );
   }
 
+  /** Votes `option` in its poll (null takes the vote back); repeating it changes nothing. */
+  votePoll(actorId: string, option: number | null): void {
+    this.assertAlive();
+    if (!this.poll) throw new BusinessRuleError('This comment has no poll');
+    if (this.pollClosed) throw new BusinessRuleError('The poll is closed');
+    assertThat(
+      option === null ||
+        (Number.isInteger(option) && option >= 0 && option < this.poll.length),
+      'No such option',
+    );
+    if ((this.pollVotes[actorId] ?? null) === option) return;
+    const votes = { ...this.pollVotes };
+    if (option === null) delete votes[actorId];
+    else votes[actorId] = option;
+    this.apply(
+      new CommentPollVotedEvent(
+        actorId,
+        this.id,
+        this.projectId,
+        this.issueId,
+        votes,
+      ),
+    );
+  }
+
+  /**
+   * Closes the poll: its author, or (`canModerate`) whoever manages the
+   * project. The winner is the most voted option; none on a tie.
+   */
+  closePoll(actorId: string, canModerate: boolean): number | null {
+    this.assertAlive();
+    if (!this.poll) throw new BusinessRuleError('This comment has no poll');
+    if (this.pollClosed) throw new BusinessRuleError('The poll is closed');
+    if (actorId !== this.authorId && !canModerate)
+      throw new ForbiddenError(
+        'Only whoever started the poll or a project admin can close it',
+      );
+    const counts = this.poll.map(
+      (_, i) => Object.values(this.pollVotes).filter((v) => v === i).length,
+    );
+    const most = Math.max(...counts);
+    const winner =
+      most > 0 && counts.filter((c) => c === most).length === 1
+        ? counts.indexOf(most)
+        : null;
+    this.apply(
+      new CommentPollClosedEvent(
+        actorId,
+        this.id,
+        this.projectId,
+        this.issueId,
+        winner,
+      ),
+    );
+    return winner;
+  }
+
   /** @param canModerate whether the actor manages the project (may delete others' comments). */
   delete(actorId: string, canModerate: boolean): void {
     this.assertAlive();
@@ -156,6 +248,16 @@ export class Comment extends VersionedAggregateRoot implements CommentProps {
 
   onCommentAddedEvent({ comment }: CommentAddedEvent): void {
     Object.assign(this, comment);
+    this.poll = comment.poll ?? null;
+  }
+
+  onCommentPollVotedEvent(event: CommentPollVotedEvent): void {
+    this.pollVotes = event.votes;
+  }
+
+  onCommentPollClosedEvent(event: CommentPollClosedEvent): void {
+    this.pollClosed = true;
+    this.pollWinner = event.winner;
   }
 
   onCommentEditedEvent(event: CommentEditedEvent): void {