feat: comments marked as decisions, on top of the ticket and searchable

Whoever can change the ticket flags a comment as a decision (new event
CommentDecisionMarkedEvent on the comment). The ticket page lists its
decisions above the description, with a link to the comment in the
conversation (`?comment=<id>` scrolls to it and points at it), and the
search palette finds them by their text across my projects.

API: markDecision / PUT-DELETE /api/comments/{id}/decision; Issue.decisions
and GET /api/issues/{issue}/decisions; decisions(projectId?, search) and
GET /api/projects/{project}/decisions, GET /api/me/decisions. MCP:
mark_decision, search_decisions, and get_issue includes them.

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

libs/api/tracker/application/src/lib/queries/decisions.query.ts

@@ -0,0 +1,112 @@
+import { IQueryHandler, Query, QueryHandler } from '@nestjs/cqrs';
+import {
+  CommentReadModel,
+  DecisionReadModel,
+} from '@task-stream/api/tracker/domain';
+import { FindCommentsRepository } from '../ports/find-comments.repository';
+import { FindIssuesRepository } from '../ports/find-issues.repository';
+import { FindProjectsRepository } from '../ports/find-projects.repository';
+import { ReadAccess } from './read-access';
+
+/** The decisions of a ticket, oldest first (shown above its conversation). */
+export class GetIssueDecisionsQuery extends Query<CommentReadModel[]> {
+  constructor(
+    /** Null: anonymous (public projects only). */
+    public readonly viewerId: string | null,
+    public readonly issueId: string,
+  ) {
+    super();
+  }
+}
+
+/**
+ * Decisions by their text, most recently decided first: of one project, or
+ * (without one) of every project the viewer belongs to.
+ */
+export class SearchDecisionsQuery extends Query<DecisionReadModel[]> {
+  constructor(
+    public readonly viewerId: string | null,
+    public readonly filter: {
+      projectId?: string;
+      search?: string;
+      limit: number;
+    },
+  ) {
+    super();
+  }
+}
+
+@QueryHandler(GetIssueDecisionsQuery)
+export class GetIssueDecisionsQueryHandler
+  implements IQueryHandler<GetIssueDecisionsQuery, CommentReadModel[]>
+{
+  constructor(
+    private readonly findIssues: FindIssuesRepository,
+    private readonly findComments: FindCommentsRepository,
+    private readonly access: ReadAccess,
+  ) {}
+
+  async execute(query: GetIssueDecisionsQuery): Promise<CommentReadModel[]> {
+    const issue = this.access.assertFound(
+      await this.findIssues.findById(query.issueId),
+      'Issue',
+      query.issueId,
+    );
+    await this.access.assertCanViewIssue(issue, query.viewerId);
+    return this.findComments.findDecisions({ issueId: issue.id, limit: 50 });
+  }
+}
+
+@QueryHandler(SearchDecisionsQuery)
+export class SearchDecisionsQueryHandler
+  implements IQueryHandler<SearchDecisionsQuery, DecisionReadModel[]>
+{
+  constructor(
+    private readonly findProjects: FindProjectsRepository,
+    private readonly findIssues: FindIssuesRepository,
+    private readonly findComments: FindCommentsRepository,
+    private readonly access: ReadAccess,
+  ) {}
+
+  async execute(query: SearchDecisionsQuery): Promise<DecisionReadModel[]> {
+    const { filter, viewerId } = query;
+    let projectIds: string[];
+    if (filter.projectId) {
+      await this.access.assertCanView(filter.projectId, viewerId);
+      projectIds = [filter.projectId];
+    } else {
+      if (!viewerId) return [];
+      projectIds = (await this.findProjects.findByMember(viewerId)).map(
+        (p) => p.id,
+      );
+    }
+    if (projectIds.length === 0) return [];
+    const limit = Math.min(filter.limit, 100);
+    // Read a few more: some may sit in the trash or, for a guest, in
+    // tickets they do not take part in.
+    const comments = await this.findComments.findDecisions({
+      projectIds,
+      search: filter.search?.trim().slice(0, 200) || undefined,
+      limit: limit * 2,
+    });
+    const issues = new Map(
+      (
+        await this.findIssues.findByIds([
+          ...new Set(comments.map((c) => c.issueId)),
+        ])
+      ).map((issue) => [issue.id, issue]),
+    );
+    const found: DecisionReadModel[] = [];
+    for (const comment of comments) {
+      const issue = issues.get(comment.issueId);
+      if (!issue || issue.trashedAt) continue;
+      if (!(await this.access.canViewIssue(issue, viewerId))) continue;
+      found.push({
+        comment,
+        issue: { id: issue.id, key: issue.key, title: issue.title },
+      });
+      if (found.length === limit) break;
+    }
+    return found;
+  }
+}

libs/api/tracker/application/src/lib/queries/query-handlers.ts

@@ -26,6 +26,10 @@ import { GetReleaseNotesDraftQueryHandler } from './get-release-notes-draft.quer
 import { GetTrashQueryHandler } from './get-trash.query';
 import { GetShowcaseQueryHandler } from './get-showcase.query';
 import { SearchMyIssuesQueryHandler } from './search-my-issues.query-handler';
+import {
+  GetIssueDecisionsQueryHandler,
+  SearchDecisionsQueryHandler,
+} from './decisions.query';
 
 export const QUERY_HANDLERS = [
   GetPublicProjectsQueryHandler,
@@ -33,6 +37,8 @@ export const QUERY_HANDLERS = [
   GetActivityQueryHandler,
   GetBoardQueryHandler,
   GetCommentsQueryHandler,
+  GetIssueDecisionsQueryHandler,
+  SearchDecisionsQueryHandler,
   GetIssueQueryHandler,
   GetIssuesByIdsQueryHandler,
   GetMyProjectsQueryHandler,