feat: a trash for tickets

Deleting a ticket now sends it to the trash, for whoever opened it or an
admin: it disappears from boards, searches and statistics, cannot change,
and comes back from the ticket page or the trash page for 30 days. After
that it is deleted for good with the usual cascade.

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

libs/api/tracker/application/src/lib/commands/trash.ts

@@ -0,0 +1,103 @@
+import {
+  Command,
+  CommandBus,
+  CommandHandler,
+  ICommandHandler,
+} from '@nestjs/cqrs';
+import { SYSTEM_ACTOR_ID } from '@task-stream/api/tracker/domain';
+import { FindIssuesRepository } from '../ports/find-issues.repository';
+import { CommandResult, ack } from './command-result';
+import { DeleteIssueCommand } from './delete-issue.command';
+import { WriteAccess } from './write-access';
+
+/** Days a ticket stays in the trash before it is deleted for good. */
+export const TRASH_DAYS = 30;
+
+export class TrashIssueCommand extends Command<CommandResult> {
+  constructor(
+    public readonly actorId: string,
+    public readonly issueId: string,
+  ) {
+    super();
+  }
+}
+
+export class RestoreIssueCommand extends Command<CommandResult> {
+  constructor(
+    public readonly actorId: string,
+    public readonly issueId: string,
+  ) {
+    super();
+  }
+}
+
+/** Scheduler only: deletes for good what went to the trash before `before`. */
+export class EmptyTrashCommand extends Command<number> {
+  constructor(public readonly before: string) {
+    super();
+  }
+}
+
+@CommandHandler(TrashIssueCommand)
+export class TrashIssueCommandHandler
+  implements ICommandHandler<TrashIssueCommand>
+{
+  constructor(private readonly access: WriteAccess) {}
+
+  async execute(command: TrashIssueCommand): Promise<CommandResult> {
+    const { issue, project } = await this.access.issueForContributor(
+      command.issueId,
+      command.actorId,
+    );
+    const role = project.roleOf(command.actorId);
+    issue.trash(command.actorId, role === 'OWNER' || role === 'ADMIN');
+    await issue.commitAndWait();
+    return ack(issue);
+  }
+}
+
+@CommandHandler(RestoreIssueCommand)
+export class RestoreIssueCommandHandler
+  implements ICommandHandler<RestoreIssueCommand>
+{
+  constructor(private readonly access: WriteAccess) {}
+
+  async execute(command: RestoreIssueCommand): Promise<CommandResult> {
+    const issue = await this.access.issue(command.issueId);
+    const project = await this.access.project(issue.projectId);
+    project.assertCanContribute(command.actorId);
+    const role = project.roleOf(command.actorId);
+    issue.restore(command.actorId, role === 'OWNER' || role === 'ADMIN');
+    await issue.commitAndWait();
+    return ack(issue);
+  }
+}
+
+/**
+ * Each deletion is the usual one: comments purged, links dropped and
+ * subtasks back to the top, by the sagas.
+ */
+@CommandHandler(EmptyTrashCommand)
+export class EmptyTrashCommandHandler
+  implements ICommandHandler<EmptyTrashCommand>
+{
+  constructor(
+    private readonly findIssues: FindIssuesRepository,
+    private readonly commandBus: CommandBus,
+  ) {}
+
+  async execute(command: EmptyTrashCommand): Promise<number> {
+    const old = await this.findIssues.findTrashedBefore(command.before);
+    for (const issue of old)
+      await this.commandBus.execute(
+        new DeleteIssueCommand(SYSTEM_ACTOR_ID, issue.id),
+      );
+    return old.length;
+  }
+}
+
+export const TRASH_HANDLERS = [
+  TrashIssueCommandHandler,
+  RestoreIssueCommandHandler,
+  EmptyTrashCommandHandler,
+];