feat: epics, subtasks and checklists

Tickets can hang from another one of the same project, three levels deep
at most (epic → ticket → subtask). The ticket page lists its subtasks with
their progress, creates new ones and moves the ticket under an epic; a new
Épicas tab shows every epic and how far it has got. Each ticket also gets a
checklist for the small steps that don't deserve a ticket.

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

libs/api/tracker/infrastructure/src/lib/mongo/find.repositories.ts

@@ -14,6 +14,7 @@ import {
 import {
   ActivityReadModel,
   CommentReadModel,
+  EpicReadModel,
   CountBy,
   defaultProjectSettings,
   IssueReadModel,
@@ -228,6 +229,53 @@ export class MongoFindIssuesRepository extends FindIssuesRepository {
     return docs.map(issueFromDoc);
   }
 
+  async epics(projectId: string): Promise<EpicReadModel[]> {
+    const finished = { $in: ['$statusCategory', FINISHED] };
+    const points = { $ifNull: ['$storyPoints', 0] };
+    const rows = await this.issues.aggregate<{
+      _id: string;
+      total: number;
+      finished: number;
+      storyPoints: number;
+      finishedStoryPoints: number;
+    }>([
+      { $match: { projectId, 'parent.id': { $type: 'string' } } },
+      {
+        $group: {
+          _id: '$parent.id',
+          total: { $sum: 1 },
+          finished: { $sum: { $cond: [finished, 1, 0] } },
+          storyPoints: { $sum: points },
+          finishedStoryPoints: { $sum: { $cond: [finished, points, 0] } },
+        },
+      },
+    ]);
+    if (rows.length === 0) return [];
+    const progress = new Map(rows.map((row) => [row._id, row]));
+    // Only the top of each tree: a ticket with subtasks under an epic is not one.
+    const docs = await this.issues
+      .find({ _id: { $in: [...progress.keys()] }, 'parent.id': null })
+      .sort({ number: 1 })
+      .lean<IssueDoc[]>();
+    return docs.map((doc) => {
+      const { _id: _ignored, ...row } = progress.get(doc._id) ?? {
+        _id: doc._id,
+        total: 0,
+        finished: 0,
+        storyPoints: 0,
+        finishedStoryPoints: 0,
+      };
+      return {
+        issue: issueFromDoc(doc),
+        progress: {
+          ...row,
+          percent:
+            row.total === 0 ? 0 : Math.round((row.finished / row.total) * 100),
+        },
+      };
+    });
+  }
+
   async releaseProgress(releaseId: string): Promise<ReleaseProgressReadModel> {
     const rows = await this.issues.aggregate<{
       _id: { status: string; category: StatusCategory };
@@ -268,6 +316,7 @@ function toMongoFilter(filter: IssueFilter): FilterQuery<IssueDoc> {
   if (filter.labels?.length)
     query.labels = { $all: filter.labels.map((l) => l.toLowerCase()) };
   if (filter.releaseId) query['release.id'] = filter.releaseId;
+  if (filter.parentId) query['parent.id'] = filter.parentId;
   if (filter.unassigned) query['assignee'] = null;
   else if (filter.assigneeId) query['assignee.id'] = filter.assigneeId;
   if (filter.search?.trim()) {

libs/api/tracker/infrastructure/src/lib/mongo/read-model.schemas.ts

@@ -78,6 +78,8 @@ export const IssueSchema = new Schema<IssueDoc>(
     outwardLinks: [link],
     inwardLinks: [link],
     watchers: [userRef],
+    parent: { _id: false, id: String, key: String, title: String },
+    checklist: [{ _id: false, id: String, text: String, done: Boolean }],
     attachments: [
       {
         _id: false,
@@ -99,6 +101,7 @@ IssueSchema.index({ projectId: 1, status: 1, updatedAt: -1 });
 IssueSchema.index({ projectId: 1, statusCategory: 1 });
 IssueSchema.index({ 'assignee.id': 1 });
 IssueSchema.index({ 'watchers.id': 1 });
+IssueSchema.index({ 'parent.id': 1 });
 IssueSchema.index({ 'release.id': 1 });
 IssueSchema.index({ title: 'text', description: 'text', key: 'text' });
 
@@ -182,5 +185,7 @@ export function issueFromDoc(doc: IssueDoc): IssueReadModel {
     // Tickets projected before attachments existed have none.
     attachments: rest.attachments ?? [],
     watchers: rest.watchers ?? [],
+    parent: rest.parent?.id ? rest.parent : null,
+    checklist: rest.checklist ?? [],
   };
 }

libs/api/tracker/infrastructure/src/lib/mongo/upsert-materialized.repositories.ts

@@ -11,6 +11,7 @@ import {
 import {
   ActivityReadModel,
   AttachmentReadModel,
+  ChecklistItemReadModel,
   CommentReadModel,
   IssueLinkReadModel,
   IssueReadModel,
@@ -130,6 +131,45 @@ export class MongoUpsertMaterializedIssueRepository extends UpsertMaterializedIs
     );
   }
 
+  async addChecklistItem(issueId: string, item: ChecklistItemReadModel) {
+    await this.issues.updateOne(
+      { _id: issueId, 'checklist.id': { $ne: item.id } },
+      { $push: { checklist: item } },
+    );
+  }
+
+  async updateChecklistItem(
+    issueId: string,
+    itemId: string,
+    changes: Partial<Pick<ChecklistItemReadModel, 'text' | 'done'>>,
+  ) {
+    const set = Object.fromEntries(
+      Object.entries(changes).map(([field, value]) => [
+        `checklist.$.${field}`,
+        value,
+      ]),
+    );
+    if (Object.keys(set).length === 0) return;
+    await this.issues.updateOne(
+      { _id: issueId, 'checklist.id': itemId },
+      { $set: set },
+    );
+  }
+
+  async removeChecklistItem(issueId: string, itemId: string) {
+    await this.issues.updateOne(
+      { _id: issueId },
+      { $pull: { checklist: { id: itemId } } },
+    );
+  }
+
+  async renameParent(parentId: string, title: string) {
+    await this.issues.updateMany(
+      { 'parent.id': parentId },
+      { $set: { 'parent.title': title } },
+    );
+  }
+
   async addAttachment(issueId: string, attachment: AttachmentReadModel) {
     await this.issues.updateOne(
       { _id: issueId, 'attachments.id': { $ne: attachment.id } },

libs/api/tracker/infrastructure/src/lib/postgres/tracker-streams.repository.ts

@@ -4,6 +4,7 @@ import {
   CommentAddedEvent,
   IssueCreatedEvent,
   IssueLinkedEvent,
+  IssueParentChangedEvent,
   ReleaseCreatedEvent,
 } from '@task-stream/api/tracker/domain';
 import { DataSource } from 'typeorm';
@@ -47,6 +48,14 @@ export class PostgresTrackerStreamsRepository extends TrackerStreamsRepository {
     );
   }
 
+  issueIdsEverUnder(issueId: string): Promise<string[]> {
+    return this.streams(
+      IssueParentChangedEvent.name,
+      `data->>'parentId'`,
+      issueId,
+    );
+  }
+
   /** `field` is one of the fixed JSON paths above, never user input. */
   private async streams(
     type: string,