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/presenters/src/lib/graphql/inputs.ts

@@ -140,6 +140,13 @@ export class CreateIssueInput extends IssueFieldsInput {
   @Field(() => ID, { nullable: true }) @IsOptional() @IsUUID() releaseId?:
     | string
     | null;
+  @Field(() => ID, {
+    nullable: true,
+    description: 'Epic or ticket of the same project the new one breaks down',
+  })
+  @IsOptional()
+  @IsUUID()
+  parentId?: string | null;
 }
 
 @InputType()
@@ -173,6 +180,25 @@ export class ChangeIssueStatusInput {
   reason?: string | null;
 }
 
+@InputType()
+export class AddChecklistItemInput {
+  @Field(() => ID) @IsUUID() issueId!: string;
+  @Field() @IsString() @MinLength(1) @MaxLength(300) text!: string;
+}
+
+@InputType()
+export class UpdateChecklistItemInput {
+  @Field(() => ID) @IsUUID() issueId!: string;
+  @Field(() => ID) @IsUUID() itemId!: string;
+  @Field({ nullable: true })
+  @IsOptional()
+  @IsString()
+  @MinLength(1)
+  @MaxLength(300)
+  text?: string;
+  @Field({ nullable: true }) @IsOptional() @IsBoolean() done?: boolean;
+}
+
 @InputType()
 export class LinkIssuesInput {
   @Field(() => ID) @IsUUID() issueId!: string;
@@ -216,6 +242,13 @@ export class IssueFilterInput {
   @IsOptional()
   @IsString({ each: true })
   labels?: string[];
+  @Field(() => ID, {
+    nullable: true,
+    description: 'Only the tickets hanging from this one',
+  })
+  @IsOptional()
+  @IsUUID()
+  parentId?: string;
   @Field({ nullable: true, description: 'Matches key, title or description' })
   @IsOptional()
   @IsString()

libs/api/tracker/presenters/src/lib/graphql/issue.resolver.ts

@@ -23,10 +23,12 @@ import {
   StatusCategory,
 } from '@task-stream/api/tracker/domain';
 import {
+  AddChecklistItemInput,
   ChangeIssueStatusInput,
   CreateIssueInput,
   IssueFilterInput,
   LinkIssuesInput,
+  UpdateChecklistItemInput,
   UpdateIssueInput,
 } from './inputs';
 import { withoutNulls } from '../common/issue-input';
@@ -35,6 +37,7 @@ import {
   ActivityGql,
   CommandResultGql,
   CommentPageGql,
+  EpicGql,
   IssueGql,
   IssuePageGql,
 } from './types';
@@ -72,6 +75,18 @@ export class IssueResolver {
     });
   }
 
+  @OptionalAuth()
+  @Query(() => [EpicGql], {
+    description:
+      "A project's epics: top-level tickets that group others, with the progress of those",
+  })
+  epics(
+    @CurrentUser() me: User | undefined,
+    @Args('projectId', { type: () => ID }) projectId: string,
+  ) {
+    return this.issuesService.epics(viewerOf(me), projectId);
+  }
+
   @Query(() => IssuePageGql, {
     description:
       'Tickets across all my projects: assigned to me (default) or any (e.g. categories [QA])',
@@ -238,6 +253,56 @@ export class IssueResolver {
     return this.issuesService.unlink(me.id, input);
   }
 
+  @Mutation(() => CommandResultGql, {
+    description:
+      'Place a ticket under an epic or another ticket of the same project (null: back to the top). Three levels at most: epic → ticket → subtask.',
+  })
+  setIssueParent(
+    @CurrentUser() me: User,
+    @Args('issueId', { type: () => ID }) issueId: string,
+    @Args('parentId', { type: () => ID, nullable: true })
+    parentId: string | null,
+  ) {
+    return this.issuesService.setParent(me.id, issueId, parentId ?? null);
+  }
+
+  @Mutation(() => CommandResultGql, {
+    description: "Add a step to a ticket's checklist",
+  })
+  addChecklistItem(
+    @CurrentUser() me: User,
+    @Args('input') input: AddChecklistItemInput,
+  ) {
+    return this.issuesService.addChecklistItem(
+      me.id,
+      input.issueId,
+      input.text,
+    );
+  }
+
+  @Mutation(() => CommandResultGql, {
+    description: 'Reword, tick or untick a checklist step',
+  })
+  updateChecklistItem(
+    @CurrentUser() me: User,
+    @Args('input') input: UpdateChecklistItemInput,
+  ) {
+    const { issueId, itemId, text, done } = input;
+    return this.issuesService.updateChecklistItem(me.id, issueId, itemId, {
+      ...(text != null && { text }),
+      ...(done != null && { done }),
+    });
+  }
+
+  @Mutation(() => CommandResultGql)
+  removeChecklistItem(
+    @CurrentUser() me: User,
+    @Args('issueId', { type: () => ID }) issueId: string,
+    @Args('itemId', { type: () => ID }) itemId: string,
+  ) {
+    return this.issuesService.removeChecklistItem(me.id, issueId, itemId);
+  }
+
   @Mutation(() => CommandResultGql, {
     description: 'Put a ticket in a release (null removes it)',
   })

libs/api/tracker/presenters/src/lib/graphql/types.ts

@@ -116,6 +116,23 @@ export class ReleaseRefGql {
   @Field() name!: string;
 }
 
+@ObjectType('ChecklistItem', {
+  description:
+    'A step inside a ticket that does not deserve a ticket of its own',
+})
+export class ChecklistItemGql {
+  @Field(() => ID) id!: string;
+  @Field() text!: string;
+  @Field() done!: boolean;
+}
+
+@ObjectType('IssueParent', { description: 'The ticket another one hangs from' })
+export class IssueParentGql {
+  @Field(() => ID) id!: string;
+  @Field() key!: string;
+  @Field() title!: string;
+}
+
 @ObjectType('Issue')
 export class IssueGql {
   @Field(() => ID) id!: string;
@@ -145,12 +162,37 @@ export class IssueGql {
   @Field(() => [AttachmentGql]) attachments!: AttachmentGql[];
   @Field(() => [UserRefGql], { description: 'People following the ticket' })
   watchers!: UserRefGql[];
+  @Field(() => IssueParentGql, {
+    nullable: true,
+    description: 'The epic or ticket this one breaks down',
+  })
+  parent!: IssueParentGql | null;
+  @Field(() => [ChecklistItemGql]) checklist!: ChecklistItemGql[];
   @Field(() => Int) commentCount!: number;
   @Field() createdAt!: string;
   @Field() updatedAt!: string;
   @Field(() => Int) version!: number;
 }
 
+@ObjectType('ChildProgress', {
+  description: 'How far the tickets hanging from one have got',
+})
+export class ChildProgressGql {
+  @Field(() => Int) total!: number;
+  @Field(() => Int, { description: 'Done or cancelled' }) finished!: number;
+  @Field(() => Int) percent!: number;
+  @Field(() => Int) storyPoints!: number;
+  @Field(() => Int) finishedStoryPoints!: number;
+}
+
+@ObjectType('Epic', {
+  description: 'A top-level ticket that groups others, with their progress',
+})
+export class EpicGql {
+  @Field(() => IssueGql) issue!: IssueGql;
+  @Field(() => ChildProgressGql) progress!: ChildProgressGql;
+}
+
 @ObjectType('IssuePage')
 export class IssuePageGql {
   @Field(() => [IssueGql]) items!: IssueGql[];