feat: release notes

Each release can carry notes in Markdown, written before or after it
ships. A draft is generated from its finished tickets grouped by type, to
edit and copy from the releases page.

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

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

@@ -6,6 +6,7 @@ import {
 import { ReleaseArchivedEvent } from '../events/release-archived.event';
 import { ReleaseCreatedEvent } from '../events/release-created.event';
 import { ReleaseDeletedEvent } from '../events/release-deleted.event';
+import { ReleaseNotesWrittenEvent } from '../events/release-notes-written.event';
 import { ReleaseShippedEvent } from '../events/release-shipped.event';
 import { ReleaseUpdatedEvent } from '../events/release-updated.event';
 import { ReleaseStatus } from './release-status';
@@ -22,6 +23,8 @@ export interface ReleaseProps {
   createdAt: string;
 }
 
+export const MAX_RELEASE_NOTES = 20_000;
+
 /** A version of the product: controls which tickets ship together. */
 export class Release extends VersionedAggregateRoot implements ReleaseProps {
   public projectId!: string;
@@ -30,6 +33,8 @@ export class Release extends VersionedAggregateRoot implements ReleaseProps {
   public targetDate: string | null = null;
   public status: ReleaseStatus = ReleaseStatus.PLANNED;
   public releasedAt: string | null = null;
+  /** What shipped, told for people (Markdown). */
+  public notes: string | null = null;
   public createdAt!: string;
   public deleted = false;
 
@@ -109,6 +114,24 @@ export class Release extends VersionedAggregateRoot implements ReleaseProps {
     );
   }
 
+  /**
+   * Writes the notes. Unlike the rest of the release they can be written
+   * after it ships: that is usually when they are needed. Not once archived.
+   */
+  writeNotes(actorId: string, notes: string | null): void {
+    if (this.status === ReleaseStatus.ARCHIVED)
+      throw new BusinessRuleError(`Release ${this.name} is archived`);
+    const next = notes?.trim() || null;
+    assertThat(
+      (next?.length ?? 0) <= MAX_RELEASE_NOTES,
+      `Release notes are at most ${MAX_RELEASE_NOTES} characters`,
+    );
+    if (next === this.notes) return;
+    this.apply(
+      new ReleaseNotesWrittenEvent(actorId, this.id, this.projectId, next),
+    );
+  }
+
   archive(actorId: string): void {
     if (this.status === ReleaseStatus.ARCHIVED) return;
     this.apply(new ReleaseArchivedEvent(actorId, this.id, this.projectId));
@@ -135,6 +158,10 @@ export class Release extends VersionedAggregateRoot implements ReleaseProps {
     this.releasedAt = event.occurredAt;
   }
 
+  onReleaseNotesWrittenEvent(event: ReleaseNotesWrittenEvent): void {
+    this.notes = event.notes;
+  }
+
   onReleaseArchivedEvent(): void {
     this.status = ReleaseStatus.ARCHIVED;
   }