Merge pull request #10 from avalon-vanguard/feat/hud-bookmarks

Keep a place, and come back to it

src/app/features/body-detail/body-detail-scene.component.ts

@@ -1,5 +1,5 @@
 import { AfterViewInit, Component, ElementRef, OnDestroy, signal, viewChild } from '@angular/core';
-import { ActivatedRoute, RouterLink } from '@angular/router';
+import { ActivatedRoute, Router, RouterLink } from '@angular/router';
 import { Subscription } from 'rxjs';
 import * as THREE from 'three/webgpu';
 import { OrbitControls } from 'three/addons/controls/OrbitControls.js';
@@ -12,6 +12,7 @@ import { atmosphereColorFor, bodyTexturePath, loadCachedTexture, MILKY_WAY_SKYBO
 import { BodyRecord } from '../../shared/models/body.model';
 import { ExoplanetRecord } from '../../shared/models/exoplanet.model';
 import { StarRecord } from '../../shared/models/star.model';
+import { Bookmark } from '../../shared/state/bookmarks.store';
 import { NavigationStore } from '../../shared/state/navigation.store';
 import { ChevronIconComponent } from '../../shared/ui/chevron-icon.component';
 import { HudDockComponent } from '../hud/hud-dock.component';
@@ -57,12 +58,23 @@ const GLOW_SCALE = 2.6;
           </a>
         </div>
       }
-      <!-- Search only: there is no scene readout here, the info panel is the reading. -->
-      <app-hud-dock />
+      <!-- Search and what has been kept: there is no scene readout here, the info panel is
+           the reading, and the panel's own control is what keeps this body. -->
+      <app-hud-dock (bookmarkChosen)="goToBookmark($event)" />
     </div>
   `
 })
 export class BodyDetailSceneComponent implements AfterViewInit, OnDestroy {
+  /** A kept place, revisited from this page: a star means leaving it for the map. */
+  goToBookmark(bookmark: Bookmark): void {
+    if (bookmark.kind === 'star') {
+      this.navigationStore.selectStar(Number(bookmark.id));
+      void this.router.navigate(['/']);
+    } else {
+      void this.router.navigate(['/body', String(bookmark.id)]);
+    }
+  }
+
   private readonly canvasRef = viewChild.required<ElementRef<HTMLCanvasElement>>('canvas');
 
   private controls?: OrbitControls;
@@ -87,6 +99,7 @@ export class BodyDetailSceneComponent implements AfterViewInit, OnDestroy {
     private readonly engine: EngineService,
     private readonly dataLoader: DataLoaderService,
     private readonly route: ActivatedRoute,
+    private readonly router: Router,
     private readonly navigationStore: NavigationStore
   ) {}
 

src/app/features/body-detail/info-panel.component.ts

@@ -1,6 +1,8 @@
-import { Component, computed, input } from '@angular/core';
+import { Component, computed, inject, input } from '@angular/core';
 import { Router } from '@angular/router';
 
+import { BookmarksStore } from '../../shared/state/bookmarks.store';
+import { BookmarkIconComponent } from '../../shared/ui/bookmark-icon.component';
 import { ChevronIconComponent } from '../../shared/ui/chevron-icon.component';
 import { bodyReadouts } from './body-readouts';
 import { BodyDetailViewModel } from './body-detail.model';
@@ -17,7 +19,7 @@ import { ReadoutSectionsComponent } from './readout-sections.component';
  */
 @Component({
   selector: 'app-info-panel',
-  imports: [ChevronIconComponent, ReadoutSectionsComponent],
+  imports: [BookmarkIconComponent, ChevronIconComponent, ReadoutSectionsComponent],
   template: `
     <!-- Top-right, clear of the dock along the bottom; nothing else shares the top edge here. -->
     <div class="hud-brackets hud-acquire hud-surface absolute top-4 right-4 w-80 max-w-[calc(100%-2rem)] font-body text-text">
@@ -30,9 +32,21 @@ import { ReadoutSectionsComponent } from './readout-sections.component';
         System
       </button>
 
-      <header class="px-4 pt-4 pb-3">
-        <h1 class="truncate text-lg leading-tight font-bold tracking-[0.04em] text-text uppercase">{{ body().name }}</h1>
-        <p class="type-eyebrow mt-1 truncate text-accent">{{ readouts().kindLabel }} · {{ body().hostStarName }}</p>
+      <header class="flex items-start gap-2 px-4 pt-4 pb-3">
+        <div class="min-w-0 flex-1">
+          <h1 class="truncate text-lg leading-tight font-bold tracking-[0.04em] text-text uppercase">{{ body().name }}</h1>
+          <p class="type-eyebrow mt-1 truncate text-accent">{{ readouts().kindLabel }} · {{ body().hostStarName }}</p>
+        </div>
+        <button
+          type="button"
+          [attr.aria-label]="(bookmarks.has('body', body().id) ? 'Forget ' : 'Keep ') + body().name"
+          [attr.aria-pressed]="bookmarks.has('body', body().id)"
+          (click)="bookmarks.toggle({ kind: 'body', id: body().id, name: body().name })"
+          class="shrink-0 p-1 transition-colors focus-visible:outline-1 focus-visible:-outline-offset-1 focus-visible:outline-accent"
+          [class]="bookmarks.has('body', body().id) ? 'text-accent' : 'text-muted hover:text-accent'"
+        >
+          <app-bookmark-icon class="h-3.5 w-3.5" [kept]="bookmarks.has('body', body().id)" />
+        </button>
       </header>
 
       <app-readout-sections [readouts]="readouts()" />
@@ -42,6 +56,8 @@ import { ReadoutSectionsComponent } from './readout-sections.component';
 export class InfoPanelComponent {
   readonly body = input.required<BodyDetailViewModel>();
 
+  readonly bookmarks = inject(BookmarksStore);
+
   readonly readouts = computed(() => bodyReadouts(this.body()));
 
   constructor(private readonly router: Router) {}

src/app/features/galaxy-system/galaxy-system-scene.component.ts

@@ -13,6 +13,7 @@ import { ExoplanetRecord } from '../../shared/models/exoplanet.model';
 import { applyMilkyWaySkybox, createGlowSprite } from '../../shared/rendering/skybox';
 import { loadCachedTexture, MILKY_WAY_SKYBOX_PATH, SUN_TEXTURE_PATH } from '../../shared/rendering/texture-catalog';
 import { StarRecord } from '../../shared/models/star.model';
+import { Bookmark } from '../../shared/state/bookmarks.store';
 import { NavigationStore, ViewLevel } from '../../shared/state/navigation.store';
 import { CameraRigController } from './camera-rig-controller';
 import { DeepSkyRenderer } from './deep-sky-renderer';
@@ -225,12 +226,14 @@ function galacticOverviewPose(): { position: THREE.Vector3; target: THREE.Vector
         [routeResult]="routeResult()"
         [routeOptions]="routeOptions()"
         [currentStar]="currentStarOption()"
+        [keepableStarId]="navigationStore.selectedStarId()"
         defaultTab="readout"
         (displayChange)="display.set($event)"
         (routeQuery)="onRouteQuery($event)"
         (routeRequested)="onRouteRequested($event)"
         (routeStarSelected)="navigationStore.selectStar($event)"
         (jumpRangeChange)="jumpRangePc.set($event)"
+        (bookmarkChosen)="goToBookmark($event)"
       />
     </div>
   `
@@ -1210,6 +1213,15 @@ export class GalaxySystemSceneComponent implements AfterViewInit, OnDestroy {
     this.clearObjectCard();
   }
 
+  /** A kept place, revisited: a star is a system to fly into, a body is a page to open. */
+  goToBookmark(bookmark: Bookmark): void {
+    if (bookmark.kind === 'star') {
+      this.navigationStore.selectStar(Number(bookmark.id));
+    } else {
+      this.openObjectDetail(String(bookmark.id));
+    }
+  }
+
   /** The deliberate step out to the dedicated route, from the card's own control. */
   openObjectDetail(id: string): void {
     this.navigationStore.selectBody(id);

src/app/features/galaxy-system/system-object-card.component.ts

@@ -1,7 +1,9 @@
-import { ChangeDetectionStrategy, Component, computed, input, output } from '@angular/core';
+import { ChangeDetectionStrategy, Component, computed, inject, input, output } from '@angular/core';
 
 import { BodyDetailViewModel } from '../body-detail/body-detail.model';
 import { bodyReadouts } from '../body-detail/body-readouts';
+import { BookmarksStore } from '../../shared/state/bookmarks.store';
+import { BookmarkIconComponent } from '../../shared/ui/bookmark-icon.component';
 import { ReadoutSectionsComponent } from '../body-detail/readout-sections.component';
 import { ChevronIconComponent } from '../../shared/ui/chevron-icon.component';
 
@@ -19,7 +21,7 @@ import { ChevronIconComponent } from '../../shared/ui/chevron-icon.component';
 @Component({
   selector: 'app-system-object-card',
   changeDetection: ChangeDetectionStrategy.OnPush,
-  imports: [ChevronIconComponent, ReadoutSectionsComponent],
+  imports: [BookmarkIconComponent, ChevronIconComponent, ReadoutSectionsComponent],
   // Positioned and full-bleed like the HUD's own host, so the panel inside it resolves against
   // the scene rather than against whatever box the inline default would have left it in — which
   // put the card off the bottom-left corner of the viewport entirely.
@@ -36,6 +38,16 @@ import { ChevronIconComponent } from '../../shared/ui/chevron-icon.component';
             <p class="truncate text-lg leading-tight font-bold tracking-[0.04em] text-text uppercase">{{ body().name }}</p>
             <p class="type-eyebrow mt-1 truncate text-accent">{{ readouts().kindLabel }} · {{ body().hostStarName }}</p>
           </header>
+          <button
+            type="button"
+            [attr.aria-label]="(bookmarks.has('body', body().id) ? 'Forget ' : 'Keep ') + body().name"
+            [attr.aria-pressed]="bookmarks.has('body', body().id)"
+            (click)="bookmarks.toggle({ kind: 'body', id: body().id, name: body().name })"
+            class="shrink-0 p-1 transition-colors focus-visible:outline-1 focus-visible:-outline-offset-1 focus-visible:outline-accent"
+            [class]="bookmarks.has('body', body().id) ? 'text-accent' : 'text-muted hover:text-accent'"
+          >
+            <app-bookmark-icon class="h-3.5 w-3.5" [kept]="bookmarks.has('body', body().id)" />
+          </button>
           <button
             type="button"
             (click)="dismissed.emit()"
@@ -69,5 +81,7 @@ export class SystemObjectCardComponent {
   /** Request for the full `/body/:id` route. */
   readonly openRequested = output<void>();
 
+  readonly bookmarks = inject(BookmarksStore);
+
   readonly readouts = computed(() => bodyReadouts(this.body()));
 }

src/app/features/hud/hud-dock.component.spec.ts

@@ -3,6 +3,7 @@ import { Router } from '@angular/router';
 import { beforeEach, describe, expect, it, vi } from 'vitest';
 
 import { DataLoaderService } from '../../core/data/data-loader.service';
+import { BookmarksStore } from '../../shared/state/bookmarks.store';
 import { DEFAULT_HUD_DISPLAY, HudDisplay, HudDockComponent } from './hud-dock.component';
 
 class EmptyDataLoaderService {
@@ -46,6 +47,7 @@ describe('HudDockComponent', () => {
   }
 
   beforeEach(async () => {
+    localStorage.clear();
     await TestBed.configureTestingModule({
       imports: [HudDockComponent],
       providers: [
@@ -56,9 +58,10 @@ describe('HudDockComponent', () => {
     fixture = TestBed.createComponent(HudDockComponent);
   });
 
-  it('offers only the search when it has nothing to read out and no layers', () => {
+  it('offers the search and what has been kept, when it has nothing else', () => {
+    // Bookmarks are always offered: it is the only place that says the map can keep anything.
     fixture.detectChanges();
-    expect(tabNames()).toEqual(['Search']);
+    expect(tabNames()).toEqual(['Search', 'Bookmarks']);
     expect(host().querySelector('[role="tabpanel"]')).toBeNull();
   });
 
@@ -66,11 +69,11 @@ describe('HudDockComponent', () => {
     setReadout();
     fixture.componentRef.setInput('display', DEFAULT_HUD_DISPLAY);
     fixture.detectChanges();
-    expect(tabNames()).toEqual(['Search', 'Readout', 'Display']);
+    expect(tabNames()).toEqual(['Search', 'Readout', 'Bookmarks', 'Display']);
 
     fixture.componentRef.setInput('routing', true);
     fixture.detectChanges();
-    expect(tabNames()).toEqual(['Search', 'Readout', 'Routes', 'Display']);
+    expect(tabNames()).toEqual(['Search', 'Readout', 'Routes', 'Bookmarks', 'Display']);
   });
 
   it('opens the default tab on mount and renders the readout from its inputs', () => {
@@ -141,6 +144,95 @@ describe('HudDockComponent', () => {
     expect(pressed).toEqual(['Labels=true', 'Orbits=true', 'Grid=false', 'Deep sky=true', 'Sky=true', 'Systems=true', 'Jump links=false']);
   });
 
+  it('says how to keep a place, rather than showing an empty list', () => {
+    fixture.componentRef.setInput('defaultTab', 'bookmarks');
+    fixture.detectChanges();
+
+    expect(host().querySelector('#dock-panel-bookmarks ul')).toBeNull();
+    expect(host().textContent).toContain('Nothing kept yet');
+  });
+
+  it('lists what has been kept, newest first, and says which kind each is', () => {
+    const bookmarks = TestBed.inject(BookmarksStore);
+    bookmarks.toggle({ kind: 'star', id: 7, name: 'Sirius' });
+    bookmarks.toggle({ kind: 'body', id: 'earth', name: 'Earth' });
+    fixture.componentRef.setInput('defaultTab', 'bookmarks');
+    fixture.detectChanges();
+
+    const rows = [...host().querySelectorAll('#dock-panel-bookmarks li')].map((li) => li.textContent?.replace(/\s+/g, ' ').trim());
+    expect(rows[0]).toContain('Earth');
+    expect(rows[0]).toContain('Body');
+    expect(rows[1]).toContain('Sirius');
+    expect(rows[1]).toContain('System');
+  });
+
+  it('hands back the place that was chosen, whole', () => {
+    const bookmarks = TestBed.inject(BookmarksStore);
+    bookmarks.toggle({ kind: 'star', id: 7, name: 'Sirius' });
+    fixture.componentRef.setInput('defaultTab', 'bookmarks');
+    fixture.detectChanges();
+    const chosen: unknown[] = [];
+    fixture.componentInstance.bookmarkChosen.subscribe((bookmark) => chosen.push(bookmark));
+
+    host().querySelector<HTMLButtonElement>('#dock-panel-bookmarks li button')?.click();
+
+    expect(chosen).toEqual([{ kind: 'star', id: 7, name: 'Sirius' }]);
+  });
+
+  it('forgets one without disturbing the rest', () => {
+    const bookmarks = TestBed.inject(BookmarksStore);
+    bookmarks.toggle({ kind: 'star', id: 7, name: 'Sirius' });
+    bookmarks.toggle({ kind: 'body', id: 'earth', name: 'Earth' });
+    fixture.componentRef.setInput('defaultTab', 'bookmarks');
+    fixture.detectChanges();
+
+    host().querySelector<HTMLButtonElement>('[aria-label="Forget Earth"]')?.click();
+    fixture.detectChanges();
+
+    expect(bookmarks.bookmarks().map((bookmark) => bookmark.name)).toEqual(['Sirius']);
+    expect(host().textContent).not.toContain('Earth');
+  });
+
+  it('keeps the star the readout is about, and says so on the control', () => {
+    const bookmarks = TestBed.inject(BookmarksStore);
+    setReadout();
+    fixture.componentRef.setInput('title', 'Sirius');
+    fixture.componentRef.setInput('keepableStarId', 7);
+    fixture.componentRef.setInput('defaultTab', 'readout');
+    fixture.detectChanges();
+
+    const keep = host().querySelector<HTMLButtonElement>('[aria-label="Keep Sirius"]');
+    expect(keep?.getAttribute('aria-pressed')).toBe('false');
+    keep?.click();
+    fixture.detectChanges();
+
+    expect(bookmarks.has('star', 7)).toBe(true);
+    expect(host().querySelector('[aria-label="Forget Sirius"]')?.getAttribute('aria-pressed')).toBe('true');
+  });
+
+  it('keeps the one system whose catalogue id is zero, which truthiness would have lost', () => {
+    // The Sun is star 0. A `@if (id; as ...)` reads that as "no star" and hides the control.
+    const bookmarks = TestBed.inject(BookmarksStore);
+    setReadout();
+    fixture.componentRef.setInput('title', 'Sol');
+    fixture.componentRef.setInput('keepableStarId', 0);
+    fixture.componentRef.setInput('defaultTab', 'readout');
+    fixture.detectChanges();
+
+    host().querySelector<HTMLButtonElement>('[aria-label="Keep Sol"]')?.click();
+    fixture.detectChanges();
+
+    expect(bookmarks.has('star', 0)).toBe(true);
+  });
+
+  it('offers nothing to keep where the readout is a scale rather than a place', () => {
+    setReadout();
+    fixture.componentRef.setInput('defaultTab', 'readout');
+    fixture.detectChanges();
+
+    expect(host().querySelector('[aria-label^="Keep"]')).toBeNull();
+  });
+
   it('opens the search on "/" from anywhere but a text field', () => {
     setReadout();
     fixture.componentRef.setInput('defaultTab', 'readout');

src/app/features/hud/hud-dock.component.ts

@@ -1,5 +1,7 @@
 import { ChangeDetectionStrategy, Component, computed, ElementRef, HostListener, inject, input, OnInit, output, signal, viewChild } from '@angular/core';
 
+import { Bookmark, BookmarksStore } from '../../shared/state/bookmarks.store';
+import { BookmarkIconComponent } from '../../shared/ui/bookmark-icon.component';
 import { SearchComponent } from '../search/search.component';
 import { RouteRequest, RouteResult, RoutesPanelComponent, RouteStarOption } from './routes-panel.component';
 
@@ -39,9 +41,9 @@ const DISPLAY_LAYERS: readonly { key: keyof HudDisplay; label: string }[] = [
   { key: 'jumpLinks', label: 'Jump links' }
 ];
 
-export type DockTab = 'search' | 'readout' | 'routes' | 'display';
+export type DockTab = 'search' | 'readout' | 'routes' | 'bookmarks' | 'display';
 
-const TAB_LABELS: Record<DockTab, string> = { search: 'Search', readout: 'Readout', routes: 'Routes', display: 'Display' };
+const TAB_LABELS: Record<DockTab, string> = { search: 'Search', readout: 'Readout', routes: 'Routes', bookmarks: 'Bookmarks', display: 'Display' };
 
 /** Tailwind's `sm` breakpoint: below it the dock is a bare tab strip and its panel is a sheet. */
 const WIDE_VIEWPORT = '(min-width: 640px)';
@@ -68,7 +70,7 @@ function isWideViewport(): boolean {
 @Component({
   selector: 'app-hud-dock',
   changeDetection: ChangeDetectionStrategy.OnPush,
-  imports: [RoutesPanelComponent, SearchComponent],
+  imports: [BookmarkIconComponent, RoutesPanelComponent, SearchComponent],
   host: { class: 'pointer-events-none fixed inset-x-2 bottom-2 z-20 block font-body sm:inset-x-6 sm:bottom-6' },
   template: `
     <!-- The column is transparent to the pointer and each surface in it opts back in: it is as
@@ -87,7 +89,24 @@ function isWideViewport(): boolean {
           @case ('readout') {
             <section id="dock-panel-readout" role="tabpanel" aria-labelledby="dock-tab-readout" class="hud-acquire hud-brackets hud-surface pointer-events-auto mb-2 w-full max-w-lg px-4 py-3">
               <p class="type-label text-muted">{{ eyebrow() }}</p>
-              <p data-testid="hud-title" class="mt-1 text-lg font-bold tracking-[0.04em] text-text uppercase">{{ title() }}</p>
+              <div class="mt-1 flex items-start gap-2">
+                <p data-testid="hud-title" class="min-w-0 flex-1 text-lg font-bold tracking-[0.04em] text-text uppercase">{{ title() }}</p>
+                <!-- Against null, not against falsiness: the Sun's catalogue id is 0, and a
+                     truthiness test is what would quietly make the Solar System the one
+                     system nobody could keep. -->
+                @if (keepableStarId() !== null) {
+                  <button
+          type="button"
+          [attr.aria-label]="(bookmarks.has('star', keepableStarId()!) ? 'Forget ' : 'Keep ') + title()"
+          [attr.aria-pressed]="bookmarks.has('star', keepableStarId()!)"
+          (click)="bookmarks.toggle({ kind: 'star', id: keepableStarId()!, name: title() })"
+          class="shrink-0 p-1 transition-colors focus-visible:outline-1 focus-visible:-outline-offset-1 focus-visible:outline-accent"
+          [class]="bookmarks.has('star', keepableStarId()!) ? 'text-accent' : 'text-muted hover:text-accent'"
+        >
+          <app-bookmark-icon class="h-3.5 w-3.5" [kept]="bookmarks.has('star', keepableStarId()!)" />
+        </button>
+                }
+              </div>
               @if (subtitle()) {
                 <p class="mt-0.5 text-xs text-muted">{{ subtitle() }}</p>
               }
@@ -119,6 +138,40 @@ function isWideViewport(): boolean {
               />
             </section>
           }
+          @case ('bookmarks') {
+            <section id="dock-panel-bookmarks" role="tabpanel" aria-labelledby="dock-tab-bookmarks" class="hud-acquire hud-brackets hud-surface pointer-events-auto mb-2 w-full max-w-lg">
+              @if (bookmarks.bookmarks().length) {
+                <ul class="max-h-64 divide-y divide-border/25 overflow-y-auto">
+                  @for (bookmark of bookmarks.bookmarks(); track bookmark.kind + ':' + bookmark.id) {
+                    <li class="flex items-stretch">
+                      <button
+                        type="button"
+                        (click)="onBookmarkChosen(bookmark)"
+                        class="flex min-w-0 flex-1 items-baseline gap-3 px-3 py-2 text-left transition-colors hover:bg-accent/8 focus-visible:bg-accent/12 focus-visible:outline-1 focus-visible:-outline-offset-1 focus-visible:outline-accent"
+                      >
+                        <span class="min-w-0 flex-1 truncate text-sm text-text">{{ bookmark.name }}</span>
+                        <span class="type-label shrink-0 text-muted">{{ bookmark.kind === 'star' ? 'System' : 'Body' }}</span>
+                      </button>
+                      <button
+                        type="button"
+                        [attr.aria-label]="'Forget ' + bookmark.name"
+                        (click)="bookmarks.remove(bookmark.kind, bookmark.id)"
+                        class="shrink-0 border-l border-border/25 px-3 text-muted transition-colors hover:bg-accent/8 hover:text-accent focus-visible:text-accent focus-visible:outline-1 focus-visible:-outline-offset-1 focus-visible:outline-accent"
+                      >
+                        <svg class="h-3 w-3" viewBox="0 0 14 14" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" aria-hidden="true">
+                          <path d="M3 3l8 8M11 3l-8 8" />
+                        </svg>
+                      </button>
+                    </li>
+                  }
+                </ul>
+              } @else {
+                <p class="px-3 py-3 text-sm text-muted">
+                  Nothing kept yet. The <app-bookmark-icon class="inline-block h-3.5 w-3.5 -mb-0.5 text-accent" /> on a readout or a body keeps it here, in this browser.
+                </p>
+              }
+            </section>
+          }
           @case ('display') {
             <section id="dock-panel-display" role="tabpanel" aria-labelledby="dock-tab-display" class="hud-acquire hud-brackets hud-surface pointer-events-auto mb-2 w-full max-w-lg px-4 py-3">
               <p class="type-label text-muted">Layers</p>
@@ -187,6 +240,8 @@ export class HudDockComponent implements OnInit {
   readonly routeResult = input<RouteResult | null>(null);
   readonly routeOptions = input<readonly RouteStarOption[]>([]);
   readonly currentStar = input<RouteStarOption | null>(null);
+  /** The star the readout is about, where there is one to keep — a scale is not a place. */
+  readonly keepableStarId = input<number | null>(null);
   /** Present makes the Routes tab available; absent means this surface cannot route. */
   readonly routing = input(false);
 
@@ -195,6 +250,7 @@ export class HudDockComponent implements OnInit {
   readonly routeRequested = output<RouteRequest>();
   readonly routeStarSelected = output<number>();
   readonly jumpRangeChange = output<number>();
+  readonly bookmarkChosen = output<Bookmark>();
 
   readonly layers = DISPLAY_LAYERS;
   readonly hasDerived = computed(() => this.readouts().some((readout) => readout.derived));
@@ -202,11 +258,16 @@ export class HudDockComponent implements OnInit {
     'search',
     ...(this.title() ? (['readout'] as const) : []),
     ...(this.routing() ? (['routes'] as const) : []),
+    // Always offered, even with nothing in it: it is the only place that says the map can keep
+    // anything at all, and a tab that appears once you already know is a tab that never taught.
+    'bookmarks',
     ...(this.display() ? (['display'] as const) : [])
   ]);
 
   readonly activeTab = signal<DockTab | null>(null);
 
+  readonly bookmarks = inject(BookmarksStore);
+
   private readonly search = viewChild(SearchComponent);
   private readonly host = inject<ElementRef<HTMLElement>>(ElementRef);
 
@@ -238,6 +299,13 @@ export class HudDockComponent implements OnInit {
     this.routeStarSelected.emit(starId);
   }
 
+  /** Choosing a kept place is the same move as choosing a search result: the panel has done
+   *  its job and the thing to look at is now the scene. */
+  onBookmarkChosen(bookmark: Bookmark): void {
+    this.bookmarkChosen.emit(bookmark);
+    this.onPicked();
+  }
+
   onPicked(): void {
     // A result was chosen: the thing to look at is now the scene, so hand the panel back to the
     // readout where there is one, and fold the sheet away where there is not. On a narrow

src/app/shared/state/bookmarks.store.spec.ts

@@ -0,0 +1,109 @@
+import { TestBed } from '@angular/core/testing';
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+
+import { Bookmark, BookmarksStore } from './bookmarks.store';
+
+const KEY = 'star-map.bookmarks';
+
+const SIRIUS: Bookmark = { kind: 'star', id: 32349, name: 'Sirius' };
+const EARTH: Bookmark = { kind: 'body', id: 'earth', name: 'Earth' };
+
+function store(): BookmarksStore {
+  // Constructed per test, because the list is read once on construction — which is the
+  // behaviour being tested for anything that seeds storage first.
+  TestBed.resetTestingModule();
+  return TestBed.inject(BookmarksStore);
+}
+
+describe('BookmarksStore', () => {
+  beforeEach(() => {
+    localStorage.clear();
+    vi.restoreAllMocks();
+  });
+
+  it('starts empty, and keeps what it is given', () => {
+    const bookmarks = store();
+    expect(bookmarks.bookmarks()).toEqual([]);
+
+    expect(bookmarks.toggle(SIRIUS)).toBe(true);
+    expect(bookmarks.bookmarks()).toEqual([SIRIUS]);
+    expect(bookmarks.has('star', 32349)).toBe(true);
+  });
+
+  it('drops what it already had, when told the same thing twice', () => {
+    const bookmarks = store();
+    bookmarks.toggle(SIRIUS);
+
+    expect(bookmarks.toggle(SIRIUS)).toBe(false);
+    expect(bookmarks.bookmarks()).toEqual([]);
+    expect(bookmarks.has('star', 32349)).toBe(false);
+  });
+
+  it('tells a star from a body that happen to share an id', () => {
+    const bookmarks = store();
+    bookmarks.toggle({ kind: 'star', id: 1, name: 'A star' });
+    bookmarks.toggle({ kind: 'body', id: 1, name: 'A body' });
+
+    expect(bookmarks.bookmarks()).toHaveLength(2);
+    bookmarks.remove('star', 1);
+    expect(bookmarks.bookmarks()).toEqual([{ kind: 'body', id: 1, name: 'A body' }]);
+  });
+
+  it('puts the newest first, since that is the one being come back to', () => {
+    const bookmarks = store();
+    bookmarks.toggle(SIRIUS);
+    bookmarks.toggle(EARTH);
+
+    expect(bookmarks.bookmarks().map((bookmark) => bookmark.name)).toEqual(['Earth', 'Sirius']);
+  });
+
+  it('survives the visit it was kept in', () => {
+    store().toggle(SIRIUS);
+
+    expect(store().bookmarks()).toEqual([SIRIUS]);
+  });
+
+  it('reads past whatever else is in there, rather than losing the lot', () => {
+    localStorage.setItem(KEY, JSON.stringify([SIRIUS, { kind: 'moon', id: 1, name: 'No such kind' }, { id: 'no-kind' }, null, 42, EARTH]));
+
+    expect(store().bookmarks()).toEqual([SIRIUS, EARTH]);
+  });
+
+  it('keeps one entry per place, however many the stored list holds', () => {
+    // Two entries for one place would each toggle the other's control on and off.
+    localStorage.setItem(KEY, JSON.stringify([SIRIUS, { ...SIRIUS, name: 'Sirius (again)' }]));
+
+    expect(store().bookmarks()).toEqual([SIRIUS]);
+  });
+
+  it('treats a store that is not a list, or not JSON at all, as no bookmarks', () => {
+    localStorage.setItem(KEY, '{"not":"a list"}');
+    expect(store().bookmarks()).toEqual([]);
+
+    localStorage.setItem(KEY, 'nonsense{');
+    expect(store().bookmarks()).toEqual([]);
+  });
+
+  it('goes on working where the browser will not store anything at all', () => {
+    // Private mode, a full quota, storage disabled by policy: reading throws, writing throws.
+    vi.spyOn(Storage.prototype, 'getItem').mockImplementation(() => {
+      throw new DOMException('denied');
+    });
+    vi.spyOn(Storage.prototype, 'setItem').mockImplementation(() => {
+      throw new DOMException('denied');
+    });
+
+    const bookmarks = store();
+    expect(bookmarks.bookmarks()).toEqual([]);
+    expect(() => bookmarks.toggle(SIRIUS)).not.toThrow();
+    // Kept for this visit, even though nothing will outlive it.
+    expect(bookmarks.bookmarks()).toEqual([SIRIUS]);
+  });
+
+  it('bounds what a hand-edited store can make it hold', () => {
+    const many = Array.from({ length: 500 }, (_, i) => ({ kind: 'star' as const, id: i, name: `Star ${i}` }));
+    localStorage.setItem(KEY, JSON.stringify(many));
+
+    expect(store().bookmarks()).toHaveLength(200);
+  });
+});

src/app/shared/state/bookmarks.store.ts

@@ -0,0 +1,111 @@
+import { Injectable, signal } from '@angular/core';
+
+/**
+ * A place someone chose to keep. Either a star, which is a system to fly into, or a body, which
+ * is a page to open — the two things the map lets you arrive at.
+ */
+export interface Bookmark {
+  readonly kind: 'star' | 'body';
+  /** A HYG star id, or a `bodies.json`/`exoplanets.json` id. */
+  readonly id: number | string;
+  /**
+   * The name as it read when it was kept. Stored rather than looked up, so the list can be
+   * shown before the catalogues have loaded — and so a bookmark to something a later catalogue
+   * no longer holds still says what it was rather than becoming a bare id.
+   */
+  readonly name: string;
+}
+
+const STORAGE_KEY = 'star-map.bookmarks';
+
+/**
+ * How many are kept. Not a limit anyone will reach by hand — it is a bound on what a corrupted
+ * or hand-edited store can make the app render, and on what is written back.
+ */
+const MAX_BOOKMARKS = 200;
+
+/** `${kind}:${id}`, since a star id and a body id are different kinds of thing. */
+function keyOf(kind: Bookmark['kind'], id: number | string): string {
+  return `${kind}:${id}`;
+}
+
+function isBookmark(value: unknown): value is Bookmark {
+  if (typeof value !== 'object' || value === null) {
+    return false;
+  }
+  const candidate = value as Partial<Bookmark>;
+  return (
+    (candidate.kind === 'star' || candidate.kind === 'body') &&
+    (typeof candidate.id === 'number' || typeof candidate.id === 'string') &&
+    typeof candidate.name === 'string'
+  );
+}
+
+/**
+ * The places kept between visits, in this browser and nowhere else.
+ *
+ * Local storage rather than an account: the map asks nobody to sign in, and a list of stars
+ * somebody liked is not worth a server. Every read of it is defensive — the store is a string
+ * a user can edit, another tab can write, and a browser can refuse to give at all — and a
+ * failure to read or write one is never allowed to take the map down with it.
+ */
+@Injectable({ providedIn: 'root' })
+export class BookmarksStore {
+  private readonly kept = signal<readonly Bookmark[]>(this.read());
+
+  /** Most recently kept first, which is the order they are useful in. */
+  readonly bookmarks = this.kept.asReadonly();
+
+  has(kind: Bookmark['kind'], id: number | string): boolean {
+    return this.kept().some((bookmark) => bookmark.kind === kind && bookmark.id === id);
+  }
+
+  /** Keeps a place, or drops it if it was already kept. Returns whether it is kept now. */
+  toggle(bookmark: Bookmark): boolean {
+    const kept = this.has(bookmark.kind, bookmark.id);
+    this.write(kept ? this.kept().filter((other) => !(other.kind === bookmark.kind && other.id === bookmark.id)) : [bookmark, ...this.kept()].slice(0, MAX_BOOKMARKS));
+    return !kept;
+  }
+
+  remove(kind: Bookmark['kind'], id: number | string): void {
+    this.write(this.kept().filter((bookmark) => !(bookmark.kind === kind && bookmark.id === id)));
+  }
+
+  private write(bookmarks: readonly Bookmark[]): void {
+    this.kept.set(bookmarks);
+    try {
+      localStorage.setItem(STORAGE_KEY, JSON.stringify(bookmarks));
+    } catch {
+      // Full, disabled, or private-mode storage. The list still works for this visit; it just
+      // will not outlive it, which is a smaller loss than the alternative of failing here.
+    }
+  }
+
+  private read(): Bookmark[] {
+    let raw: string | null = null;
+    try {
+      raw = localStorage.getItem(STORAGE_KEY);
+    } catch {
+      return [];
+    }
+    if (!raw) {
+      return [];
+    }
+    try {
+      const parsed: unknown = JSON.parse(raw);
+      if (!Array.isArray(parsed)) {
+        return [];
+      }
+      // Filtered rather than rejected wholesale: one bad entry should not lose the others, and
+      // deduplicated because two entries for one place would each toggle the other's control.
+      const seen = new Set<string>();
+      return parsed
+        .filter(isBookmark)
+        .filter((bookmark) => !seen.has(keyOf(bookmark.kind, bookmark.id)) && seen.add(keyOf(bookmark.kind, bookmark.id)))
+        .slice(0, MAX_BOOKMARKS)
+        .map(({ kind, id, name }) => ({ kind, id, name }));
+    } catch {
+      return [];
+    }
+  }
+}

src/app/shared/ui/bookmark-icon.component.ts

@@ -0,0 +1,22 @@
+import { ChangeDetectionStrategy, Component, input } from '@angular/core';
+
+/**
+ * The mark on a place worth coming back to. Hollow when it is not kept, filled when it is —
+ * the same two states as the Display panel's layer ticks, which is where the eye has already
+ * learned what a filled mark means here.
+ *
+ * Size and colour come from the classes on the host; the svg fills it.
+ */
+@Component({
+  selector: 'app-bookmark-icon',
+  changeDetection: ChangeDetectionStrategy.OnPush,
+  host: { class: 'block', 'aria-hidden': 'true' },
+  template: `
+    <svg class="h-full w-full" viewBox="0 0 24 24" [attr.fill]="kept() ? 'currentColor' : 'none'" stroke="currentColor" stroke-width="1.5" stroke-linejoin="round">
+      <path d="M7 4h10v16l-5-4-5 4z" />
+    </svg>
+  `
+})
+export class BookmarkIconComponent {
+  readonly kept = input(false);
+}