From b9f2ba9e47899196cc1d3a6db39acb5f6e2c8a39 Mon Sep 17 00:00:00 2001
From: th <th@skilleven.de>
Date: Wed, 22 Apr 2026 07:44:43 +0200
Subject: [PATCH] 0.9.1: jumpToScene action + auto-play on scene switch

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
---
 package.json                         |   2 +-
 src/components/ActionEditor.vue      |  25 +++
 src/components/FullscreenPreview.vue |  52 ++++-
 src/devtools/tests.ts                | 315 ++++++++++++++++++++++++++-
 src/i18n/messages.ts                 |   3 +
 src/lib/actions.ts                   |  20 ++
 src/lib/exportPlayer.ts              |  19 +-
 src/stores/scene.ts                  |  11 +-
 src/types/scene.ts                   |   4 +
 9 files changed, 436 insertions(+), 15 deletions(-)

diff --git a/package.json b/package.json
index f1f35a2..41cc20b 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "animatr",
   "private": true,
-  "version": "0.9.0",
+  "version": "0.9.1",
   "type": "module",
   "scripts": {
     "dev": "vite",
diff --git a/src/components/ActionEditor.vue b/src/components/ActionEditor.vue
index 4542115..fdf9107 100644
--- a/src/components/ActionEditor.vue
+++ b/src/components/ActionEditor.vue
@@ -19,6 +19,10 @@ const markerNames = computed(() =>
   (store.scene.markers ?? []).map((m) => m.name),
 )
 
+const sceneOptions = computed(() =>
+  store.project.scenes.map((s) => ({ id: s.id, name: s.name })),
+)
+
 const ACTION_TYPES: Action['type'][] = [
   'play',
   'pause',
@@ -26,6 +30,7 @@ const ACTION_TYPES: Action['type'][] = [
   'jumpTo',
   'jumpToFrame',
   'jumpToMarker',
+  'jumpToScene',
   'script',
 ]
 
@@ -45,6 +50,14 @@ function makeDefault(type: Action['type']): Action {
       return { type: 'jumpToFrame', frame: 0 }
     case 'jumpToMarker':
       return { type: 'jumpToMarker', name: markerNames.value[0] ?? '' }
+    case 'jumpToScene': {
+      // Default to the first scene that ISN'T the current one so the
+      // action is immediately useful; fall back to the first if there's
+      // only one scene.
+      const others = sceneOptions.value.filter((s) => s.id !== store.project.activeSceneId)
+      const target = others[0] ?? sceneOptions.value[0]
+      return { type: 'jumpToScene', sceneId: target?.id ?? '' }
+    }
     case 'script':
       return { type: 'script', source: '' }
   }
@@ -152,6 +165,18 @@ function onTypeChange(index: number, newType: Action['type']) {
             </select>
           </label>
         </div>
+        <div v-else-if="a.type === 'jumpToScene'" class="params">
+          <label>
+            {{ t('actions.param.scene') }}
+            <select
+              :value="a.sceneId"
+              @change="setAt(i, { type: 'jumpToScene', sceneId: ($event.target as HTMLSelectElement).value })"
+            >
+              <option v-if="!sceneOptions.length" value="" disabled>{{ t('actions.noScenes') }}</option>
+              <option v-for="s in sceneOptions" :key="s.id" :value="s.id">{{ s.name }}</option>
+            </select>
+          </label>
+        </div>
         <div v-else-if="a.type === 'script'" class="params">
           <label class="block">
             {{ t('actions.param.source') }}
diff --git a/src/components/FullscreenPreview.vue b/src/components/FullscreenPreview.vue
index e23bed8..d9c84bc 100644
--- a/src/components/FullscreenPreview.vue
+++ b/src/components/FullscreenPreview.vue
@@ -42,17 +42,53 @@ async function startPreview() {
   const end = rangeOut.value
   const head = store.playhead
   const initialTime = head < start || head >= end ? start : head
-  player = mountPlayer(el, store.scene, {
-    loop: true,
-    onFrame(time: number, paused: boolean) {
-      localTime.value = time
-      playing.value = !paused
-    },
-  })
-  player.seek(initialTime)
+  mountAt(el, initialTime, true)
   requestBrowserFullscreen()
 }
 
+/** Mount (or re-mount) the player against `store.scene` and seek to `time`.
+ *  Used both by the initial `startPreview` and when a scripted / button
+ *  `jumpToScene` swaps the active page under us — we blow away the old
+ *  player and rebuild at the same playhead so visual continuity stays
+ *  intact across the switch. */
+function mountAt(el: HTMLElement, time: number, wasPlaying: boolean) {
+  player = mountPlayer(el, store.scene, {
+    loop: true,
+    onFrame(t: number, paused: boolean) {
+      localTime.value = t
+      playing.value = !paused
+    },
+    onJumpToScene(sceneId: string) {
+      // Route the runtime's jump into the store. The watcher below
+      // picks up the activeSceneId change and re-mounts the player
+      // against the new page at the current time.
+      store.switchScene(sceneId)
+    },
+  })
+  player.seek(time)
+  if (!wasPlaying) player.pause()
+}
+
+watch(
+  () => store.project.activeSceneId,
+  () => {
+    if (!props.modelValue) return
+    const el = frameEl.value
+    if (!el) return
+    // Every scene switch auto-plays on the new page — matches the
+    // store-level switchScene contract. We keep the current playhead
+    // so animation continuity stays intact across the swap.
+    const keepTime = player ? player.getTime() : store.playhead
+    destroyPlayer()
+    nextTick(() => {
+      if (!props.modelValue) return
+      const still = frameEl.value
+      if (!still) return
+      mountAt(still, keepTime, true)
+    })
+  },
+)
+
 function stopPreview() {
   destroyPlayer()
   playing.value = false
diff --git a/src/devtools/tests.ts b/src/devtools/tests.ts
index 6521b0c..a14ffeb 100644
--- a/src/devtools/tests.ts
+++ b/src/devtools/tests.ts
@@ -41,6 +41,8 @@ import IconButton from '@/components/ui/IconButton.vue'
 import Toast from '@/components/ui/Toast.vue'
 import PropertiesPanel from '@/components/PropertiesPanel.vue'
 import ClipartDrawer from '@/components/ClipartDrawer.vue'
+import SceneDrawer from '@/components/SceneDrawer.vue'
+import ActionEditor from '@/components/ActionEditor.vue'
 import { vTooltip } from '@/directives/tooltip'
 import { expect, suite, test } from './testRunner'
 
@@ -1280,22 +1282,40 @@ export function registerAllTests(): void {
       expect(s.scene.layers[0].id).toBe(l2.id)
     })
 
-    test('switchScene clears editor context (selection, clip-edit, playback, drawing)', () => {
+    test('switchScene clears editor context (selection, clip-edit, drawing) and auto-plays', () => {
       const s = makeFreshStore()
       const a = s.addAsset({ kind: 'rect', name: 'SW', width: 10, height: 10, fill: '#111' })
       const l = s.addLayer(a.id)!
       s.selectLayer(l.id)
-      s.play()
+      s.pause()
       const clip = s.addClip('C')
       s.activeClipId = clip.id
       const two = s.addScene()
       // addScene already routed through switchScene — cross-check.
       expect(s.selectedLayerId).toBeNull()
       expect(s.selectedLayerIds).toHaveLength(0)
-      expect(s.playing).toBe(false)
       expect(s.activeClipId).toBeNull()
       expect(s.activeButtonAssetId).toBeNull()
       expect(s.project.activeSceneId).toBe(two.id)
+      // Switching always auto-plays on the new page — even if the
+      // editor was paused beforehand.
+      expect(s.playing).toBe(true)
+    })
+
+    test('switchScene auto-plays even when the editor was paused', () => {
+      const s = makeFreshStore()
+      s.pause()
+      const second = s.addScene('Two')
+      const firstId = s.project.scenes[0].id
+      s.pause()
+      expect(s.playing).toBe(false)
+      s.switchScene(firstId)
+      expect(s.playing).toBe(true)
+      expect(s.project.activeSceneId).toBe(firstId)
+      // And the inverse direction — Two plays too.
+      s.pause()
+      s.switchScene(second.id)
+      expect(s.playing).toBe(true)
     })
 
     test('switchScene returns false for an unknown id and leaves state alone', () => {
@@ -3818,6 +3838,219 @@ export function registerAllTests(): void {
     })
   })
 
+  suite('ui — SceneDrawer', () => {
+    async function settlePromptCancel() {
+      // The drawer's `+` button dispatches addScene and then kicks off a
+      // promptDialog for renaming. Tests don't render DialogsHost, so
+      // we resolve the pending prompt explicitly to keep the dialog
+      // queue empty between tests.
+      const { cancelDialog } = await import('@/components/ui/dialogs')
+      cancelDialog()
+    }
+
+    test('renders one .scene-row per page, with .active on the current one', async () => {
+      const s = makeFreshStore()
+      s.addScene('Two')
+      s.addScene('Three')
+      const activeId = s.project.activeSceneId
+      const handle = mountComponent(SceneDrawer, {})
+      await nextTick()
+      const rows = handle.host.querySelectorAll('.scene-row')
+      expect(rows.length).toBe(3)
+      // Order matches `project.scenes`.
+      const names = Array.from(rows).map((r) => r.querySelector('.scene-name')?.textContent?.trim())
+      expect(names).toEqual(s.project.scenes.map((p) => p.name))
+      // Exactly one row is .active, and it's the active scene.
+      const active = Array.from(rows).filter((r) => r.classList.contains('active'))
+      expect(active.length).toBe(1)
+      const activeName = active[0].querySelector('.scene-name')?.textContent?.trim()
+      expect(activeName).toBe(s.project.scenes.find((p) => p.id === activeId)!.name)
+      handle.unmount()
+    })
+
+    test('layer-count badge reflects each scene\'s layer count', async () => {
+      const s = makeFreshStore()
+      const asset = s.addAsset({ kind: 'rect', name: 'D', width: 10, height: 10, fill: '#abc' })
+      s.addLayer(asset.id)
+      s.addLayer(asset.id)
+      const two = s.addScene('Two')
+      s.addLayer(asset.id) // lands on Two (active after addScene)
+      // Render AFTER state is set up so the component's reactive read
+      // captures the final layer counts.
+      const handle = mountComponent(SceneDrawer, {})
+      await nextTick()
+      const rows = handle.host.querySelectorAll('.scene-row')
+      expect(rows.length).toBe(2)
+      const metas = Array.from(rows).map((r) =>
+        r.querySelector('.scene-meta')?.textContent?.trim(),
+      )
+      // First row = Scene 1 (2 layers), second row = Two (1 layer).
+      expect(metas).toEqual(['2', '1'])
+      void two
+      handle.unmount()
+    })
+
+    test('clicking a non-active row switches to that page and auto-plays', async () => {
+      const s = makeFreshStore()
+      const firstId = s.project.activeSceneId
+      const second = s.addScene('Two')
+      // Go back to Scene 1 and pause so we can observe the auto-play flip.
+      s.switchScene(firstId)
+      s.pause()
+      const handle = mountComponent(SceneDrawer, {})
+      await nextTick()
+      const rows = handle.host.querySelectorAll('.scene-row') as NodeListOf<HTMLButtonElement>
+      // Row index 1 = Two (non-active).
+      rows[1].click()
+      await nextTick()
+      expect(s.project.activeSceneId).toBe(second.id)
+      expect(s.playing).toBe(true)
+      handle.unmount()
+    })
+
+    test('clicking the already-active row is a no-op', async () => {
+      const s = makeFreshStore()
+      const firstId = s.project.activeSceneId
+      s.pause()
+      const handle = mountComponent(SceneDrawer, {})
+      await nextTick()
+      const rows = handle.host.querySelectorAll('.scene-row') as NodeListOf<HTMLButtonElement>
+      // Row index 0 = the active one.
+      rows[0].click()
+      await nextTick()
+      // Still paused — no sneaky re-switch triggered auto-play.
+      expect(s.playing).toBe(false)
+      expect(s.project.activeSceneId).toBe(firstId)
+      handle.unmount()
+    })
+
+    test('+ button appends a new scene and activates it', async () => {
+      const s = makeFreshStore()
+      expect(s.project.scenes).toHaveLength(1)
+      const handle = mountComponent(SceneDrawer, {})
+      await nextTick()
+      const addBtn = handle.host.querySelector('.add-btn') as HTMLButtonElement
+      expect(addBtn).toBeTruthy()
+      addBtn.click()
+      // Let addScene + the nextTick inside addScene resolve.
+      await nextTick()
+      await nextTick()
+      expect(s.project.scenes).toHaveLength(2)
+      expect(s.project.activeSceneId).toBe(s.project.scenes[1].id)
+      // Clean up the pending rename prompt.
+      await settlePromptCancel()
+      handle.unmount()
+    })
+
+    test('right-click on a row surfaces the context menu', async () => {
+      const s = makeFreshStore()
+      s.addScene('Two')
+      const handle = mountComponent(SceneDrawer, {})
+      await nextTick()
+      expect(handle.host.querySelector('.scene-menu')).toBeNull()
+      const row = handle.host.querySelector('.scene-row') as HTMLElement
+      row.dispatchEvent(new MouseEvent('contextmenu', { bubbles: true, cancelable: true }))
+      await nextTick()
+      expect(handle.host.querySelector('.scene-menu')).toBeTruthy()
+      // Delete option is disabled only when there's just one scene left.
+      const deleteBtn = handle.host.querySelector('.scene-menu .menu-item.danger') as HTMLButtonElement
+      expect(deleteBtn).toBeTruthy()
+      expect(deleteBtn.disabled).toBe(false)
+      handle.unmount()
+    })
+
+    test('context menu disables Delete when only one scene remains', async () => {
+      const s = makeFreshStore()
+      expect(s.project.scenes.length).toBe(1)
+      const handle = mountComponent(SceneDrawer, {})
+      await nextTick()
+      const row = handle.host.querySelector('.scene-row') as HTMLElement
+      row.dispatchEvent(new MouseEvent('contextmenu', { bubbles: true, cancelable: true }))
+      await nextTick()
+      const deleteBtn = handle.host.querySelector('.scene-menu .menu-item.danger') as HTMLButtonElement
+      expect(deleteBtn).toBeTruthy()
+      expect(deleteBtn.disabled).toBe(true)
+      handle.unmount()
+    })
+  })
+
+  suite('ui — ActionEditor (jumpToScene)', () => {
+    test('jumpToScene appears in the type dropdown', async () => {
+      const s = makeFreshStore()
+      s.addScene('Two')
+      const handle = mountComponent(
+        ActionEditor,
+        { actions: [{ type: 'pause' } as const] },
+      )
+      await nextTick()
+      const select = handle.host.querySelector('.type-select') as HTMLSelectElement
+      expect(select).toBeTruthy()
+      const values = Array.from(select.options).map((o) => o.value)
+      expect(values.includes('jumpToScene')).toBe(true)
+      handle.unmount()
+    })
+
+    test('switching a row to jumpToScene seeds it with the first non-active scene', async () => {
+      const s = makeFreshStore()
+      const activeId = s.project.activeSceneId
+      const other = s.addScene('Other')
+      s.switchScene(activeId) // pull the active marker back to Scene 1
+      let latest: unknown = null
+      const handle = mountComponent(ActionEditor, {
+        actions: [{ type: 'pause' } as const],
+        'onUpdate:actions': (v: unknown) => {
+          latest = v
+        },
+      })
+      await nextTick()
+      const select = handle.host.querySelector('.type-select') as HTMLSelectElement
+      select.value = 'jumpToScene'
+      select.dispatchEvent(new Event('change', { bubbles: true }))
+      await nextTick()
+      expect(Array.isArray(latest)).toBe(true)
+      const arr = latest as unknown[]
+      expect(arr.length).toBe(1)
+      const next = arr[0] as { type: string; sceneId?: string }
+      expect(next.type).toBe('jumpToScene')
+      // Defaults to the first non-active scene so the action is useful out of the box.
+      expect(next.sceneId).toBe(other.id)
+      handle.unmount()
+    })
+
+    test('scene dropdown enumerates every scene by name, emits sceneId on change', async () => {
+      const s = makeFreshStore()
+      const firstId = s.project.scenes[0].id
+      const second = s.addScene('Two')
+      const third = s.addScene('Three')
+      // Active is now Three. The seed action points at Two; changing
+      // to Three via the dropdown should emit { sceneId: third.id }.
+      let latest: unknown = null
+      const handle = mountComponent(ActionEditor, {
+        actions: [{ type: 'jumpToScene', sceneId: second.id } as const],
+        'onUpdate:actions': (v: unknown) => {
+          latest = v
+        },
+      })
+      await nextTick()
+      // Find the scene dropdown (second select on the row — the first
+      // is the action-type select).
+      const selects = handle.host.querySelectorAll('select')
+      expect(selects.length).toBe(2)
+      const sceneSelect = selects[1] as HTMLSelectElement
+      const sceneValues = Array.from(sceneSelect.options).map((o) => o.value)
+      expect(sceneValues).toEqual([firstId, second.id, third.id])
+      const sceneLabels = Array.from(sceneSelect.options).map((o) => o.textContent?.trim())
+      expect(sceneLabels).toEqual(['Scene 1', 'Two', 'Three'])
+      sceneSelect.value = third.id
+      sceneSelect.dispatchEvent(new Event('change', { bubbles: true }))
+      await nextTick()
+      const next = (latest as unknown[])[0] as { type: string; sceneId: string }
+      expect(next.type).toBe('jumpToScene')
+      expect(next.sceneId).toBe(third.id)
+      handle.unmount()
+    })
+  })
+
   suite('polygon — vertex bezier actions', () => {
     function makeSquare() {
       const s = makeFreshStore()
@@ -4811,6 +5044,40 @@ export function registerAllTests(): void {
       expect(rt.warnings[0]).toContain('missing')
     })
 
+    test('jumpToScene dispatches switchScene on the runtime', () => {
+      let switched: string | null = null
+      const rt = makeMockRuntime({
+        sceneIds: new Set(['s-a', 's-b']),
+        switchScene(id: string) {
+          switched = id
+        },
+      })
+      evalAction({ type: 'jumpToScene', sceneId: 's-b' }, rt)
+      expect(switched).toBe('s-b')
+      expect(rt.warnings.length).toBe(0)
+    })
+
+    test('jumpToScene warns on unknown sceneId and does not switch', () => {
+      let switched: string | null = null
+      const rt = makeMockRuntime({
+        sceneIds: new Set(['s-a']),
+        switchScene(id: string) {
+          switched = id
+        },
+      })
+      evalAction({ type: 'jumpToScene', sceneId: 's-ghost' }, rt)
+      expect(switched).toBe(null)
+      expect(rt.warnings.length).toBe(1)
+      expect(rt.warnings[0]).toContain('s-ghost')
+    })
+
+    test('jumpToScene warns if runtime has no switchScene handler (e.g. exported bundle)', () => {
+      const rt = makeMockRuntime() // no switchScene, no sceneIds
+      evalAction({ type: 'jumpToScene', sceneId: 's-x' }, rt)
+      expect(rt.warnings.length).toBe(1)
+      expect(rt.warnings[0].toLowerCase()).toContain('does not support')
+    })
+
     test('script action parses and dispatches sub-actions (no warn on valid DSL)', () => {
       const rt = makeMockRuntime()
       evalAction({ type: 'script', source: 'play\npause' }, rt)
@@ -4898,6 +5165,48 @@ export function registerAllTests(): void {
       expect(s.playhead).toBe(0) // rewindToLoop → playbackIn=0
       await tick()
     })
+
+    test('a scripted jumpToScene switches the active scene and keeps playing', async () => {
+      // User-facing contract: a script track fires a scene-switch in the
+      // middle of a running timeline — the active scene flips and the
+      // timeline keeps running on the new page. All pages share
+      // duration/fps, so the playhead stays put and continues onward.
+      const s = makeFreshStore()
+      s.setDuration(10)
+      const aId = s.project.activeSceneId
+      const bId = s.addScene('B').id
+      s.switchScene(aId)
+      const track = s.addScriptTrack()
+      s.addScriptFrame(track.id, 3, [{ type: 'jumpToScene', sceneId: bId }])
+      s.play()
+      s.tick(3)
+      expect(s.project.activeSceneId).toBe(bId)
+      expect(s.playing).toBe(true)
+      await tick()
+    })
+
+    test('scripted jumpToScene with an unknown id warns and leaves state alone', async () => {
+      const s = makeFreshStore()
+      s.setDuration(10)
+      const aId = s.project.activeSceneId
+      const track = s.addScriptTrack()
+      s.addScriptFrame(track.id, 2, [{ type: 'jumpToScene', sceneId: 'bogus-id' }])
+      s.play()
+      const warnings: string[] = []
+      const origWarn = console.warn
+      console.warn = (...args: unknown[]) => {
+        warnings.push(args.map(String).join(' '))
+      }
+      try {
+        s.tick(2)
+      } finally {
+        console.warn = origWarn
+      }
+      expect(s.project.activeSceneId).toBe(aId)
+      expect(s.playing).toBe(true)
+      expect(warnings.some((w) => w.includes('bogus-id'))).toBe(true)
+      await tick()
+    })
   })
 
   suite('scriptDsl — parser', () => {
diff --git a/src/i18n/messages.ts b/src/i18n/messages.ts
index 1b98596..5a39cfb 100644
--- a/src/i18n/messages.ts
+++ b/src/i18n/messages.ts
@@ -468,6 +468,7 @@ export const en = {
     moveUp: 'Move up',
     moveDown: 'Move down',
     noMarkers: 'No markers defined',
+    noScenes: 'No other scenes defined',
     type: {
       play: 'Play',
       pause: 'Pause',
@@ -475,12 +476,14 @@ export const en = {
       jumpTo: 'Jump to time',
       jumpToFrame: 'Jump to frame',
       jumpToMarker: 'Jump to marker',
+      jumpToScene: 'Jump to scene',
       script: 'Run script',
     },
     param: {
       time: 'Seconds',
       frame: 'Frame',
       marker: 'Marker',
+      scene: 'Scene',
       source: 'Script source',
     },
   },
diff --git a/src/lib/actions.ts b/src/lib/actions.ts
index b04f60d..5fff632 100644
--- a/src/lib/actions.ts
+++ b/src/lib/actions.ts
@@ -7,9 +7,17 @@ export interface ActionRuntime {
   playbackOut: number
   duration: number
   markers: Record<string, number>
+  /** Set of valid scene ids the runtime knows about. Used so jumpToScene
+   *  can warn on stale references (e.g., the target scene was deleted)
+   *  instead of silently failing. */
+  sceneIds?: Set<string>
   setPlayhead(t: number): void
   play(): void
   pause(): void
+  /** Switch the active scene page. Implementations should preserve the
+   *  current playback state so a script-fired jump doesn't surprise-pause
+   *  the timeline. */
+  switchScene?(sceneId: string): void
   warn(msg: string): void
 }
 
@@ -49,6 +57,18 @@ export function evalAction(action: Action, rt: ActionRuntime): void {
       rt.setPlayhead(clamp(t, 0, rt.duration))
       return
     }
+    case 'jumpToScene': {
+      if (!rt.switchScene) {
+        rt.warn('jumpToScene: runtime does not support scene switching')
+        return
+      }
+      if (rt.sceneIds && !rt.sceneIds.has(action.sceneId)) {
+        rt.warn(`jumpToScene: unknown scene id "${action.sceneId}"`)
+        return
+      }
+      rt.switchScene(action.sceneId)
+      return
+    }
     case 'script': {
       const parsed = parseScript(action.source)
       if (parsed.errors.length) {
diff --git a/src/lib/exportPlayer.ts b/src/lib/exportPlayer.ts
index fab6efb..eb295e7 100644
--- a/src/lib/exportPlayer.ts
+++ b/src/lib/exportPlayer.ts
@@ -1,6 +1,6 @@
 import type { Scene } from '@/types/scene'
 
-const RUNTIME_VERSION = '17'
+const RUNTIME_VERSION = '19'
 
 const ENGINE_SOURCE = `(function(){
   if (window.AnimatrPlayer && window.AnimatrPlayer.__v === '${RUNTIME_VERSION}') return;
@@ -350,6 +350,15 @@ const ENGINE_SOURCE = `(function(){
           runtime.jumpTo=Math.max(0,Math.min(runtime.duration,mt));
           return;
         }
+        case 'jumpToScene': {
+          // Exports only carry one scene at a time, so jumpToScene is a
+          // warn-and-continue in standalone bundles. The in-editor
+          // fullscreen preview passes an onJumpToScene hook which routes
+          // the jump back to the store and re-mounts at the same time.
+          if (onJumpToScene){ try { onJumpToScene(act.sceneId); } catch(e){ runtime.warn('jumpToScene: '+((e&&e.message)||String(e))); } return; }
+          runtime.warn('jumpToScene: exported runtime does not support multi-scene playback');
+          return;
+        }
         case 'script': {
           var parsed=parseScriptSource(act.source);
           if(parsed.errors.length){
@@ -381,6 +390,7 @@ const ENGINE_SOURCE = `(function(){
     var lastNow=0;
     var rafId=0;
     var onFrame=opts.onFrame||null;
+    var onJumpToScene=opts.onJumpToScene||null;
     var destroyed=false;
     function frame(now){
       if(destroyed) return;
@@ -866,6 +876,13 @@ export interface PlayerHandle {
 export interface MountOptions {
   loop?: boolean
   onFrame?: (time: number, paused: boolean) => void
+  /** In-editor hook used by the fullscreen preview: a scripted (or
+   *  button-click) `jumpToScene` calls this instead of the runtime's
+   *  own warn-and-skip path. The host is responsible for swapping the
+   *  Scene the player renders (typically by mutating the store and
+   *  re-mounting with the new active page). Exported bundles omit this
+   *  — they carry a single scene and warn on jumpToScene. */
+  onJumpToScene?: (sceneId: string) => void
 }
 
 // eslint-disable-next-line @typescript-eslint/no-explicit-any
diff --git a/src/stores/scene.ts b/src/stores/scene.ts
index fd2452d..834ee49 100644
--- a/src/stores/scene.ts
+++ b/src/stores/scene.ts
@@ -1798,7 +1798,10 @@ export const useSceneStore = defineStore('scene', {
     },
     /** Activate a page by id. Clears any drill-down state (clip-edit,
      *  button-edit, selections, drawing) so the new page isn't shown
-     *  through the lens of a context that belongs to another page. */
+     *  through the lens of a context that belongs to another page.
+     *  Every switch auto-starts playback — clicking a scene in the
+     *  drawer or having a script/button jump to one always hands the
+     *  user a running timeline on the new page. */
     switchScene(id: string): boolean {
       if (!this.project.scenes.find((s) => s.id === id)) return false
       this.project.activeSceneId = id
@@ -1812,7 +1815,7 @@ export const useSceneStore = defineStore('scene', {
       this.drawingMode = null
       this.drawingAssetId = null
       this.drawingLayerId = null
-      this.playing = false
+      this.playing = true
       return true
     },
     renameScene(id: string, name: string): boolean {
@@ -2401,6 +2404,7 @@ export const useSceneStore = defineStore('scene', {
         playbackOut: self.playbackOut,
         duration: self.scene.duration,
         markers: buildMarkerMap(self.scene.markers),
+        sceneIds: new Set(self.project.scenes.map((s) => s.id)),
         setPlayhead(t: number) {
           self.setPlayhead(t)
         },
@@ -2410,6 +2414,9 @@ export const useSceneStore = defineStore('scene', {
         pause() {
           self.pause()
         },
+        switchScene(sceneId: string) {
+          self.switchScene(sceneId)
+        },
         warn(msg: string) {
           // eslint-disable-next-line no-console
           console.warn('[ruwio]', msg)
diff --git a/src/types/scene.ts b/src/types/scene.ts
index cb0df4b..bfe4667 100644
--- a/src/types/scene.ts
+++ b/src/types/scene.ts
@@ -269,6 +269,10 @@ export type Action =
   | { type: 'jumpTo'; time: number }
   | { type: 'jumpToFrame'; frame: number }
   | { type: 'jumpToMarker'; name: string }
+  /** Switch the active scene page. Stored by stable id so scene renames
+   *  don't break existing actions. Playback state is preserved across
+   *  the jump — all pages share the same timeline. */
+  | { type: 'jumpToScene'; sceneId: string }
   | { type: 'script'; source: string }
 
 // ---------------------------------------------------------------------------