diff --git a/src/devtools/tests.ts b/src/devtools/tests.ts
index 06eb7af..e0479a8 100644
--- a/src/devtools/tests.ts
+++ b/src/devtools/tests.ts
@@ -1,5 +1,12 @@
 import { createApp, h, nextTick, type Component, type Slot } from 'vue'
 import { createBlankScene, useSceneStore } from '@/stores/scene'
+import {
+  buildMarkerMap,
+  evalAction,
+  scriptFramesInRange,
+  type ActionRuntime,
+} from '@/lib/actions'
+import type { Action } from '@/types/scene'
 import { sampleLayer, lerpColor } from '@/lib/interpolate'
 import { snapToCandidates } from '@/lib/timelineSnap'
 import {
@@ -3198,6 +3205,183 @@ export function registerAllTests(): void {
     })
   })
 
+  suite('actions — evalAction with mock runtime', () => {
+    function makeMockRuntime(init?: Partial<ActionRuntime>): ActionRuntime & {
+      calls: string[]
+      playhead: number
+      playing: boolean
+      buttonStates: Record<string, string>
+      buttonDisabled: Record<string, boolean>
+      warnings: string[]
+    } {
+      const rt = {
+        fps: 60,
+        playbackIn: 0,
+        playbackOut: 10,
+        duration: 10,
+        markers: { intro: 2, outro: 8 },
+        playhead: 0,
+        playing: false,
+        buttonStates: {} as Record<string, string>,
+        buttonDisabled: {} as Record<string, boolean>,
+        warnings: [] as string[],
+        calls: [] as string[],
+        setPlayhead(t: number) {
+          this.calls.push(`setPlayhead:${t}`)
+          this.playhead = t
+        },
+        play() {
+          this.calls.push('play')
+          this.playing = true
+        },
+        pause() {
+          this.calls.push('pause')
+          this.playing = false
+        },
+        setButtonState(id: string, state: string) {
+          this.calls.push(`btnState:${id}=${state}`)
+          this.buttonStates[id] = state
+        },
+        setButtonDisabled(id: string, d: boolean) {
+          this.calls.push(`btnDisabled:${id}=${d}`)
+          this.buttonDisabled[id] = d
+        },
+        warn(msg: string) {
+          this.warnings.push(msg)
+        },
+        ...init,
+      }
+      return rt as ReturnType<typeof makeMockRuntime>
+    }
+
+    test('play / pause / rewindToLoop', () => {
+      const rt = makeMockRuntime({ playbackIn: 2 })
+      evalAction({ type: 'play' }, rt)
+      evalAction({ type: 'pause' }, rt)
+      evalAction({ type: 'rewindToLoop' }, rt)
+      expect(rt.playing).toBe(false)
+      expect(rt.playhead).toBe(2)
+      expect(rt.calls).toEqual(['play', 'pause', 'setPlayhead:2'])
+    })
+
+    test('jumpTo clamps to [0, duration]', () => {
+      const rt = makeMockRuntime()
+      evalAction({ type: 'jumpTo', time: -3 }, rt)
+      expect(rt.playhead).toBe(0)
+      evalAction({ type: 'jumpTo', time: 99 }, rt)
+      expect(rt.playhead).toBe(10)
+      evalAction({ type: 'jumpTo', time: 5 }, rt)
+      expect(rt.playhead).toBe(5)
+    })
+
+    test('jumpToFrame divides by fps', () => {
+      const rt = makeMockRuntime({ fps: 30 })
+      evalAction({ type: 'jumpToFrame', frame: 90 }, rt)
+      expect(rt.playhead).toBe(3)
+    })
+
+    test('jumpToMarker resolves via markers map', () => {
+      const rt = makeMockRuntime()
+      evalAction({ type: 'jumpToMarker', name: 'outro' }, rt)
+      expect(rt.playhead).toBe(8)
+    })
+
+    test('jumpToMarker warns on unknown name and does not move playhead', () => {
+      const rt = makeMockRuntime()
+      const before = rt.playhead
+      evalAction({ type: 'jumpToMarker', name: 'missing' }, rt)
+      expect(rt.playhead).toBe(before)
+      expect(rt.warnings.length).toBe(1)
+      expect(rt.warnings[0]).toContain('missing')
+    })
+
+    test('setButtonState + setButtonDisabled dispatch to runtime', () => {
+      const rt = makeMockRuntime()
+      evalAction({ type: 'setButtonState', instanceId: 'b1', state: 'pressed' }, rt)
+      evalAction({ type: 'setButtonDisabled', instanceId: 'b2', disabled: true }, rt)
+      expect(rt.buttonStates.b1).toBe('pressed')
+      expect(rt.buttonDisabled.b2).toBe(true)
+    })
+
+    test("script action warns that DSL isn't implemented yet", () => {
+      const rt = makeMockRuntime()
+      evalAction({ type: 'script', source: 'play' }, rt)
+      expect(rt.warnings.length).toBe(1)
+    })
+
+    test('buildMarkerMap maps name → time', () => {
+      const map = buildMarkerMap([
+        { id: 'a', name: 'intro', time: 1 },
+        { id: 'b', name: 'outro', time: 5 },
+      ])
+      expect(map.intro).toBe(1)
+      expect(map.outro).toBe(5)
+    })
+
+    test('scriptFramesInRange returns only forward frames, sorted', () => {
+      const frames = [
+        { id: 'a', trackId: 't', time: 3, actions: [] as Action[] },
+        { id: 'b', trackId: 't', time: 1, actions: [] as Action[] },
+        { id: 'c', trackId: 't', time: 6, actions: [] as Action[] },
+      ]
+      // (0, 4] → only 1 and 3, sorted
+      const got = scriptFramesInRange(frames, 0, 4).map((f) => f.id)
+      expect(got).toEqual(['b', 'a'])
+      // backwards → empty
+      expect(scriptFramesInRange(frames, 5, 1)).toHaveLength(0)
+    })
+
+    test('scriptFramesInRange uses open-closed interval', () => {
+      const frames = [{ id: 'a', trackId: 't', time: 2, actions: [] as Action[] }]
+      // prev=2 (exclusive), next=2 → empty
+      expect(scriptFramesInRange(frames, 2, 2)).toHaveLength(0)
+      // prev=1, next=2 → includes 2
+      expect(scriptFramesInRange(frames, 1, 2)).toHaveLength(1)
+    })
+  })
+
+  suite('scene store — tick fires script frames forward-only', () => {
+    test('tick fires frames crossed during forward advance in time order', async () => {
+      const s = makeFreshStore()
+      s.setDuration(10)
+      const t = s.addScriptTrack()
+      s.addScriptFrame(t.id, 2, [{ type: 'pause' }])
+      s.addScriptFrame(t.id, 1, [{ type: 'jumpTo', time: 9 }])
+      s.play()
+      // From 0 → 2: both frames get crossed; time-1 frame fires first and
+      // jumps the playhead to 9, time-2 frame fires second and pauses.
+      s.tick(2)
+      expect(s.playhead).toBe(9)
+      expect(s.playing).toBe(false)
+      await tick()
+    })
+
+    test('setPlayhead alone does not fire frames', async () => {
+      const s = makeFreshStore()
+      s.setDuration(10)
+      const t = s.addScriptTrack()
+      s.addScriptFrame(t.id, 2, [{ type: 'pause' }])
+      s.play()
+      s.setPlayhead(5) // scrub over the frame without ticking
+      expect(s.playing).toBe(true)
+      s.pause()
+      await tick()
+    })
+
+    test('frames fire even after natural stop at playbackOut', async () => {
+      const s = makeFreshStore()
+      s.setDuration(10)
+      s.setPlaybackRange(0, 5)
+      const t = s.addScriptTrack()
+      s.addScriptFrame(t.id, 5, [{ type: 'rewindToLoop' }])
+      s.play()
+      s.tick(6) // lands at playbackOut=5, playing=false, frame at 5 fires
+      expect(s.playing).toBe(false)
+      expect(s.playhead).toBe(0) // rewindToLoop → playbackIn=0
+      await tick()
+    })
+  })
+
   suite('scene store — macro model normalization', () => {
     test('loadScene initializes new arrays when missing', () => {
       const s = makeFreshStore()
diff --git a/src/lib/actions.ts b/src/lib/actions.ts
new file mode 100644
index 0000000..4f85bde
--- /dev/null
+++ b/src/lib/actions.ts
@@ -0,0 +1,85 @@
+import type { Action, ButtonState, Marker } from '@/types/scene'
+
+export interface ActionRuntime {
+  fps: number
+  playbackIn: number
+  playbackOut: number
+  duration: number
+  markers: Record<string, number>
+  setPlayhead(t: number): void
+  play(): void
+  pause(): void
+  setButtonState(instanceId: string, state: ButtonState): void
+  setButtonDisabled(instanceId: string, disabled: boolean): void
+  warn(msg: string): void
+}
+
+export function buildMarkerMap(
+  markers: Marker[] | undefined,
+): Record<string, number> {
+  const out: Record<string, number> = {}
+  for (const m of markers ?? []) out[m.name] = m.time
+  return out
+}
+
+export function evalAction(action: Action, rt: ActionRuntime): void {
+  switch (action.type) {
+    case 'play':
+      rt.play()
+      return
+    case 'pause':
+      rt.pause()
+      return
+    case 'rewindToLoop':
+      rt.setPlayhead(rt.playbackIn)
+      return
+    case 'jumpTo':
+      rt.setPlayhead(clamp(action.time, 0, rt.duration))
+      return
+    case 'jumpToFrame': {
+      const fps = rt.fps || 60
+      rt.setPlayhead(clamp(action.frame / fps, 0, rt.duration))
+      return
+    }
+    case 'jumpToMarker': {
+      const t = rt.markers[action.name]
+      if (t == null) {
+        rt.warn(`Unknown marker: ${action.name}`)
+        return
+      }
+      rt.setPlayhead(clamp(t, 0, rt.duration))
+      return
+    }
+    case 'setButtonState':
+      rt.setButtonState(action.instanceId, action.state)
+      return
+    case 'setButtonDisabled':
+      rt.setButtonDisabled(action.instanceId, action.disabled)
+      return
+    case 'script':
+      rt.warn('Script DSL is not implemented yet')
+      return
+  }
+}
+
+function clamp(n: number, lo: number, hi: number): number {
+  return Math.max(lo, Math.min(hi, n))
+}
+
+/**
+ * Return the script frames whose time sits in the open-closed interval
+ * `(prev, next]`, sorted by time ascending. Forward-only — callers must
+ * pass `next >= prev`, and the caller is responsible for suppressing
+ * firing across loop wraps or scrubs.
+ */
+export function scriptFramesInRange<
+  F extends { time: number; actions: unknown[] },
+>(frames: F[] | undefined, prev: number, next: number): F[] {
+  if (!frames || !frames.length || next <= prev) return []
+  const out: F[] = []
+  for (const f of frames) {
+    if (f.time > prev && f.time <= next) out.push(f)
+  }
+  out.sort((a, b) => a.time - b.time)
+  return out
+}
diff --git a/src/stores/scene.ts b/src/stores/scene.ts
index 6f80856..5d9ec5b 100644
--- a/src/stores/scene.ts
+++ b/src/stores/scene.ts
@@ -21,6 +21,12 @@ import type {
 } from '@/types/scene'
 import { DEFAULT_BASE_PROPS } from '@/types/scene'
 import { sampleLayer } from '@/lib/interpolate'
+import {
+  buildMarkerMap,
+  evalAction,
+  scriptFramesInRange,
+  type ActionRuntime,
+} from '@/lib/actions'
 
 const uid = () => Math.random().toString(36).slice(2, 10)
 
@@ -1464,13 +1470,55 @@ export const useSceneStore = defineStore('scene', {
     },
     tick(deltaSeconds: number) {
       if (!this.playing) return
+      const prev = this.playhead
       const end = this.playbackOut
-      const next = this.playhead + deltaSeconds
-      if (next >= end) {
+      const nextRaw = prev + deltaSeconds
+      if (nextRaw >= end) {
         this.playhead = end
         this.playing = false
       } else {
-        this.playhead = next
+        this.playhead = nextRaw
+      }
+      const landed = this.playhead
+      // Forward-only firing: script frames whose time sits in (prev, landed].
+      // Scrubs/setPlayhead/loop-wraps never reach this path, so the rule
+      // is naturally preserved.
+      const frames = scriptFramesInRange(this.scene.scriptFrames, prev, landed)
+      if (frames.length) {
+        const rt = this.actionRuntime()
+        for (const f of frames) {
+          for (const action of f.actions) evalAction(action, rt)
+        }
+      }
+    },
+    actionRuntime(): ActionRuntime {
+      const self = this
+      return {
+        fps: self.scene.fps,
+        playbackIn: self.playbackIn,
+        playbackOut: self.playbackOut,
+        duration: self.scene.duration,
+        markers: buildMarkerMap(self.scene.markers),
+        setPlayhead(t: number) {
+          self.setPlayhead(t)
+        },
+        play() {
+          self.play()
+        },
+        pause() {
+          self.pause()
+        },
+        setButtonState() {
+          // No-op in editor for now — runtime-state management lands in
+          // the export-runtime slice together with pointer handling.
+        },
+        setButtonDisabled(instanceId: string, disabled: boolean) {
+          self.setButtonInstanceDisabled(instanceId, disabled)
+        },
+        warn(msg: string) {
+          // eslint-disable-next-line no-console
+          console.warn('[animatr]', msg)
+        },
       }
     },
   },