diff --git a/package-lock.json b/package-lock.json
index f23f0f4a..6fc0122f 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -5984,9 +5984,9 @@
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+      "resolved": "https://registry.npmjs.org/flatted/-/flatted-3.4.2.tgz",
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       "dev": true,
       "license": "ISC"
     },
@@ -8948,9 +8948,9 @@
       "license": "ISC"
     },
     "node_modules/nan": {
-      "version": "2.25.0",
-      "resolved": "https://registry.npmjs.org/nan/-/nan-2.25.0.tgz",
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+      "version": "2.26.1",
+      "resolved": "https://registry.npmjs.org/nan/-/nan-2.26.1.tgz",
+      "integrity": "sha512-vodKprLlmaKmraa9E/TxHQwpH4eKYTJbLdeQE49pb9GOmrLs68zESjJu0LQOz1W6JwJmftOWD5Ls4dpd/elQtQ==",
       "dev": true,
       "license": "MIT",
       "optional": true
diff --git a/packages/app/studio/public/manuals/devices/midi/spielwerk.md b/packages/app/studio/public/manuals/devices/midi/spielwerk.md
new file mode 100644
index 00000000..76372deb
--- /dev/null
+++ b/packages/app/studio/public/manuals/devices/midi/spielwerk.md
@@ -0,0 +1,457 @@
+# Spielwerk
+
+A programmable MIDI effect that lets you write custom note transformations in JavaScript. Filter, reshape, generate, or delay notes — declare parameters with knobs and hot-reload changes in real time.
+
+---
+
+![screenshot](spielwerk.webp)
+
+---
+
+## 0. Overview
+
+_Spielwerk_ is a scriptable MIDI effect device. You write a `Processor` class in JavaScript that receives incoming notes and yields transformed or new notes. Parameters declared in the code appear as automatable knobs on the device panel.
+
+Example uses:
+
+- Custom velocity curves and mapping
+- Pitch transposition and micro-tuning
+- Chord generators
+- Arpeggiators and step sequencers
+- Probability-based note filtering
+- Note echo and delay
+- Humanization and timing randomization
+
+---
+
+## 1. Editor
+
+Click the **Editor** button on the device panel to open the full-screen code editor. The editor uses Monaco (the engine behind VS Code) with JavaScript syntax highlighting.
+
+The status bar at the bottom shows the current state:
+
+- **Idle** — No compilation attempted yet
+- **Successfully compiled** — Code compiled and loaded into the engine
+- **Error message** — Syntax error, runtime error, or validation failure
+
+---
+
+## 2. Parameters
+
+Declare parameters using `// @param` comments at the top of your code:
+
+```javascript
+// @param amount 0.5
+// @param chance 1.0
+// @param offset
+```
+
+Each `@param` directive creates an automatable knob on the device panel. The syntax is:
+
+```
+// @param <label> [default]
+```
+
+- **label** — Parameter name (single word, no spaces). Appears on the knob.
+- **default** — Optional default value between 0.0 and 1.0. Defaults to 0.0 if omitted.
+
+Parameters are reconciled on each compile: new parameters are added, removed parameters are deleted, and existing parameters keep their current value.
+
+---
+
+## 3. Keyboard Shortcuts
+
+| Shortcut            | Action                              |
+|---------------------|-------------------------------------|
+| `Alt+Enter`         | Compile and run                     |
+| `Ctrl+S` / `Cmd+S` | Compile, run, and save to project   |
+
+---
+
+## 4. Safety
+
+The engine validates every note your code yields:
+
+- **Pitch range** — Must be 0–127. Out-of-range values silence the processor.
+- **Velocity range** — Must be 0.0–1.0. Out-of-range values silence the processor.
+- **Duration** — Must be positive. Zero or negative durations silence the processor.
+- **Position** — Must not be in the past (before block start). Past positions silence the processor.
+- **NaN detection** — If any note property is NaN, the processor is silenced.
+- **Note flood** — Maximum 128 notes per block. Exceeding this silences the processor.
+- **Scheduler overflow** — Maximum 128 future-scheduled notes. Exceeding this silences the processor.
+- **Runtime errors** — If `processNotes()` throws, the processor is silenced.
+
+When silenced, all active notes are released and the device passes nothing until the next successful compile.
+
+---
+
+## 5. API Reference
+
+Your code must define a `class Processor` with a generator method `processNotes`. Optionally implement `paramChanged` to receive parameter updates.
+
+### Processor class
+
+```javascript
+class Processor {
+    * processNotes(block, notes) {
+        // block.from  — start position in ppqn (inclusive)
+        // block.to    — end position in ppqn (exclusive)
+        // block.bpm   — current project tempo in BPM
+        // block.flags — bitmask:
+        //   1 (transporting)  — transport is active
+        //   2 (discontinuous) — position jumped (seek, loop restart)
+        //
+        // notes — iterator of upstream note starts in [from, to)
+        // Each note: { position, duration, pitch, velocity, cent }
+        //
+        // Yield notes with: { position, duration, pitch, velocity, cent }
+        // - position in [from, to) → emitted immediately
+        // - position >= to → held in scheduler, emitted in a future block
+        // - position < from → ERROR (note in the past)
+        for (const note of notes) {
+            yield note // passthrough
+        }
+    }
+    paramChanged(label, value) {
+        // label — string matching the @param name
+        // value — number between 0.0 and 1.0
+    }
+    reset() {
+        // optional — called on transport jump (seek, loop restart)
+        // use to clear accumulated state like held note arrays
+    }
+}
+```
+
+### Note properties
+
+| Property   | Type     | Range     | Description                           |
+|------------|----------|-----------|---------------------------------------|
+| `position` | `number` | ppqn      | Start position (480 ppqn per quarter) |
+| `duration` | `number` | ppqn      | Note length                           |
+| `pitch`    | `number` | 0–127     | MIDI note number                      |
+| `velocity` | `number` | 0.0–1.0   | Note velocity                         |
+| `cent`     | `number` | any       | Fine pitch offset in cents            |
+
+### Future scheduling
+
+Notes with `position >= block.to` are not emitted immediately. They are held in an internal scheduler and emitted automatically when the transport reaches their position in a later block. This enables effects like echo/delay and humanizers that shift notes across block boundaries.
+
+### State across blocks
+
+Your processor instance persists across blocks. Use class fields to track state:
+
+```javascript
+class Processor {
+    held = []    // survives between blocks
+    counter = 0  // survives between blocks
+    * processNotes(block, notes) { ... }
+}
+```
+
+State is reset when the code is recompiled (a new instance is created).
+
+---
+
+## 6. Examples
+
+### Passthrough
+
+```javascript
+class Processor {
+    * processNotes(block, notes) {
+        for (const note of notes) {
+            yield note
+        }
+    }
+}
+```
+
+### Velocity Curve
+
+```javascript
+// @param target 0.5
+// @param strength 0.0
+// @param mix 1.0
+
+class Processor {
+    target = 0.5
+    strength = 0
+    mix = 1
+    paramChanged(label, value) {
+        if (label === "target") this.target = value
+        if (label === "strength") this.strength = value
+        if (label === "mix") this.mix = value
+    }
+    * processNotes(block, notes) {
+        for (const note of notes) {
+            const magnet = note.velocity + (this.target - note.velocity) * this.strength
+            const velocity = note.velocity * (1 - this.mix) + Math.max(0, Math.min(1, magnet)) * this.mix
+            yield { ...note, velocity }
+        }
+    }
+}
+```
+
+### Pitch Shift
+
+```javascript
+// @param semitones 0.5
+
+class Processor {
+    semitones = 0
+    paramChanged(label, value) {
+        if (label === "semitones") this.semitones = Math.round(value * 24 - 12)
+    }
+    * processNotes(block, notes) {
+        for (const note of notes) {
+            yield { ...note, pitch: note.pitch + this.semitones }
+        }
+    }
+}
+```
+
+### Chord Generator
+
+```javascript
+// @param mode 0.0
+
+class Processor {
+    chords = [[0, 4, 7], [0, 3, 7], [0, 4, 7, 11], [0, 3, 7, 10]]
+    mode = 0
+    paramChanged(label, value) {
+        if (label === "mode") this.mode = Math.floor(value * this.chords.length * 0.999)
+    }
+    * processNotes(block, notes) {
+        for (const note of notes) {
+            for (const interval of this.chords[this.mode]) {
+                yield { ...note, pitch: note.pitch + interval }
+            }
+        }
+    }
+}
+```
+
+### Probability Gate
+
+```javascript
+// @param chance 0.5
+
+class Processor {
+    chance = 0.5
+    paramChanged(label, value) {
+        if (label === "chance") this.chance = value
+    }
+    * processNotes(block, notes) {
+        for (const note of notes) {
+            if (Math.random() < this.chance) {
+                yield note
+            }
+        }
+    }
+}
+```
+
+### Echo / Note Delay
+
+```javascript
+// @param repeats 0.25
+// @param delay 0.25
+// @param decay 0.7
+
+class Processor {
+    repeats = 3
+    delay = 120
+    decay = 0.7
+    paramChanged(label, value) {
+        if (label === "repeats") this.repeats = Math.round(value * 7) + 1
+        if (label === "delay") this.delay = Math.round(24 + value * 456)
+        if (label === "decay") this.decay = value
+    }
+    * processNotes(block, notes) {
+        for (const note of notes) {
+            for (let i = 0; i < this.repeats; i++) {
+                yield {
+                    ...note,
+                    position: note.position + i * this.delay,
+                    velocity: note.velocity * Math.pow(this.decay, i)
+                }
+            }
+        }
+    }
+}
+```
+
+Future repeats are automatically scheduled and emitted in the correct block.
+
+### Humanizer
+
+```javascript
+// @param timing 0.2
+// @param velRange 0.3
+
+class Processor {
+    timing = 10
+    velRange = 0.1
+    paramChanged(label, value) {
+        if (label === "timing") this.timing = value * 50
+        if (label === "velRange") this.velRange = value * 0.3
+    }
+    * processNotes(block, notes) {
+        for (const note of notes) {
+            yield {
+                ...note,
+                position: note.position + Math.random() * this.timing,
+                velocity: Math.max(0, Math.min(1, note.velocity + (Math.random() - 0.5) * this.velRange))
+            }
+        }
+    }
+}
+```
+
+### Arpeggiator
+
+```javascript
+// @param rate 0.25
+// @param gate 0.8
+
+class Processor {
+    rate = 120
+    gate = 0.8
+    held = []
+    paramChanged(label, value) {
+        if (label === "rate") this.rate = Math.round(24 + value * 456)
+        if (label === "gate") this.gate = 0.1 + value * 0.9
+    }
+    reset() {
+        this.held = []
+    }
+    activeAt(position) {
+        return this.held
+            .filter(note => note.position <= position && position < note.position + note.duration)
+            .sort((noteA, noteB) => noteA.pitch - noteB.pitch)
+    }
+    * processNotes(block, notes) {
+        for (const note of notes) {
+            this.held.push(note)
+        }
+        this.held = this.held.filter(note => note.position + note.duration > block.from)
+        const duration = Math.max(1, Math.floor(this.rate * this.gate))
+        let index = Math.ceil(block.from / this.rate)
+        let position = index * this.rate
+        while (position < block.to) {
+            const stack = this.activeAt(position)
+            if (stack.length > 0) {
+                const source = stack[index % stack.length]
+                yield { position, duration, pitch: source.pitch, velocity: source.velocity, cent: source.cent }
+            }
+            position = ++index * this.rate
+        }
+    }
+}
+```
+
+---
+
+## 7. AI Prompt
+
+Copy the following prompt into an AI assistant to get help writing Spielwerk processors:
+
+```
+You are helping the user write a MIDI effect processor for the openDAW Spielwerk device.
+The user writes plain JavaScript (no imports, no modules). The code runs inside an AudioWorklet.
+
+The code MUST define a class called `Processor` with the following interface:
+
+class Processor {
+    * processNotes(block, notes) { }   // required, generator function
+    paramChanged(label, value) { }     // optional
+    reset() { }                        // optional, called on transport jump
+}
+
+## processNotes(block, notes)
+A generator function called on every audio block. Receives upstream notes and yields output notes.
+
+block (timing and transport):
+- block.from  — start position in ppqn, inclusive (480 ppqn = 1 quarter note)
+- block.to    — end position in ppqn, exclusive
+- block.bpm   — current project tempo in beats per minute
+- block.flags — bitmask of transport state:
+    1 = transporting (transport is active)
+    2 = discontinuous (position jumped, e.g. seek or loop restart)
+
+notes (upstream note starts):
+- An iterator of note objects in the range [block.from, block.to)
+- Each note has: { position, duration, pitch, velocity, cent }
+  - position: number (ppqn) — when the note starts
+  - duration: number (ppqn) — how long the note lasts
+  - pitch: number (0–127) — MIDI note number
+  - velocity: number (0.0–1.0) — note velocity
+  - cent: number — fine pitch offset in cents
+
+You MUST yield note objects with the same shape: { position, duration, pitch, velocity, cent }
+
+Position rules:
+- position >= block.from and < block.to → emitted immediately
+- position >= block.to → held in an internal scheduler and emitted in the correct future block
+- position < block.from → ERROR, the processor will be silenced
+
+You can yield zero notes (filter), the same note modified (transform), or multiple notes
+per input (generator). You can also yield notes not derived from any input.
+
+## paramChanged(label, value)
+Called when a parameter knob changes value.
+- label — string, matches the name from the @param comment
+- value — number between 0.0 and 1.0
+
+## Declaring parameters
+Parameters are declared as comments at the top of the file:
+
+// @param <name> [default]
+
+- name: single word, no spaces
+- default: optional float between 0.0 and 1.0, defaults to 0.0
+
+Each @param creates an automatable knob on the device UI.
+
+Examples:
+// @param amount 0.5
+// @param chance 1.0
+// @param rate
+
+## reset()
+Optional. Called when the transport jumps (seek, loop restart — discontinuous flag).
+Use to clear accumulated state like held note arrays. If not implemented, the host
+still clears its own internal state (retainer, scheduler), but YOUR state persists.
+
+## State
+The Processor instance persists across blocks. Use class fields to store state
+(e.g., held notes for an arpeggiator, counters, buffers). State is reset on recompile.
+Implement reset() to clear state on transport jumps.
+
+## Constraints
+- Notes are validated every block. Invalid pitch (outside 0-127), velocity (outside 0-1),
+  NaN values, negative duration, or position in the past will silence the processor.
+- Maximum 128 notes per block. Exceeding this will silence the processor.
+- Maximum 128 scheduled (future) notes. Exceeding this will silence the processor.
+- Do not use import/export/require. No access to DOM or fetch.
+- The code runs in an AudioWorklet thread. Only AudioWorklet-safe APIs are available
+  (Math, typed arrays, basic JS). No console, no setTimeout, no DOM.
+- You can define and use helper classes alongside the Processor class.
+
+## Template
+
+// @param amount 0.5
+
+class Processor {
+    amount = 0.5
+    paramChanged(label, value) {
+        if (label === "amount") this.amount = value
+    }
+    * processNotes(block, notes) {
+        for (const note of notes) {
+            yield { ...note, velocity: note.velocity * this.amount }
+        }
+    }
+}
+```
diff --git a/packages/app/studio/public/manuals/devices/midi/spielwerk.webp b/packages/app/studio/public/manuals/devices/midi/spielwerk.webp
new file mode 100644
index 00000000..0f14f439
Binary files /dev/null and b/packages/app/studio/public/manuals/devices/midi/spielwerk.webp differ
diff --git a/packages/app/studio/src/ui/devices/DeviceEditorFactory.tsx b/packages/app/studio/src/ui/devices/DeviceEditorFactory.tsx
index 25ba983a..28f4dedf 100644
--- a/packages/app/studio/src/ui/devices/DeviceEditorFactory.tsx
+++ b/packages/app/studio/src/ui/devices/DeviceEditorFactory.tsx
@@ -20,6 +20,7 @@ import {
     RevampDeviceBox,
     ReverbDeviceBox,
     SoundfontDeviceBox,
+    SpielwerkDeviceBox,
     StereoToolDeviceBox,
     TapeDeviceBox,
     TidalDeviceBox,
@@ -53,6 +54,7 @@ import {
     RevampDeviceBoxAdapter,
     ReverbDeviceBoxAdapter,
     SoundfontDeviceBoxAdapter,
+    SpielwerkDeviceBoxAdapter,
     StereoToolDeviceBoxAdapter,
     TapeDeviceBoxAdapter,
     TidalDeviceBoxAdapter,
@@ -93,6 +95,7 @@ import {TidalDeviceEditor} from "@/ui/devices/audio-effects/TidalDeviceEditor"
 import {DattorroReverbDeviceEditor} from "@/ui/devices/audio-effects/DattorroReverbDeviceEditor"
 import {NeuralAmpDeviceEditor} from "@/ui/devices/audio-effects/NeuralAmpDeviceEditor"
 import {WaveshaperDeviceEditor} from "@/ui/devices/audio-effects/WaveshaperDeviceEditor"
+import {SpielwerkDeviceEditor} from "@/ui/devices/midi-effects/SpielwerkDeviceEditor"
 import {WerkstattDeviceEditor} from "@/ui/devices/audio-effects/WerkstattDeviceEditor"
 
 export namespace DeviceEditorFactory {
@@ -128,6 +131,12 @@ export namespace DeviceEditorFactory {
                                        service={service}
                                        adapter={service.project.boxAdapters.adapterFor(box, ZeitgeistDeviceBoxAdapter)}
                                        deviceHost={deviceHost}/>
+            ),
+            visitSpielwerkDeviceBox: (box: SpielwerkDeviceBox) => (
+                <SpielwerkDeviceEditor lifecycle={lifecycle}
+                                       service={service}
+                                       adapter={service.project.boxAdapters.adapterFor(box, SpielwerkDeviceBoxAdapter)}
+                                       deviceHost={deviceHost}/>
             )
         }), `No MidiEffectDeviceEditor found for ${box}`)
 
diff --git a/packages/app/studio/src/ui/devices/audio-effects/WerkstattDeviceEditor.sass b/packages/app/studio/src/ui/devices/audio-effects/WerkstattDeviceEditor.sass
index d505c7b0..0d205bb9 100644
--- a/packages/app/studio/src/ui/devices/audio-effects/WerkstattDeviceEditor.sass
+++ b/packages/app/studio/src/ui/devices/audio-effects/WerkstattDeviceEditor.sass
@@ -12,6 +12,7 @@ component
   > .knobs
     display: grid
     grid-template-rows: repeat(3, 3.5em)
+    grid-template-columns: repeat(1, 3.5em)
     grid-auto-columns: 3.5em
     grid-auto-flow: column
     row-gap: 0.25em
\ No newline at end of file
diff --git a/packages/app/studio/src/ui/devices/midi-effects/SpielwerkCompiler.ts b/packages/app/studio/src/ui/devices/midi-effects/SpielwerkCompiler.ts
new file mode 100644
index 00000000..83ddd564
--- /dev/null
+++ b/packages/app/studio/src/ui/devices/midi-effects/SpielwerkCompiler.ts
@@ -0,0 +1,132 @@
+import {asInstanceOf, Editing, isDefined, Nullable, UUID} from "@opendaw/lib-std"
+import {SpielwerkDeviceBox, WerkstattParameterBox} from "@opendaw/studio-boxes"
+
+const COMPILER_VERSION = 1
+const HEADER_PATTERN = /^\/\/ @spielwerk (\w+) (\d+) (\d+)\n/
+const PARAM_PATTERN = /^\/\/ @param (\w+)(?: ([.\d]+))?$/gm
+
+interface ParamDeclaration {
+    label: string
+    defaultValue: number
+}
+
+const parseHeader = (source: string): { userCode: string, update: number } => {
+    const match = source.match(HEADER_PATTERN)
+    return match !== null ? {
+        userCode: source.slice(match[0].length),
+        update: parseInt(match[3])
+    } : {
+        userCode: source,
+        update: 0
+    }
+}
+
+const createHeader = (update: number): string => `// @spielwerk js ${COMPILER_VERSION} ${update}\n`
+
+const parseParams = (code: string): ReadonlyArray<ParamDeclaration> => {
+    const params: Array<ParamDeclaration> = []
+    let match: Nullable<RegExpExecArray>
+    PARAM_PATTERN.lastIndex = 0
+    while ((match = PARAM_PATTERN.exec(code)) !== null) {
+        params.push({
+            label: match[1],
+            defaultValue: isDefined(match[2]) ? parseFloat(match[2]) : 0.0
+        })
+    }
+    return params
+}
+
+const reconcileParameters = (deviceBox: SpielwerkDeviceBox, declared: ReadonlyArray<ParamDeclaration>): void => {
+    const boxGraph = deviceBox.graph
+    const existingPointers = deviceBox.parameters.pointerHub.filter()
+    const existingByLabel = new Map<string, WerkstattParameterBox>()
+    for (const pointer of existingPointers) {
+        const paramBox = asInstanceOf(pointer.box, WerkstattParameterBox)
+        existingByLabel.set(paramBox.label.getValue(), paramBox)
+    }
+    const seen = new Set<string>()
+    for (const {label} of declared) {seen.add(label)}
+    for (const [label, paramBox] of existingByLabel) {
+        if (!seen.has(label)) {
+            paramBox.delete()
+        }
+    }
+    seen.clear()
+    for (let index = 0; index < declared.length; index++) {
+        const {label, defaultValue} = declared[index]
+        if (seen.has(label)) {continue}
+        seen.add(label)
+        const existing = existingByLabel.get(label)
+        if (isDefined(existing)) {
+            existing.index.setValue(index)
+            if (existing.defaultValue.getValue() !== defaultValue) {
+                existing.defaultValue.setValue(defaultValue)
+                existing.value.setValue(defaultValue)
+            }
+        } else {
+            WerkstattParameterBox.create(boxGraph, UUID.generate(), paramBox => {
+                paramBox.owner.refer(deviceBox.parameters)
+                paramBox.label.setValue(label)
+                paramBox.index.setValue(index)
+                paramBox.value.setValue(defaultValue)
+                paramBox.defaultValue.setValue(defaultValue)
+            })
+        }
+    }
+}
+
+const registerWorklet = async (audioContext: BaseAudioContext,
+                               uuid: string,
+                               update: number,
+                               userCode: string): Promise<void> => {
+    const wrappedCode = `
+        if (typeof globalThis.openDAW === "undefined") { globalThis.openDAW = {} }
+        if (typeof globalThis.openDAW.spielwerkProcessors === "undefined") { globalThis.openDAW.spielwerkProcessors = {} }
+        globalThis.openDAW.spielwerkProcessors["${uuid}"] = {
+            update: ${update},
+            create: (function spielwerk() {
+                ${userCode}
+                return Processor
+            })()
+        }
+    `
+    new Function(wrappedCode)
+    const blob = new Blob([wrappedCode], {type: "application/javascript"})
+    const blobUrl = URL.createObjectURL(blob)
+    try {
+        await audioContext.audioWorklet.addModule(blobUrl)
+    } finally {
+        URL.revokeObjectURL(blobUrl)
+    }
+}
+
+export namespace SpielwerkCompiler {
+    export const stripHeader = (source: string): string => parseHeader(source).userCode
+    export const load = async (audioContext: BaseAudioContext, deviceBox: SpielwerkDeviceBox): Promise<void> => {
+        const {userCode, update} = parseHeader(deviceBox.code.getValue())
+        if (update === 0) {return}
+        const uuid = UUID.toString(deviceBox.address.uuid)
+        return registerWorklet(audioContext, uuid, update, userCode)
+    }
+    export const compile = async (audioContext: BaseAudioContext,
+                                  editing: Editing,
+                                  deviceBox: SpielwerkDeviceBox,
+                                  source: string,
+                                  append: boolean = false): Promise<void> => {
+        const userCode = parseHeader(source).userCode
+        const currentUpdate = parseHeader(deviceBox.code.getValue()).update
+        const newUpdate = currentUpdate + 1
+        const uuid = UUID.toString(deviceBox.address.uuid)
+        const params = parseParams(userCode)
+        const modifier = () => {
+            deviceBox.code.setValue(createHeader(newUpdate) + userCode)
+            reconcileParameters(deviceBox, params)
+        }
+        if (append) {
+            editing.append(modifier)
+        } else {
+            editing.modify(modifier)
+        }
+        return registerWorklet(audioContext, uuid, newUpdate, userCode)
+    }
+}
diff --git a/packages/app/studio/src/ui/devices/midi-effects/SpielwerkDeviceEditor.sass b/packages/app/studio/src/ui/devices/midi-effects/SpielwerkDeviceEditor.sass
new file mode 100644
index 00000000..0d205bb9
--- /dev/null
+++ b/packages/app/studio/src/ui/devices/midi-effects/SpielwerkDeviceEditor.sass
@@ -0,0 +1,18 @@
+@use "@/mixins"
+
+component
+  display: flex
+  flex-direction: row
+  align-items: stretch
+  align-content: start
+  column-gap: 1em
+  margin-right: 1em
+  @include mixins.Control
+
+  > .knobs
+    display: grid
+    grid-template-rows: repeat(3, 3.5em)
+    grid-template-columns: repeat(1, 3.5em)
+    grid-auto-columns: 3.5em
+    grid-auto-flow: column
+    row-gap: 0.25em
\ No newline at end of file
diff --git a/packages/app/studio/src/ui/devices/midi-effects/SpielwerkDeviceEditor.tsx b/packages/app/studio/src/ui/devices/midi-effects/SpielwerkDeviceEditor.tsx
new file mode 100644
index 00000000..5409aa86
--- /dev/null
+++ b/packages/app/studio/src/ui/devices/midi-effects/SpielwerkDeviceEditor.tsx
@@ -0,0 +1,120 @@
+import css from "./SpielwerkDeviceEditor.sass?inline"
+import defaultCode from "./spielwerk-default.txt?raw"
+import {DeviceHost, SpielwerkDeviceBoxAdapter} from "@opendaw/studio-adapters"
+import {asInstanceOf, EmptyExec, Lifecycle, Terminable, Terminator, UUID} from "@opendaw/lib-std"
+import {createElement} from "@opendaw/lib-jsx"
+import {DeviceEditor} from "@/ui/devices/DeviceEditor.tsx"
+import {MenuItems} from "@/ui/devices/menu-items.ts"
+import {Html} from "@opendaw/lib-dom"
+import {StudioService} from "@/service/StudioService"
+import {SpielwerkCompiler} from "./SpielwerkCompiler"
+import {WerkstattParameterBox} from "@opendaw/studio-boxes"
+import {ControlBuilder} from "@/ui/devices/ControlBuilder"
+import {Button} from "@/ui/components/Button"
+import {Icon} from "@/ui/components/Icon"
+import {IconSymbol} from "@opendaw/studio-enums"
+
+const className = Html.adoptStyleSheet(css, "SpielwerkDeviceEditor")
+
+type Construct = {
+    lifecycle: Lifecycle
+    service: StudioService
+    adapter: SpielwerkDeviceBoxAdapter
+    deviceHost: DeviceHost
+}
+
+export const SpielwerkDeviceEditor = ({lifecycle, service, adapter, deviceHost}: Construct) => {
+    const {project} = service
+    const {editing, midiLearning} = project
+    const box = adapter.box
+    const storedCode = box.code.getValue()
+    const userCode = storedCode.length > 0 ? SpielwerkCompiler.stripHeader(storedCode) : defaultCode
+    const compile = async (code: string) => SpielwerkCompiler.compile(service.audioContext, editing, box, code)
+    if (storedCode.length > 0) {
+        SpielwerkCompiler.load(service.audioContext, box).finally(EmptyExec)
+    } else {
+        SpielwerkCompiler.compile(service.audioContext, editing, box, userCode, true).finally(EmptyExec)
+    }
+    const toggleEditor = () => {
+        const isActive = service.activeCodeEditor
+            .map(state => UUID.equals(state.handler.uuid, adapter.uuid)).unwrapOrElse(false)
+        if (isActive) {
+            service.closeCodeEditor()
+        } else {
+            service.openWerkstattEditor({
+                handler: {
+                    uuid: adapter.uuid,
+                    name: adapter.labelField,
+                    compile,
+                    subscribeErrors: observer =>
+                        service.engine.subscribeDeviceMessage(UUID.toString(adapter.uuid), observer),
+                    subscribeCode: observer =>
+                        box.code.subscribe(owner => observer(SpielwerkCompiler.stripHeader(owner.getValue())))
+                },
+                initialCode: SpielwerkCompiler.stripHeader(box.code.getValue()) || defaultCode,
+                previousScreen: service.layout.screen.getValue()
+            })
+        }
+    }
+    const knobs: HTMLElement = (<div className="knobs"/>)
+    const toggleEditorButton: HTMLElement = (
+        <Button lifecycle={lifecycle}
+                onClick={toggleEditor}
+                appearance={{framed: true, tooltip: "Toggle Code Editor"}}
+                style={{
+                    fontSize: "16px",
+                    height: "min-content",
+                    marginTop: "1em"
+                }}><Icon symbol={IconSymbol.Code}/></Button>
+    )
+    const set = UUID.newSet<{ uuid: UUID.Bytes, lifecycle: Terminable }>(({uuid}) => uuid)
+    lifecycle.ownAll(
+        {
+            terminate: () => {
+                const isActive = service.activeCodeEditor
+                    .map(state => UUID.equals(state.handler.uuid, adapter.uuid)).unwrapOrElse(false)
+                if (isActive) {service.closeCodeEditor()}
+            }
+        },
+        service.activeCodeEditor.catchupAndSubscribe(option => {
+            const isActive = option.map(state => UUID.equals(state.handler.uuid, adapter.uuid)).unwrapOrElse(false)
+            toggleEditorButton.classList.toggle("active", isActive)
+        }),
+        box.parameters.pointerHub.catchupAndSubscribe({
+            onAdded: ({box: paramBox}) => {
+                const werkstattParam = asInstanceOf(paramBox, WerkstattParameterBox)
+                const parameter = adapter.parameters.parameterAt(werkstattParam.value.address)
+                const terminator = new Terminator()
+                const element: HTMLElement = ControlBuilder.createKnob({
+                    lifecycle: terminator,
+                    editing,
+                    midiLearning,
+                    adapter,
+                    parameter
+                })
+                element.style.order = String(werkstattParam.index.getValue())
+                terminator.own(werkstattParam.index.catchupAndSubscribe(owner =>
+                    element.style.order = String(owner.getValue())))
+                knobs.appendChild(element)
+                set.add({uuid: paramBox.address.uuid, lifecycle: terminator})
+                terminator.own({terminate: () => element.remove()})
+            },
+            onRemoved: ({box: {address: {uuid}}}) =>
+                set.removeByKey(uuid).lifecycle.terminate()
+        })
+    )
+    return (
+        <DeviceEditor lifecycle={lifecycle}
+                      project={project}
+                      adapter={adapter}
+                      populateMenu={parent => MenuItems.forEffectDevice(parent, service, deviceHost, adapter)}
+                      populateControls={() => (
+                          <div className={className}>
+                              {knobs}
+                              {toggleEditorButton}
+                          </div>
+                      )}
+                      populateMeter={() => null}
+                      icon={IconSymbol.Code}/>
+    )
+}
diff --git a/packages/app/studio/src/ui/devices/midi-effects/spielwerk-default.txt b/packages/app/studio/src/ui/devices/midi-effects/spielwerk-default.txt
new file mode 100644
index 00000000..56c82ef2
--- /dev/null
+++ b/packages/app/studio/src/ui/devices/midi-effects/spielwerk-default.txt
@@ -0,0 +1,7 @@
+class Processor {
+    * processNotes(block, notes) {
+        for (const note of notes) {
+            yield note
+        }
+    }
+}
diff --git a/packages/studio/adapters/src/BoxAdapters.ts b/packages/studio/adapters/src/BoxAdapters.ts
index 77f7243a..3dcc0a2f 100644
--- a/packages/studio/adapters/src/BoxAdapters.ts
+++ b/packages/studio/adapters/src/BoxAdapters.ts
@@ -58,6 +58,7 @@ import {
     SignatureEventBox,
     SoundfontDeviceBox,
     SoundfontFileBox,
+    SpielwerkDeviceBox,
     StereoToolDeviceBox,
     TapeDeviceBox,
     TidalDeviceBox,
@@ -111,6 +112,7 @@ import {TapeDeviceBoxAdapter} from "./devices/instruments/TapeDeviceBoxAdapter"
 import {VaporisateurDeviceBoxAdapter} from "./devices/instruments/VaporisateurDeviceBoxAdapter"
 import {ArpeggioDeviceBoxAdapter} from "./devices/midi-effects/ArpeggioDeviceBoxAdapter"
 import {PitchDeviceBoxAdapter} from "./devices/midi-effects/PitchDeviceBoxAdapter"
+import {SpielwerkDeviceBoxAdapter} from "./devices/midi-effects/SpielwerkDeviceBoxAdapter"
 import {NanoDeviceBoxAdapter} from "./devices/instruments/NanoDeviceBoxAdapter"
 import {PlayfieldDeviceBoxAdapter} from "./devices/instruments/PlayfieldDeviceBoxAdapter"
 import {StereoToolDeviceBoxAdapter} from "./devices/audio-effects/StereoToolDeviceBoxAdapter"
@@ -242,6 +244,7 @@ export class BoxAdapters implements Terminable {
             visitRootBox: (box: RootBox): BoxAdapter => new RootBoxAdapter(this.#context, box),
             visitSoundfontDeviceBox: (box: SoundfontDeviceBox) => new SoundfontDeviceBoxAdapter(this.#context, box),
             visitSoundfontFileBox: (box: SoundfontFileBox) => new SoundfontFileBoxAdapter(this.#context, box),
+            visitSpielwerkDeviceBox: (box: SpielwerkDeviceBox) => new SpielwerkDeviceBoxAdapter(this.#context, box),
             visitStereoToolDeviceBox: (box: StereoToolDeviceBox) => new StereoToolDeviceBoxAdapter(this.#context, box),
             visitTapeDeviceBox: (box: TapeDeviceBox) => new TapeDeviceBoxAdapter(this.#context, box),
             visitTimelineBox: (box: TimelineBox) => new TimelineBoxAdapter(this.#context, box),
diff --git a/packages/studio/adapters/src/DeviceManualUrls.ts b/packages/studio/adapters/src/DeviceManualUrls.ts
index dde91231..c54c5f40 100644
--- a/packages/studio/adapters/src/DeviceManualUrls.ts
+++ b/packages/studio/adapters/src/DeviceManualUrls.ts
@@ -5,6 +5,7 @@ export namespace DeviceManualUrls {
     // MIDI Effects
     export const Arpeggio = "manuals/devices/midi/arpeggio"
     export const Pitch = "manuals/devices/midi/pitch"
+    export const Spielwerk = "manuals/devices/midi/spielwerk"
     export const Velocity = "manuals/devices/midi/velocity"
     export const Zeitgeist = "manuals/devices/midi/zeitgeist"
 
diff --git a/packages/studio/adapters/src/devices/midi-effects/SpielwerkDeviceBoxAdapter.ts b/packages/studio/adapters/src/devices/midi-effects/SpielwerkDeviceBoxAdapter.ts
new file mode 100644
index 00000000..ce663cb0
--- /dev/null
+++ b/packages/studio/adapters/src/devices/midi-effects/SpielwerkDeviceBoxAdapter.ts
@@ -0,0 +1,57 @@
+import {asInstanceOf, StringMapping, Terminator, UUID, ValueMapping} from "@opendaw/lib-std"
+import {Address, BooleanField, Int32Field, PointerField, StringField} from "@opendaw/lib-box"
+import {SpielwerkDeviceBox, WerkstattParameterBox} from "@opendaw/studio-boxes"
+import {Pointers} from "@opendaw/studio-enums"
+import {DeviceHost, Devices, MidiEffectDeviceAdapter} from "../../DeviceAdapter"
+import {BoxAdaptersContext} from "../../BoxAdaptersContext"
+import {DeviceManualUrls} from "../../DeviceManualUrls"
+import {AudioUnitBoxAdapter} from "../../audio-unit/AudioUnitBoxAdapter"
+import {ParameterAdapterSet} from "../../ParameterAdapterSet"
+
+export class SpielwerkDeviceBoxAdapter implements MidiEffectDeviceAdapter {
+    readonly #terminator = new Terminator()
+
+    readonly type = "midi-effect"
+    readonly accepts = "midi"
+    readonly manualUrl = DeviceManualUrls.Spielwerk
+
+    readonly #context: BoxAdaptersContext
+    readonly #box: SpielwerkDeviceBox
+    readonly #parametric: ParameterAdapterSet
+
+    constructor(context: BoxAdaptersContext, box: SpielwerkDeviceBox) {
+        this.#context = context
+        this.#box = box
+        this.#parametric = this.#terminator.own(new ParameterAdapterSet(this.#context))
+        this.#terminator.own(
+            box.parameters.pointerHub.catchupAndSubscribe({
+                onAdded: (({box}) => this.#parametric
+                    .createParameter(
+                        asInstanceOf(box, WerkstattParameterBox).value,
+                        ValueMapping.unipolar(), StringMapping.percent({fractionDigits: 1}),
+                        asInstanceOf(box, WerkstattParameterBox).label.getValue())),
+                onRemoved: (({box}) => this.#parametric
+                    .removeParameter(asInstanceOf(box, WerkstattParameterBox).value.address))
+            })
+        )
+    }
+
+    get box(): SpielwerkDeviceBox {return this.#box}
+    get uuid(): UUID.Bytes {return this.#box.address.uuid}
+    get address(): Address {return this.#box.address}
+    get indexField(): Int32Field {return this.#box.index}
+    get labelField(): StringField {return this.#box.label}
+    get enabledField(): BooleanField {return this.#box.enabled}
+    get minimizedField(): BooleanField {return this.#box.minimized}
+    get host(): PointerField<Pointers.MIDIEffectHost> {return this.#box.host}
+    get parameters(): ParameterAdapterSet {return this.#parametric}
+
+    deviceHost(): DeviceHost {
+        return this.#context.boxAdapters
+            .adapterFor(this.#box.host.targetVertex.unwrap("no device-host").box, Devices.isHost)
+    }
+
+    audioUnitBoxAdapter(): AudioUnitBoxAdapter {return this.deviceHost().audioUnitBoxAdapter()}
+
+    terminate(): void {this.#terminator.terminate()}
+}
diff --git a/packages/studio/core-processors/src/DeviceProcessorFactory.ts b/packages/studio/core-processors/src/DeviceProcessorFactory.ts
index 9d3a062c..14b1f8e4 100644
--- a/packages/studio/core-processors/src/DeviceProcessorFactory.ts
+++ b/packages/studio/core-processors/src/DeviceProcessorFactory.ts
@@ -18,6 +18,7 @@ import {
     RevampDeviceBox,
     ReverbDeviceBox,
     SoundfontDeviceBox,
+    SpielwerkDeviceBox,
     StereoToolDeviceBox,
     TapeDeviceBox,
     TidalDeviceBox,
@@ -49,6 +50,7 @@ import {
     RevampDeviceBoxAdapter,
     ReverbDeviceBoxAdapter,
     SoundfontDeviceBoxAdapter,
+    SpielwerkDeviceBoxAdapter,
     StereoToolDeviceBoxAdapter,
     TapeDeviceBoxAdapter,
     TidalDeviceBoxAdapter,
@@ -92,6 +94,7 @@ import {DattorroReverbDeviceProcessor} from "./devices/audio-effects/DattorroRev
 import {NeuralAmpDeviceProcessor} from "./devices/audio-effects/NeuralAmpDeviceProcessor"
 import {WaveshaperDeviceProcessor} from "./devices/audio-effects/WaveshaperDeviceProcessor"
 import {WerkstattDeviceProcessor} from "./devices/audio-effects/WerkstattDeviceProcessor"
+import {SpielwerkDeviceProcessor} from "./devices/midi-effects/SpielwerkDeviceProcessor"
 
 export namespace InstrumentDeviceProcessorFactory {
     export const create = (context: EngineContext,
@@ -127,7 +130,9 @@ export namespace MidiEffectDeviceProcessorFactory {
             visitVelocityDeviceBox: (box: VelocityDeviceBox): MidiEffectProcessor =>
                 new VelocityDeviceProcessor(context, context.boxAdapters.adapterFor(box, VelocityDeviceBoxAdapter)),
             visitZeitgeistDeviceBox: (box: ZeitgeistDeviceBox): MidiEffectProcessor =>
-                new ZeitgeistDeviceProcessor(context, context.boxAdapters.adapterFor(box, ZeitgeistDeviceBoxAdapter))
+                new ZeitgeistDeviceProcessor(context, context.boxAdapters.adapterFor(box, ZeitgeistDeviceBoxAdapter)),
+            visitSpielwerkDeviceBox: (box: SpielwerkDeviceBox): MidiEffectProcessor =>
+                new SpielwerkDeviceProcessor(context, context.boxAdapters.adapterFor(box, SpielwerkDeviceBoxAdapter))
         }), `Could not create midi-effect for'${box.name}'`)
 }
 
diff --git a/packages/studio/core-processors/src/devices/midi-effects/SpielwerkDeviceProcessor.ts b/packages/studio/core-processors/src/devices/midi-effects/SpielwerkDeviceProcessor.ts
new file mode 100644
index 00000000..9689b592
--- /dev/null
+++ b/packages/studio/core-processors/src/devices/midi-effects/SpielwerkDeviceProcessor.ts
@@ -0,0 +1,310 @@
+import {
+    Arrays,
+    asInstanceOf,
+    assert,
+    Bits,
+    byte,
+    float,
+    Id,
+    int,
+    isDefined,
+    Nullable,
+    Option,
+    Terminable,
+    UUID
+} from "@opendaw/lib-std"
+import {EngineToClient, SpielwerkDeviceBoxAdapter} from "@opendaw/studio-adapters"
+import {WerkstattParameterBox} from "@opendaw/studio-boxes"
+import {Event, EventSpanRetainer, NoteEvent, ppqn} from "@opendaw/lib-dsp"
+import {EngineContext} from "../../EngineContext"
+import {EventProcessor} from "../../EventProcessor"
+import {Block, BlockFlag, Processor} from "../../processing"
+import {AutomatableParameter} from "../../AutomatableParameter"
+import {NoteEventSource, NoteEventTarget, NoteLifecycleEvent} from "../../NoteEventSource"
+import {MidiEffectProcessor} from "../../MidiEffectProcessor"
+
+const HEADER_PATTERN = /^\/\/ @spielwerk (\w+) (\d+) (\d+)\n/
+
+const MAX_NOTES_PER_BLOCK: int = 128
+const MAX_SCHEDULED_NOTES: int = 128
+
+const parseUpdate = (code: string): int => {
+    const match = code.match(HEADER_PATTERN)
+    return match !== null ? parseInt(match[3]) : -1
+}
+
+interface ScheduledNote {
+    readonly position: ppqn
+    readonly duration: ppqn
+    readonly pitch: byte
+    readonly velocity: float
+    readonly cent: number
+}
+
+interface UserNote {
+    readonly position: ppqn
+    readonly duration: ppqn
+    readonly pitch: byte
+    readonly velocity: float
+    readonly cent: number
+}
+
+interface UserBlock {
+    readonly from: ppqn
+    readonly to: ppqn
+    readonly bpm: number
+    readonly s0: int
+    readonly s1: int
+    readonly flags: int
+}
+
+interface UserProcessor {
+    processNotes(block: UserBlock, notes: IterableIterator<UserNote>): IterableIterator<UserNote>
+    paramChanged?(label: string, value: number): void
+    reset?(): void
+}
+
+const validateNote = (note: any, from: ppqn): Nullable<string> => {
+    if (!isDefined(note)) {return "processNotes yielded undefined"}
+    if (typeof note.pitch !== "number" || note.pitch !== note.pitch) {return `Invalid pitch: ${note.pitch}`}
+    if (note.pitch < 0 || note.pitch > 127) {return `Pitch out of range: ${note.pitch} (must be 0–127)`}
+    if (typeof note.velocity !== "number" || note.velocity !== note.velocity) {return `Invalid velocity: ${note.velocity}`}
+    if (note.velocity < 0 || note.velocity > 1) {return `Velocity out of range: ${note.velocity} (must be 0–1)`}
+    if (typeof note.duration !== "number" || note.duration !== note.duration) {return `Invalid duration: ${note.duration}`}
+    if (note.duration <= 0) {return `Duration must be positive: ${note.duration}`}
+    if (typeof note.position !== "number" || note.position !== note.position) {return `Invalid position: ${note.position}`}
+    if (note.position < from) {return `Position ${note.position} is in the past (block starts at ${from})`}
+    return null
+}
+
+export class SpielwerkDeviceProcessor extends EventProcessor implements MidiEffectProcessor {
+    readonly #adapter: SpielwerkDeviceBoxAdapter
+    readonly #engineToClient: EngineToClient
+    readonly #retainer: EventSpanRetainer<Id<NoteEvent>>
+    readonly #scheduled: Array<ScheduledNote>
+    readonly #uuid: string
+    readonly #boundParameters: Array<AutomatableParameter<number>>
+
+    #source: Option<NoteEventSource> = Option.None
+    #userProcessor: Option<UserProcessor> = Option.None
+    #currentUpdate: int = -1
+    #silenced: boolean = false
+    #wasPlaying: boolean = false
+
+    constructor(context: EngineContext, adapter: SpielwerkDeviceBoxAdapter) {
+        super(context)
+
+        this.#adapter = adapter
+        this.#engineToClient = context.engineToClient
+        this.#retainer = new EventSpanRetainer<Id<NoteEvent>>()
+        this.#scheduled = []
+        this.#uuid = UUID.toString(adapter.uuid)
+        this.#boundParameters = []
+        const {parameters, box} = adapter
+        this.ownAll(
+            box.code.catchupAndSubscribe(owner => {
+                const newUpdate = parseUpdate(owner.getValue())
+                if (newUpdate > 0 && newUpdate !== this.#currentUpdate) {
+                    this.#silenced = true
+                    this.#userProcessor = Option.None
+                    this.#tryLoad(newUpdate)
+                }
+            }),
+            box.parameters.pointerHub.catchupAndSubscribe({
+                onAdded: (({box}) => {
+                    const paramBox = asInstanceOf(box, WerkstattParameterBox)
+                    const bound = this.bindParameter(parameters.parameterAt(paramBox.value.address))
+                    this.#boundParameters.push(bound)
+                    this.parameterChanged(bound)
+                }),
+                onRemoved: (({box}) => {
+                    const paramBox = asInstanceOf(box, WerkstattParameterBox)
+                    Arrays.removeIf(this.#boundParameters, parameter =>
+                        parameter.address === paramBox.value.address)
+                })
+            }),
+            context.registerProcessor(this)
+        )
+        this.readAllParameters()
+    }
+
+    get uuid(): UUID.Bytes {return this.#adapter.uuid}
+    get incoming(): Processor {return this}
+    get outgoing(): Processor {return this}
+    get noteEventTarget(): Option<NoteEventTarget> {return Option.wrap(this)}
+
+    setNoteEventSource(source: NoteEventSource): Terminable {
+        assert(this.#source.isEmpty(), "NoteEventSource already set")
+        this.#source = Option.wrap(source)
+        return Terminable.create(() => this.#source = Option.None)
+    }
+
+    * processNotes(from: ppqn, to: ppqn, flags: int): IterableIterator<NoteLifecycleEvent> {
+        const playing = Bits.every(flags, BlockFlag.transporting | BlockFlag.playing)
+        if (this.#retainer.nonEmpty()) {
+            if (Bits.every(flags, BlockFlag.discontinuous) || (this.#wasPlaying && !playing)) {
+                for (const event of this.#retainer.releaseAll()) {
+                    yield NoteLifecycleEvent.stop(event, from)
+                }
+                Arrays.clear(this.#scheduled)
+                this.#userProcessor.ifSome(proc => {
+                    if (isDefined(proc.reset)) {proc.reset()}
+                })
+            } else {
+                for (const event of this.#retainer.releaseLinearCompleted(to)) {
+                    yield NoteLifecycleEvent.stop(event, event.position + event.duration)
+                }
+            }
+        }
+        this.#wasPlaying = playing
+        if (this.#silenced) {
+            const expectedUpdate = parseUpdate(this.#adapter.box.code.getValue())
+            if (expectedUpdate > 0 && expectedUpdate !== this.#currentUpdate) {
+                this.#tryLoad(expectedUpdate)
+            }
+        }
+        if (this.#source.nonEmpty() && this.#userProcessor.nonEmpty() && !this.#silenced) {
+            const source = this.#source.unwrap()
+            const proc = this.#userProcessor.unwrap()
+            const starts: Array<UserNote> = []
+            let hasStops = false
+            for (const event of source.processNotes(from, to, flags)) {
+                if (NoteLifecycleEvent.isStart(event)) {
+                    starts.push({
+                        position: event.position,
+                        duration: event.duration,
+                        pitch: event.pitch,
+                        velocity: event.velocity,
+                        cent: event.cent
+                    })
+                } else {
+                    hasStops = true
+                }
+            }
+            if (hasStops && !playing) {
+                for (const event of this.#retainer.releaseAll()) {
+                    yield NoteLifecycleEvent.stop(event, from)
+                }
+                Arrays.clear(this.#scheduled)
+                proc.reset?.()
+            }
+            if (Bits.every(flags, BlockFlag.transporting)) {
+                for (let i = this.#scheduled.length - 1; i >= 0; i--) {
+                    const note = this.#scheduled[i]
+                    if (note.position >= from && note.position < to) {
+                        this.#scheduled.splice(i, 1)
+                        yield* this.#emitNote(note)
+                    }
+                }
+            }
+            const userBlock: UserBlock = {from, to, bpm: 0, s0: 0, s1: 0, flags}
+            try {
+                let noteCount: int = 0
+                for (const yielded of proc.processNotes(userBlock, starts[Symbol.iterator]())) {
+                    if (++noteCount > MAX_NOTES_PER_BLOCK) {
+                        this.#silence(`Note flood: exceeded ${MAX_NOTES_PER_BLOCK} notes per block`)
+                        return
+                    }
+                    const error = validateNote(yielded, from)
+                    if (error !== null) {
+                        this.#silence(error)
+                        return
+                    }
+                    if (yielded.position >= to) {
+                        if (this.#scheduled.length >= MAX_SCHEDULED_NOTES) {
+                            this.#silence(`Scheduler full: exceeded ${MAX_SCHEDULED_NOTES} scheduled notes`)
+                            return
+                        }
+                        this.#scheduled.push({
+                            position: yielded.position,
+                            duration: yielded.duration,
+                            pitch: yielded.pitch,
+                            velocity: yielded.velocity,
+                            cent: yielded.cent ?? 0
+                        })
+                    } else {
+                        yield* this.#emitNote(yielded)
+                    }
+                }
+            } catch (err) {
+                this.#silence(`Runtime error: ${err}`)
+                return
+            }
+            for (const event of this.#retainer.releaseLinearCompleted(to)) {
+                yield NoteLifecycleEvent.stop(event, event.position + event.duration)
+            }
+        }
+    }
+
+    * iterateActiveNotesAt(position: ppqn, _onlyExternal: boolean): IterableIterator<NoteEvent> {
+        yield* this.#retainer.overlapping(position, NoteEvent.Comparator)
+    }
+
+    reset(): void {
+        this.#retainer.clear()
+        Arrays.clear(this.#scheduled)
+        this.eventInput.clear()
+    }
+
+    processEvents(_block: Block, _from: ppqn, _to: ppqn): void {}
+
+    parameterChanged(parameter: AutomatableParameter): void {
+        this.#userProcessor.ifSome(proc => {
+            if (isDefined(proc.paramChanged)) {
+                const paramBox = asInstanceOf(parameter.adapter.field.box, WerkstattParameterBox)
+                proc.paramChanged(paramBox.label.getValue(), parameter.getValue())
+            }
+        })
+    }
+
+    handleEvent(_block: Block, _event: Event): void {}
+
+    index(): number {return this.#adapter.indexField.getValue()}
+    adapter(): SpielwerkDeviceBoxAdapter {return this.#adapter}
+
+    #tryLoad(update: int): void {
+        const registry = (globalThis as any).openDAW?.spielwerkProcessors?.[this.#uuid]
+        if (isDefined(registry) && registry.update === update) {
+            this.#swapProcessor(registry.create, update)
+        }
+    }
+
+    #swapProcessor(ProcessorClass: any, update: int): void {
+        try {
+            this.#userProcessor = Option.wrap(new ProcessorClass() as UserProcessor)
+            this.#currentUpdate = update
+            this.#silenced = false
+            this.#pushAllParameters()
+        } catch (error) {
+            this.#silence(`Failed to instantiate Processor: ${error}`)
+        }
+    }
+
+    #pushAllParameters(): void {
+        this.#userProcessor.ifSome(proc => {
+            if (isDefined(proc.paramChanged)) {
+                for (const bound of this.#boundParameters) {
+                    const paramBox = asInstanceOf(bound.adapter.field.box, WerkstattParameterBox)
+                    proc.paramChanged(paramBox.label.getValue(), bound.getValue())
+                }
+            }
+        })
+    }
+
+    #reportError(message: string): void {
+        this.#engineToClient.deviceMessage(this.#uuid, message)
+    }
+
+    #silence(message: string): void {
+        this.#silenced = true
+        Arrays.clear(this.#scheduled)
+        this.#reportError(message)
+    }
+
+    * #emitNote(note: ScheduledNote): IterableIterator<NoteLifecycleEvent> {
+        const lifecycle = NoteLifecycleEvent.start(note.position, note.duration, note.pitch, note.velocity, note.cent)
+        this.#retainer.addAndRetain({...lifecycle})
+        yield lifecycle
+    }
+
+}
diff --git a/packages/studio/core/src/EffectBox.ts b/packages/studio/core/src/EffectBox.ts
index 70a14a05..ecb6e626 100644
--- a/packages/studio/core/src/EffectBox.ts
+++ b/packages/studio/core/src/EffectBox.ts
@@ -18,12 +18,14 @@ import {
     UnknownMidiEffectDeviceBox,
     VelocityDeviceBox,
     WaveshaperDeviceBox,
+    SpielwerkDeviceBox,
     WerkstattDeviceBox,
     ZeitgeistDeviceBox
 } from "@opendaw/studio-boxes"
 
 export type EffectBox =
     | ArpeggioDeviceBox | PitchDeviceBox | VelocityDeviceBox | ZeitgeistDeviceBox | UnknownMidiEffectDeviceBox
+    | SpielwerkDeviceBox
     | MaximizerDeviceBox | DelayDeviceBox | ReverbDeviceBox | RevampDeviceBox | StereoToolDeviceBox | TidalDeviceBox
     | ModularDeviceBox | UnknownAudioEffectDeviceBox | CompressorDeviceBox | GateDeviceBox
     | CrusherDeviceBox | FoldDeviceBox | DattorroReverbDeviceBox | NeuralAmpDeviceBox | WaveshaperDeviceBox
diff --git a/packages/studio/core/src/EffectFactories.ts b/packages/studio/core/src/EffectFactories.ts
index 6b198191..a3d94d10 100644
--- a/packages/studio/core/src/EffectFactories.ts
+++ b/packages/studio/core/src/EffectFactories.ts
@@ -20,6 +20,7 @@ import {
     ReverbDeviceBox,
     StereoToolDeviceBox,
     TidalDeviceBox,
+    SpielwerkDeviceBox,
     VelocityDeviceBox,
     WaveshaperDeviceBox,
     WerkstattDeviceBox,
@@ -112,6 +113,22 @@ export namespace EffectFactories {
         }
     }
 
+    export const Spielwerk: EffectFactory = {
+        defaultName: "Spielwerk",
+        defaultIcon: IconSymbol.Code,
+        description: "User-scripted MIDI effect processor",
+        manualPage: DeviceManualUrls.Spielwerk,
+        separatorBefore: false,
+        external: false,
+        type: "midi",
+        create: ({boxGraph}, hostField, index) =>
+            SpielwerkDeviceBox.create(boxGraph, UUID.generate(), (box) => {
+                box.label.setValue("Spielwerk")
+                box.index.setValue(index)
+                box.host.refer(hostField)
+            })
+    }
+
     export const StereoTool: EffectFactory = {
         defaultName: "Stereo Tool",
         defaultIcon: IconSymbol.Stereo,
@@ -402,7 +419,8 @@ export namespace EffectFactories {
         Arpeggio,
         Pitch,
         Velocity,
-        Zeitgeist
+        Zeitgeist,
+        Spielwerk
     }
 
     export const AudioNamed = {
diff --git a/packages/studio/forge-boxes/src/schema/devices/index.ts b/packages/studio/forge-boxes/src/schema/devices/index.ts
index a05e9f5c..a3cf06c0 100644
--- a/packages/studio/forge-boxes/src/schema/devices/index.ts
+++ b/packages/studio/forge-boxes/src/schema/devices/index.ts
@@ -28,6 +28,7 @@ import {NeuralAmpDeviceBox} from "./audio-effects/NeuralAmpDeviceBox"
 import {WaveshaperDeviceBox} from "./audio-effects/WaveshaperDeviceBox"
 import {WerkstattDeviceBox} from "./audio-effects/WerkstattDeviceBox"
 import {WerkstattParameterBox} from "./audio-effects/WerkstattParameterBox"
+import {SpielwerkDeviceBox} from "./midi-effects/SpielwerkDeviceBox"
 
 export const DeviceDefinitions = [
     UnknownAudioEffectDevice,
@@ -61,5 +62,6 @@ export const DeviceDefinitions = [
     NeuralAmpDeviceBox,
     WaveshaperDeviceBox,
     WerkstattDeviceBox,
-    WerkstattParameterBox
+    WerkstattParameterBox,
+    SpielwerkDeviceBox
 ]
\ No newline at end of file
diff --git a/packages/studio/forge-boxes/src/schema/devices/midi-effects/SpielwerkDeviceBox.ts b/packages/studio/forge-boxes/src/schema/devices/midi-effects/SpielwerkDeviceBox.ts
new file mode 100644
index 00000000..970d2674
--- /dev/null
+++ b/packages/studio/forge-boxes/src/schema/devices/midi-effects/SpielwerkDeviceBox.ts
@@ -0,0 +1,8 @@
+import {BoxSchema} from "@opendaw/lib-box-forge"
+import {Pointers} from "@opendaw/studio-enums"
+import {DeviceFactory} from "../../std/DeviceFactory"
+
+export const SpielwerkDeviceBox: BoxSchema<Pointers> = DeviceFactory.createMidiEffect("SpielwerkDeviceBox", {
+    10: {type: "string", name: "code", value: ""},
+    11: {type: "field", name: "parameters", pointerRules: {accepts: [Pointers.Parameter], mandatory: false}}
+})
diff --git a/plans/spielwerk.md b/plans/spielwerk.md
index a8122f7f..8fef9891 100644
--- a/plans/spielwerk.md
+++ b/plans/spielwerk.md
@@ -27,6 +27,7 @@ This works universally — for transformers (1:1), generators (1:N), and filters
 ```typescript
 class Processor {
     paramChanged?(name: string, value: number): void
+    reset?(): void  // called on transport jump (seek, loop restart)
 
     // Called per block. Receives upstream note starts, yields output notes.
     // Each yielded note must have: { position, duration, pitch, velocity, cent }
@@ -42,6 +43,7 @@ class Processor {
 - `notes` — an iterator of upstream note starts in `[block.from, block.to)`. Each note is `{ position, duration, pitch, velocity, cent }`. Stop events are hidden from the user.
 - The user yields zero or more notes per input note. Each must have `position`, `duration`, `pitch`, `velocity`, `cent`. Position must be `>= block.from`. Notes with position in `[from, to)` are emitted immediately. Notes with position `>= to` are held in an internal scheduler and emitted in the appropriate future block.
 - `paramChanged` — optional, same as audio Werkstatt. Receives mapped parameter values from `// @param` declarations.
+- `reset` — optional. Called when the transport jumps (discontinuous flag: seek, loop restart). Use to clear accumulated state like held note arrays.
 
 ---
 
@@ -375,6 +377,9 @@ class Processor {
         if (name === "repeat") this.repeat = value
         if (name === "octaves") this.octaves = value
     }
+    reset() {
+        this.held = []
+    }
     activeAt(position) {
         return this.held
             .filter(note => note.position <= position && position < note.position + note.duration)