diff --git a/src/App/App.css b/src/App/App.css
index 0a4805b..0076de7 100644
--- a/src/App/App.css
+++ b/src/App/App.css
@@ -33,6 +33,9 @@ details:has(+ details) {
   background-color: rgba(0,0,255,0.2);
   border: solid blue 1px;
 }
+.runtimeState.plantStep * {
+  color: grey;
+}
 
 .runtimeState.runtimeError {
   background-color: lightpink;
diff --git a/src/App/App.tsx b/src/App/App.tsx
index c3a0df0..41fdc31 100644
--- a/src/App/App.tsx
+++ b/src/App/App.tsx
@@ -1,54 +1,26 @@
-import { ReactElement, useCallback, useEffect, useMemo, useRef, useState } from "react";
-
-import { handleInputEvent, initialize, RuntimeError } from "../statecharts/interpreter";
-import { BigStepOutput, RT_Event, RT_Statechart } from "../statecharts/runtime_types";
-import { InsertMode, VisualEditor, VisualEditorState } from "./VisualEditor/VisualEditor";
-import { getSimTime, getWallClkDelay, TimeMode } from "../statecharts/time";
-
 import "../index.css";
 import "./App.css";
 
-import { TopPanel } from "./TopPanel/TopPanel";
-import { ShowAST, ShowInputEvents, ShowInternalEvents, ShowOutputEvents } from "./ShowAST";
-import { parseStatechart } from "../statecharts/parser";
-import { getKeyHandler } from "./VisualEditor/shortcut_handler";
-import { BottomPanel } from "./BottomPanel";
+import { ReactElement, useCallback, useEffect, useMemo, useRef, useState } from "react";
+
 import { emptyState } from "@/statecharts/concrete_syntax";
-import { PersistentDetails } from "./PersistentDetails";
-import { DigitalWatchPlant } from "./Plant/DigitalWatch/DigitalWatch";
-import { DummyPlant } from "./Plant/Dummy/Dummy";
-import { Plant } from "./Plant/Plant";
-import { usePersistentState } from "./persistent_state";
-import { RTHistory } from "./RTHistory";
 import { detectConnections } from "@/statecharts/detect_connections";
+import { Conns, coupledExecution, EventDestination, exposeStatechartInputs, statechartExecution } from "@/statecharts/timed_reactive";
+import { RuntimeError } from "../statecharts/interpreter";
+import { parseStatechart } from "../statecharts/parser";
+import { BigStep, RaisedEvent } from "../statecharts/runtime_types";
+import { getSimTime, getWallClkDelay, TimeMode } from "../statecharts/time";
+import { BottomPanel } from "./BottomPanel";
+import { usePersistentState } from "./persistent_state";
+import { PersistentDetails } from "./PersistentDetails";
+import { DummyPlant } from "./Plant/Dummy/Dummy";
 import { MicrowavePlant } from "./Plant/Microwave/Microwave";
-import { coupledExecution, dummyExecution, exposeStatechartInputs, statechartExecution, TimedReactive } from "@/statecharts/timed_reactive";
-
-// const clock1: TimedReactive<{nextTick: number}> = {
-//   initial: () => ({nextTick: 1}),
-//   timeAdvance: (c) => c.nextTick,
-//   intTransition: (c) => [[{name: "tick"}], {nextTick: c.nextTick+1}],
-//   extTransition: (simtime, c, e) => [[], (c)],
-// }
-
-// const clock2: TimedReactive<{nextTick: number}> = {
-//   initial: () => ({nextTick: 0.5}),
-//   timeAdvance: (c) => c.nextTick,
-//   intTransition: (c) => [[{name: "tick"}], {nextTick: c.nextTick+1}],
-//   extTransition: (simtime, c, e) => [[], (c)],
-// }
-
-// const coupled = coupledExecution({clock1, clock2}, {inputEvents: {}, outputEvents: {
-//   clock1: {tick: {kind:"output", eventName: 'tick'}},
-//   clock2: {tick: {kind:"output", eventName: 'tick'}},
-// }})
-
-// let state = coupled.initial();
-// for (let i=0; i<10; i++) {
-//   const nextWakeup = coupled.timeAdvance(state);
-//   console.log({state, nextWakeup});
-//   [[], state] = coupled.intTransition(state);
-// }
+import { autoConnect, exposePlantInputs, Plant } from "./Plant/Plant";
+import { RTHistory } from "./RTHistory";
+import { ShowAST, ShowInputEvents, ShowInternalEvents, ShowOutputEvents } from "./ShowAST";
+import { TopPanel } from "./TopPanel/TopPanel";
+import { getKeyHandler } from "./VisualEditor/shortcut_handler";
+import { InsertMode, VisualEditor, VisualEditorState } from "./VisualEditor/VisualEditor";
 
 export type EditHistory = {
   current: VisualEditorState,
@@ -58,8 +30,9 @@ export type EditHistory = {
 
 const plants: [string, Plant<any>][] = [
   ["dummy", DummyPlant],
-  ["digital watch", DigitalWatchPlant],
   ["microwave", MicrowavePlant],
+
+  // ["digital watch", DigitalWatchPlant],
 ]
 
 export type TraceItemError = {
@@ -69,13 +42,13 @@ export type TraceItemError = {
 }
 
 type CoupledState = {
-  sc: BigStepOutput,
-  plant: any,
+  sc: BigStep,
+  plant: BigStep,
 };
 
 export type TraceItem =
   { kind: "error" } & TraceItemError
-| { kind: "bigstep", simtime: number, cause: string, state: CoupledState };
+| { kind: "bigstep", simtime: number, cause: string, state: CoupledState, outputEvents: RaisedEvent[] };
 
 export type TraceState = {
   // executor: TimedReactive<CoupledState>,
@@ -83,10 +56,6 @@ export type TraceState = {
   idx: number,
 }; // <-- null if there is no trace
 
-function current(ts: TraceState) {
-  return ts.trace[ts.idx]!;
-}
-
 // function getPlantState<T>(plant: Plant<T>, trace: TraceItem[], idx: number): T | null {
 //   if (idx === -1) {
 //     return plant.initial;
@@ -240,21 +209,27 @@ export function App() {
     }
   }, [refRightSideBar.current]);
 
-  const cE = useMemo(() => ast && coupledExecution({sc: statechartExecution(ast), plant: dummyExecution}, exposeStatechartInputs(ast, "sc")), [ast]);
+  const plantConns = ast && ({
+    inputEvents: {
+      ...exposeStatechartInputs(ast, "sc", (eventName: string) => "DEBUG_"+eventName),
+      ...exposePlantInputs(plant, "plant", (eventName: string) => "PLANT_UI_"+eventName),
+    },
+    outputEvents: autoConnect(ast, "sc", plant, "plant"),
+  }) as Conns;
+  const cE = useMemo(() => ast && coupledExecution({
+    sc: statechartExecution(ast),
+    plant: plant.execution,
+  }, plantConns!), [ast]);
 
   const onInit = useCallback(() => {
     if (cE === null) return;
     const metadata = {simtime: 0, cause: "<init>"};
     try {
-      const state = cE.initial(); // may throw if initialing the statechart results in a RuntimeError
+      const [outputEvents, state] = cE.initial(); // may throw if initialing the statechart results in a RuntimeError
       setTrace({
-        trace: [{kind: "bigstep", ...metadata, state}],
+        trace: [{kind: "bigstep", ...metadata, state, outputEvents}],
         idx: 0,
       });
-      // config = initialize(ast);
-      // const item = {kind: "bigstep", ...timestampedEvent, ...config};
-      // const plantState = getPlantState(plant, [item], 0);
-      // setTrace({trace: [{...item, plantState}], idx: 0});
     }
     catch (error) {
       if (error instanceof RuntimeError) {
@@ -262,7 +237,6 @@ export function App() {
           trace: [{kind: "error", ...metadata, error}],
           idx: 0,
         });
-        // setTrace({trace: [{kind: "error", ...timestampedEvent, error}], idx: 0});
       }
       else {
         throw error; // probably a bug in the interpreter
@@ -291,8 +265,7 @@ export function App() {
       if (currentTraceItem.kind === "bigstep") {
         const simtime = getSimTime(time, Math.round(performance.now()));
         appendNewConfig(simtime, inputEvent, () => {
-          const [_, newState] = cE.extTransition(simtime, currentTraceItem.state, {kind: "input", name: inputEvent, param});
-          return newState;
+          return cE.extTransition(simtime, currentTraceItem.state, {kind: "input", name: inputEvent, param});
         });
       }
     }
@@ -307,8 +280,7 @@ export function App() {
 
         const raiseTimeEvent = () => {
           appendNewConfig(nextTimeout, "<timer>", () => {
-            const [_, newState] = cE.intTransition(currentTraceItem.state);
-            return newState;
+            return cE.intTransition(currentTraceItem.state);
           });
         }
 
@@ -330,12 +302,12 @@ export function App() {
     }
   }, [time, trace]); // <-- todo: is this really efficient?
 
-  function appendNewConfig(simtime: number, cause: string, computeNewState: () => CoupledState) {
+  function appendNewConfig(simtime: number, cause: string, computeNewState: () => [RaisedEvent[], CoupledState]) {
     let newItem: TraceItem;
     const metadata = {simtime, cause}
     try {
-      const state = computeNewState(); // may throw RuntimeError
-      newItem = {kind: "bigstep", ...metadata, state};
+      const [outputEvents, state] = computeNewState(); // may throw RuntimeError
+      newItem = {kind: "bigstep", ...metadata, state, outputEvents};
     }
     catch (error) {
       if (error instanceof RuntimeError) {
@@ -397,6 +369,9 @@ export function App() {
   const highlightTransitions = currentBigStep && currentBigStep.state.sc.firedTransitions || [];
 
   const [showExecutionTrace, setShowExecutionTrace] = usePersistentState("showExecutionTrace", true);
+  const [showPlantTrace, setShowPlantTrace] = usePersistentState("showPlantTrace", false);
+
+  const speed = time.kind === "paused" ? 0 : time.scale;
 
   return <>
 
@@ -437,11 +412,10 @@ export function App() {
 
       {/* Right: sidebar */}
       <div style={{
-        borderLeft: 1,
-        borderColor: "divider",
         flex: '0 0 content',
+        borderLeft: '1px solid lightgrey',
         overflowY: "auto",
-        overflowX: "visible",
+        overflowX: "auto",
         maxWidth: 'min(400px, 50vw)',
       }}>
         <div className="stackVertical" style={{height:'100%'}}>
@@ -459,7 +433,7 @@ export function App() {
               <summary>input events</summary>
               {ast && <ShowInputEvents
                 inputEvents={ast.inputEvents}
-                onRaise={onRaise}
+                onRaise={(e,p) => onRaise("DEBUG_"+e,p)}
                 disabled={trace===null || trace.trace[trace.idx].kind === "error"}
                 showKeys={showKeys}/>}
             </PersistentDetails>
@@ -481,16 +455,15 @@ export function App() {
                   <option>{plantName}</option>
                 )}
               </select>
-              {/* {trace !== null && trace.trace[trace.idx].plantState &&
-                <div>{
-                  plant.render(
-                    trace.trace[trace.idx].plantState,
-                    event => onRaise(event.name, event.param),
-                    time.kind === "paused" ? 0 : time.scale,
-                  )
-                }</div>} */}
+              {plantConns && <ShowConns {...plantConns} />}
+              {currentBigStep && <plant.render state={currentBigStep.state.plant} speed={speed}
+                raiseInput={e => onRaise("PLANT_UI_"+e.name, e.param)}
+                raiseOutput={() => {}}
+                />}
             </PersistentDetails>
-            <details open={showExecutionTrace} onToggle={e => setShowExecutionTrace(e.newState === "open")}><summary>execution trace</summary></details>
+            <details open={showExecutionTrace} onToggle={e => setShowExecutionTrace(e.newState === "open")}><summary>execution trace</summary>
+              <input id="checkbox-show-plant-items" type="checkbox" checked={showPlantTrace} onChange={e => setShowPlantTrace(e.target.checked)}/><label htmlFor="checkbox-show-plant-items">show plant steps</label>
+            </details>
           </div>
 
           {/* We cheat a bit, and render the execution trace depending on whether the <details> above is 'open' or not, rather than putting it as a child of the <details>. We do this because only then can we get the execution trace to scroll without the rest scrolling as well. */}
@@ -502,10 +475,9 @@ export function App() {
               // minHeight: '75%', // <-- allows us to always scroll down the sidebar far enough such that the execution history is enough in view
               }}>
                 <div ref={refRightSideBar}>
-                  {ast && <RTHistory {...{ast, trace, setTrace, setTime}}/>}
+                  {ast && <RTHistory {...{ast, trace, setTrace, setTime, showPlantTrace}}/>}
                 </div>
             </div>}
-
           <div style={{flex: '0 0 content'}}>
           </div>
         </div>
@@ -520,4 +492,25 @@ export function App() {
   </>;
 }
 
+function ShowEventDestination(dst: EventDestination) {
+  if (dst.kind === "model") {
+    return <>{dst.model}.{dst.eventName}</>;
+  }
+  else if (dst.kind === "output") {
+    return <>{dst.eventName}</>;
+  }
+  else {
+    return <>&#x1F5D1;</>; // <-- garbage can icon
+  }
+}
+
+function ShowConns({inputEvents, outputEvents}: Conns) {
+  return <div>
+    <div style={{color: "grey"}}>
+      {Object.entries(inputEvents).map(([eventName, destination]) => <div>{eventName} &#x2192; <ShowEventDestination {...destination}/></div>)}
+    </div>
+    {Object.entries(outputEvents).map(([modelName, mapping]) => <>{Object.entries(mapping).map(([eventName, destination]) => <div>{modelName}.{eventName} &#x2192; <ShowEventDestination {...destination}/></div>)}</>)}
+  </div>;
+}
+
 export default App;
diff --git a/src/App/Plant/Dummy/Dummy.tsx b/src/App/Plant/Dummy/Dummy.tsx
index 8274253..917ccde 100644
--- a/src/App/Plant/Dummy/Dummy.tsx
+++ b/src/App/Plant/Dummy/Dummy.tsx
@@ -1,10 +1,16 @@
-import { RaisedEvent } from "@/statecharts/runtime_types";
 import { Plant } from "../Plant";
+import { TimedReactive } from "@/statecharts/timed_reactive";
 
-export const DummyPlant: Plant<{}> = {
+export const dummyExecution: TimedReactive<null> = {
+  initial: () => [[], null],
+  timeAdvance: () => Infinity,
+  intTransition: () => { throw new Error("dummy never makes intTransition"); },
+  extTransition: () => [[], null],
+};
+
+export const DummyPlant: Plant<null> = {
   inputEvents: [],
   outputEvents: [],
-  initial: () => ({}),
-  reduce: (_inputEvent: RaisedEvent, _state: {}) => ({}),
-  render: (_state: {}, _raise: (event: RaisedEvent) => void) => <></>,
+  execution: dummyExecution,
+  render: (props) => <></>,
 }
diff --git a/src/App/Plant/Microwave/Microwave.css b/src/App/Plant/Microwave/Microwave.css
index 48c7d9e..db6fdcd 100644
--- a/src/App/Plant/Microwave/Microwave.css
+++ b/src/App/Plant/Microwave/Microwave.css
@@ -14,5 +14,9 @@ rect.microwaveButtonHelper:active {
 }
 
 rect.microwaveDoorHelper {
+  fill: rgba(46, 211, 197);
   fill-opacity: 0;
+}
+rect.microwaveDoorHelper:hover {
+  fill-opacity: 0.3;
 }
\ No newline at end of file
diff --git a/src/App/Plant/Microwave/Microwave.tsx b/src/App/Plant/Microwave/Microwave.tsx
index 6600d2b..5f45b15 100644
--- a/src/App/Plant/Microwave/Microwave.tsx
+++ b/src/App/Plant/Microwave/Microwave.tsx
@@ -2,59 +2,31 @@ import { preload } from "react-dom";
 import imgSmallClosedOff from "./small_closed_off.png";
 import imgSmallClosedOn from "./small_closed_on.png";
 import imgSmallOpenedOff from "./small_opened_off.png";
-import imgSmallOpenedOn from "./small_opened_off.png";
+import imgSmallOpenedOn from "./small_opened_on.png";
 
 import fontDigital from "../DigitalWatch/digital-font.ttf";
 
 import sndBell from "./bell.wav";
 import sndRunning from "./running.wav";
-import { Plant } from "../Plant";
-import { RaisedEvent } from "@/statecharts/runtime_types";
-import { useEffect, useState } from "react";
+import { BigStep, RaisedEvent, RT_Statechart } from "@/statecharts/runtime_types";
+import { useEffect } from "react";
 
 import "./Microwave.css";
 import { useAudioContext } from "../../useAudioContext";
-
-export type MagnetronState = "on" | "off";
-export type DoorState = "open" | "closed";
-
-export function toggleDoor(d: DoorState) {
-  if (d === "open") {
-    return "closed";
-  }
-  else return "open";
-}
-
-export function toggleMagnetron(m: MagnetronState) {
-  if (m === "on") {
-    return "off";
-  }
-  return "on";
-}
-
-export type MicrowaveState = {
-  // Note: the door state is not part of the MicrowaveState because it is not controlled by the statechart, but by the plant.
-  timeDisplay: number,
-  bell: boolean, // whether the bell should ring
-  magnetron: MagnetronState,
-}
+import { Plant } from "../Plant";
+import { statechartExecution } from "@/statecharts/timed_reactive";
+import { microwaveAbstractSyntax } from "./model";
 
 export type MicrowaveProps = {
-  state: MicrowaveState,
+  state: RT_Statechart,
   speed: number,
-  callbacks: {
-    startPressed: () => void;
-    stopPressed: () => void;
-    incTimePressed: () => void;
-    incTimeReleased: () => void;
-    doorOpened: () => void;
-    doorClosed: () => void;
-  }
+  raiseInput: (event: RaisedEvent) => void;
+  raiseOutput: (event: RaisedEvent) => void;
 }
 
 const imgs = {
-  closed: { off: imgSmallClosedOff, on: imgSmallClosedOn },
-  open: { off: imgSmallOpenedOff, on: imgSmallOpenedOn },
+  "false": { "false": imgSmallClosedOff, "true": imgSmallClosedOn },
+  "true": { "false": imgSmallOpenedOff, "true": imgSmallOpenedOn },
 }
 
 const BUTTON_HEIGHT = 18;
@@ -71,9 +43,7 @@ const DOOR_Y0 = 68;
 const DOOR_WIDTH = 353;
 const DOOR_HEIGHT = 217;
 
-export function Magnetron({state: {timeDisplay, bell, magnetron}, speed, callbacks}: MicrowaveProps) {
-  const [door, setDoor] = useState<DoorState>("closed");
-
+export function Magnetron({state, speed, raiseInput, raiseOutput}: MicrowaveProps) {
   const [playSound, preloadAudio] = useAudioContext(speed);
 
   // preload(imgSmallClosedOff, {as: "image"});
@@ -84,30 +54,25 @@ export function Magnetron({state: {timeDisplay, bell, magnetron}, speed, callbac
   preloadAudio(sndRunning);
   preloadAudio(sndBell);
 
+  const bellRinging = state.mode.has("45");
+  const magnetronRunning = state.mode.has("28");
+  const doorOpen = state.mode.has("13");
+  const timeDisplay = state.environment.get("timeDisplay");
+
   // a bit hacky: when the bell-state changes to true, we play the bell sound...
   useEffect(() => {
-    if (bell) {
+    if (bellRinging) {
       playSound(sndBell, false);
     }
-  }, [bell]);
+  }, [bellRinging]);
 
   useEffect(() => {
-    if (magnetron === "on") {
+    if (magnetronRunning) {
       const stopSoundRunning = playSound(sndRunning, true);
       return () => stopSoundRunning();
     }
     return () => {};
-  }, [magnetron])
-
-
-  const openDoor = () => {
-    setDoor("open");
-    callbacks.doorOpened();
-  }
-  const closeDoor = () => {
-    setDoor("closed");
-    callbacks.doorClosed();
-  }
+  }, [magnetronRunning])
 
   return <>
     <style>{`
@@ -117,52 +82,57 @@ export function Magnetron({state: {timeDisplay, bell, magnetron}, speed, callbac
       }
     `}</style>
     <svg width='400px' height='auto' viewBox="0 0 520 348">
-      <image xlinkHref={imgs[door][magnetron]} width={520} height={348}/>
+      {/* @ts-ignore */}
+      <image xlinkHref={imgs[doorOpen][magnetronRunning]} width={520} height={348}/>
 
       <rect className="microwaveButtonHelper" x={START_X0} y={START_Y0} width={BUTTON_WIDTH} height={BUTTON_HEIGHT} 
-        onMouseDown={() => callbacks.startPressed()}
+        onMouseDown={() => raiseInput({name: "startPressed"})}
+        onMouseUp={() => raiseInput({name: "startReleased"})}
       />
       <rect className="microwaveButtonHelper" x={STOP_X0} y={STOP_Y0} width={BUTTON_WIDTH} height={BUTTON_HEIGHT} 
-        onMouseDown={() => callbacks.stopPressed()}
+        onMouseDown={() => raiseInput({name: "stopPressed"})}
+        onMouseUp={() => raiseInput({name: "stopReleased"})}
       />
       <rect className="microwaveButtonHelper" x={INCTIME_X0} y={INCTIME_Y0} width={BUTTON_WIDTH} height={BUTTON_HEIGHT} 
-        onMouseDown={() => callbacks.incTimePressed()}
-        onMouseUp={() => callbacks.incTimeReleased()}
+        onMouseDown={() => raiseInput({name: "incTimePressed"})}
+        onMouseUp={() => raiseInput({name: "incTimeReleased"})}
       />
-      <rect className="microwaveDoorHelper" x={DOOR_X0} y={DOOR_Y0} width={DOOR_WIDTH} height={DOOR_HEIGHT}         onMouseDown={() => door === "open" ? closeDoor() : openDoor()}
+      <rect className="microwaveDoorHelper"
+        x={DOOR_X0} y={DOOR_Y0} width={DOOR_WIDTH} height={DOOR_HEIGHT}
+        onMouseDown={() => raiseInput({name: "doorMouseDown"})}
+        onMouseUp={() => raiseInput({name: "doorMouseUp"})}
       />
-
       <text x={472} y={106} textAnchor="end" fontFamily="digital-font" fontSize={24} fill="lightgreen">{timeDisplay}</text>
     </svg>
   </>;
 }
 
-export const MicrowavePlant: Plant<MicrowaveState> = {
-  inputEvents: [],
-  outputEvents: [],
-  initial: {
-    timeDisplay: 0,
-    magnetron: "off",
-    bell: false,
-  },
-  reduce: (inputEvent: RaisedEvent, state: MicrowaveState) => {
-    if (inputEvent.name === "setMagnetron") {
-      return { ...state, magnetron: inputEvent.param, bell: false };
-    }
-    if (inputEvent.name === "setTimeDisplay") {
-      return { ...state, timeDisplay: inputEvent.param, bell: false };
-    }
-    if (inputEvent.name === "ringBell") {
-      return { ...state, bell: true };
-    }
-    return state; // unknown event - ignore it
-  },
-  render: (state, raiseEvent, speed) => <Magnetron state={state} speed={speed} callbacks={{
-    startPressed: () => raiseEvent({name: "startPressed"}),
-    stopPressed: () => raiseEvent({name: "stopPressed"}),
-    incTimePressed: () => raiseEvent({name: "incTimePressed"}),
-    incTimeReleased: () => raiseEvent({name: "incTimeReleased"}),
-    doorOpened: () => raiseEvent({name: "door", param: "open"}),
-    doorClosed: () => raiseEvent({name: "door", param: "closed"}),
-  }}/>,
+export const MicrowavePlant: Plant<BigStep> = {
+  inputEvents: [
+    // events coming from statechart    
+    {kind: "event", event: "setTimeDisplay", paramName: "t"},
+    {kind: "event", event: "setMagnetron", paramName: "state"},
+    {kind: "event", event: "ringBell"},
+
+    // events coming from UI:
+    {kind: "event", event: "doorMouseDown"},
+    {kind: "event", event: "doorMouseUp"},
+    {kind: "event", event: "startPressed"},
+    {kind: "event", event: "stopPressed"},
+    {kind: "event", event: "incTimePressed"},
+    {kind: "event", event: "startReleased"},
+    {kind: "event", event: "stopReleased"},
+    {kind: "event", event: "incTimeReleased"},
+  ],
+  outputEvents: [
+    {kind: "event", event: "door", paramName: "state"},
+    {kind: "event", event: "startPressed"},
+    {kind: "event", event: "stopPressed"},
+    {kind: "event", event: "incTimePressed"},
+    {kind: "event", event: "startReleased"},
+    {kind: "event", event: "stopReleased"},
+    {kind: "event", event: "incTimeReleased"},
+  ],
+  execution: statechartExecution(microwaveAbstractSyntax),
+  render: Magnetron,
 }
diff --git a/src/App/Plant/Microwave/model.ts b/src/App/Plant/Microwave/model.ts
new file mode 100644
index 0000000..084e850
--- /dev/null
+++ b/src/App/Plant/Microwave/model.ts
@@ -0,0 +1,15 @@
+import { ConcreteSyntax } from "@/App/VisualEditor/VisualEditor";
+import { detectConnections } from "@/statecharts/detect_connections";
+import { parseStatechart } from "@/statecharts/parser";
+
+// export const microwaveConcreteSyntax: ConcreteSyntax = {"rountangles":[{"uid":"25","topLeft":{"x":134.99999999999972,"y":136.9999999999999},"size":{"x":1686.9999999999995,"y":623.9999999999997},"kind":"and"},{"uid":"24","topLeft":{"x":517.9999999999994,"y":173.99999999999983},"size":{"x":482.99999999999943,"y":554.9999999999998},"kind":"or"},{"uid":"57","topLeft":{"x":1403.999999999999,"y":175.9999999999999},"size":{"x":378.99999999999983,"y":553.9999999999997},"kind":"or"},{"uid":"32","topLeft":{"x":558.9999999999993,"y":240.99999999999983},"size":{"x":392.9999999999999,"y":462.99999999999983},"kind":"or"},{"uid":"43","topLeft":{"x":1034.999999999999,"y":180.9999999999999},"size":{"x":328.9999999999999,"y":549.9999999999998},"kind":"or"},{"uid":"23","topLeft":{"x":169.99999999999972,"y":170.99999999999983},"size":{"x":317.9999999999998,"y":556.9999999999998},"kind":"or"},{"uid":"13","topLeft":{"x":232.99999999999972,"y":550.9999999999997},"size":{"x":198.9999999999999,"y":124.99999999999994},"kind":"and"},{"uid":"28","topLeft":{"x":728.9999999999993,"y":551.9999999999997},"size":{"x":183.99999999999994,"y":108.99999999999994},"kind":"and"},{"uid":"11","topLeft":{"x":244.99999999999972,"y":298.9999999999998},"size":{"x":183.99999999999994,"y":94.99999999999994},"kind":"and"},{"uid":"58","topLeft":{"x":1447.9999999999989,"y":407.9999999999997},"size":{"x":148.99999999999994,"y":113.99999999999997},"kind":"and"},{"uid":"44","topLeft":{"x":1128.9999999999989,"y":306.9999999999998},"size":{"x":156.99999999999994,"y":102.99999999999996},"kind":"and"},{"uid":"27","topLeft":{"x":731.9999999999993,"y":316.9999999999998},"size":{"x":173.9999999999999,"y":87.99999999999996},"kind":"and"},{"uid":"45","topLeft":{"x":1133.9999999999989,"y":571.9999999999997},"size":{"x":162.99999999999997,"y":89.99999999999999},"kind":"and"}],"diamonds":[{"uid":"34","topLeft":{"x":657.9999999999993,"y":458.99999999999966},"size":{"x":59,"y":60}}],"history":[],"arrows":[{"uid":"18","start":{"x":376.99999999999955,"y":393.9999999999998},"end":{"x":375.99999999999955,"y":541.9999999999998}},{"uid":"20","start":{"x":279.9999999999997,"y":547.9999999999997},"end":{"x":279.9999999999997,"y":401.99999999999966}},{"uid":"22","start":{"x":278.9999999999997,"y":244.99999999999977},"end":{"x":310.99999999999966,"y":295.9999999999998}},{"uid":"26","start":{"x":202.99999999999972,"y":82.99999999999991},"end":{"x":245.99999999999972,"y":130.99999999999983}},{"uid":"29","start":{"x":559.9999999999993,"y":493.99999999999966},"end":{"x":652.9999999999993,"y":492.99999999999966}},{"uid":"30","start":{"x":791.9999999999993,"y":275.99999999999983},"end":{"x":808.9999999999993,"y":306.99999999999983}},{"uid":"33","start":{"x":630.9999999999993,"y":201.99999999999986},"end":{"x":671.9999999999993,"y":234.99999999999986}},{"uid":"35","start":{"x":691.9999999999993,"y":517.9999999999997},"end":{"x":730.9999999999993,"y":553.9999999999997}},{"uid":"37","start":{"x":687.9999999999993,"y":458.99999999999966},"end":{"x":733.9999999999993,"y":398.99999999999966}},{"uid":"46","start":{"x":1163.9999999999989,"y":238.99999999999983},"end":{"x":1206.9999999999989,"y":303.99999999999983}},{"uid":"47","start":{"x":1260.9999999999989,"y":410.9999999999997},"end":{"x":1261.9999999999989,"y":569.9999999999997}},{"uid":"48","start":{"x":1170.9999999999989,"y":568.9999999999997},"end":{"x":1169.9999999999989,"y":413.99999999999966}},{"uid":"59","start":{"x":1600.9999999999989,"y":470.9999999999997},"end":{"x":1546.9999999999989,"y":524.9999999999997}},{"uid":"66","start":{"x":1467.9999999999989,"y":355.9999999999998},"end":{"x":1528.9999999999989,"y":402.9999999999998}}],"texts":[{"uid":"12","text":"// Door closed","topLeft":{"x":336.99999999999955,"y":334.99999999999983}},{"uid":"14","text":"// Door opened","topLeft":{"x":331.9999999999993,"y":592.9999999999997}},{"uid":"15","text":"entry / ^door(\"closed\")","topLeft":{"x":335.99999999999966,"y":364.9999999999998}},{"uid":"16","text":"entry / ^door(\"open\")","topLeft":{"x":331.99999999999966,"y":642.9999999999997}},{"uid":"19","text":"toggleDoor","topLeft":{"x":267.9999999999996,"y":463.9999999999998}},{"uid":"21","text":"toggleDoor","topLeft":{"x":373.99999999999955,"y":485.9999999999998}},{"uid":"31","text":"setMagnetron(state)","topLeft":{"x":616.9999999999993,"y":480.99999999999955}},{"uid":"36","text":"[state==\"on\"]","topLeft":{"x":718.9999999999991,"y":537.9999999999997}},{"uid":"38","text":"[state == \"off\"]","topLeft":{"x":706.9999999999993,"y":439.9999999999997}},{"uid":"39","text":"// Magnetron off","topLeft":{"x":818.9999999999991,"y":364.9999999999998}},{"uid":"40","text":"// Magnetron on","topLeft":{"x":824.9999999999991,"y":613.9999999999995}},{"uid":"49","text":"ringBell","topLeft":{"x":1269.9999999999989,"y":496.99999999999966}},{"uid":"50","text":"after 10 ms","topLeft":{"x":1163.9999999999989,"y":490.99999999999966}},{"uid":"51","text":"// bell","topLeft":{"x":1212.9999999999989,"y":616.9999999999995}},{"uid":"52","text":"// no bell","topLeft":{"x":1205.9999999999989,"y":364.9999999999998}},{"uid":"60","text":"setTimeDisplay(value) / timeDisplay = value;","topLeft":{"x":1610.9999999999989,"y":498.9999999999998}},{"uid":"65","text":"entry / timeDisplay = 0;","topLeft":{"x":435.9999999999997,"y":102.99999999999996}}]};
+
+
+export const microwaveConcreteSyntax: ConcreteSyntax = {"rountangles":[{"uid":"25","topLeft":{"x":53.99999999999977,"y":125.99999999999989},"size":{"x":2025.9999999999995,"y":623.9999999999997},"kind":"and"},{"uid":"57","topLeft":{"x":1432.999999999999,"y":164.9999999999999},"size":{"x":607.9999999999998,"y":553.9999999999997},"kind":"or"},{"uid":"24","topLeft":{"x":546.9999999999994,"y":162.99999999999983},"size":{"x":482.99999999999943,"y":554.9999999999998},"kind":"or"},{"uid":"23","topLeft":{"x":88.99999999999974,"y":159.99999999999983},"size":{"x":427.9999999999998,"y":556.9999999999998},"kind":"or"},{"uid":"32","topLeft":{"x":587.9999999999993,"y":229.99999999999983},"size":{"x":392.9999999999999,"y":462.99999999999983},"kind":"or"},{"uid":"43","topLeft":{"x":1063.999999999999,"y":169.9999999999999},"size":{"x":328.9999999999999,"y":549.9999999999998},"kind":"or"},{"uid":"58","topLeft":{"x":1638.9999999999989,"y":248.99999999999972},"size":{"x":148.99999999999994,"y":389.99999999999994},"kind":"and"},{"uid":"13","topLeft":{"x":261.9999999999997,"y":539.9999999999997},"size":{"x":198.9999999999999,"y":124.99999999999994},"kind":"and"},{"uid":"28","topLeft":{"x":757.9999999999993,"y":540.9999999999997},"size":{"x":183.99999999999994,"y":108.99999999999994},"kind":"and"},{"uid":"11","topLeft":{"x":273.9999999999997,"y":287.9999999999998},"size":{"x":183.99999999999994,"y":94.99999999999994},"kind":"and"},{"uid":"44","topLeft":{"x":1157.9999999999989,"y":295.9999999999998},"size":{"x":156.99999999999994,"y":102.99999999999996},"kind":"and"},{"uid":"27","topLeft":{"x":760.9999999999993,"y":305.9999999999998},"size":{"x":173.9999999999999,"y":87.99999999999996},"kind":"and"},{"uid":"45","topLeft":{"x":1162.9999999999989,"y":560.9999999999997},"size":{"x":162.99999999999997,"y":89.99999999999999},"kind":"and"},{"uid":"80","topLeft":{"x":127.99999999999993,"y":426.9999999999997},"size":{"x":108.99999999999996,"y":73.99999999999997},"kind":"and"}],"diamonds":[{"uid":"34","topLeft":{"x":686.9999999999993,"y":447.99999999999966},"size":{"x":59,"y":60}}],"history":[],"arrows":[{"uid":"18","start":{"x":405.99999999999955,"y":382.9999999999998},"end":{"x":404.99999999999955,"y":530.9999999999998}},{"uid":"20","start":{"x":308.9999999999997,"y":536.9999999999997},"end":{"x":240.99999999999972,"y":503.99999999999966}},{"uid":"22","start":{"x":307.9999999999997,"y":233.99999999999977},"end":{"x":339.99999999999966,"y":284.9999999999998}},{"uid":"26","start":{"x":231.99999999999972,"y":71.99999999999991},"end":{"x":274.9999999999997,"y":119.99999999999983}},{"uid":"29","start":{"x":588.9999999999993,"y":482.99999999999966},"end":{"x":681.9999999999993,"y":481.99999999999966}},{"uid":"30","start":{"x":820.9999999999993,"y":264.99999999999983},"end":{"x":837.9999999999993,"y":295.99999999999983}},{"uid":"33","start":{"x":659.9999999999993,"y":190.99999999999986},"end":{"x":700.9999999999993,"y":223.99999999999986}},{"uid":"35","start":{"x":720.9999999999993,"y":506.99999999999966},"end":{"x":759.9999999999993,"y":542.9999999999997}},{"uid":"37","start":{"x":716.9999999999993,"y":447.99999999999966},"end":{"x":762.9999999999993,"y":387.99999999999966}},{"uid":"46","start":{"x":1192.9999999999989,"y":227.99999999999983},"end":{"x":1235.9999999999989,"y":292.99999999999983}},{"uid":"47","start":{"x":1289.9999999999989,"y":399.9999999999997},"end":{"x":1290.9999999999989,"y":558.9999999999997}},{"uid":"48","start":{"x":1199.9999999999989,"y":557.9999999999997},"end":{"x":1198.9999999999989,"y":402.99999999999966}},{"uid":"59","start":{"x":1789.9999999999989,"y":587.9999999999997},"end":{"x":1736.9999999999989,"y":643.9999999999997}},{"uid":"66","start":{"x":1643.9999999999989,"y":200.99999999999977},"end":{"x":1672.9999999999989,"y":242.99999999999977}},{"uid":"67","start":{"x":1633.9999999999989,"y":322.99999999999983},"end":{"x":1630.9999999999989,"y":367.99999999999983}},{"uid":"70","start":{"x":1632.9999999999989,"y":405.99999999999983},"end":{"x":1629.9999999999989,"y":450.99999999999983}},{"uid":"72","start":{"x":1632.9999999999989,"y":482.99999999999983},"end":{"x":1629.9999999999989,"y":527.9999999999998}},{"uid":"74","start":{"x":1791.9999999999989,"y":454.9999999999998},"end":{"x":1788.9999999999989,"y":499.9999999999998}},{"uid":"76","start":{"x":1789.9999999999989,"y":373.9999999999998},"end":{"x":1786.9999999999989,"y":418.9999999999998}},{"uid":"78","start":{"x":1793.9999999999989,"y":288.9999999999998},"end":{"x":1790.9999999999989,"y":333.9999999999998}},{"uid":"81","start":{"x":209.9999999999999,"y":419.9999999999997},"end":{"x":265.9999999999999,"y":368.9999999999997}}],"texts":[{"uid":"12","text":"// Door closed","topLeft":{"x":365.99999999999955,"y":323.99999999999983}},{"uid":"14","text":"// Door opened","topLeft":{"x":360.9999999999993,"y":581.9999999999997}},{"uid":"15","text":"entry / ^door(\"closed\")","topLeft":{"x":364.99999999999966,"y":353.9999999999998}},{"uid":"16","text":"entry / ^door(\"open\")","topLeft":{"x":360.99999999999966,"y":631.9999999999997}},{"uid":"19","text":"doorMouseDown","topLeft":{"x":260.9999999999996,"y":527.9999999999998}},{"uid":"21","text":"doorMouseUp","topLeft":{"x":402.99999999999955,"y":474.9999999999998}},{"uid":"31","text":"setMagnetron(state)","topLeft":{"x":645.9999999999993,"y":469.99999999999955}},{"uid":"36","text":"[state==\"on\"]","topLeft":{"x":747.9999999999991,"y":526.9999999999997}},{"uid":"38","text":"[state == \"off\"]","topLeft":{"x":735.9999999999993,"y":428.9999999999997}},{"uid":"39","text":"// Magnetron off","topLeft":{"x":847.9999999999991,"y":353.9999999999998}},{"uid":"40","text":"// Magnetron on","topLeft":{"x":853.9999999999991,"y":602.9999999999995}},{"uid":"49","text":"ringBell","topLeft":{"x":1298.9999999999989,"y":485.99999999999966}},{"uid":"50","text":"after 10 ms","topLeft":{"x":1192.9999999999989,"y":479.99999999999966}},{"uid":"51","text":"// bell","topLeft":{"x":1241.9999999999989,"y":605.9999999999995}},{"uid":"52","text":"// no bell","topLeft":{"x":1234.9999999999989,"y":353.9999999999998}},{"uid":"60","text":"setTimeDisplay(value) / timeDisplay = value;","topLeft":{"x":1799.9999999999989,"y":615.9999999999998}},{"uid":"65","text":"entry / timeDisplay = 0;","topLeft":{"x":464.9999999999997,"y":91.99999999999996}},{"uid":"68","text":"startPressed / ^startPressed","topLeft":{"x":1664.9999999999989,"y":349.99999999999983}},{"uid":"71","text":"stopPressed / ^stopPressed","topLeft":{"x":1646.9999999999989,"y":433.99999999999983}},{"uid":"73","text":"incTimePressed / ^incTimePressed","topLeft":{"x":1643.9999999999989,"y":509.9999999999998}},{"uid":"75","text":"incTimeReleased / ^incTimeReleased","topLeft":{"x":1825.9999999999989,"y":477.9999999999998}},{"uid":"77","text":"stopReleased / ^stopReleased","topLeft":{"x":1823.9999999999989,"y":397.9999999999998}},{"uid":"79","text":"startReleased / ^startReleased","topLeft":{"x":1830.9999999999989,"y":311.9999999999998}},{"uid":"82","text":"doorMouseUp","topLeft":{"x":230.99999999999986,"y":404.9999999999998}},{"uid":"83","text":"// closing door","topLeft":{"x":181.9999999999999,"y":464.9999999999997}}]};
+
+export const [microwaveAbstractSyntax, microwaveErrors] = parseStatechart(microwaveConcreteSyntax, detectConnections(microwaveConcreteSyntax));
+
+if (microwaveErrors.length > 0) {
+  console.log({microwaveErrors});
+  throw new Error("there were errors parsing microwave plant model. see console.")
+}
diff --git a/src/App/Plant/Plant.ts b/src/App/Plant/Plant.ts
index 239f774..492bfef 100644
--- a/src/App/Plant/Plant.ts
+++ b/src/App/Plant/Plant.ts
@@ -1,12 +1,51 @@
+import { ReactElement } from "react";
+import { Statechart } from "@/statecharts/abstract_syntax";
 import { EventTrigger } from "@/statecharts/label_ast";
 import { RaisedEvent } from "@/statecharts/runtime_types";
-import { ReactElement } from "react";
+import { Conns, TimedReactive } from "@/statecharts/timed_reactive";
+
+export type PlantRenderProps<StateType> = {
+  state: StateType,
+  speed: number,
+  raiseInput: (e: RaisedEvent) => void,
+  raiseOutput: (e: RaisedEvent) => void,
+};
 
 export type Plant<StateType> = {
   inputEvents: EventTrigger[];
   outputEvents: EventTrigger[];
-
-  initial: StateType;
-  reduce: (inputEvent: RaisedEvent, state: StateType) => StateType;
-  render: (state: StateType, raise: (event: RaisedEvent) => void, timescale: number) => ReactElement;
+  execution: TimedReactive<StateType>;
+  render: (props: PlantRenderProps<StateType>) => ReactElement;
+}
+
+// Automatically connect Statechart and Plant inputs/outputs if their event names match.
+export function autoConnect(ast: Statechart, scName: string, plant: Plant<any>, plantName: string) {
+  const outputs = {
+    [scName]: {},
+    [plantName]: {},
+  }
+  for (const o of ast.outputEvents) {
+    const plantInputEvent = plant.inputEvents.find(e => e.event === o)
+    if (plantInputEvent) {
+      // @ts-ignore
+      outputs[scName][o] = {kind: "model", model: plantName, eventName: plantInputEvent.event};
+    }
+  }
+  for (const o of plant.outputEvents) {
+    const scInputEvent = ast.inputEvents.find(e => e.event === o.event);
+    if (scInputEvent) {
+      // @ts-ignore
+      outputs[plantName][o.event] = {kind: "model", model: scName, eventName: scInputEvent.event};
+    }
+  }
+  return outputs;
+}
+
+export function exposePlantInputs(plant: Plant<any>, plantName: string, tfm = (s: string) => s) {
+  const inputs = {};
+  for (const i of plant.inputEvents) {
+    // @ts-ignore
+    inputs[tfm(i.event)] = {kind: "model", model: plantName, eventName: i.event};
+  }
+  return inputs
 }
diff --git a/src/App/RTHistory.tsx b/src/App/RTHistory.tsx
index 656c983..9019460 100644
--- a/src/App/RTHistory.tsx
+++ b/src/App/RTHistory.tsx
@@ -1,51 +1,77 @@
 import { Dispatch, memo, SetStateAction, useCallback } from "react";
 import { Statechart, stateDescription } from "../statecharts/abstract_syntax";
-import { Mode, RaisedEvent } from "../statecharts/runtime_types";
+import { Mode, RaisedEvent, RT_Event } from "../statecharts/runtime_types";
 import { formatTime } from "../util/util";
-import { TimeMode } from "../statecharts/time";
+import { TimeMode, timeTravel } from "../statecharts/time";
 import { TraceItem, TraceState } from "./App";
 import { Environment } from "@/statecharts/environment";
+import { Conns } from "@/statecharts/timed_reactive";
 
 type RTHistoryProps = {
   trace: TraceState|null,
   setTrace: Dispatch<SetStateAction<TraceState|null>>;
   ast: Statechart,
   setTime: Dispatch<SetStateAction<TimeMode>>,
+  showPlantTrace: boolean,
 }
 
-export function RTHistory({trace, setTrace, ast, setTime}: RTHistoryProps) {
+export function RTHistory({trace, setTrace, ast, setTime, showPlantTrace}: RTHistoryProps) {
   const onMouseDown = useCallback((idx: number, timestamp: number) => {
     setTrace(trace => trace && {
       ...trace,
       idx,
     });
-    setTime({kind: "paused", simtime: timestamp});
+    setTime(time => timeTravel(time, timestamp, performance.now()));
   }, [setTrace, setTime]);
 
   if (trace === null) {
     return <></>;
   }
-  return <div>
-    {trace.trace.map((item, i) => <RTHistoryItem ast={ast} idx={i} item={item} prevItem={trace.trace[i-1]} active={i === trace.idx} onMouseDown={onMouseDown}/>)}
-  </div>;
+  return trace.trace.map((item, i) => {
+    const prevItem = trace.trace[i-1];
+    // @ts-ignore
+    const isPlantStep = item.state?.sc === prevItem?.state?.sc;
+    if (!showPlantTrace && isPlantStep) {
+      return <></>
+    }
+    return <RTHistoryItem ast={ast} idx={i} item={item} prevItem={prevItem} isPlantStep={isPlantStep} active={i === trace.idx} onMouseDown={onMouseDown}/>;
+  });
 }
 
-export const RTHistoryItem = memo(function RTHistoryItem({ast, idx, item, prevItem, active, onMouseDown}: {idx: number, ast: Statechart, item: TraceItem, prevItem?: TraceItem, active: boolean, onMouseDown: (idx: number, timestamp: number) => void}) {
+function RTCause(props: {cause?: RT_Event}) {
+  if (props.cause === undefined) {
+    return <>{"<init>"}</>;
+  }
+  if (props.cause.kind === "timer") {
+    return <>{"<timer>"}</>;
+  }
+  else if (props.cause.kind === "input") {
+    return <>{props.cause.name}<RTEventParam param={props.cause.param}/></>
+  }
+  console.log(props.cause);
+  throw new Error("unreachable");
+}
+
+function RTEventParam(props: {param?: any}) {
+  return <>{props.param !== undefined && <>({JSON.stringify(props.param)})</>}</>;
+}
+
+export const RTHistoryItem = memo(function RTHistoryItem({ast, idx, item, prevItem, isPlantStep, active, onMouseDown}: {idx: number, ast: Statechart, item: TraceItem, prevItem?: TraceItem, isPlantStep: boolean, active: boolean, onMouseDown: (idx: number, timestamp: number) => void}) {
   if (item.kind === "bigstep") {
     // @ts-ignore
     const newStates = item.state.sc.mode.difference(prevItem?.state.sc.mode || new Set());
     return <div
-      className={"runtimeState" + (active ? " active" : "")}
+      className={"runtimeState" + (active ? " active" : "") + (isPlantStep ? " plantStep" : "")}
       onMouseDown={useCallback(() => onMouseDown(idx, item.simtime), [idx, item.simtime])}>
       <div>
         {formatTime(item.simtime)}
         &emsp;
-        <div className="inputEvent">{item.cause}</div>
+        <div className="inputEvent"><RTCause cause={item.state.sc.inputEvent}/></div>
       </div>
       <ShowMode mode={newStates} statechart={ast}/>
       <ShowEnvironment environment={item.state.sc.environment}/>
       {item.state.sc.outputEvents.length>0 && <>^
-        {item.state.sc.outputEvents.map((e:RaisedEvent) => <span className="outputEvent">{e.name}</span>)}
+        {item.state.sc.outputEvents.map((e:RaisedEvent) => <span className="outputEvent">{e.name}<RTEventParam param={e.param}/></span>)}
       </>}
     </div>;
   }
diff --git a/src/App/ShowAST.tsx b/src/App/ShowAST.tsx
index 8a63081..bdfdecd 100644
--- a/src/App/ShowAST.tsx
+++ b/src/App/ShowAST.tsx
@@ -73,6 +73,7 @@ export const ShowAST = memo(function ShowASTx(props: {root: ConcreteState | Unst
 import BoltIcon from '@mui/icons-material/Bolt';
 import { KeyInfoHidden, KeyInfoVisible } from "./TopPanel/KeyInfo";
 import { memo, useEffect } from "react";
+import { usePersistentState } from "./persistent_state";
 
 export function ShowInputEvents({inputEvents, onRaise, disabled, showKeys}: {inputEvents: EventTrigger[], onRaise: (e: string, p: any) => void, disabled: boolean, showKeys: boolean}) {
   const raiseHandlers = inputEvents.map(({event}) => {
@@ -93,6 +94,9 @@ export function ShowInputEvents({inputEvents, onRaise, disabled, showKeys}: {inp
     };
   });
   const onKeyDown = (e: KeyboardEvent) => {
+    // don't capture keyboard events when focused on an input element:
+    if (["INPUT", "TEXTAREA", "SELECT"].includes(e.target?.tagName)) return;
+
     const n = (parseInt(e.key)+9) % 10;
     if (raiseHandlers[n] !== undefined) {
       raiseHandlers[n]();
@@ -106,10 +110,16 @@ export function ShowInputEvents({inputEvents, onRaise, disabled, showKeys}: {inp
   }, [raiseHandlers]);
   // const KeyInfo = showKeys ? KeyInfoVisible : KeyInfoHidden;
   const KeyInfo = KeyInfoVisible; // always show keyboard shortcuts on input events, we can't expect the user to remember them
+
+  const [inputParams, setInputParams] = usePersistentState<{[eventName:string]: string}>("inputParams", {});
+
   return inputEvents.map(({event, paramName}, i) => {
+    const key = event+'/'+paramName;
+    const value = inputParams[key] || "";
+    const width = Math.max(value.length, (paramName||"").length)*6;
     const shortcut = (i+1)%10;
     const KI = (i <= 10) ? KeyInfo : KeyInfoHidden;
-    return <div key={event+'/'+paramName} className="toolbarGroup">
+    return <div key={key} className="toolbarGroup">
       <KI keyInfo={<kbd>{shortcut}</kbd>} horizontal={true}>
         <button
           className="inputEvent"
@@ -121,7 +131,7 @@ export function ShowInputEvents({inputEvents, onRaise, disabled, showKeys}: {inp
         </button>
       </KI>
       {paramName &&
-        <><input id={`input-${event}-param`} style={{width: 20}} placeholder={paramName}/></>
+        <><input id={`input-${event}-param`} style={{width, overflow: 'visible'}} placeholder={paramName} value={value} onChange={e => setInputParams(params => ({...params, [key]: e.target.value, }))}/></>
       }
       &nbsp;
     </div>;
diff --git a/src/App/TopPanel/TopPanel.tsx b/src/App/TopPanel/TopPanel.tsx
index e29c609..2beede9 100644
--- a/src/App/TopPanel/TopPanel.tsx
+++ b/src/App/TopPanel/TopPanel.tsx
@@ -122,6 +122,9 @@ export const TopPanel = memo(function TopPanel({trace, time, setTime, onUndo, on
 
   useEffect(() => {
     const onKeyDown = (e: KeyboardEvent) => {
+      // don't capture keyboard events when focused on an input element:
+      if (["INPUT", "TEXTAREA", "SELECT"].includes(e.target?.tagName)) return;
+
       if (!e.ctrlKey) {
         if (e.key === " ") {
           e.preventDefault();
diff --git a/src/App/VisualEditor/VisualEditor.tsx b/src/App/VisualEditor/VisualEditor.tsx
index 160da43..150d21b 100644
--- a/src/App/VisualEditor/VisualEditor.tsx
+++ b/src/App/VisualEditor/VisualEditor.tsx
@@ -18,12 +18,15 @@ import { TraceState } from "@/App/App";
 import { Mode } from "@/statecharts/runtime_types";
 import { arraysEqual, objectsEqual, setsEqual } from "@/util/util";
 
-export type VisualEditorState = {
+export type ConcreteSyntax = {
   rountangles: Rountangle[];
   texts: Text[];
   arrows: Arrow[];
   diamonds: Diamond[];
   history: History[];
+};
+
+export type VisualEditorState = ConcreteSyntax & {
   nextID: number;
   selection: Selection;
 };
@@ -373,6 +376,9 @@ export const VisualEditor = memo(function VisualEditor({state, setState, trace,
   }, [setState]);
 
   const onKeyDown = useCallback((e: KeyboardEvent) => {
+    // don't capture keyboard events when focused on an input element:
+    if (["INPUT", "TEXTAREA", "SELECT"].includes(e.target?.tagName)) return;
+
     if (e.key === "Delete") {
       // delete selection
       makeCheckPoint();
diff --git a/src/App/VisualEditor/shortcut_handler.ts b/src/App/VisualEditor/shortcut_handler.ts
index d7792f7..366d7d6 100644
--- a/src/App/VisualEditor/shortcut_handler.ts
+++ b/src/App/VisualEditor/shortcut_handler.ts
@@ -3,6 +3,9 @@ import { InsertMode } from "./VisualEditor";
 
 export function getKeyHandler(setMode: Dispatch<SetStateAction<InsertMode>>) {
   return function onKeyDown(e: KeyboardEvent) {
+    // don't capture keyboard events when focused on an input element:
+    if (["INPUT", "TEXTAREA", "SELECT"].includes(e.target?.tagName)) return;
+
     if (!e.ctrlKey) {
       if (e.key === "a") {
         setMode("and");
diff --git a/src/statecharts/detect_connections.ts b/src/statecharts/detect_connections.ts
index 4d7b00f..eefc02e 100644
--- a/src/statecharts/detect_connections.ts
+++ b/src/statecharts/detect_connections.ts
@@ -1,4 +1,4 @@
-import { VisualEditorState } from "@/App/VisualEditor/VisualEditor";
+import { ConcreteSyntax, VisualEditorState } from "@/App/VisualEditor/VisualEditor";
 import { findNearestArrow, findNearestHistory, findNearestSide, findRountangle, RectSide } from "./concrete_syntax";
 
 export type Connections = {
@@ -12,7 +12,7 @@ export type Connections = {
   history2ArrowMap: Map<string, string[]>,
 }
 
-export function detectConnections(state: VisualEditorState): Connections {
+export function detectConnections(state: ConcreteSyntax): Connections {
   const startTime = performance.now();
   // detect what is 'connected'
   const arrow2SideMap = new Map<string,[{ uid: string; part: RectSide; } | undefined, { uid: string; part: RectSide; } | undefined]>();
diff --git a/src/statecharts/interpreter.ts b/src/statecharts/interpreter.ts
index 28c53cd..e1326d1 100644
--- a/src/statecharts/interpreter.ts
+++ b/src/statecharts/interpreter.ts
@@ -2,20 +2,20 @@ import { AbstractState, computeArena, computePath, ConcreteState, getDescendants
 import { evalExpr } from "./actionlang_interpreter";
 import { Environment, FlatEnvironment, ScopedEnvironment } from "./environment";
 import { Action, EventTrigger, TransitionLabel } from "./label_ast";
-import { BigStepOutput, initialRaised, Mode, RaisedEvents, RT_Event, RT_History, RT_Statechart, TimerElapseEvent, Timers } from "./runtime_types";
+import { BigStep, initialRaised, Mode, RaisedEvents, RT_Event, RT_History, RT_Statechart, TimerElapseEvent, Timers } from "./runtime_types";
 
 const initialEnv = new Map<string, any>([
   ["_timers", []],
   ["_log", (str: string) => console.log(str)],
 ]);
-const initialScopedEnvironment = new ScopedEnvironment({env: initialEnv, children: {}});
-// const intiialFlatEnvironment = new FlatEnvironment(initialEnv);
+// const initialScopedEnvironment = new ScopedEnvironment({env: initialEnv, children: {}});
+const intiialFlatEnvironment = new FlatEnvironment(initialEnv);
 
-export function initialize(ast: Statechart): BigStepOutput {
+export function initialize(ast: Statechart): BigStep {
   let history = new Map();
   let enteredStates, environment, rest;
   ({enteredStates, environment, history, ...rest} = enterDefault(0, ast.root, {
-    environment: initialScopedEnvironment,
+    environment: intiialFlatEnvironment,
     history,
     ...initialRaised,
   }));
@@ -256,8 +256,11 @@ function attemptSrcState(simtime: number, sourceState: AbstractState, event: RT_
   const addEventParam = (event && event.kind === "input" && event.param !== undefined) ?
     (environment: Environment, label: TransitionLabel) => {
       const varName = (label.trigger as EventTrigger).paramName as string;
-      const result = environment.newVar(varName, event.param);
-      return result;
+      if (varName) {
+        const result = environment.newVar(varName, event.param);
+        return result;
+      }
+      return environment;
     }
     : (environment: Environment) => environment;
   // console.log('attemptSrcState', stateDescription(sourceState), arenasFired);
@@ -342,15 +345,15 @@ export function fairStep(simtime: number, event: RT_Event, statechart: Statechar
   return {arenasFired, environment, ...config};
 }
 
-export function handleInputEvent(simtime: number, event: RT_Event, statechart: Statechart, {mode, environment, history}: {mode: Mode, environment: Environment, history: RT_History}): BigStepOutput {
+export function handleInputEvent(simtime: number, event: RT_Event, statechart: Statechart, {mode, environment, history}: {mode: Mode, environment: Environment, history: RT_History}): BigStep {
   let raised = initialRaised;
 
   ({mode, environment, ...raised} = fairStep(simtime, event, statechart, statechart.root, {mode, environment, history, arenasFired: [], ...raised}));
 
-  return handleInternalEvents(simtime, statechart, {mode, environment, history, ...raised});
+  return {inputEvent: event, ...handleInternalEvents(simtime, statechart, {mode, environment, history, ...raised})};
 }
 
-export function handleInternalEvents(simtime: number, statechart: Statechart, {internalEvents, ...rest}: RT_Statechart & RaisedEvents): BigStepOutput {
+export function handleInternalEvents(simtime: number, statechart: Statechart, {internalEvents, ...rest}: RT_Statechart & RaisedEvents) {
   while (internalEvents.length > 0) {
     const [nextEvent, ...remainingEvents] = internalEvents;
     ({internalEvents, ...rest} = fairStep(simtime, 
@@ -389,11 +392,12 @@ export function fire(simtime: number, t: Transition, ts: Map<string, Transition[
   // console.log('exitedMode', exitedMode);
 
   // transition actions
+  environment = addEventParam(environment.enterScope("<transition>"), label);
   for (const action of label.actions) {
-    environment = addEventParam(environment.enterScope("<transition>"), label);
+    console.log('environment after adding event param:', environment);
     ({environment, history, ...rest} = execAction(action, {environment, history, ...rest}, [t.uid]));
-    environment = environment.dropScope();
   }
+  environment = environment.dropScope();
 
   const tgtPath = computePath({ancestor: arena, descendant: t.tgt});
   const state = tgtPath[0] as ConcreteState; // first state to enter
diff --git a/src/statecharts/parser.ts b/src/statecharts/parser.ts
index d20ea61..3bcaa20 100644
--- a/src/statecharts/parser.ts
+++ b/src/statecharts/parser.ts
@@ -5,7 +5,7 @@ import { Action, EventTrigger, Expression, ParsedText } from "./label_ast";
 import { parse as parseLabel, SyntaxError } from "./label_parser";
 import { Connections } from "./detect_connections";
 import { HISTORY_RADIUS } from "../App/parameters";
-import { VisualEditorState } from "@/App/VisualEditor/VisualEditor";
+import { ConcreteSyntax, VisualEditorState } from "@/App/VisualEditor/VisualEditor";
 import { memoize } from "@/util/util";
 
 export type TraceableError = {
@@ -34,7 +34,7 @@ function addEvent(events: EventTrigger[], e: EventTrigger, textUid: string) {
   }
 }
 
-export function parseStatechart(state: VisualEditorState, conns: Connections): [Statechart, TraceableError[]] {
+export function parseStatechart(state: ConcreteSyntax, conns: Connections): [Statechart, TraceableError[]] {
   const errors: TraceableError[] = [];
 
   // implicitly, the root is always an Or-state
diff --git a/src/statecharts/runtime_types.ts b/src/statecharts/runtime_types.ts
index 19f06b8..033b39e 100644
--- a/src/statecharts/runtime_types.ts
+++ b/src/statecharts/runtime_types.ts
@@ -27,16 +27,14 @@ export type RT_Statechart = {
   history: RT_History; // history-uid -> set of states
 }
 
-export type BigStepOutput = RT_Statechart & {
+export type BigStep = RT_Statechart & {
+  inputEvent?: RT_Event,
   outputEvents: RaisedEvent[],
+
+  // we also record the transitions that fired, to highlight them in the UI:
   firedTransitions: string[],
 };
 
-// export type BigStep = {
-//   inputEvent: string | null, // null if initialization
-//   simtime: number,
-// } & BigStepOutput;
-
 // internal or output event
 export type RaisedEvent = {
   name: string,
diff --git a/src/statecharts/time.ts b/src/statecharts/time.ts
index c7c6bff..6c09cba 100644
--- a/src/statecharts/time.ts
+++ b/src/statecharts/time.ts
@@ -58,3 +58,12 @@ export function setPaused(currentMode: TimeMode, wallclktime: number): TimePause
     simtime: getSimTime(currentMode, wallclktime),
   };
 }
+
+export function timeTravel(currentMode: TimeMode, simtime: number, wallclktime: number): TimeMode {
+  if (currentMode.kind === "paused") {
+    return {kind: "paused", simtime};
+  }
+  else {
+    return {kind: "realtime", scale: currentMode.scale, since: {simtime, wallclktime}};
+  }
+}
\ No newline at end of file
diff --git a/src/statecharts/timed_reactive.ts b/src/statecharts/timed_reactive.ts
index 0039569..2afad51 100644
--- a/src/statecharts/timed_reactive.ts
+++ b/src/statecharts/timed_reactive.ts
@@ -1,21 +1,24 @@
 import { Statechart } from "./abstract_syntax";
-import { handleInputEvent, initialize } from "./interpreter";
-import { BigStepOutput, InputEvent, RaisedEvent, RT_Statechart, Timers } from "./runtime_types";
+import { handleInputEvent, initialize, RuntimeError } from "./interpreter";
+import { BigStep, InputEvent, RaisedEvent, RT_Statechart, Timers } from "./runtime_types";
 
 // an abstract interface for timed reactive discrete event systems somewhat similar but not equal to DEVS
 // differences from DEVS:
 //   - extTransition can have output events
 //   - time is kept as absolute simulated time (since beginning of simulation), not relative to the last transition
 export type TimedReactive<RT_Config> = {
-  initial: () => RT_Config,
+  initial: () => [RaisedEvent[], RT_Config],
   timeAdvance: (c: RT_Config) => number,
   intTransition: (c: RT_Config) => [RaisedEvent[], RT_Config],
   extTransition: (simtime: number, c: RT_Config, e: InputEvent) => [RaisedEvent[], RT_Config],
 }
 
-export function statechartExecution(ast: Statechart): TimedReactive<BigStepOutput> {
+export function statechartExecution(ast: Statechart): TimedReactive<BigStep> {
   return {
-    initial: () => initialize(ast),
+    initial: () => {
+      const bigstep = initialize(ast);
+      return [bigstep.outputEvents, bigstep];
+    },
     timeAdvance: (c: RT_Statechart) => (c.environment.get("_timers") as Timers)[0]?.[0] || Infinity,
     intTransition: (c: RT_Statechart) => {
       const timers = c.environment.get("_timers") as Timers;
@@ -33,13 +36,6 @@ export function statechartExecution(ast: Statechart): TimedReactive<BigStepOutpu
   }
 }
 
-export const dummyExecution: TimedReactive<null> = {
-  initial: () => null,
-  timeAdvance: () => Infinity,
-  intTransition: () => { throw new Error("dummy never makes intTransition"); },
-  extTransition: () => [[], null],
-};
-
 export type EventDestination = ModelDestination | OutputDestination;
 
 export type ModelDestination = {
@@ -53,13 +49,35 @@ export type OutputDestination = {
   eventName: string,
 };
 
-export function exposeStatechartInputs(ast: Statechart, model: string): Conns {
+// export type NowhereDestination = {
+//   kind: "nowhere",
+// };
+
+export function exposeStatechartInputsOutputs(ast: Statechart, model: string): Conns {
   return {
-    inputEvents: Object.fromEntries(ast.inputEvents.map(e => [e.event, {kind: "model", model, eventName: e.event}])),
-    outputEvents: {},
+    // all the coupled execution's input events become input events for the statechart
+    inputEvents: exposeStatechartInputs(ast, model),
+    outputEvents: exposeStatechartOutputs(ast, model),
   }
 }
 
+export function exposeStatechartInputs(ast: Statechart, model: string, tfm = (s: string) => s): {[eventName: string]: ModelDestination} {
+  return Object.fromEntries(ast.inputEvents.map(e => [tfm(e.event), {kind: "model", model, eventName: e.event}]));
+}
+
+export function exposeStatechartOutputs(ast: Statechart, model: string): {[modelName: string]: {[eventName: string]: EventDestination}} {
+  return {
+    // all the statechart's output events become output events of our coupled execution
+    [model]: Object.fromEntries([...ast.outputEvents].map(e => [e, {kind: "output", model, eventName: e}])),
+  };
+}
+
+// export function hideStatechartOutputs(ast: Statechart, model: string) {
+//   return {
+//     [model]: Object.fromEntries([...ast.outputEvents].map(e => [e, {kind: "nowhere" as const}])),
+//   }
+// }
+
 export type Conns = {
   // inputs coming from outside are routed to the right models
   inputEvents: {[eventName: string]: ModelDestination},
@@ -85,10 +103,12 @@ export function coupledExecution<T extends {[name: string]: any}>(models: {[name
       const destination = conns.outputEvents[model]?.[event.name];
       if (destination === undefined) {
         // ignore
+        console.log(`${model}.${event.name} goes nowhere`);
         return processOutputs(simtime, rest, model, c);
       }
       if (destination.kind === "model") {
         // output event is input for another model
+        console.log(`${model}.${event.name} goes to ${destination.model}.${destination.eventName}`);
         const inputEvent = {
           kind: "input" as const,
           name: destination.eventName,
@@ -100,11 +120,13 @@ export function coupledExecution<T extends {[name: string]: any}>(models: {[name
         const [restOutputEvents, newConfig2] = processOutputs(simtime, rest, model, newConfig);
         return [[...outputEvents, ...restOutputEvents], newConfig2];
       }
-      else {
+      else if (destination.kind === "output") {
         // kind === "output"
+        console.log(`${model}.${event.name} becomes ^${destination.eventName}`);
         const [outputEvents, newConfig] = processOutputs(simtime, rest, model, c);
         return [[event, ...outputEvents], newConfig];
       }
+      throw new Error("unreachable");
     }
     else {
       return [[], c];
@@ -112,13 +134,33 @@ export function coupledExecution<T extends {[name: string]: any}>(models: {[name
   }
 
   return {
-    initial: () => Object.fromEntries(Object.entries(models).map(([name, model]) => {
-      return [name, model.initial()];
-    })) as T,
+    initial: () => {
+      // 1. initialize every model
+      const allOutputs = [];
+      let state = {} as T;
+      for (const [modelName, model] of Object.entries(models)) {
+        const [outputEvents, modelState] = model.initial();
+        for (const o of outputEvents) {
+          allOutputs.push([modelName, o]);
+        }
+        // @ts-ignore
+        state[modelName] = modelState;
+      }
+      console.log({state});
+      // 2. handle all output events (models' outputs may be inputs for each other)
+      let finalOutputs = [];
+      for (const [modelName, outputEvents] of allOutputs) {
+        let newOutputs;
+        [newOutputs, state] = processOutputs(0, outputEvents, modelName, state);
+        finalOutputs.push(...newOutputs);
+      }
+      return [finalOutputs, state];
+    },
     timeAdvance: (c) => {
       return Object.entries(models).reduce((acc, [name, {timeAdvance}]) => Math.min(timeAdvance(c[name]), acc), Infinity);
     },
     intTransition: (c) => {
+      // find earliest internal transition among all models:
       const [when, name] = Object.entries(models).reduce(([earliestSoFar, earliestModel], [name, {timeAdvance}]) => {
         const when = timeAdvance(c[name]);
         if (when < earliestSoFar) {
@@ -133,8 +175,9 @@ export function coupledExecution<T extends {[name: string]: any}>(models: {[name
       throw new Error("cannot make intTransition - timeAdvance is infinity");
     },
     extTransition: (simtime, c, e) => {
+      console.log(e);
       const {model, eventName} = conns.inputEvents[e.name];
-      // console.log('input event', e, 'goes to', model);
+      console.log('input event', e.name, 'goes to', `${model}.${eventName}`);
       const inputEvent: InputEvent = {
         kind: "input",
         name: eventName,
@@ -144,3 +187,32 @@ export function coupledExecution<T extends {[name: string]: any}>(models: {[name
     },
   }
 }
+
+
+// Example of a coupled execution:
+
+// const clock1: TimedReactive<{nextTick: number}> = {
+//   initial: () => ({nextTick: 1}),
+//   timeAdvance: (c) => c.nextTick,
+//   intTransition: (c) => [[{name: "tick"}], {nextTick: c.nextTick+1}],
+//   extTransition: (simtime, c, e) => [[], (c)],
+// }
+
+// const clock2: TimedReactive<{nextTick: number}> = {
+//   initial: () => ({nextTick: 0.5}),
+//   timeAdvance: (c) => c.nextTick,
+//   intTransition: (c) => [[{name: "tick"}], {nextTick: c.nextTick+1}],
+//   extTransition: (simtime, c, e) => [[], (c)],
+// }
+
+// const coupled = coupledExecution({clock1, clock2}, {inputEvents: {}, outputEvents: {
+//   clock1: {tick: {kind:"output", eventName: 'tick'}},
+//   clock2: {tick: {kind:"output", eventName: 'tick'}},
+// }})
+
+// let state = coupled.initial();
+// for (let i=0; i<10; i++) {
+//   const nextWakeup = coupled.timeAdvance(state);
+//   console.log({state, nextWakeup});
+//   [[], state] = coupled.intTransition(state);
+// }
diff --git a/todo.txt b/todo.txt
index a82e787..f51944e 100644
--- a/todo.txt
+++ b/todo.txt
@@ -52,7 +52,6 @@ TODO
     - hovering over error in bottom panel should highlight that rror in the SC
     - highlight selected shapes while making a selection
 
-    - highlight fired transitions
     - highlight about-to-fire transitions
 
     - when there is a runtime error, e.g.,