diff --git a/src/client/initial-app/App/index.tsx b/src/client/initial-app/App/index.tsx
index 70ef1aa9..a96ea6ee 100644
--- a/src/client/initial-app/App/index.tsx
+++ b/src/client/initial-app/App/index.tsx
@@ -14,7 +14,7 @@ import 'shared/initial-app/custom-els/loading-spinner';
 
 const ROUTE_EDITOR = '/editor';
 
-//const compressPromise = import('client/lazy-app/Compress');
+const compressPromise = import('client/lazy-app/Compress');
 const swBridgePromise = import('client/lazy-app/sw-bridge');
 
 function back() {
@@ -27,7 +27,7 @@ interface State {
   awaitingShareTarget: boolean;
   file?: File;
   isEditorOpen: Boolean;
-  Compress?: undefined; // typeof import('../compress').default;
+  Compress?: typeof import('client/lazy-app/Compress').default;
 }
 
 export default class App extends Component<Props, State> {
@@ -45,13 +45,13 @@ export default class App extends Component<Props, State> {
   constructor() {
     super();
 
-    /*compressPromise
+    compressPromise
       .then((module) => {
         this.setState({ Compress: module.default });
       })
       .catch(() => {
         this.showSnack('Failed to load app');
-      });*/
+      });
 
     swBridgePromise.then(async ({ offliner, getSharedImage }) => {
       offliner(this.showSnack);
@@ -123,9 +123,9 @@ export default class App extends Component<Props, State> {
           {showSpinner ? (
             <loading-spinner class={style.appLoader} />
           ) : isEditorOpen ? (
-            Compress &&
-            //<Compress file={file!} showSnack={this.showSnack} onBack={back} />
-            'TODO: uncomment above'
+            Compress && (
+              <Compress file={file!} showSnack={this.showSnack} onBack={back} />
+            )
           ) : (
             <Intro onFile={this.onIntroPickFile} showSnack={this.showSnack} />
           )}
diff --git a/src/client/lazy-app/Compress/index.tsx b/src/client/lazy-app/Compress/index.tsx
index 9ed0038e..9fcf418a 100644
--- a/src/client/lazy-app/Compress/index.tsx
+++ b/src/client/lazy-app/Compress/index.tsx
@@ -19,11 +19,13 @@ import {
   encoderMap,
   defaultPreprocessorState,
   defaultProcessorState,
+  EncoderType,
+  EncoderOptions,
 } from '../feature-meta';
 import Output from '../Output';
 import Options from '../Options';
 import ResultCache from './result-cache';
-import { cleanMerge, cleanSet } from '../../lib/clean-modify';
+import { cleanMerge, cleanSet } from '../util/clean-modify';
 import './custom-els/MultiPanel';
 import Results from '../results';
 import { ExpandIcon, CopyAcrossIconProps } from '../../lib/icons';
@@ -31,6 +33,8 @@ import SnackBarElement from '../../lib/SnackBar';
 import WorkerBridge from '../worker-bridge';
 import { resize } from 'features/processors/resize/client';
 
+type OutputType = EncoderType | 'identity';
+
 export interface SourceImage {
   file: File;
   decoded: ImageData;
@@ -248,7 +252,6 @@ export default class Compress extends Component<Props, State> {
   };
 
   private readonly encodeCache = new ResultCache();
-  // YOU ARE HERE
   private readonly leftWorkerBridge = new WorkerBridge();
   private readonly rightWorkerBridge = new WorkerBridge();
   // For debouncing calls to updateImage for each side.
@@ -262,34 +265,36 @@ export default class Compress extends Component<Props, State> {
     this.widthQuery.addListener(this.onMobileWidthChange);
     this.updateFile(props.file);
 
-    import('../../lib/sw-bridge').then(({ mainAppLoaded }) => mainAppLoaded());
+    import('../sw-bridge').then(({ mainAppLoaded }) => mainAppLoaded());
   }
 
   private onMobileWidthChange = () => {
     this.setState({ mobileView: this.widthQuery.matches });
   };
 
-  private onEncoderTypeChange(index: 0 | 1, newType: EncoderType): void {
+  private onEncoderTypeChange(index: 0 | 1, newType: OutputType): void {
     this.setState({
       sides: cleanSet(
         this.state.sides,
         `${index}.latestSettings.encoderState`,
-        {
-          type: newType,
-          options: encoderMap[newType].defaultOptions,
-        },
+        newType === 'identity'
+          ? undefined
+          : {
+              type: newType,
+              options: encoderMap[newType].meta.defaultOptions,
+            },
       ),
     });
   }
 
-  private onPreprocessorOptionsChange(
+  private onProcessorOptionsChange(
     index: 0 | 1,
-    options: PreprocessorState,
+    options: ProcessorState,
   ): void {
     this.setState({
       sides: cleanSet(
         this.state.sides,
-        `${index}.latestSettings.preprocessorState`,
+        `${index}.latestSettings.processorState`,
         options,
       ),
     });
@@ -654,7 +659,7 @@ export default class Compress extends Component<Props, State> {
           this,
           index as 0 | 1,
         )}
-        onPreprocessorOptionsChange={this.onPreprocessorOptionsChange.bind(
+        onPreprocessorOptionsChange={this.onProcessorOptionsChange.bind(
           this,
           index as 0 | 1,
         )}
diff --git a/src/client/lazy-app/util/clean-modify.ts b/src/client/lazy-app/util/clean-modify.ts
new file mode 100644
index 00000000..aefb0370
--- /dev/null
+++ b/src/client/lazy-app/util/clean-modify.ts
@@ -0,0 +1,62 @@
+function cleanSetOrMerge<A extends any[] | object>(
+  source: A,
+  keys: string | number | string[],
+  toSetOrMerge: any[] | object,
+  merge: boolean,
+): A {
+  const splitKeys = Array.isArray(keys) ? keys : ('' + keys).split('.');
+
+  // Going off road in terms of types, otherwise TypeScript doesn't like the access-by-index.
+  // The assumptions in this code break if the object contains things which aren't arrays or
+  // plain objects.
+  let last = copy(source) as any;
+  const newObject = last;
+
+  const lastIndex = splitKeys.length - 1;
+
+  for (const [i, key] of splitKeys.entries()) {
+    if (i !== lastIndex) {
+      // Copy everything along the path.
+      last = last[key] = copy(last[key]);
+    } else {
+      // Merge or set.
+      last[key] = merge
+        ? Object.assign(copy(last[key]), toSetOrMerge)
+        : toSetOrMerge;
+    }
+  }
+
+  return newObject;
+}
+
+function copy<A extends any[] | object>(source: A): A {
+  // Some type cheating here, as TypeScript can't infer between generic types.
+  if (Array.isArray(source)) return [...source] as any;
+  return { ...(source as any) };
+}
+
+/**
+ * @param source Object to copy from.
+ * @param keys Path to modify, eg "foo.bar.baz".
+ * @param toMerge A value to merge into the value at the path.
+ */
+export function cleanMerge<A extends any[] | object>(
+  source: A,
+  keys: string | number | string[],
+  toMerge: any[] | object,
+): A {
+  return cleanSetOrMerge(source, keys, toMerge, true);
+}
+
+/**
+ * @param source Object to copy from.
+ * @param keys Path to modify, eg "foo.bar.baz".
+ * @param newValue A value to set at the path.
+ */
+export function cleanSet<A extends any[] | object>(
+  source: A,
+  keys: string | number | string[],
+  newValue: any,
+): A {
+  return cleanSetOrMerge(source, keys, newValue, false);
+}
diff --git a/src/client/lazy-app/util.ts b/src/client/lazy-app/util/index.ts
similarity index 100%
rename from src/client/lazy-app/util.ts
rename to src/client/lazy-app/util/index.ts