diff --git a/src/index.js b/src/index.js
index a3b3b7a..10e825b 100644
--- a/src/index.js
+++ b/src/index.js
@@ -68,14 +68,27 @@ editor.addEventListener("change", () => {
 });
 
 importButton.onclick = async () => {
-    const files = await promptUpload("", false);
+    const files = await promptUpload(".karlkode", false);
     if (files.length === 0) {
         return;
     }
     if (files.length > 1) {
-        throw new Error("unreachable: something went wrong ! files.length > 1");
+        throw new Error(
+            `unreachable: something went wrong ! files.length > 1 : files.length = ${files.length}`,
+        );
     }
-    const item = Vermiparous.de(await fetch(URL.createObjectURL(files[0])).then((x) => x.bytes()));
+    const items = Vermiparous.de(await fetch(URL.createObjectURL(files[0])).then((x) => x.bytes()));
+    const sprites = items
+        .filter((x) => x.tag === "asset")
+        .map((x) => {
+            delete x.tag;
+            return x;
+        });
+    const code = items.find((x) => x.tag === "code");
+    delete code.tag;
+    spriteEditor.importSprites(sprites);
+    const dec = new TextDecoder();
+    editor.setValue(dec.decode(code.content));
 };
 
 runButton.onclick = () => {
@@ -95,7 +108,26 @@ runButton.onclick = () => {
     }
 };
 
-function downloadFile(content, mime, extension) {
+function downloadBinaryFile(content, extension) {
+    const filename = prompt("Filename?");
+
+    const blob = new Blob([content]);
+    const url = URL.createObjectURL(blob);
+
+    const element = document.createElement("a");
+
+    element.href = url;
+    element.download = filename.endsWith(extension) ? filename : filename + extension;
+    element.style.display = "none";
+
+    document.body.appendChild(element);
+
+    element.click();
+
+    document.body.removeChild(element);
+}
+
+function downloadTextFile(content, mime, extension) {
     const filename = prompt("Filename?");
 
     const element = document.createElement("a");
@@ -129,7 +161,7 @@ saveButton.onclick = () => {
 };
 
 saveJsButton.onclick = () => {
-    downloadFile(editor.getValue(), "text/javascript", ".js");
+    downloadTextFile(editor.getValue(), "text/javascript", ".js");
 };
 
 saveHtmlButton.onclick = async () => {
@@ -154,6 +186,9 @@ saveHtmlButton.onclick = async () => {
 				height: 100vh;
 				margin: 0;
 			}
+
+
+    An iterable object such as an Array, having ArrayBuffers, TypedArrays, DataViews, Blobs, strings, or a mix of any of such elements, that will be put inside the Blob. Strings should be well-formed Unicode, and lone surrogates are sanitized using the same algorithm as String.prototype.toWellFormed().
 		</style>
 		<script type="importmap">
 			{
@@ -171,18 +206,15 @@ ${js}
 	</body>
 </html>`;
 
-    downloadFile(html, "text/html", ".html");
+    downloadTextFile(html, "text/html", ".html");
 };
 
 saveKarlkoderButton.onclick = () => {
-    downloadFile(
+    downloadBinaryFile(
         Vermiparous.en(
-            editor.getValue()
-                .split("\n")
-                .map((line) => " ".repeat(12) + line).join("\n"),
+            editor.getValue(),
             spriteEditor.sprites,
         ),
-        "",
         ".karlkode",
     );
 };
diff --git a/src/sprite_editor.js b/src/sprite_editor.js
index c247a3b..56e9c59 100644
--- a/src/sprite_editor.js
+++ b/src/sprite_editor.js
@@ -1,7 +1,7 @@
 import { promptUpload } from "./prompt_upload.js";
 
 export class SpriteEditor {
-    constructor(rootEl, sprites) {
+    constructor(rootEl) {
         this.list = rootEl.querySelector("#sprite-editor-sprite-list");
         this.editor = rootEl.querySelector("#sprite-editor");
         this.toggleButton = rootEl.querySelector("#toggle-sprite-editor-button");
@@ -11,7 +11,7 @@ export class SpriteEditor {
         this.preview.title = rootEl.querySelector("#sprite-editor-preview-title");
         this.preview.image = rootEl.querySelector("#sprite-editor-preview-image");
         this.preview.snippet = rootEl.querySelector("#sprite-editor-preview-snippet");
-        this.sprites = sprites;
+        this.sprites = [];
 
         rootEl.querySelector("#sprite-editor-upload-button").addEventListener("click", () => {
             this.promptUpload();
@@ -20,6 +20,11 @@ export class SpriteEditor {
         this.renderList();
     }
 
+    importSprites(sprites) {
+        this.sprites = sprites;
+        this.renderList();
+    }
+
     async promptUpload() {
         for (const file of await promptUpload("image/*", true)) {
             const rootName = file.name;
diff --git a/src/vermiparous.js b/src/vermiparous.js
index d0e53fd..8f533d9 100644
--- a/src/vermiparous.js
+++ b/src/vermiparous.js
@@ -41,8 +41,12 @@ export class Vermiparous {
         let idx = 0;
         while (idx < bytes.length) {
             buffer.push(bytes[idx]);
-            if (buffer.length >= MAX_KW_LENGTH) {
-                throw new Error("unreachable: something went wrong ! unrecognized action");
+            if (buffer.length > MAX_KW_LENGTH) {
+                throw new Error(
+                    `unreachable: something went wrong ! unrecognized action '${
+                        JSON.stringify(buffer)
+                    }'`,
+                );
             }
             if (buffer.length < MIN_KW_LENGTH || !isKeyword(buffer)) {
                 ++idx;