diff --git a/.envrc b/.envrc
new file mode 100644
index 0000000..3550a30
--- /dev/null
+++ b/.envrc
@@ -0,0 +1 @@
+use flake
diff --git a/.gitignore b/.gitignore
index 4241c17..829d632 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 node_modules
 dist
-*~
\ No newline at end of file
+*~
+.direnv
diff --git a/backend/app.ts b/backend/app.ts
index a0e1365..80d8c95 100644
--- a/backend/app.ts
+++ b/backend/app.ts
@@ -84,7 +84,7 @@ export function createFrontend(
   app.post<any, { status: string }>("/fake-update", (req, res) => {
     const instanceId = Array.from(instances.instances.keys())[0];
     const instance = instances.instances.get(instanceId);
-    instance?.webXdc.sendUpdate({ payload: req.body }, "fake update");
+    instance?.webXdc.sendUpdate({ payload: req.body }, "");
     res.json({
       status: "ok",
     });
diff --git a/backend/instance.ts b/backend/instance.ts
index 5a7f57f..d751d86 100644
--- a/backend/instance.ts
+++ b/backend/instance.ts
@@ -19,7 +19,6 @@ export type Options = {
 type SendUpdateMessage = {
   type: "sendUpdate";
   update: ReceivedStatusUpdate<any>;
-  descr: string;
 };
 
 type SetUpdateListenerMessage = {
@@ -125,7 +124,7 @@ export class Instances {
         const parsed = JSON.parse(msg);
         // XXX should validate parsed
         if (isSendUpdateMessage(parsed)) {
-          instance.webXdc.sendUpdate(parsed.update, parsed.descr);
+          instance.webXdc.sendUpdate(parsed.update, "");
         } else if (isSetUpdateListenerMessage(parsed)) {
           instance.webXdc.connect(
             (updates) => {
@@ -133,7 +132,7 @@ export class Instances {
                 wss,
                 JSON.stringify({
                   type: "updates",
-                  updates: updates.map(([update]) => update),
+                  updates: updates.map((update) => update),
                 }),
               );
             },
diff --git a/backend/message.test.ts b/backend/message.test.ts
index f6a1ec0..3f462eb 100644
--- a/backend/message.test.ts
+++ b/backend/message.test.ts
@@ -1,5 +1,6 @@
-import { createProcessor, UpdateDescr } from "./message";
+import { createProcessor } from "./message";
 import type { Message } from "../types/message";
+import { ReceivedStatusUpdate } from "@webxdc/types";
 
 // a little helper to let us track messages for testing purposes
 function track(): [() => Message[], (message: Message) => void] {
@@ -19,17 +20,17 @@ test("distribute to self", () => {
   const processor = createProcessor(onMessage);
   const client0 = processor.createClient("3001");
 
-  const client0Heard: UpdateDescr[] = [];
+  const client0Heard: ReceivedStatusUpdate<any>[] = [];
 
   client0.connect((updates) => {
     client0Heard.push(...updates);
     return true;
   }, 0);
 
-  client0.sendUpdate({ payload: "Hello" }, "update");
+  client0.sendUpdate({ payload: "Hello" }, "");
 
   expect(client0Heard).toMatchObject([
-    [{ payload: "Hello", serial: 1, max_serial: 1 }, "update"],
+    { payload: "Hello", serial: 1, max_serial: 1 },
   ]);
 
   expect(prepare(getMessages())).toEqual([
@@ -43,13 +44,11 @@ test("distribute to self", () => {
         serial: 1,
         max_serial: 1,
       },
-      descr: "update",
     },
     {
       type: "received",
       update: { payload: "Hello", serial: 1, max_serial: 1 },
       instanceId: "3001",
-      descr: "update",
     },
   ]);
 });
@@ -60,8 +59,8 @@ test("distribute to self and other", () => {
   const client0 = processor.createClient("3001");
   const client1 = processor.createClient("3002");
 
-  const client0Heard: UpdateDescr[] = [];
-  const client1Heard: UpdateDescr[] = [];
+  const client0Heard: ReceivedStatusUpdate<any>[] = [];
+  const client1Heard: ReceivedStatusUpdate<any>[] = [];
 
   client0.connect((updates) => {
     client0Heard.push(...updates);
@@ -73,15 +72,15 @@ test("distribute to self and other", () => {
     return true;
   }, 0);
 
-  client0.sendUpdate({ payload: "Hello" }, "update");
-  client1.sendUpdate({ payload: "Bye" }, "update 2");
+  client0.sendUpdate({ payload: "Hello" }, "");
+  client1.sendUpdate({ payload: "Bye" }, "");
   expect(client0Heard).toMatchObject([
-    [{ payload: "Hello", serial: 1, max_serial: 1 }, "update"],
-    [{ payload: "Bye", serial: 2, max_serial: 2 }, "update 2"],
+    { payload: "Hello", serial: 1, max_serial: 1 },
+    { payload: "Bye", serial: 2, max_serial: 2 },
   ]);
   expect(client1Heard).toMatchObject([
-    [{ payload: "Hello", serial: 1, max_serial: 1 }, "update"],
-    [{ payload: "Bye", serial: 2, max_serial: 2 }, "update 2"],
+    { payload: "Hello", serial: 1, max_serial: 1 },
+    { payload: "Bye", serial: 2, max_serial: 2 },
   ]);
 
   expect(prepare(getMessages())).toEqual([
@@ -93,37 +92,31 @@ test("distribute to self and other", () => {
       type: "sent",
       instanceId: "3001",
       update: { payload: "Hello", serial: 1, max_serial: 1 },
-      descr: "update",
     },
     {
       type: "received",
       update: { payload: "Hello", serial: 1, max_serial: 1 },
       instanceId: "3001",
-      descr: "update",
     },
     {
       type: "received",
       update: { payload: "Hello", serial: 1, max_serial: 1 },
       instanceId: "3002",
-      descr: "update",
     },
     {
       type: "sent",
       instanceId: "3002",
       update: { payload: "Bye", serial: 2, max_serial: 2 },
-      descr: "update 2",
     },
     {
       type: "received",
       update: { payload: "Bye", serial: 2, max_serial: 2 },
       instanceId: "3001",
-      descr: "update 2",
     },
     {
       type: "received",
       update: { payload: "Bye", serial: 2, max_serial: 2 },
       instanceId: "3002",
-      descr: "update 2",
     },
   ]);
 });
@@ -133,8 +126,8 @@ test("setUpdateListener serial should skip older", () => {
   const client0 = processor.createClient("3001");
   const client1 = processor.createClient("3002");
 
-  const client0Heard: UpdateDescr[] = [];
-  const client1Heard: UpdateDescr[] = [];
+  const client0Heard: ReceivedStatusUpdate<any>[] = [];
+  const client1Heard: ReceivedStatusUpdate<any>[] = [];
 
   client0.connect((updates) => {
     client0Heard.push(...updates);
@@ -146,14 +139,14 @@ test("setUpdateListener serial should skip older", () => {
     return true;
   }, 1);
 
-  client0.sendUpdate({ payload: "Hello" }, "update");
-  client0.sendUpdate({ payload: "Bye" }, "update 2");
+  client0.sendUpdate({ payload: "Hello" }, "");
+  client0.sendUpdate({ payload: "Bye" }, "");
   expect(client0Heard).toMatchObject([
-    [{ payload: "Hello", serial: 1, max_serial: 1 }, "update"],
-    [{ payload: "Bye", serial: 2, max_serial: 2 }, "update 2"],
+    { payload: "Hello", serial: 1, max_serial: 1 },
+    { payload: "Bye", serial: 2, max_serial: 2 },
   ]);
   expect(client1Heard).toMatchObject([
-    [{ payload: "Bye", serial: 2, max_serial: 2 }, "update 2"],
+    { payload: "Bye", serial: 2, max_serial: 2 },
   ]);
 });
 
@@ -163,20 +156,20 @@ test("other starts listening later", () => {
   const client0 = processor.createClient("3001");
   const client1 = processor.createClient("3002");
 
-  const client0Heard: UpdateDescr[] = [];
-  const client1Heard: UpdateDescr[] = [];
+  const client0Heard: ReceivedStatusUpdate<any>[] = [];
+  const client1Heard: ReceivedStatusUpdate<any>[] = [];
 
   client0.connect((updates) => {
     client0Heard.push(...updates);
     return true;
   }, 0);
 
-  client0.sendUpdate({ payload: "Hello" }, "update");
-  client0.sendUpdate({ payload: "Bye" }, "update 2");
+  client0.sendUpdate({ payload: "Hello" }, "");
+  client0.sendUpdate({ payload: "Bye" }, "");
 
   expect(client0Heard).toMatchObject([
-    [{ payload: "Hello", serial: 1, max_serial: 1 }, "update"],
-    [{ payload: "Bye", serial: 2, max_serial: 2 }, "update 2"],
+    { payload: "Hello", serial: 1, max_serial: 1 },
+    { payload: "Bye", serial: 2, max_serial: 2 },
   ]);
   // we only join later, so we haven't heard a thing yet
   expect(client1Heard).toMatchObject([]);
@@ -187,12 +180,12 @@ test("other starts listening later", () => {
   }, 0);
 
   expect(client0Heard).toMatchObject([
-    [{ payload: "Hello", serial: 1, max_serial: 1 }, "update"],
-    [{ payload: "Bye", serial: 2, max_serial: 2 }, "update 2"],
+    { payload: "Hello", serial: 1, max_serial: 1 },
+    { payload: "Bye", serial: 2, max_serial: 2 },
   ]);
   expect(client1Heard).toMatchObject([
-    [{ payload: "Hello", serial: 1, max_serial: 2 }, "update"],
-    [{ payload: "Bye", serial: 2, max_serial: 2 }, "update 2"],
+    { payload: "Hello", serial: 1, max_serial: 2 },
+    { payload: "Bye", serial: 2, max_serial: 2 },
   ]);
 
   expect(prepare(getMessages())).toEqual([
@@ -202,25 +195,21 @@ test("other starts listening later", () => {
       type: "sent",
       instanceId: "3001",
       update: { payload: "Hello", serial: 1, max_serial: 1 },
-      descr: "update",
     },
     {
       type: "received",
       update: { payload: "Hello", serial: 1, max_serial: 1 },
       instanceId: "3001",
-      descr: "update",
     },
     {
       type: "sent",
       instanceId: "3001",
       update: { payload: "Bye", serial: 2, max_serial: 2 },
-      descr: "update 2",
     },
     {
       type: "received",
       update: { payload: "Bye", serial: 2, max_serial: 2 },
       instanceId: "3001",
-      descr: "update 2",
     },
     { type: "connect", instanceId: "3002" },
     { type: "clear", instanceId: "3002" },
@@ -228,13 +217,11 @@ test("other starts listening later", () => {
       type: "received",
       update: { payload: "Hello", serial: 1, max_serial: 2 },
       instanceId: "3002",
-      descr: "update",
     },
     {
       type: "received",
       update: { payload: "Bye", serial: 2, max_serial: 2 },
       instanceId: "3002",
-      descr: "update 2",
     },
   ]);
 });
@@ -243,20 +230,20 @@ test("client is created later and needs to catch up", () => {
   const processor = createProcessor();
   const client0 = processor.createClient("3001");
 
-  const client0Heard: UpdateDescr[] = [];
-  const client1Heard: UpdateDescr[] = [];
+  const client0Heard: ReceivedStatusUpdate<any>[] = [];
+  const client1Heard: ReceivedStatusUpdate<any>[] = [];
 
   client0.connect((updates) => {
     client0Heard.push(...updates);
     return true;
   }, 0);
 
-  client0.sendUpdate({ payload: "Hello" }, "update");
-  client0.sendUpdate({ payload: "Bye" }, "update 2");
+  client0.sendUpdate({ payload: "Hello" }, "");
+  client0.sendUpdate({ payload: "Bye" }, "");
 
   expect(client0Heard).toMatchObject([
-    [{ payload: "Hello", serial: 1, max_serial: 1 }, "update"],
-    [{ payload: "Bye", serial: 2, max_serial: 2 }, "update 2"],
+    { payload: "Hello", serial: 1, max_serial: 1 },
+    { payload: "Bye", serial: 2, max_serial: 2 },
   ]);
 
   // we only join later, so we haven't heard a thing yet
@@ -269,12 +256,12 @@ test("client is created later and needs to catch up", () => {
   }, 0);
 
   expect(client0Heard).toMatchObject([
-    [{ payload: "Hello", serial: 1, max_serial: 1 }, "update"],
-    [{ payload: "Bye", serial: 2, max_serial: 2 }, "update 2"],
+    { payload: "Hello", serial: 1, max_serial: 1 },
+    { payload: "Bye", serial: 2, max_serial: 2 },
   ]);
   expect(client1Heard).toMatchObject([
-    [{ payload: "Hello", serial: 1, max_serial: 2 }, "update"],
-    [{ payload: "Bye", serial: 2, max_serial: 2 }, "update 2"],
+    { payload: "Hello", serial: 1, max_serial: 2 },
+    { payload: "Bye", serial: 2, max_serial: 2 },
   ]);
 });
 
@@ -283,19 +270,19 @@ test("other starts listening later but is partially caught up", () => {
   const client0 = processor.createClient("3001");
   const client1 = processor.createClient("3002");
 
-  const client0Heard: UpdateDescr[] = [];
-  const client1Heard: UpdateDescr[] = [];
+  const client0Heard: ReceivedStatusUpdate<any>[] = [];
+  const client1Heard: ReceivedStatusUpdate<any>[] = [];
 
   client0.connect((updates) => {
     client0Heard.push(...updates);
     return true;
   }, 0);
 
-  client0.sendUpdate({ payload: "Hello" }, "update");
-  client0.sendUpdate({ payload: "Bye" }, "update 2");
+  client0.sendUpdate({ payload: "Hello" }, "");
+  client0.sendUpdate({ payload: "Bye" }, "");
   expect(client0Heard).toMatchObject([
-    [{ payload: "Hello", serial: 1, max_serial: 1 }, "update"],
-    [{ payload: "Bye", serial: 2, max_serial: 2 }, "update 2"],
+    { payload: "Hello", serial: 1, max_serial: 1 },
+    { payload: "Bye", serial: 2, max_serial: 2 },
   ]);
   // we only join later, so we haven't heard a thing yet
   expect(client1Heard).toMatchObject([]);
@@ -307,11 +294,11 @@ test("other starts listening later but is partially caught up", () => {
   }, 1);
 
   expect(client0Heard).toMatchObject([
-    [{ payload: "Hello", serial: 1, max_serial: 1 }, "update"],
-    [{ payload: "Bye", serial: 2, max_serial: 2 }, "update 2"],
+    { payload: "Hello", serial: 1, max_serial: 1 },
+    { payload: "Bye", serial: 2, max_serial: 2 },
   ]);
   expect(client1Heard).toMatchObject([
-    [{ payload: "Bye", serial: 2, max_serial: 2 }, "update 2"],
+    { payload: "Bye", serial: 2, max_serial: 2 },
   ]);
 });
 
@@ -470,8 +457,8 @@ test("connect with clear means we get no catchup if no new updates", () => {
   const processor = createProcessor();
   const client0 = processor.createClient("3001");
 
-  const client0Heard: (UpdateDescr | string)[] = [];
-  const client1Heard: (UpdateDescr | string)[] = [];
+  const client0Heard: (ReceivedStatusUpdate<any> | string)[] = [];
+  const client1Heard: (ReceivedStatusUpdate<any> | string)[] = [];
 
   client0.connect(
     (updates) => {
@@ -485,16 +472,16 @@ test("connect with clear means we get no catchup if no new updates", () => {
     },
   );
 
-  client0.sendUpdate({ payload: "Hello" }, "update");
-  client0.sendUpdate({ payload: "Bye" }, "update 2");
+  client0.sendUpdate({ payload: "Hello" }, "");
+  client0.sendUpdate({ payload: "Bye" }, "");
 
   // now we clear
   processor.clear();
 
   expect(client0Heard).toMatchObject([
     "cleared",
-    [{ payload: "Hello", serial: 1, max_serial: 1 }, "update"],
-    [{ payload: "Bye", serial: 2, max_serial: 2 }, "update 2"],
+    { payload: "Hello", serial: 1, max_serial: 1 },
+    { payload: "Bye", serial: 2, max_serial: 2 },
     "cleared",
   ]);
 
@@ -516,8 +503,8 @@ test("connect with clear means we get no catchup if no new updates", () => {
 
   expect(client0Heard).toMatchObject([
     "cleared",
-    [{ payload: "Hello", serial: 1, max_serial: 1 }, "update"],
-    [{ payload: "Bye", serial: 2, max_serial: 2 }, "update 2"],
+    { payload: "Hello", serial: 1, max_serial: 1 },
+    { payload: "Bye", serial: 2, max_serial: 2 },
     "cleared",
   ]);
   expect(client1Heard).toMatchObject(["cleared"]);
@@ -528,8 +515,8 @@ test("connect with clear means catchup only with updates after clear", () => {
   const processor = createProcessor(onMessage);
   const client0 = processor.createClient("3001");
 
-  const client0Heard: (UpdateDescr | string)[] = [];
-  const client1Heard: (UpdateDescr | string)[] = [];
+  const client0Heard: (ReceivedStatusUpdate<any> | string)[] = [];
+  const client1Heard: (ReceivedStatusUpdate<any> | string)[] = [];
 
   client0.connect(
     (updates) => {
@@ -543,20 +530,20 @@ test("connect with clear means catchup only with updates after clear", () => {
     },
   );
 
-  client0.sendUpdate({ payload: "Hello" }, "update");
-  client0.sendUpdate({ payload: "Bye" }, "update 2");
+  client0.sendUpdate({ payload: "Hello" }, "");
+  client0.sendUpdate({ payload: "Bye" }, "");
 
   processor.clear();
 
   // the aftermath update, which the newly connecting client should get
-  client0.sendUpdate({ payload: "Aftermath" }, "update 3");
+  client0.sendUpdate({ payload: "Aftermath" }, "");
 
   expect(client0Heard).toMatchObject([
     "cleared",
-    [{ payload: "Hello", serial: 1, max_serial: 1 }, "update"],
-    [{ payload: "Bye", serial: 2, max_serial: 2 }, "update 2"],
+    { payload: "Hello", serial: 1, max_serial: 1 },
+    { payload: "Bye", serial: 2, max_serial: 2 },
     "cleared",
-    [{ payload: "Aftermath", serial: 1, max_serial: 1 }, "update 3"],
+    { payload: "Aftermath", serial: 1, max_serial: 1 },
   ]);
 
   // we only join later, so we haven't heard a thing yet
@@ -577,14 +564,14 @@ test("connect with clear means catchup only with updates after clear", () => {
 
   expect(client0Heard).toMatchObject([
     "cleared",
-    [{ payload: "Hello", serial: 1, max_serial: 1 }, "update"],
-    [{ payload: "Bye", serial: 2, max_serial: 2 }, "update 2"],
+    { payload: "Hello", serial: 1, max_serial: 1 },
+    { payload: "Bye", serial: 2, max_serial: 2 },
     "cleared",
-    [{ payload: "Aftermath", serial: 1, max_serial: 1 }, "update 3"],
+    { payload: "Aftermath", serial: 1, max_serial: 1 },
   ]);
   expect(client1Heard).toMatchObject([
     "cleared",
-    [{ payload: "Aftermath", serial: 1, max_serial: 1 }, "update 3"],
+    { payload: "Aftermath", serial: 1, max_serial: 1 },
   ]);
 
   expect(getMessages()).toMatchObject([
@@ -594,38 +581,32 @@ test("connect with clear means catchup only with updates after clear", () => {
       type: "sent",
       instanceId: "3001",
       update: { payload: "Hello", serial: 1, max_serial: 1 },
-      descr: "update",
     },
     {
       type: "received",
       update: { payload: "Hello", serial: 1, max_serial: 1 },
       instanceId: "3001",
-      descr: "update",
     },
     {
       type: "sent",
       instanceId: "3001",
       update: { payload: "Bye", serial: 2, max_serial: 2 },
-      descr: "update 2",
     },
     {
       type: "received",
       update: { payload: "Bye", serial: 2, max_serial: 2 },
       instanceId: "3001",
-      descr: "update 2",
     },
     { type: "clear", instanceId: "3001" },
     {
       type: "sent",
       instanceId: "3001",
       update: { payload: "Aftermath", serial: 1, max_serial: 1 },
-      descr: "update 3",
     },
     {
       type: "received",
       update: { payload: "Aftermath", serial: 1, max_serial: 1 },
       instanceId: "3001",
-      descr: "update 3",
     },
     { type: "connect", instanceId: "3002" },
     { type: "clear", instanceId: "3002" },
@@ -633,7 +614,6 @@ test("connect with clear means catchup only with updates after clear", () => {
       type: "received",
       instanceId: "3002",
       update: { payload: "Aftermath", serial: 1, max_serial: 1 },
-      descr: "update 3",
     },
   ]);
 });
@@ -644,8 +624,8 @@ test("distribute to self and other, but other was disconnected", () => {
   const client0 = processor.createClient("3001");
   const client1 = processor.createClient("3002");
 
-  const client0Heard: UpdateDescr[] = [];
-  const client1Heard: UpdateDescr[] = [];
+  const client0Heard: ReceivedStatusUpdate<any>[] = [];
+  const client1Heard: ReceivedStatusUpdate<any>[] = [];
 
   client0.connect((updates) => {
     client0Heard.push(...updates);
@@ -657,9 +637,9 @@ test("distribute to self and other, but other was disconnected", () => {
     return false;
   }, 0);
 
-  client0.sendUpdate({ payload: "Hello" }, "update");
+  client0.sendUpdate({ payload: "Hello" }, "");
   expect(client0Heard).toMatchObject([
-    [{ payload: "Hello", serial: 1, max_serial: 1 }, "update"],
+    { payload: "Hello", serial: 1, max_serial: 1 },
   ]);
   expect(client1Heard).toMatchObject([]);
 
@@ -672,13 +652,11 @@ test("distribute to self and other, but other was disconnected", () => {
       type: "sent",
       instanceId: "3001",
       update: { payload: "Hello", serial: 1, max_serial: 1 },
-      descr: "update",
     },
     {
       type: "received",
       update: { payload: "Hello", serial: 1, max_serial: 1 },
       instanceId: "3001",
-      descr: "update",
     },
   ]);
 });
@@ -747,7 +725,7 @@ test("instanceColor", () => {
     return true;
   }, 0);
 
-  client0.sendUpdate({ payload: "Hello" }, "update");
+  client0.sendUpdate({ payload: "Hello" }, "");
 
   const instanceColors = getMessages().map((message) => message.instanceColor);
   expect(instanceColors).toEqual([
@@ -789,7 +767,7 @@ test("timestamp", async () => {
 
   await waitFor(10);
 
-  client0.sendUpdate({ payload: "Hello" }, "update");
+  client0.sendUpdate({ payload: "Hello" }, "");
 
   await waitFor(10);
 
diff --git a/backend/message.ts b/backend/message.ts
index 573ab89..cab5fc2 100644
--- a/backend/message.ts
+++ b/backend/message.ts
@@ -6,9 +6,7 @@ import type {
 import type { Message } from "../types/message";
 import { getColorForId } from "./color";
 
-type UpdateListenerMulti = (
-  updates: [ReceivedStatusUpdate<any>, string][],
-) => boolean;
+type UpdateListenerMulti = (updates: ReceivedStatusUpdate<any>[]) => boolean;
 
 type ClearListener = () => boolean;
 type DeleteListener = () => boolean;
@@ -25,8 +23,6 @@ export type WebXdcMulti = {
   sendUpdate: Webxdc<any>["sendUpdate"];
 };
 
-export type UpdateDescr = [ReceivedStatusUpdate<any>, string];
-
 export type OnMessage = (message: Message) => void;
 
 export interface IProcessor {
@@ -46,8 +42,8 @@ class Client implements WebXdcMulti {
     public id: string,
   ) {}
 
-  sendUpdate(update: SendingStatusUpdate<any>, descr: string): void {
-    this.processor.distribute(this.id, update, descr);
+  sendUpdate(update: SendingStatusUpdate<any>, _descr: ""): void {
+    this.processor.distribute(this.id, update);
   }
 
   connect(
@@ -74,17 +70,16 @@ class Client implements WebXdcMulti {
       }
       return hasReceived;
     });
-    const updateListener = (updates: UpdateDescr[]) => {
+    const updateListener = (updates: ReceivedStatusUpdate<any>[]) => {
       const hasReceived = listener(updates);
       if (hasReceived) {
-        for (const [update, descr] of updates) {
+        for (const update of updates) {
           this.processor.onMessage({
             type: "received",
             update: update,
             instanceId: this.id,
             instanceColor: getColorForId(this.id),
             timestamp: Date.now(),
-            descr,
           });
         }
       }
@@ -102,7 +97,7 @@ class Client implements WebXdcMulti {
     this.clear();
   }
 
-  receiveUpdate(update: ReceivedStatusUpdate<any>, descr: string) {
+  receiveUpdate(update: ReceivedStatusUpdate<any>) {
     if (this.updateListener == null || this.updateSerial == null) {
       return;
     }
@@ -110,7 +105,7 @@ class Client implements WebXdcMulti {
     if (update.serial <= this.updateSerial) {
       return;
     }
-    this.updateListener([[update, descr]]);
+    this.updateListener([update]);
   }
 
   clear() {
@@ -136,7 +131,7 @@ class Client implements WebXdcMulti {
 class Processor implements IProcessor {
   clients: Client[] = [];
   currentSerial: number = 0;
-  updates: UpdateDescr[] = [];
+  updates: ReceivedStatusUpdate<any>[] = [];
   clearInstanceIds: Set<string> = new Set();
 
   constructor(public onMessage: OnMessage) {}
@@ -153,28 +148,23 @@ class Processor implements IProcessor {
     this.clients.splice(client_index, 1);
   }
 
-  distribute(
-    instanceId: string,
-    update: SendingStatusUpdate<any>,
-    descr: string,
-  ) {
+  distribute(instanceId: string, update: SendingStatusUpdate<any>) {
     this.currentSerial++;
     const receivedUpdate: ReceivedStatusUpdate<any> = {
       ...update,
       serial: this.currentSerial,
       max_serial: this.updates.length + 1,
     };
-    this.updates.push([receivedUpdate, descr]);
+    this.updates.push(receivedUpdate);
     this.onMessage({
       type: "sent",
       instanceId: instanceId,
       instanceColor: getColorForId(instanceId),
       update: receivedUpdate,
       timestamp: Date.now(),
-      descr,
     });
     for (const client of this.clients) {
-      client.receiveUpdate(receivedUpdate, descr);
+      client.receiveUpdate(receivedUpdate);
     }
   }
 
@@ -192,10 +182,7 @@ class Processor implements IProcessor {
     updateListener(
       this.updates
         .slice(serial)
-        .map(([update, descr]) => [
-          { ...update, max_serial: maxSerial },
-          descr,
-        ]),
+        .map((update) => ({ ...update, max_serial: maxSerial })),
     );
   }
 }
diff --git a/flake.lock b/flake.lock
new file mode 100644
index 0000000..e7ea89c
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,25 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1731676054,
+        "narHash": "sha256-OZiZ3m8SCMfh3B6bfGC/Bm4x3qc1m2SVEAlkV6iY7Yg=",
+        "rev": "5e4fbfb6b3de1aa2872b76d49fafc942626e2add",
+        "revCount": 708622,
+        "type": "tarball",
+        "url": "https://api.flakehub.com/f/pinned/NixOS/nixpkgs/0.1.708622%2Brev-5e4fbfb6b3de1aa2872b76d49fafc942626e2add/0193363c-ab27-7bbd-af1d-3e6093ed5e2d/source.tar.gz"
+      },
+      "original": {
+        "type": "tarball",
+        "url": "https://flakehub.com/f/NixOS/nixpkgs/0.1.%2A.tar.gz"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.nix b/flake.nix
new file mode 100644
index 0000000..f32f02c
--- /dev/null
+++ b/flake.nix
@@ -0,0 +1,20 @@
+{
+  description = "A Nix-flake-based Node.js development environment";
+
+  inputs.nixpkgs.url = "https://flakehub.com/f/NixOS/nixpkgs/0.1.*.tar.gz";
+
+  outputs = { self, nixpkgs }:
+    let
+      supportedSystems = [ "x86_64-linux" "aarch64-linux" "x86_64-darwin" "aarch64-darwin" ];
+      forEachSupportedSystem = f: nixpkgs.lib.genAttrs supportedSystems (system: f {
+        pkgs = import nixpkgs { inherit system; };
+      });
+    in
+    {
+      devShells = forEachSupportedSystem ({ pkgs }: {
+        default = pkgs.mkShell {
+          packages = with pkgs; [ nodejs nodePackages.typescript-language-server ];
+        };
+      });
+    };
+}
diff --git a/package-lock.json b/package-lock.json
index 2f95e6c..dd434f5 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -46,7 +46,7 @@
         "@types/node": "^18.0.0",
         "@types/node-fetch": "^2.6.2",
         "@types/wait-on": "^5.3.1",
-        "@webxdc/types": "^2.0.0",
+        "@webxdc/types": "^2.0.1",
         "babel-loader": "^8.2.5",
         "babel-preset-solid": "~1.5.0",
         "concurrently": "^7.2.2",
@@ -3759,10 +3759,11 @@
       }
     },
     "node_modules/@webxdc/types": {
-      "version": "2.0.0",
-      "resolved": "https://registry.npmjs.org/@webxdc/types/-/types-2.0.0.tgz",
-      "integrity": "sha512-gtddNq2PsUZZwESXOjpI3sHG185fm7QXEolm9sWVIM1iV0sD4Zs8jLL1MKjuYn04/WuX8jVDKDGBDv4qLimhlA==",
-      "dev": true
+      "version": "2.1.2",
+      "resolved": "https://registry.npmjs.org/@webxdc/types/-/types-2.1.2.tgz",
+      "integrity": "sha512-oklcyHvUXqCS5JwbPVaN8tt7nSB8ffRmyrUlVt0HeSn4kDyNE46oKSbw3KtrDzl530KHnm67LfcK/AjWbBoXUA==",
+      "dev": true,
+      "license": "unlicense"
     },
     "node_modules/@xtuc/ieee754": {
       "version": "1.2.0",
@@ -13889,9 +13890,9 @@
       "requires": {}
     },
     "@webxdc/types": {
-      "version": "2.0.0",
-      "resolved": "https://registry.npmjs.org/@webxdc/types/-/types-2.0.0.tgz",
-      "integrity": "sha512-gtddNq2PsUZZwESXOjpI3sHG185fm7QXEolm9sWVIM1iV0sD4Zs8jLL1MKjuYn04/WuX8jVDKDGBDv4qLimhlA==",
+      "version": "2.1.2",
+      "resolved": "https://registry.npmjs.org/@webxdc/types/-/types-2.1.2.tgz",
+      "integrity": "sha512-oklcyHvUXqCS5JwbPVaN8tt7nSB8ffRmyrUlVt0HeSn4kDyNE46oKSbw3KtrDzl530KHnm67LfcK/AjWbBoXUA==",
       "dev": true
     },
     "@xtuc/ieee754": {
diff --git a/package.json b/package.json
index 3c11f16..5ce88d6 100644
--- a/package.json
+++ b/package.json
@@ -17,6 +17,10 @@
       "name": "Martijn Faassen",
       "email": "faassen@startifact.com",
       "url": "http://blog.startifact.com"
+    },
+    {
+      "name": "Sebastian Klähn",
+      "email": "info@sebastian-klaehn.de"
     }
   ],
   "files": [
@@ -54,7 +58,7 @@
     "@types/node": "^18.0.0",
     "@types/node-fetch": "^2.6.2",
     "@types/wait-on": "^5.3.1",
-    "@webxdc/types": "^2.0.0",
+    "@webxdc/types": "^2.0.1",
     "babel-loader": "^8.2.5",
     "babel-preset-solid": "~1.5.0",
     "concurrently": "^7.2.2",
diff --git a/sim/create.ts b/sim/create.ts
index 1445970..aa60079 100644
--- a/sim/create.ts
+++ b/sim/create.ts
@@ -1,4 +1,4 @@
-import { WebXdc, ReceivedStatusUpdate } from "@webxdc/types";
+import { Webxdc, ReceivedStatusUpdate } from "@webxdc/types";
 
 type UpdatesMessage = {
   type: "updates";
@@ -45,13 +45,13 @@ type Log = (...args: any[]) => void;
 export function createWebXdc(
   transport: Transport,
   log: Log = () => {},
-): WebXdc<any> {
+): Webxdc<any> {
   let resolveUpdateListenerPromise: (() => void) | null = null;
 
-  const webXdc: WebXdc<any> = {
-    sendUpdate: (update, descr) => {
-      transport.send({ type: "sendUpdate", update, descr });
-      log("send", { update, descr });
+  const webXdc: Webxdc<any> = {
+    sendUpdate: (update: any) => {
+      transport.send({ type: "sendUpdate", update });
+      log("send", { update });
     },
     setUpdateListener: (listener, serial = 0): Promise<void> => {
       transport.onMessage((message) => {
diff --git a/sim/webxdc.test.ts b/sim/webxdc.test.ts
index 7a198d6..8847cd9 100644
--- a/sim/webxdc.test.ts
+++ b/sim/webxdc.test.ts
@@ -27,15 +27,15 @@ class FakeTransport implements Transport {
 
   send(data: any) {
     if (data.type === "sendUpdate") {
-      const { update, descr } = data;
-      this.client.sendUpdate(update, descr);
+      const { update } = data;
+      this.client.sendUpdate(update, "");
     } else if (data.type === "setUpdateListener") {
       this.client.connect(
         (updates) => {
           if (this.messageCallback != null) {
             this.messageCallback({
               type: "updates",
-              updates: updates.map(([update]) => update),
+              updates,
             });
           }
           return true;
@@ -106,7 +106,7 @@ test("webxdc sends", async () => {
   }, 0);
   fakeTransport.connect();
   await promise;
-  webXdc.sendUpdate({ payload: "hello" }, "sent 1");
+  webXdc.sendUpdate({ payload: "hello" }, "");
   expect(updates).toEqual([
     {
       payload: "hello",
@@ -148,7 +148,7 @@ test("webxdc distributes", async () => {
   fakeTransportB.connect();
   await promiseB;
 
-  webXdcA.sendUpdate({ payload: "hello" }, "sent 1");
+  webXdcA.sendUpdate({ payload: "hello" }, "");
   expect(updatesA).toEqual([
     {
       payload: "hello",
diff --git a/sim/webxdc.ts b/sim/webxdc.ts
index f7739a8..7d0130b 100644
--- a/sim/webxdc.ts
+++ b/sim/webxdc.ts
@@ -1,4 +1,4 @@
-import { WebXdc } from "@webxdc/types";
+import { Webxdc } from "@webxdc/types";
 import {
   Transport,
   TransportMessageCallback,
@@ -114,7 +114,7 @@ export class DevServerTransport implements Transport {
   }
 }
 
-function getWebXdc(): WebXdc<any> {
+function getWebXdc(): Webxdc<any> {
   return (window as any).webxdc;
 }
 
diff --git a/types/message.ts b/types/message.ts
index 46f7801..123c228 100644
--- a/types/message.ts
+++ b/types/message.ts
@@ -8,7 +8,6 @@ export type InstanceMessage = {
 
 export type BaseUpdateMessage = {
   update: ReceivedStatusUpdate<any>;
-  descr: string;
 } & InstanceMessage;
 
 export type UpdateMessage =