diff --git a/src/controllers/api/streaming.ts b/src/controllers/api/streaming.ts
index 19149fa..b99000c 100644
--- a/src/controllers/api/streaming.ts
+++ b/src/controllers/api/streaming.ts
@@ -1,12 +1,12 @@
 import { AppController } from '@/app.ts';
 import { TOKEN_REGEX } from '@/middleware/auth.ts';
-import ws from '@/stream.ts';
+import { streamSchema, ws } from '@/stream.ts';
 import { bech32ToPubkey } from '@/utils.ts';
 
 const streamingController: AppController = (c) => {
   const upgrade = c.req.headers.get('upgrade');
   const token = c.req.headers.get('sec-websocket-protocol');
-  const stream = c.req.query('stream');
+  const stream = streamSchema.optional().catch(undefined).parse(c.req.query('stream'));
 
   if (upgrade?.toLowerCase() !== 'websocket') {
     return c.text('Please use websocket protocol', 400);
@@ -32,7 +32,7 @@ const streamingController: AppController = (c) => {
   socket.addEventListener('open', () => {
     console.log('websocket: connection opened');
     if (stream) {
-      ws.subscribe(conn, { name: stream });
+      ws.subscribe(conn, { stream });
     }
   });
 
diff --git a/src/sign.ts b/src/sign.ts
index 69416c9..f222e11 100644
--- a/src/sign.ts
+++ b/src/sign.ts
@@ -1,7 +1,7 @@
 import { type AppContext } from '@/app.ts';
 import { getEventHash, getPublicKey, getSignature, HTTPException, z } from '@/deps.ts';
 import { eventSchema } from '@/schema.ts';
-import ws from '@/stream.ts';
+import { ws } from '@/stream.ts';
 
 import type { Event, EventTemplate, SignedEvent } from '@/event.ts';
 
diff --git a/src/stream.ts b/src/stream.ts
index a96e71c..fa352ee 100644
--- a/src/stream.ts
+++ b/src/stream.ts
@@ -1,5 +1,23 @@
+import { z } from '@/deps.ts';
+
 /** Internal key for event subscriptions. */
-type Topic = string;
+type Topic =
+  | `nostr:${string}:${string}`
+  | 'public'
+  | 'public:local';
+
+/**
+ * Streaming timelines/categories.
+ * https://docs.joinmastodon.org/methods/streaming/#streams
+ */
+const streamSchema = z.enum([
+  'nostr',
+  'public',
+  'public:local',
+  'user',
+]);
+
+type Stream = z.infer<typeof streamSchema>;
 
 /** Only the necessary metadata needed from the request. */
 interface StreamConn {
@@ -13,9 +31,9 @@ interface StreamConn {
 
 /** Requested streaming channel, eg `user`, `notifications`. Some channels like `hashtag` have additional params. */
 // TODO: Make this a discriminated union (needed for hashtags).
-interface Stream {
+interface StreamSub {
   /** Name of the channel, eg `user`. */
-  name: string;
+  stream: Stream;
   /** Additional query params, eg `tag`. */
   params?: Record<string, string>;
 }
@@ -28,8 +46,8 @@ class WebSocketConnections {
   #topics = new WeakMap<WebSocket, Set<Topic>>();
 
   /** Add the WebSocket to the streaming channel. */
-  subscribe(conn: StreamConn, stream: Stream): void {
-    const topic = getTopic(conn, stream);
+  subscribe(conn: StreamConn, sub: StreamSub): void {
+    const topic = getTopic(conn, sub);
 
     if (topic) {
       this.#addSocket(conn.socket, topic);
@@ -38,8 +56,8 @@ class WebSocketConnections {
   }
 
   /** Remove the WebSocket from the streaming channel. */
-  unsubscribe(conn: StreamConn, stream: Stream): void {
-    const topic = getTopic(conn, stream);
+  unsubscribe(conn: StreamConn, sub: StreamSub): void {
+    const topic = getTopic(conn, sub);
 
     if (topic) {
       this.#removeSocket(conn.socket, topic);
@@ -120,22 +138,21 @@ class WebSocketConnections {
  * Convert the "stream" parameter into a "topic".
  * The stream parameter is part of the public-facing API, while the topic is internal.
  */
-function getTopic(conn: StreamConn, stream: Stream): Topic | undefined {
-  // Global topics will share the same name as the stream.
-  if (stream.name.startsWith('public')) {
-    return stream.name;
-    // Can't subscribe to non-public topics without a pubkey.
-  } else if (!conn.pubkey) {
-    return;
-    // Nostr signing topics contain the session ID for privacy reasons.
-  } else if (stream.name === 'nostr') {
-    return conn.session ? `${stream.name}:${conn.pubkey}:${conn.session}` : undefined;
-    // User topics will be suffixed with the pubkey.
-  } else {
-    return `${stream.name}:${conn.pubkey}`;
+function getTopic(conn: StreamConn, sub: StreamSub): Topic | undefined {
+  switch (sub.stream) {
+    case 'public':
+    case 'public:local':
+      return sub.stream;
+    default:
+      if (!conn.pubkey) {
+        return;
+        // Nostr signing topics contain the session ID for privacy reasons.
+      } else if (sub.stream === 'nostr') {
+        return conn.session ? `nostr:${conn.pubkey}:${conn.session}` : undefined;
+      }
   }
 }
 
 const ws = new WebSocketConnections();
 
-export default ws;
+export { type Stream, streamSchema, ws };