diff --git a/src/components/NotePostForm.tsx b/src/components/NotePostForm.tsx
index f74c4e3..fa5ca04 100644
--- a/src/components/NotePostForm.tsx
+++ b/src/components/NotePostForm.tsx
@@ -60,6 +60,9 @@ const extract = (parsed: ParsedTextNote) => {
       } else if (node.data.type === 'note') {
         eventReferences.push(node.data.data);
       }
+      // TODO nevent can contain an event not only textnote (kind:1).
+      // In my understanding, it is not allowed to include other kinds of events in `tags`.
+      // It is needed to verify that the kind of the event is 1.
     }
   });
 
diff --git a/src/components/column/FollwingColumn.tsx b/src/components/column/FollwingColumn.tsx
index 551e2d6..3434332 100644
--- a/src/components/column/FollwingColumn.tsx
+++ b/src/components/column/FollwingColumn.tsx
@@ -1,4 +1,4 @@
-import { Component } from 'solid-js';
+import { Component, createEffect, onCleanup, onMount } from 'solid-js';
 
 import Home from 'heroicons/24/outline/home.svg';
 import { uniq } from 'lodash';
@@ -25,7 +25,7 @@ const FollowingColumn: Component<FollowingColumnDisplayProps> = (props) => {
 
   const { followingPubkeys } = useFollowings(() => ({ pubkey: props.column.pubkey }));
 
-  const { events: followingsPosts } = useSubscription(() => {
+  const { events } = useSubscription(() => {
     const authors = uniq([...followingPubkeys()]);
     if (authors.length === 0) return null;
     return {
@@ -45,6 +45,13 @@ const FollowingColumn: Component<FollowingColumnDisplayProps> = (props) => {
     };
   });
 
+  createEffect(() => {
+    console.log('home', events());
+  });
+
+  onMount(() => console.log('home timeline mounted'));
+  onCleanup(() => console.log('home timeline unmounted'));
+
   return (
     <Column
       header={
@@ -59,7 +66,7 @@ const FollowingColumn: Component<FollowingColumnDisplayProps> = (props) => {
       columnIndex={props.columnIndex}
       lastColumn={props.lastColumn}
     >
-      <Timeline events={followingsPosts()} />
+      <Timeline events={events()} />
     </Column>
   );
 };
diff --git a/src/nostr/event.ts b/src/nostr/event.ts
index 9d0f4d4..6dfa14a 100644
--- a/src/nostr/event.ts
+++ b/src/nostr/event.ts
@@ -1,5 +1,6 @@
 import uniq from 'lodash/uniq';
 import { Kind, Event as NostrEvent } from 'nostr-tools';
+import { z } from 'zod';
 
 export type EventMarker = 'reply' | 'root' | 'mention';
 
@@ -22,13 +23,25 @@ export type ContentWarning = {
   reason?: string;
 };
 
-const IdRegex = /^[0-9a-fA-f]{64}$/;
+const IdRegex = /^[0-9a-f]{64}$/;
 export const isValidId = (s: string): boolean => {
   const result = typeof s === 'string' && s.length === 64 && IdRegex.test(s);
   if (!result) console.warn('invalid id is ignored: ', s);
   return result;
 };
 
+/*
+// TODO event validation and normalization
+const eventSchema = z.object({
+  id: z.string().length(64).regex(IdRegex),
+  pubkey: z.string().length(64).regex(IdRegex),
+  created_at: z.number().int(),
+  kind: z.number(),
+  tags: z.array(z.array(z.string())),
+  content: z.string(),
+});
+*/
+
 const eventWrapper = (event: NostrEvent) => {
   let memoizedMarkedEventTags: MarkedEventTag[] | undefined;