fix: exclude replies from the Feed and Profile timelines

Per NIP-10 a kind-1 event with an `e` tag is a reply, but the Feed and
Profile timelines rendered every kind-1 event with no such check, so
replies showed up indistinguishable from root posts. `isReply()` was
already written for this in nostrUtils but never used anywhere.

Fixes #20

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BYiUtZMQeA5RHggQw73wto

src/apps/feed/index.tsx

@@ -11,6 +11,7 @@ import { Skeleton } from '@/components/ui/skeleton';
 import { useCurrentUser } from '@/hooks/useCurrentUser';
 import { useMyFollows } from '@/hooks/useFollows';
 import { cn } from '@/lib/utils';
+import { isReply } from '@/lib/nostrUtils';
 import type { AppProps } from '@/os/types';
 
 type Scope = 'following' | 'global';
@@ -20,9 +21,17 @@ const PAGE_SIZE = 50;
 /**
  * A kind 1 event is only worth rendering if it has something to render. Relays
  * happily return blanks and oddities, so the feed validates before it draws.
+ * Replies (NIP-10 `e` tags) are excluded too: without their parent for
+ * context they read as indistinguishable, orphaned root posts — open the
+ * thread from the Note app instead.
  */
 function isRenderableNote(event: NostrEvent): boolean {
-  return event.kind === 1 && typeof event.content === 'string' && event.content.trim().length > 0;
+  return (
+    event.kind === 1 &&
+    typeof event.content === 'string' &&
+    event.content.trim().length > 0 &&
+    !isReply(event)
+  );
 }
 
 function useFeed(scope: Scope, authors: string[] | undefined) {

src/apps/profile/index.tsx

@@ -14,9 +14,14 @@ import { useCurrentUser } from '@/hooks/useCurrentUser';
 import { useMyFollows } from '@/hooks/useFollows';
 import { useNostrPublish } from '@/hooks/useNostrPublish';
 import { useToast } from '@/hooks/useToast';
-import { decodeRelayHints, displayName, npubOf, sanitizeUrl } from '@/lib/nostrUtils';
+import { decodeRelayHints, displayName, isReply, npubOf, sanitizeUrl } from '@/lib/nostrUtils';
 import type { AppProps } from '@/os/types';
 
+/**
+ * Replies are excluded here for the same reason as the Feed: without their
+ * parent for context, a reply on a profile's timeline reads as an orphaned
+ * root post rather than what it is.
+ */
 function useAuthorNotes(pubkey: string | undefined, relays: string[] | undefined) {
   const { nostr } = useNostr();
 
@@ -29,7 +34,7 @@ function useAuthorNotes(pubkey: string | undefined, relays: string[] | undefined
         { signal: AbortSignal.any([signal, AbortSignal.timeout(6000)]), relays },
       );
       return events
-        .filter((event) => event.content.trim().length > 0)
+        .filter((event) => event.content.trim().length > 0 && !isReply(event))
         .sort((a, b) => b.created_at - a.created_at);
     },
     staleTime: 60_000,

src/lib/nostrUtils.test.ts

@@ -0,0 +1,51 @@
+import { describe, expect, it } from 'vitest';
+import type { NostrEvent } from '@nostrify/nostrify';
+import { isReply, rootReference } from './nostrUtils';
+
+function note(tags: string[][]): NostrEvent {
+  return {
+    id: 'x',
+    pubkey: 'y',
+    created_at: 0,
+    kind: 1,
+    tags,
+    content: 'hello',
+    sig: '',
+  };
+}
+
+describe('isReply', () => {
+  it('is false for a root note with no e tag', () => {
+    expect(isReply(note([]))).toBe(false);
+  });
+
+  it('is true for a note with a marked root e tag', () => {
+    expect(isReply(note([['e', 'root-id', '', 'root']]))).toBe(true);
+  });
+
+  it('is true for a note using the deprecated positional e tag', () => {
+    expect(isReply(note([['e', 'parent-id']]))).toBe(true);
+  });
+});
+
+describe('rootReference', () => {
+  it('prefers the marked root tag over positional ones', () => {
+    const event = note([
+      ['e', 'mention-id', '', 'mention'],
+      ['e', 'root-id', '', 'root'],
+    ]);
+    expect(rootReference(event)).toBe('root-id');
+  });
+
+  it('falls back to the first positional e tag per the deprecated scheme', () => {
+    const event = note([
+      ['e', 'root-id'],
+      ['e', 'reply-id'],
+    ]);
+    expect(rootReference(event)).toBe('root-id');
+  });
+
+  it('is undefined for a root note', () => {
+    expect(rootReference(note([]))).toBeUndefined();
+  });
+});