From 37bf33df8111c1718de7c8fe2cfaa096d6d1edcd Mon Sep 17 00:00:00 2001
From: Samy <samy@ap4.sh>
Date: Thu, 13 Aug 2026 02:28:32 +0200
Subject: [PATCH] fix: prevent duplicate attachment sends

---
 .../composition/CompositionBox.tsx            | 13 ++-
 .../composition/messageSendGuard.ts           | 16 ++++
 .../conversation/messageSendGuard_test.ts     | 80 +++++++++++++++++++
 3 files changed, 108 insertions(+), 1 deletion(-)
 create mode 100644 ts/components/conversation/composition/messageSendGuard.ts
 create mode 100644 ts/test/session/unit/components/conversation/messageSendGuard_test.ts

diff --git a/ts/components/conversation/composition/CompositionBox.tsx b/ts/components/conversation/composition/CompositionBox.tsx
index d5b3237db..ef61ea4de 100644
--- a/ts/components/conversation/composition/CompositionBox.tsx
+++ b/ts/components/conversation/composition/CompositionBox.tsx
@@ -67,6 +67,7 @@ import { updateOutgoingLightBoxOptions } from '../../../state/ducks/modalDialog'
 import { isEnterKey, isEscapeKey } from '../../../util/keyboardShortcuts';
 import type { CommunityInvitation } from '../../../session/messages/outgoing/visibleMessage/VisibleMessage';
 import { SessionGifPanel } from './gif/SessionGifPanel';
+import { createMessageSendGuard } from './messageSendGuard';
 
 export interface ReplyingToMessageProps {
   convoId: string;
@@ -243,6 +244,7 @@ class CompositionBoxInner extends Component<Props, State> {
   private readonly emojiPanel: RefObject<HTMLDivElement | null>;
   private readonly emojiPanelButton: any;
   private readonly showGifsButtonRef: RefObject<HTMLButtonElement | null>;
+  private readonly messageSendGuard = createMessageSendGuard();
   private linkPreviewAbortController?: AbortController;
 
   constructor(props: Props) {
@@ -640,7 +642,16 @@ class CompositionBoxInner extends Component<Props, State> {
     return text.length > 0;
   }
 
-  private async onSendMessage() {
+  private onSendMessage() {
+    const { selectedConversationKey } = this.props;
+    if (!selectedConversationKey) {
+      return this.sendCurrentMessage();
+    }
+
+    return this.messageSendGuard(selectedConversationKey, () => this.sendCurrentMessage());
+  }
+
+  private async sendCurrentMessage() {
     const {
       selectedConversationKey,
       selectedConversation,
diff --git a/ts/components/conversation/composition/messageSendGuard.ts b/ts/components/conversation/composition/messageSendGuard.ts
new file mode 100644
index 000000000..7f3e9ad40
--- /dev/null
+++ b/ts/components/conversation/composition/messageSendGuard.ts
@@ -0,0 +1,16 @@
+export function createMessageSendGuard() {
+  const conversationsSending = new Set<string>();
+
+  return async (conversationKey: string, sendMessage: () => Promise<void>) => {
+    if (conversationsSending.has(conversationKey)) {
+      return;
+    }
+
+    conversationsSending.add(conversationKey);
+    try {
+      await sendMessage();
+    } finally {
+      conversationsSending.delete(conversationKey);
+    }
+  };
+}
diff --git a/ts/test/session/unit/components/conversation/messageSendGuard_test.ts b/ts/test/session/unit/components/conversation/messageSendGuard_test.ts
new file mode 100644
index 000000000..5c0404e6f
--- /dev/null
+++ b/ts/test/session/unit/components/conversation/messageSendGuard_test.ts
@@ -0,0 +1,80 @@
+import chai from 'chai';
+
+import { createMessageSendGuard } from '../../../../../components/conversation/composition/messageSendGuard';
+
+const { expect } = chai;
+
+describe('createMessageSendGuard', () => {
+  it('ignores another send to the same conversation while one is in progress', async () => {
+    const sendMessage = createMessageSendGuard();
+    let resolveFirstSend!: () => void;
+    let sendCount = 0;
+
+    const firstSend = sendMessage(
+      'conversation-a',
+      () =>
+        new Promise<void>(resolve => {
+          sendCount += 1;
+          resolveFirstSend = resolve;
+        })
+    );
+    await sendMessage('conversation-a', async () => {
+      sendCount += 1;
+    });
+
+    expect(sendCount).to.equal(1);
+
+    resolveFirstSend();
+    await firstSend;
+    await sendMessage('conversation-a', async () => {
+      sendCount += 1;
+    });
+
+    expect(sendCount).to.equal(2);
+  });
+
+  it('allows sends to different conversations at the same time', async () => {
+    const sendMessage = createMessageSendGuard();
+    let resolveFirstSend!: () => void;
+    let secondSendCompleted = false;
+
+    const firstSend = sendMessage(
+      'conversation-a',
+      () =>
+        new Promise<void>(resolve => {
+          resolveFirstSend = resolve;
+        })
+    );
+    await sendMessage('conversation-b', async () => {
+      secondSendCompleted = true;
+    });
+
+    expect(secondSendCompleted).to.equal(true);
+
+    resolveFirstSend();
+    await firstSend;
+  });
+
+  it('allows another send after a failure', async () => {
+    const sendMessage = createMessageSendGuard();
+    const failure = new Error('send failed');
+    let caught: unknown;
+
+    try {
+      await sendMessage('conversation-a', async () => {
+        throw failure;
+      });
+    } catch (error) {
+      caught = error;
+    }
+
+    expect(caught).to.equal(failure);
+
+    let didRetry = false;
+    await sendMessage('conversation-a', async () => {
+      didRetry = true;
+    });
+
+    expect(didRetry).to.equal(true);
+  });
+});