diff --git a/CHANGELOG.md b/CHANGELOG.md
index a18b2094..997ae7fd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ All notable changes to this project will be documented in this file.
 - **Dictation:** speech is now transcribed after you stop recording. The composer shows a live waveform and timer, and long recordings split at pauses instead of cutting words.
 - Chat: file paths in messages now open from the session's project, even if you last browsed files in another project (thanks to @tomzx).
 - Diff: creating an inline comment now opens the chat and focuses the composer for your follow-up.
+- Chat: in the expanded composer, Enter now starts a new line and Cmd/Ctrl+Enter sends, so a long prompt is harder to send by accident.
 - Providers: expanded support for custom providers.
 - Small Model: summaries, goal audits, commit messages, and walkthroughs now support more providers.
 - Git: generated commit messages now match the repository's recent commit style and language.
diff --git a/packages/ui/src/components/chat/ChatInput.tsx b/packages/ui/src/components/chat/ChatInput.tsx
index 27610e32..1ff3bca0 100644
--- a/packages/ui/src/components/chat/ChatInput.tsx
+++ b/packages/ui/src/components/chat/ChatInput.tsx
@@ -1625,8 +1625,12 @@ const ChatInputComponent: React.FC<ChatInputProps> = ({
             return;
         }
 
-        // Handle Enter/Ctrl+Enter based on selected follow-up behavior.
-        if (e.key === 'Enter' && !e.shiftKey && (!isMobile || e.ctrlKey || e.metaKey)) {
+        // Handle Enter/Ctrl+Enter based on selected follow-up behavior. On
+        // mobile, and in desktop focus mode, plain Enter writes a newline and
+        // only Cmd/Ctrl+Enter sends: both are surfaces for composing long
+        // prompts, where an accidental send costs more than an extra keypress.
+        const requiresModifierToSend = isMobile || isDesktopExpanded;
+        if (e.key === 'Enter' && !e.shiftKey && (!requiresModifierToSend || e.ctrlKey || e.metaKey)) {
             e.preventDefault();
 
             const isCtrlEnter = e.ctrlKey || e.metaKey;