diff --git a/apps/web/src/components/ChatView.tsx b/apps/web/src/components/ChatView.tsx
index 185fa7c2ee..48f79da415 100644
--- a/apps/web/src/components/ChatView.tsx
+++ b/apps/web/src/components/ChatView.tsx
@@ -647,6 +647,8 @@ export default function ChatView({ threadId }: ChatViewProps) {
     (store) => store.draftThreadsByThreadId[threadId] ?? null,
   );
   const promptRef = useRef(prompt);
+  const historyIndexRef = useRef(-1); // -1 = live draft
+  const savedDraftRef = useRef('');
   const [showScrollToBottom, setShowScrollToBottom] = useState(false);
   const [isDragOverComposer, setIsDragOverComposer] = useState(false);
   const [expandedImage, setExpandedImage] = useState<ExpandedImagePreview | null>(null);
@@ -2389,6 +2391,8 @@ export default function ChatView({ threadId }: ChatViewProps) {
     setComposerCursor(collapseExpandedComposerCursor(promptRef.current, promptRef.current.length));
     setComposerTrigger(detectComposerTrigger(promptRef.current, promptRef.current.length));
     dragDepthRef.current = 0;
+    historyIndexRef.current = -1;
+    savedDraftRef.current = '';
     setIsDragOverComposer(false);
     setExpandedImage(null);
   }, [resetLocalDispatch, threadId]);
@@ -2871,6 +2875,8 @@ export default function ChatView({ threadId }: ChatViewProps) {
         planMarkdown: activeProposedPlan.planMarkdown,
       });
       promptRef.current = "";
+      historyIndexRef.current = -1;
+      savedDraftRef.current = '';
       clearComposerDraftContent(activeThread.id);
       setComposerHighlightedItemId(null);
       setComposerCursor(0);
@@ -2888,6 +2894,8 @@ export default function ChatView({ threadId }: ChatViewProps) {
     if (standaloneSlashCommand) {
       handleInteractionModeChange(standaloneSlashCommand);
       promptRef.current = "";
+      historyIndexRef.current = -1;
+      savedDraftRef.current = '';
       clearComposerDraftContent(activeThread.id);
       setComposerHighlightedItemId(null);
       setComposerCursor(0);
@@ -2991,6 +2999,8 @@ export default function ChatView({ threadId }: ChatViewProps) {
       });
     }
     promptRef.current = "";
+    historyIndexRef.current = -1;
+    savedDraftRef.current = '';
     clearComposerDraftContent(threadIdForSend);
     setComposerHighlightedItemId(null);
     setComposerCursor(0);
@@ -3853,6 +3863,19 @@ export default function ChatView({ threadId }: ChatViewProps) {
       }
     }
 
+    if (key === "ArrowUp" || (key === "ArrowDown" && historyIndexRef.current !== -1)) {
+      const userMsgs = activeThread?.messages.filter((m) => m.role === 'user') ?? [];
+      const nextIndex = historyIndexRef.current + (key === "ArrowUp" ? 1 : -1);
+      if (key === "ArrowUp" && nextIndex >= userMsgs.length) return false;
+      if (historyIndexRef.current === -1) savedDraftRef.current = promptRef.current;
+      historyIndexRef.current = nextIndex;
+      const next = nextIndex === -1 ? savedDraftRef.current : (userMsgs[userMsgs.length - 1 - nextIndex]?.text ?? '');
+      setPrompt(next);
+      setComposerCursor(next.length);
+      setComposerTrigger(detectComposerTrigger(next, next.length));
+      return true;
+    }
+
     if (key === "Enter" && !event.shiftKey) {
       void onSend();
       return true;