Including a test harness for it, and making sure the cursor is always at the end.

packages/cli/src/ui/hooks/useInputHistory.ts

@@ -0,0 +1,92 @@
+import { useState, useCallback } from 'react';
+import { useInput } from 'ink';
+
+interface UseInputHistoryProps {
+  userMessages: readonly string[]; // Use readonly string[] instead
+  isActive: boolean; // To enable/disable the useInput hook
+}
+
+interface UseInputHistoryReturn {
+  query: string;
+  setQuery: React.Dispatch<React.SetStateAction<string>>;
+  resetHistoryNav: () => void;
+  inputKey: number; // Key to force input reset
+}
+
+export function useInputHistory({
+  userMessages,
+  isActive,
+}: UseInputHistoryProps): UseInputHistoryReturn {
+  const [query, setQuery] = useState('');
+  const [historyIndex, setHistoryIndex] = useState<number>(-1); // -1 means current query
+  const [originalQueryBeforeNav, setOriginalQueryBeforeNav] =
+    useState<string>('');
+  const [inputKey, setInputKey] = useState<number>(0); // Add key state
+
+  const resetHistoryNav = useCallback(() => {
+    setHistoryIndex(-1);
+    setOriginalQueryBeforeNav('');
+    // Don't reset inputKey here, only on explicit nav actions
+  }, []);
+
+  useInput(
+    (input, key) => {
+      // Do nothing if the hook is not active
+      if (!isActive) {
+        return;
+      }
+
+      if (key.upArrow) {
+        if (userMessages.length === 0) return;
+        // Store current query if starting navigation
+        if (historyIndex === -1) {
+          setOriginalQueryBeforeNav(query);
+        }
+        const nextIndex = Math.min(historyIndex + 1, userMessages.length - 1);
+        if (nextIndex !== historyIndex) {
+          setHistoryIndex(nextIndex);
+          const newValue = userMessages[userMessages.length - 1 - nextIndex];
+          setQuery(newValue);
+          setInputKey(k => k + 1); // Increment key on navigation change
+        }
+      } else if (key.downArrow) {
+        if (historyIndex < 0) return; // Already at the bottom
+        const nextIndex = Math.max(historyIndex - 1, -1);
+        setHistoryIndex(nextIndex);
+        if (nextIndex === -1) {
+          // Restore original query
+          setQuery(originalQueryBeforeNav);
+          setInputKey(k => k + 1); // Increment key on navigation change
+        } else {
+          // Set query based on reversed index
+          const newValue = userMessages[userMessages.length - 1 - nextIndex];
+          setQuery(newValue);
+          setInputKey(k => k + 1); // Increment key on navigation change
+        }
+      } else {
+        // If user types anything other than arrows, reset history navigation state
+        // This check might be too broad, adjust if handling more special keys
+        if (
+          input ||
+          key.backspace ||
+          key.delete ||
+          key.leftArrow ||
+          key.rightArrow
+        ) {
+          if (historyIndex !== -1) {
+            resetHistoryNav();
+            // Note: The actual input change is handled by the component using setQuery/onChange
+          }
+        }
+      }
+    },
+    { isActive }, // Pass isActive to useInput
+  );
+
+  return {
+    query,
+    setQuery, // Return setQuery directly for flexibility
+    resetHistoryNav,
+    inputKey, // Return the key
+  };
+}