fix: add left/right arrow key cursor navigation in approval text inputs (#489)

Co-authored-by: Letta <noreply@letta.com>

src/cli/hooks/useTextInputCursor.ts

@@ -0,0 +1,78 @@
+import { useState } from "react";
+
+interface Key {
+  leftArrow?: boolean;
+  rightArrow?: boolean;
+  backspace?: boolean;
+  delete?: boolean;
+  ctrl?: boolean;
+  meta?: boolean;
+}
+
+/**
+ * Custom hook for managing text input with cursor position tracking.
+ *
+ * Handles:
+ * - Left/right arrow key navigation within text
+ * - Backspace at cursor position (not just end)
+ * - Character insertion at cursor position
+ *
+ * @returns Object with text state, cursor position, key handler, and clear function
+ */
+export function useTextInputCursor(initialText = "") {
+  const [text, setText] = useState(initialText);
+  const [cursorPos, setCursorPos] = useState(0);
+
+  /**
+   * Handle keyboard input for text editing.
+   * @returns true if the key was handled, false otherwise
+   */
+  const handleKey = (input: string, key: Key): boolean => {
+    // Arrow key navigation
+    if (key.leftArrow) {
+      setCursorPos((prev) => Math.max(0, prev - 1));
+      return true;
+    }
+    if (key.rightArrow) {
+      setCursorPos((prev) => Math.min(text.length, prev + 1));
+      return true;
+    }
+
+    // Backspace: delete character before cursor
+    if (key.backspace || key.delete) {
+      if (cursorPos > 0) {
+        setText((prev) => prev.slice(0, cursorPos - 1) + prev.slice(cursorPos));
+        setCursorPos((prev) => prev - 1);
+      }
+      return true;
+    }
+
+    // Typing: insert at cursor position
+    if (input && !key.ctrl && !key.meta && input.length === 1) {
+      setText(
+        (prev) => prev.slice(0, cursorPos) + input + prev.slice(cursorPos),
+      );
+      setCursorPos((prev) => prev + 1);
+      return true;
+    }
+
+    return false;
+  };
+
+  /**
+   * Clear text and reset cursor to start
+   */
+  const clear = () => {
+    setText("");
+    setCursorPos(0);
+  };
+
+  return {
+    text,
+    setText,
+    cursorPos,
+    setCursorPos,
+    handleKey,
+    clear,
+  };
+}