feat(cli): add PageUp/PageDown keyboard shortcuts for scrolling chat history

- Add use-scroll-management.ts hook for scroll state management
- Update use-chat-keyboard.ts with PageUp/PageDown handlers
- Extend keyboard-actions.ts with scroll actions
- Wire up scroll management in chat.tsx

Author: brandonkachen

cli/src/chat.tsx

@@ -394,7 +394,7 @@ export const Chat = ({
     return isUserCollapsingRef.current
   }, [])
 
-  const { scrollToLatest, scrollboxProps, isAtBottom } = useChatScrollbox(
+  const { scrollToLatest, scrollUp, scrollDown, scrollboxProps, isAtBottom } = useChatScrollbox(
     scrollRef,
     messages,
     isUserCollapsing,
@@ -1275,6 +1275,8 @@ export const Chat = ({
           }
         })
       },
+      onScrollUp: scrollUp,
+      onScrollDown: scrollDown,
       onOpenBuyCredits: () => {
         // If credits have been restored, just return to default mode
         if (areCreditsRestored()) {
@@ -1314,6 +1316,8 @@ export const Chat = ({
       inputRef,
       handleCtrlC,
       clearQueue,
+      scrollUp,
+      scrollDown,
     ],
   )
 

cli/src/hooks/use-chat-keyboard.ts

@@ -75,6 +75,10 @@ export type ChatKeyboardHandlers = {
   onPasteImagePath: (imagePath: string) => void
   onPasteText: (text: string) => void
 
+  // Scroll handlers
+  onScrollUp: () => void
+  onScrollDown: () => void
+
   // Out of credits handler
   onOpenBuyCredits: () => void
 }
@@ -229,6 +233,12 @@ function dispatchAction(
       }
       return true
     }
+    case 'scroll-up':
+      handlers.onScrollUp()
+      return true
+    case 'scroll-down':
+      handlers.onScrollDown()
+      return true
     case 'open-buy-credits':
       handlers.onOpenBuyCredits()
       return true

cli/src/hooks/use-scroll-management.ts

@@ -9,6 +9,9 @@ const SCROLL_NEAR_BOTTOM_THRESHOLD = 1
 const ANIMATION_FRAME_INTERVAL_MS = 16 // ~60fps
 const DEFAULT_SCROLL_ANIMATION_DURATION_MS = 200
 
+// Page scroll amount (fraction of viewport height)
+const PAGE_SCROLL_FRACTION = 0.8
+
 // Delay before auto-scrolling after content changes
 const AUTO_SCROLL_DELAY_MS = 50
 
@@ -86,6 +89,30 @@ export const useChatScrollbox = (
     animateScrollTo(maxScroll)
   }, [scrollRef, animateScrollTo])
 
+  const scrollUp = useCallback((): void => {
+    const scrollbox = scrollRef.current
+    if (!scrollbox) return
+
+    const viewportHeight = scrollbox.viewport.height
+    const scrollAmount = Math.floor(viewportHeight * PAGE_SCROLL_FRACTION)
+    const targetScroll = Math.max(0, scrollbox.scrollTop - scrollAmount)
+    animateScrollTo(targetScroll)
+  }, [scrollRef, animateScrollTo])
+
+  const scrollDown = useCallback((): void => {
+    const scrollbox = scrollRef.current
+    if (!scrollbox) return
+
+    const viewportHeight = scrollbox.viewport.height
+    const maxScroll = Math.max(
+      0,
+      scrollbox.scrollHeight - viewportHeight,
+    )
+    const scrollAmount = Math.floor(viewportHeight * PAGE_SCROLL_FRACTION)
+    const targetScroll = Math.min(maxScroll, scrollbox.scrollTop + scrollAmount)
+    animateScrollTo(targetScroll)
+  }, [scrollRef, animateScrollTo])
+
   useEffect(() => {
     const scrollbox = scrollRef.current
     if (!scrollbox) return
@@ -149,6 +176,8 @@ export const useChatScrollbox = (
 
   return {
     scrollToLatest,
+    scrollUp,
+    scrollDown,
     scrollboxProps: {},
     isAtBottom,
   }

cli/src/utils/keyboard-actions.ts

@@ -93,6 +93,10 @@ export type ChatKeyboardAction =
   | { type: 'bash-history-up' }
   | { type: 'bash-history-down' }
 
+  // Scroll actions
+  | { type: 'scroll-up' }
+  | { type: 'scroll-down' }
+
   // Paste action (dispatcher checks clipboard content to route to image or text handler)
   | { type: 'paste' }
 
@@ -126,6 +130,8 @@ export function resolveChatKeyboardAction(
     (key.name === 'return' || key.name === 'enter') &&
     !key.shift &&
     !hasModifier(key)
+  const isPageUp = key.name === 'pageup' && !hasModifier(key)
+  const isPageDown = key.name === 'pagedown' && !hasModifier(key)
 
   // Priority 0: Out of credits mode - Enter opens buy credits page
   if (state.inputMode === 'outOfCredits') {
@@ -312,12 +318,20 @@ export function resolveChatKeyboardAction(
     return { type: 'unfocus-agent' }
   }
 
-  // Priority 13: Paste (ctrl-v)
+  // Priority 13: Scroll with PageUp/PageDown
+  if (isPageUp) {
+    return { type: 'scroll-up' }
+  }
+  if (isPageDown) {
+    return { type: 'scroll-down' }
+  }
+
+  // Priority 14: Paste (ctrl-v)
   if (isCtrlV) {
     return { type: 'paste' }
   }
 
-  // Priority 14: Exit app (ctrl-c double-tap)
+  // Priority 15: Exit app (ctrl-c double-tap)
   if (isCtrlC) {
     if (state.nextCtrlCWillExit) {
       return { type: 'exit-app' }