diff --git a/.jules/palette.md b/.jules/palette.md
new file mode 100644
index 00000000..89cec960
--- /dev/null
+++ b/.jules/palette.md
@@ -0,0 +1,3 @@
+## 2023-10-13 - 세션 타임라인 리본 툴팁 키보드 접근성 개선
+**Learning:** 마우스 호버(`onMouseEnter`, `onMouseMove`)에만 의존하여 툴팁을 띄우는 커스텀 UI 패턴에서는 키보드 사용자(Tab 키 이동)가 정보를 전혀 확인할 수 없는 문제가 발생할 수 있습니다.
+**Action:** 인터랙티브 요소(버튼 등)에 호버 액션을 추가할 때는 항상 `onFocus`와 `onBlur`를 병행하여 키보드 포커스 시에도 동일한 컨텍스트(툴팁 등)가 제공되도록 설계해야 합니다.
diff --git a/packages/web/src/components/dashboard/session-activity-ribbon.tsx b/packages/web/src/components/dashboard/session-activity-ribbon.tsx
index 12228af3..bc2c5b94 100644
--- a/packages/web/src/components/dashboard/session-activity-ribbon.tsx
+++ b/packages/web/src/components/dashboard/session-activity-ribbon.tsx
@@ -158,13 +158,21 @@ export function SessionActivityRibbon({
   const [hover, setHover] = useState<HoverState | null>(null)
   const containerRef = useRef<HTMLDivElement>(null)
 
-  const trackMouse = useCallback((e: React.MouseEvent) => {
+  const trackMouse = useCallback((e: React.MouseEvent | React.FocusEvent) => {
     const rect = containerRef.current?.getBoundingClientRect()
-    if (!rect) return e.clientX
-    return e.clientX - rect.left
+    if (!rect) {
+      if ('clientX' in e) return e.clientX
+      return 0
+    }
+    if ('clientX' in e) {
+      return e.clientX - rect.left
+    }
+    // For focus events, calculate the center of the focused element relative to the container
+    const targetRect = (e.target as HTMLElement).getBoundingClientRect()
+    return targetRect.left - rect.left + targetRect.width / 2
   }, [])
 
-  const handleEventHover = useCallback((idx: number) => (e: React.MouseEvent) => {
+  const handleEventHover = useCallback((idx: number) => (e: React.MouseEvent | React.FocusEvent) => {
     setHover({ kind: 'event', idx, x: trackMouse(e) })
   }, [trackMouse])
 
@@ -173,7 +181,7 @@ export function SessionActivityRibbon({
     toolName: string,
     count: number,
     firstEvent: TimelineEvent,
-  ) => (e: React.MouseEvent) => {
+  ) => (e: React.MouseEvent | React.FocusEvent) => {
     setHover({
       kind: 'merged',
       firstIdx,
@@ -200,6 +208,8 @@ export function SessionActivityRibbon({
             onMouseEnter={handleEventHover(idx)}
             onMouseMove={handleEventHover(idx)}
             onMouseLeave={() => setHover(null)}
+            onFocus={handleEventHover(idx)}
+            onBlur={() => setHover(null)}
             aria-label={`Event ${idx + 1}`}
             aria-current={selected ? 'true' : undefined}
             className={`h-full ${bg} transition-opacity ${
@@ -225,6 +235,8 @@ export function SessionActivityRibbon({
             onMouseEnter={handleEventHover(idx)}
             onMouseMove={handleEventHover(idx)}
             onMouseLeave={() => setHover(null)}
+            onFocus={handleEventHover(idx)}
+            onBlur={() => setHover(null)}
             aria-label={`Event ${idx + 1}`}
             aria-current={selected ? 'true' : undefined}
             className={`h-full ${bg} transition-opacity ${
@@ -288,6 +300,13 @@ export function SessionActivityRibbon({
             group.items[0].event,
           )}
           onMouseLeave={() => setHover(null)}
+          onFocus={handleMergedHover(
+            firstIdx,
+            group.toolName,
+            group.items.length,
+            group.items[0].event,
+          )}
+          onBlur={() => setHover(null)}
           aria-label={`Expand ${group.toolName} group, ${group.items.length} events`}
           className={`relative h-full ${segmentVisuals(group.items[0].event).bg} transition-opacity hover:opacity-70`}
         >