diff --git a/.Jules/palette.md b/.Jules/palette.md
index 432aa05f..e2a98206 100644
--- a/.Jules/palette.md
+++ b/.Jules/palette.md
@@ -16,3 +16,9 @@
 ## 2026-06-25 - Explicit Loading Feedback for Intent Generation
 **Learning:** In deeply nested data-action layouts (like DataLayout's document and thread intent generation), missing explicit loading spinners and text changes (e.g., from "실행" to "처리 중") leaves users guessing if the button click registered. `disabled` alone is insufficient feedback for intent-checking actions which often take several seconds.
 **Action:** When adding asynchronous intent check actions (like WebDAV or thread validations), always combine `disabled={isLoading}`, `aria-busy={isLoading}`, a `Loader2` spinner, and a dynamic text label (e.g. `isLoading ? '점검 중' : '점검'`) to give immediate, unambiguous feedback.
+## 2024-07-06 - Ensure active tabs use `aria-current` and keyboard focus styles
+**Learning:** When using raw HTML `<button>` elements to create custom active tabs, missing `aria-current="page"` fails to expose the active state to screen readers. Also, missing Tailwind `focus-visible` utilities prevents keyboard navigation users from seeing which tab is focused.
+**Action:** Always include `aria-current={active ? 'page' : undefined}` (and optionally `aria-pressed={active}`) on active tabs, and explicitly add Tailwind's `focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring/40 focus-visible:ring-offset-1 focus-visible:ring-offset-background` to maintain keyboard accessibility and visual focus indicators when using raw HTML buttons over UI components.
+## 2024-07-06 - Update: Use semantic `role="tab"` for view mode toggles
+**Learning:** For view mode toggles acting as tabs (switching content panes without navigating away), using `aria-current="page"` or `aria-pressed` is incorrect.
+**Action:** When implementing view toggles, wrap the buttons in a container with `role="tablist"` and give each button `role="tab"` and `aria-selected={active}` to correctly convey the semantic relationship to screen readers.
diff --git a/frontend/src/components/ProjectsLayout.tsx b/frontend/src/components/ProjectsLayout.tsx
index d57b71ef..cee5e885 100644
--- a/frontend/src/components/ProjectsLayout.tsx
+++ b/frontend/src/components/ProjectsLayout.tsx
@@ -851,13 +851,15 @@ export function ProjectsLayout() {
                 </button>
               ))}
             </div>
-            <div className="flex overflow-x-auto rounded-md border border-border">
+            <div className="flex overflow-x-auto rounded-md border border-border" role="tablist" aria-label="프로젝트 뷰 모드">
               {(['프로젝트 상세', '마일스톤', '의사결정 로그'] as ProjectViewMode[]).map((mode) => (
                 <button
                   key={mode}
                   type="button"
+                  role="tab"
                   onClick={() => setViewMode(mode)}
-                  className={`min-h-9 shrink-0 px-3 text-xs font-semibold transition-colors sm:px-4 sm:text-sm ${viewMode === mode ? 'bg-primary text-primary-foreground' : 'bg-background hover:bg-secondary'}`}
+                  aria-selected={viewMode === mode}
+                  className={`min-h-9 shrink-0 px-3 text-xs font-semibold transition-colors focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-ring/40 focus-visible:ring-offset-1 focus-visible:ring-offset-background sm:px-4 sm:text-sm ${viewMode === mode ? 'bg-primary text-primary-foreground' : 'bg-background hover:bg-secondary'}`}
                 >
                   {mode}
                 </button>