diff --git a/.Jules/palette.md b/.Jules/palette.md
index 5c1c1698..033000b7 100644
--- a/.Jules/palette.md
+++ b/.Jules/palette.md
@@ -37,3 +37,7 @@
 ## 2026-07-02 - Inline clear buttons preserve focus
 **Learning:** Inline clear buttons often unmount immediately after clearing state, which can drop keyboard focus to the document body.
 **Action:** Move focus back to the owning input before clearing state, and cover the behavior with a DOM focus test.
+
+## 2026-07-20 - Adding aria-disabled styles to UI primitive buttons
+**Learning:** While replacing the native `disabled` attribute with `aria-disabled="true"` correctly enables pointer events for tooltips and preserves keyboard tab order, custom primitive components (like `<Button />`) often rely on the native `disabled:` pseudoclass for their visual state (e.g., opacity and cursor). If the base component styles aren't updated, they may visually appear fully enabled when only `aria-disabled` is used.
+**Action:** When updating a custom `<Button>` component or native `<button>` element to use `aria-disabled="true"`, ensure its base Tailwind styles or variants also include corresponding `aria-disabled:` classes (like `aria-disabled:opacity-50 aria-disabled:cursor-not-allowed`) so that it visually reflects its disabled state.
diff --git a/apps/desktop/src/features/score/ScoreView.test.tsx b/apps/desktop/src/features/score/ScoreView.test.tsx
index de4ccb95..371e99f2 100644
--- a/apps/desktop/src/features/score/ScoreView.test.tsx
+++ b/apps/desktop/src/features/score/ScoreView.test.tsx
@@ -95,9 +95,9 @@ describe("ScoreView", () => {
     render(<ScoreView song={song} projectId={null} onSongUpdate={vi.fn()} />);
 
     expect(screen.getByText("Scores attach to the active analysis project.")).toBeInTheDocument();
-    expect(screen.getByRole("button", { name: "Add score" })).toBeDisabled();
-    expect(screen.getByRole("button", { name: "Open score: opener.pdf" })).toBeDisabled();
-    expect(screen.getByRole("button", { name: "Remove: opener.pdf" })).toBeDisabled();
+    expect(screen.getByRole("button", { name: "Add score" })).toHaveAttribute("aria-disabled", "true");
+    expect(screen.getByRole("button", { name: "Open score: opener.pdf" })).toHaveAttribute("aria-disabled", "true");
+    expect(screen.getByRole("button", { name: "Remove: opener.pdf" })).toHaveAttribute("aria-disabled", "true");
 
     fireEvent.click(screen.getByRole("button", { name: "Open score: opener.pdf" }));
     expect(mockInvoke).not.toHaveBeenCalled();
diff --git a/apps/desktop/src/features/score/ScoreView.tsx b/apps/desktop/src/features/score/ScoreView.tsx
index 72732450..cf1a4348 100644
--- a/apps/desktop/src/features/score/ScoreView.tsx
+++ b/apps/desktop/src/features/score/ScoreView.tsx
@@ -134,8 +134,9 @@ export function ScoreView({ song, projectId, onSongUpdate }: ScoreViewProps) {
               <p className="mt-1 max-w-2xl text-sm text-slate-400">{t("scoreViewSubtitle")}</p>
             </div>
             <Button
-              onClick={projectId ? () => void handleAttach(projectId) : undefined}
-              disabled={!projectId || isAttaching}
+              onClick={projectId && !isAttaching ? () => void handleAttach(projectId) : undefined}
+              aria-disabled={!projectId || isAttaching ? "true" : undefined}
+              title={!projectId ? t("scoreRequiresProject") : undefined}
               variant="secondary"
               className="min-h-11 border border-cyan-300/20 bg-cyan-300/10 font-semibold text-cyan-50 hover:bg-cyan-300/20"
             >
@@ -184,10 +185,11 @@ export function ScoreView({ song, projectId, onSongUpdate }: ScoreViewProps) {
                     <button
                       type="button"
                       onClick={projectId ? () => void openAttachment(projectId, attachment) : undefined}
-                      disabled={!projectId}
+                      aria-disabled={!projectId ? "true" : undefined}
+                      title={!projectId ? t("scoreRequiresProject") : undefined}
                       aria-current={selected?.id === attachment.id ? "true" : undefined}
                       aria-label={`${t("scoreOpen")}: ${attachment.fileName}`}
-                      className="flex min-h-10 min-w-0 flex-1 items-center gap-2 text-left text-sm font-semibold text-slate-100 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-cyan-300 disabled:cursor-not-allowed disabled:opacity-60"
+                      className="flex min-h-10 min-w-0 flex-1 items-center gap-2 text-left text-sm font-semibold text-slate-100 focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-cyan-300 aria-disabled:cursor-not-allowed aria-disabled:opacity-60"
                     >
                       <FileMusic className="size-4 shrink-0 text-cyan-300" aria-hidden="true" />
                       <span className="truncate">{attachment.fileName}</span>
@@ -196,7 +198,8 @@ export function ScoreView({ song, projectId, onSongUpdate }: ScoreViewProps) {
                       variant="outline"
                       size="icon"
                       onClick={projectId ? () => void handleRemove(projectId, attachment) : undefined}
-                      disabled={!projectId}
+                      aria-disabled={!projectId ? "true" : undefined}
+                      title={!projectId ? t("scoreRequiresProject") : undefined}
                       aria-label={`${t("scoreRemove")}: ${attachment.fileName}`}
                       className="size-10 border-rose-300/25 text-rose-200 hover:bg-rose-400/10"
                     >
diff --git a/apps/desktop/src/features/score/ScoreViewer.test.tsx b/apps/desktop/src/features/score/ScoreViewer.test.tsx
index 3ac2dd60..9b9d89db 100644
--- a/apps/desktop/src/features/score/ScoreViewer.test.tsx
+++ b/apps/desktop/src/features/score/ScoreViewer.test.tsx
@@ -120,8 +120,8 @@ describe("ScoreViewer", () => {
       expect(page.render).toHaveBeenCalled();
     });
     expect(page.getViewport).toHaveBeenCalledWith({ scale: 1 });
-    expect(screen.getByRole("button", { name: "Previous page" })).toBeDisabled();
-    expect(screen.getByRole("button", { name: "Next page" })).toBeEnabled();
+    expect(screen.getByRole("button", { name: "Previous page" })).toHaveAttribute("aria-disabled", "true");
+    expect(screen.getByRole("button", { name: "Next page" })).not.toHaveAttribute("aria-disabled");
   });
 
   it("shows the file name when provided", async () => {
@@ -174,14 +174,14 @@ describe("ScoreViewer", () => {
     expect(await screen.findByText("Page 1 of 3")).toBeInTheDocument();
     const previousButton = screen.getByRole("button", { name: "Previous page" });
     const nextButton = screen.getByRole("button", { name: "Next page" });
-    expect(previousButton).toBeDisabled();
+    expect(previousButton).toHaveAttribute("aria-disabled", "true");
 
     fireEvent.click(nextButton);
     expect(screen.getByText("Page 2 of 3")).toBeInTheDocument();
 
     fireEvent.click(nextButton);
     expect(screen.getByText("Page 3 of 3")).toBeInTheDocument();
-    expect(nextButton).toBeDisabled();
+    expect(nextButton).toHaveAttribute("aria-disabled", "true");
 
     await waitFor(() => {
       expect(doc.getPage).toHaveBeenCalledWith(3);
diff --git a/apps/desktop/src/features/score/ScoreViewer.tsx b/apps/desktop/src/features/score/ScoreViewer.tsx
index 82692469..d09decd7 100644
--- a/apps/desktop/src/features/score/ScoreViewer.tsx
+++ b/apps/desktop/src/features/score/ScoreViewer.tsx
@@ -258,6 +258,7 @@ export function ScoreViewer({ data, fileName, onStatusChange }: ScoreViewerProps
               size="icon-lg"
               className="size-12"
               aria-label={t("scoreViewerZoomOut")}
+              title={t("scoreViewerZoomOut")}
               onClick={zoomOut}
             >
               <ZoomOut aria-hidden="true" />
@@ -267,6 +268,7 @@ export function ScoreViewer({ data, fileName, onStatusChange }: ScoreViewerProps
               size="icon-lg"
               className="size-12"
               aria-label={t("scoreViewerZoomIn")}
+              title={t("scoreViewerZoomIn")}
               onClick={zoomIn}
             >
               <ZoomIn aria-hidden="true" />
@@ -275,6 +277,7 @@ export function ScoreViewer({ data, fileName, onStatusChange }: ScoreViewerProps
               variant={fitWidth ? "secondary" : "outline"}
               className="h-12 px-4 text-base"
               aria-label={t("scoreViewerFitWidth")}
+              title={t("scoreViewerFitWidth")}
               aria-pressed={fitWidth}
               onClick={fitToWidth}
             >
@@ -292,8 +295,9 @@ export function ScoreViewer({ data, fileName, onStatusChange }: ScoreViewerProps
             size="icon-lg"
             className="size-14"
             aria-label={t("scoreViewerPrevPage")}
-            disabled={pageNumber <= 1}
-            onClick={goToPreviousPage}
+            title={t("scoreViewerPrevPage")}
+            aria-disabled={pageNumber <= 1 ? "true" : undefined}
+            onClick={pageNumber <= 1 ? undefined : goToPreviousPage}
           >
             <ChevronLeft className="size-6" aria-hidden="true" />
           </Button>
@@ -305,8 +309,9 @@ export function ScoreViewer({ data, fileName, onStatusChange }: ScoreViewerProps
             size="icon-lg"
             className="size-14"
             aria-label={t("scoreViewerNextPage")}
-            disabled={pageNumber >= pageCount}
-            onClick={goToNextPage}
+            title={t("scoreViewerNextPage")}
+            aria-disabled={pageNumber >= pageCount ? "true" : undefined}
+            onClick={pageNumber >= pageCount ? undefined : goToNextPage}
           >
             <ChevronRight className="size-6" aria-hidden="true" />
           </Button>