fix(ui): trigger sidebar peek on iPad Safari with a trackpad

iPadOS Safari never flips the `(hover: hover) and (pointer: fine)` media
query when a trackpad/mouse is attached, so `pointerCanPeek` stayed false
and the collapsed-sidebar hover peek never opened even though a real cursor
was driving the UI (PAP-10725).

Detect a fine pointer at runtime: a genuine mouse/trackpad emits pointer
events with `pointerType: "mouse"` (touch → "touch", Pencil → "pen"), so
listening for the first such event unlocks peek without false-positives on
touch-only input. Peek capability is a one-way latch for the session.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

ui/src/context/SidebarContext.test.tsx

@@ -248,6 +248,42 @@ describe("SidebarContext", () => {
       act(() => capturedValue?.setPeeking(true));
       expect(capturedValue?.peeking).toBe(false);
     });
+
+    // iPadOS Safari keeps the hover/pointer media query false even with a
+    // trackpad attached (PAP-10725); a real cursor still emits "mouse" pointer
+    // events, which must unlock peek at runtime.
+    it("peeks once a mouse-type pointer event is seen (iPad + trackpad)", () => {
+      localStorage.setItem(COLLAPSED_STORAGE_KEY, "1");
+      setViewport({ mobile: false, hoverFine: false });
+      active = renderProvider();
+      expect(capturedValue?.collapsed).toBe(true);
+
+      // No cursor seen yet → peek stays gated despite the media query.
+      act(() => capturedValue?.setPeeking(true));
+      expect(capturedValue?.peeking).toBe(false);
+
+      // A trackpad/mouse moves: a "mouse" pointer event unlocks peek.
+      act(() => {
+        const e = new Event("pointermove");
+        (e as unknown as { pointerType: string }).pointerType = "mouse";
+        window.dispatchEvent(e);
+      });
+      expect(capturedValue?.peeking).toBe(true);
+    });
+
+    it("ignores touch pointer events (touch-only stays gated)", () => {
+      localStorage.setItem(COLLAPSED_STORAGE_KEY, "1");
+      setViewport({ mobile: false, hoverFine: false });
+      active = renderProvider();
+
+      act(() => capturedValue?.setPeeking(true));
+      act(() => {
+        const e = new Event("pointerover");
+        (e as unknown as { pointerType: string }).pointerType = "touch";
+        window.dispatchEvent(e);
+      });
+      expect(capturedValue?.peeking).toBe(false);
+    });
   });
 
   describe("back-compat", () => {

ui/src/context/SidebarContext.tsx

@@ -112,11 +112,36 @@ export function SidebarProvider({ children }: { children: ReactNode }) {
   useEffect(() => {
     if (typeof window.matchMedia !== "function") return;
     const mql = window.matchMedia(PEEK_POINTER_QUERY);
-    const onChange = (e: MediaQueryListEvent) => setPointerCanPeek(e.matches);
+    // Latch on only — see the runtime detection below for why this never flips
+    // back to false.
+    const onChange = (e: MediaQueryListEvent) => {
+      if (e.matches) setPointerCanPeek(true);
+    };
     mql.addEventListener("change", onChange);
     return () => mql.removeEventListener("change", onChange);
   }, []);
 
+  // iPadOS Safari does not flip the `(hover: hover) and (pointer: fine)` media
+  // query when a trackpad/mouse is attached, so the query above stays false even
+  // though a real cursor is driving the UI — and hover-peek never triggers
+  // (PAP-10725). Detect a fine pointer at runtime instead: a genuine
+  // mouse/trackpad emits pointer events with `pointerType: "mouse"`, whereas
+  // touch reports "touch" and the Pencil reports "pen", so this never enables on
+  // touch-only input. Treat peek capability as a one-way latch — once a cursor
+  // has been seen we keep peek available for the session.
+  useEffect(() => {
+    if (pointerCanPeek || typeof window.PointerEvent !== "function") return;
+    const onPointer = (e: PointerEvent) => {
+      if (e.pointerType === "mouse") setPointerCanPeek(true);
+    };
+    window.addEventListener("pointerover", onPointer, { passive: true });
+    window.addEventListener("pointermove", onPointer, { passive: true });
+    return () => {
+      window.removeEventListener("pointerover", onPointer);
+      window.removeEventListener("pointermove", onPointer);
+    };
+  }, [pointerCanPeek]);
+
   // Precedence (highest wins): forced (active secondary sidebar) > explicit user
   // pin > route request > default expanded. The force is ephemeral and never
   // touches the persisted pin, so dropping it restores the user's preference.