fix(signals): expose useSessionStorage as a bare window global

window.useLocalStorage was assigned and window.useSessionStorage was not, so
the two composables behaved differently depending on where they were called
from. Both are in STX_RUNTIME_GLOBALS, so a <script client> block receives
either through the setup destructure and the gap is invisible there — but code
reading the window global directly (a plain <script>, or a bundled module the
auto-import transform didn't rewrite) found useLocalStorage defined and
useSessionStorage undefined.

Covered in use-storage-guards.test.ts against both window and window.stx;
verified the assertion fails without the assignment.

Author: glennmichael123

packages/stx/src/signals.ts

@@ -5946,6 +5946,12 @@ else {
   window.nextTick = nextTick;
   window.useAsync = useAsync;
   window.useLocalStorage = useLocalStorage;
+  // Paired with the line above. Both are in STX_RUNTIME_GLOBALS, so a
+  // <script client> block gets either via the setup destructure — but code
+  // that reads the bare window global directly (a plain <script>, or a
+  // bundled module that wasn't rewritten) found useLocalStorage defined and
+  // useSessionStorage undefined.
+  window.useSessionStorage = useSessionStorage;
   window.useEventListener = useEventListener;
   window.useWebSocket = useWebSocket;
   window.useColorMode = useColorMode;

packages/stx/test/signals/use-storage-guards.test.ts

@@ -323,3 +323,19 @@ describe('useLocalStorage guards (module impl)', () => {
     expect(ref.value).toBe('default')
   })
 })
+
+describe('bare window globals', () => {
+  // Both names are in STX_RUNTIME_GLOBALS, so a <script client> block gets
+  // either through the setup destructure. Code reading the window global
+  // directly — a plain <script>, or a bundled module that wasn't rewritten —
+  // depends on these assignments, and useSessionStorage was missing one.
+  it('exposes both storage composables on window', () => {
+    expect(typeof g.window.useLocalStorage).toBe('function')
+    expect(typeof g.window.useSessionStorage).toBe('function')
+  })
+
+  it('exposes both on window.stx', () => {
+    expect(typeof g.window.stx.useLocalStorage).toBe('function')
+    expect(typeof g.window.stx.useSessionStorage).toBe('function')
+  })
+})