First commit

frontend/app/composables/useSignInPopup.ts

@@ -0,0 +1,26 @@
+/* Shared open state for the sign-in popup (AuthModal.vue), shaped like
+   useSearch and useSettings. The account row in the sidebar, the gate on the
+   editor pages and the editor itself all reach the popup through this, so only
+   one is ever on screen. */
+
+export type SignInMode = 'signin' | 'signup'
+
+export function useSignInPopup() {
+  const open = useState<boolean>('signin:open', () => false)
+  const mode = useState<SignInMode>('signin:mode', () => 'signin')
+  /* Why the popup was opened — shown above the form when a session has just
+     expired mid-edit, so the person knows what happened to their save. */
+  const notice = useState<string>('signin:notice', () => '')
+
+  function show(opts: { mode?: SignInMode; notice?: string } = {}) {
+    mode.value = opts.mode ?? 'signin'
+    notice.value = opts.notice ?? ''
+    open.value = true
+  }
+
+  function hide() {
+    open.value = false
+  }
+
+  return { open, mode, notice, show, hide }
+}