expose whether we already have a 4s key,to show the 4s setup in settings

it's a tri-state of null/false/true with null meaning we need to
go online first to know as only then we try to setup session backup

src/domain/session/settings/SessionBackupViewModel.js

@@ -23,6 +23,9 @@ export class SessionBackupViewModel extends ViewModel {
         this._showKeySetup = true;
         this._error = null;
         this._isBusy = false;
+        this.track(this._session.hasSecretStorageKey.subscribe(() => {
+            this.emitChange("status");
+        }));
     }
     
     get isBusy() {
@@ -37,7 +40,11 @@ export class SessionBackupViewModel extends ViewModel {
         if (this._session.sessionBackup) {
             return "enabled";
         } else {
-            return this._showKeySetup ? "setupKey" : "setupPhrase";
+            if (this._session.hasSecretStorageKey.get() === false) {
+                return this._showKeySetup ? "setupKey" : "setupPhrase";
+            } else {
+                return "pending";
+            }
         }
     }
 

src/matrix/Session.js

@@ -63,6 +63,7 @@ export class Session {
         this._olmWorker = olmWorker;
         this._cryptoDriver = cryptoDriver;
         this._sessionBackup = null;
+        this._hasSecretStorageKey = new ObservableValue(null);
 
         if (olm) {
             this._olmUtil = new olm.Utility();
@@ -82,6 +83,10 @@ export class Session {
         return this._e2eeAccount?.identityKeys.ed25519;
     }
 
+    get hasSecretStorageKey() {
+        return this._hasSecretStorageKey;
+    }
+
     get deviceId() {
         return this._sessionInfo.deviceId;
     }
@@ -175,6 +180,9 @@ export class Session {
         if (!this._olm) {
             throw new Error("olm required");
         }
+        if (this._sessionBackup) {
+            return false;
+        }
         const key = await ssssKeyFromCredential(type, credential, this._storage, this._cryptoDriver, this._olm);
         // and create session backup, which needs to read from accountData
         const readTxn = this._storage.readTxn([
@@ -193,6 +201,7 @@ export class Session {
             throw err;
         }
         await writeTxn.complete();
+        this._hasSecretStorageKey.set(true);
     }
 
     async _createSessionBackup(ssssKey, txn) {
@@ -297,6 +306,7 @@ export class Session {
                 // txn will end here as this does a network request
                 await this._createSessionBackup(ssssKey, txn);
             }
+            this._hasSecretStorageKey.set(!!ssssKey);
         }
         // restore unfinished operations, like sending out room keys
         const opsTxn = this._storage.readWriteTxn([

src/ui/web/session/settings/SessionBackupSettingsView.js

@@ -15,6 +15,7 @@ limitations under the License.
 */
 
 import {TemplateView} from "../../general/TemplateView.js";
+import {StaticView} from "../../general/StaticView.js";
 
 export class SessionBackupSettingsView extends TemplateView {
     render(t, vm) {
@@ -23,6 +24,7 @@ export class SessionBackupSettingsView extends TemplateView {
                 case "enabled": return new TemplateView(vm, renderEnabled)
                 case "setupKey": return new TemplateView(vm, renderEnableFromKey)
                 case "setupPhrase": return new TemplateView(vm, renderEnableFromPhrase)
+                case "pending": return new StaticView(vm, t => t.p(vm.i18n`Waiting to go online…`))
             }
         });
     }