Handle restore on reinstall sync scenario

[MiSikora]

Task/Issue URL: https://app.asana.com/1/137249556945/project/1216103556496795/task/1216422585541212?focus=true
Tech Design URL (if applicable): https://app.asana.com/1/137249556945/project/1216103556496795/task/1216509582049467?focus=true
API Proposals URL(s) (if applicable): N/A

Description

Adds the recover on reinstall step to the simplified Sync & Backup setup. When the app finds Sync & Backup recovery data preserved from a previous install, starting any sync setup from the simplified Sync Settings first offers to resume the previous session instead of starting from scratch.

• A new screen titled "Your previous Sync & Backup session is ready." is shown after device authentication when the user taps the "Sync This Device" toggle, "Sync With Another Device", or "I Have a Recovery Code". It only appears when preserved recovery data exists in Block Store and the syncAutoRestore feature flag is enabled.
• "Resume Sync & Backup" feeds the preserved recovery code into the existing recovery connection flow. On success, the recovery code confirmation screen opens and Sync Settings switches to the enabled state. The preserved recovery data is kept.
• If the preserved data cannot be read, a generic error dialog is shown and the user stays on the screen.
• If the recovery itself fails, the standard recovery error dialog is shown. Dismissing it returns to Sync Settings and the setup is treated as cancelled.
• "Set Up New Sync" clears the preserved recovery data (the server account is untouched) and continues into whichever setup flow the user originally tapped: create account for "Sync This Device", the QR scanner for "Sync With Another Device", or the recovery screen for "I Have a Recovery Code". If clearing fails, an error dialog is shown and the original flow does not start.
• Closing the screen with the close button or system back keeps the preserved data, so the offer appears again on the next setup attempt.

The screen reports its outcome through the new PreviousSessionReadyContract. A finished recovery is returned as a SyncPairingResult and handled by SyncActivity through the existing handlePairingResult, so completion behaves exactly like the manual recovery flow.

Steps to test this PR

Setup

• Install the internal build on a device with Google Play services and a device lock set.
• On another device signed into Sync & Backup, copy the recovery code.
• On the test device, make sure sync is off.
• Open Sync Dev Settings.
• Paste the code into the "Recovery code" field in the "Persistent Storage / Block Store" section.
• Tap "Write".

Resume the previous session

• Open Sync Dev Settings.
• Tap "Launch Sync Settings V2".
• Tap "Sync With Another Device".
• Complete the device authentication prompt.
• Verify the "Your previous Sync & Backup session is ready." screen is shown.
• Tap "Resume Sync & Backup".
• Verify the connecting screen appears with the "Recovering data" headline.
• Verify the recovery code screen opens with the headline "<this device's name> has been added to Sync & Backup".
• Tap "Done".
• Verify Sync Settings shows sync as enabled.
• Verify in Sync Dev Settings that "Current stored value (SyncRecovery key)" still shows the stored payload.

Set up new sync instead

• With sync off and a preserved session stored, open Sync Settings V2.
• Turn on the "Sync This Device" toggle.
• Complete the device authentication prompt.
• Tap "Set Up New Sync".
• Verify the Sync This Device screen opens.
• Verify in Sync Dev Settings that "Current stored value (SyncRecovery key)" is now empty.

Dismiss the offer

• With sync off and a preserved session stored, open Sync Settings V2.
• Tap "I Have a Recovery Code".
• Complete the device authentication prompt.
• Tap the close button.
• Verify you are back in Sync Settings with sync still off.
• Tap "I Have a Recovery Code" again.
• Complete the device authentication prompt.
• Verify the previous session screen is shown again.

No preserved session

• In Sync Dev Settings, tap "Clear" in the "Persistent Storage / Block Store" section.
• Open Sync Settings V2.
• Tap "Sync With Another Device".
• Complete the device authentication prompt.
• Verify the QR scanner opens directly without the previous session screen.

UI changes

---

Note

Medium Risk
Touches sync setup routing and recovery-code exchange after reinstall; mistakes could block setup or mishandle preserved credentials, though flows reuse existing pairing/recovery infrastructure and add tests.

Overview
When preserved Block Store recovery data exists and auto-restore is enabled, simplified Sync Settings now shows a previous session ready screen after device auth instead of jumping straight into setup.

Resume Sync & Backup returns the stored recovery code through PreviousSessionReadyContract and SyncActivity runs the existing ExchangeSyncCode recovery path, then the normal recovery-code completion flow. Set Up New Sync clears preserved local auto-restore data (server account unchanged) and continues the flow the user originally chose—sync this device, pair with another device, or manual recovery—via the newly implemented LaunchOriginalFlow handling. Dismissal leaves preserved data so the offer can appear again.

SyncActivityViewModel resets the “sync this device” in-progress UI if clearing preserved data fails on skip-restore. Adds screen layout, illustration, strings, and ViewModel tests for the new step.

^{Reviewed by Cursor Bugbot for commit fe4ce10. Bugbot is set up for automated code reviews on this repo. Configure here.}

[MiSikora]

• Replace ScrollView with NestedScrollView in sync settings #9424
• Simplified sync translations #9414
• Parameterize sync pixels tests #9413
• Apply correct edge to edge handling in simplified sync #9412
• Add simplified sync pixels #9401
• Clean up sync code before integrating pixels #9386
• Avoid signing out of a device when renaming it #9374
• Handle simplified sync deep linking #9373
• Handle restore on reinstall sync scenario #9368 👈 (View in Graphite)
• Simplified sync UI updates #9363
• Handle v1 exchange sync codes #9362
• Handle sync recovery basic scenario #9356
• Add syncing with another device logic and navigation #9343
• Add generic handling of v1 sync errors #9337
• Add sync with another device UI #9334
• Detect scanned QR sync codes #9333
• Handle sync code pasting #9332
• Refactor simplified sync class names #9329
• Handle sync logic on the displayed QR code page #9328
• Display sync QR code in simplified sync #9321
• Make remove device dialog destructive #9317
• Mitigate sync settings UI race condtions #9316
• develop

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[MiSikora]

Merge activity

• Aug 4, 12:40 PM UTC: A user started a stack merge that includes this pull request via Graphite.
• Aug 4, 1:11 PM UTC: The Graphite merge of this pull request was cancelled.
• Aug 4, 1:39 PM UTC: A user started a stack merge that includes this pull request via Graphite.
• Aug 4, 2:26 PM UTC: Graphite rebased this pull request as part of a merge.
• Aug 4, 2:40 PM UTC: @MiSikora merged this pull request with Graphite.

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[cursor]

Missing onConnectionCancelled on auth cancel for non-SYNC_THIS_DEVICE flows

Low Severity

The ShowPreviousSessionReady handler calls viewModel.onConnectionCancelled() in the previousSessionReadyLauncher dismiss callback but omits it in the onCancelled and onError authentication callbacks. For the SYNC_THIS_DEVICE flow, onSyncThisDevice() calls syncSetupWideEvent.onFlowStarted(), so a subsequent onConnectionCancelled() (which fires syncSetupWideEvent.onFlowCancelled()) is needed to properly close the wide event. When auth is cancelled or errors, only onSyncThisDeviceCanceled() is called, leaving the wide event flow open without a matching cancellation signal.

 

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