Conflict Resolution

When Conflicts Occur

A data conflict occurs when the same record is modified from different sources before the changes have been synchronized. Typical scenarios:

Two Devices Offline

Two team members work offline on different devices and modify the same record. For example:

• An operator at the entrance checks in a participant and adds the comment "VIP"
• A manager on another device checks in the same participant and adds the comment "Extra seat"
• When connectivity is restored, both changes are sent to the server

Offline + Online

One team member works offline, another works online:

• A manager at their computer (online) changes a registration status
• An operator at the venue (offline) changes the same status
• During synchronization, the offline change conflicts with the already-applied online change

When Conflicts Are Unlikely

In practice, conflicts occur rarely because:

• Different team members usually work with different participants
• Check-in is a unidirectional operation (marking arrival); a check-in conflict is only possible with a double scan
• Payment operations are protected by an idempotency key

Strategy: Last-Writer-Wins (Free, Pro)

On the Free and Pro plans, the automatic last-writer-wins strategy is used:

How It Works

1. During synchronization, the server compares the clientTs timestamps of the conflicting changes.
2. The change with the later timestamp is automatically saved.
3. The change with the earlier timestamp is overwritten.
4. Both changes are recorded in the audit log (even the overwritten one).

Example

Advantages and Limitations

Advantages:

• Fully automatic -- requires no user intervention
• Does not interrupt the workflow
• Suitable for most scenarios (check-in, simple statuses)

Limitations:

• The earlier change is lost without notification
• No ability to merge two changes
• For critically important data, this may lead to information loss

Strategy: Optimistic Locking + Merge UI (Business, Enterprise)

On the Business and Enterprise plans, an interactive conflict resolution strategy with a visual interface is available.

How It Works

1. During synchronization, the server detects a conflict (the record was modified after the last state known to the client).
2. Instead of automatically overwriting, the server returns both versions.
3. The user is shown the merge UI -- a version comparison interface.
4. The user chooses which version to keep or merges the changes manually.

Merge UI

The conflict resolution interface shows:

• Left column: your version (local change)

  • Change author
  • Change time
  • Modified fields with their values

• Right column: server version (someone else's change)

  • Change author
  • Change time
  • Modified fields with their values

• Actions:

  • "Keep my version" -- your change overwrites the server version
  • "Accept server version" -- the server version is kept, your change is discarded
  • "Merge" -- you manually select the value for each field

Example

You can accept the check-in from both versions (they match), take your comment, and use the server's status.

Optimistic Locking

Under the hood, optimistic locking is used:

• Each record has a version (version counter)
• When sending a change, the client specifies which version it was based on
• If the version on the server has changed (someone else updated the record), the server returns a conflict
• The client shows the merge UI

Conflict Notifications

When a conflict is detected:

Free / Pro: a toast notification "Data conflict resolved automatically" (informational, no action needed).

Business / Enterprise: a toast notification "Conflict detected. Your input is needed" with a button to open the merge UI. The conflict blocks synchronization of remaining changes until it is resolved.

Recommendations

• Assign areas of responsibility. Assign team members to different groups of participants or check-in zones to minimize conflicts.
• Sync more often. Short periods of offline work reduce the likelihood of conflicts.
• Use the merge UI for critical data. If your team actively works with the same records, consider upgrading to Business for access to interactive conflict resolution.