Ideally the source article of a translation should reflect the latest version. When small changes happen to the source article, those can be updated automatically. However, in some other cases where changes affect the content more heavily, it is not possible to update the source article without losing the translation contents.
In such cases, we want to show a warning about the original translation having changed too much. This warning is useful to explain the user that they are not translating the latest version of the article, and provide them the option to restart the translation.
The system to communicate issues (T189488) will be used to show a warning as illustrated below:
**Initial message when loading the translation**
- The issue summary will show a message to surface the warning.
- The content of the message will be: "This translation is based on an older version of the content. The source page may have changed significantly, and you may want to restart the translation."
- The "view issues" link closes the summary message and expands the issue card (more details below).
- When expanded, the issue card will show more details.
- The content of the message will be: "This translation is based on an older version of the content. The source page may have changed significantly. You can continue this translation, or start it again to use the updated content. If you restart the translation, your current changes will be lost."
- "Changed significantly" in the message will be a link pointing to the diff between the version used in the translation and the most recent version which should open in a new window (T146761). That will help users to decide whether it is worth incorporating the new changes.
- The "Mark as resolved" action will discard the issue and not show it again until the article is affected by further changes.
- The "Restart the translation" action will discard the current contents and start a new translation with the most recent version of the article. A confirmation dialog will be shown to prevent accidental data loss (more details below).
- A confirmation dialog will be shown after selecting the option to restart the translation: "**Restart the translation?** You will start a new translation for the most recent version of the page. All your changes will be lost."
- Users can "cancel" to go back or confirm and "restart the translation".
Related ticket: T176843