Don't mark migrations as "rejected" if they were closed long after migration

Question

A question was asked on Site A, where it collected answers before being migrated to Site B. On Site B it collected more answers and lived happily for a time. More than two years later, it was closed.

Because it had been migrated originally, the closure was treated as a rejected migration. This meant that answers that were migrated from Site A were locked and deleted on Site B's copy of the question, and the migrated question became eligible for automatic deletion as a rejected migration. If the closure happens soon after the migration, this is OK -- when a migration is rejected, the affected answers are undeleted on the originating site. Nothing is lost and no answers are duplicated.

However, if it's been more than 30 days since the question was migrated, this presents a problem. Migration stubs are deleted after 30 days, so there was no (undeleted) question on Site A to host those answers. The result is that they were deleted on both sites. Closing the question caused content to be lost.

Now you might argue that hey, it was closed, so how valuable could the question and its answers be (regardless of voting)? But we have logic that isn't "delete all the things", so regardless of how you feel about keeping closed questions, this behavior violated user expectations. When a non-migrated ("native") question is closed, nothing happens to its answers. This question had been on Site B long enough to be treated as a "native" question.

Also, site scopes and the definition of what constitutes a good, on-topic question do change over time. A question that was perfectly on-topic on the destination site at the time of migration may be considered off-topic later, and leaving those questions open presents the usual problem, but closing them doesn't necessarily mean that the migration shouldn't have taken place.

Migration is often confusing and counter-productive anyway, but so long as we're stuck with it, there should be a statute of limitations on migration rejections. If the receiving site doesn't close it within 30 days -- the time that, on the original site, we've decided it's not coming back -- then it should stop being treated as a migration. Site A is done with it; it should henceforth be treated the same way as if it had been asked on Site B in the first place. Specifically, if it's closed it's just...closed. Not sent back. Not left around with deleted/locked answers. Not annotated as a rejected migration. Just closed.

For reference: the case study that prompted this request.

Also, another example: before meta sites existed, it was common for people to post meta questions on Stack Overflow itself. Then, many of these were migrated to then-MSO (now MSE). Later on, many of these were closed as pertaining to only a specific site in the SE network, which has caused the old content to be deleted. Even though rejected migrations on meta sites do not cause answers to be deleted, the migrated question is still eligible for automatic deletion as a rejected migration, regardless of score. Here's an example (screenshot from before the migration history was cleared) that had +31 score at the time of deletion.

Answer 1

As Robert suggests, the most expedient way of solving this is to ignore the migration in cases where the stub has already been deleted - this handles both the case where the migration is old (and the stub was automatically deleted) and the case where the stub was deleted manually (for whatever reason - only moderators can do this, so presumably they have a good reason to do so).

In either case, any answers that might've been migrated will no longer be visible on the originating site due to the question's deletion, so unlocking and undeleting them is pointless at best and subverts the intent of migration at worst.

This change is live as of yesterday.

Answer 2

That makes sense. Once a migration stub is removed, the question should be treated like any other post on the site. I dropped this into the feature-request queue as a Community Request.

Answer 3

While this feature does not (yet) exist, there is a workaround, but it requires moderator intervention.

If a migrated question with good answers is likely to be closed due to a site scope change or pure oversight in the past, and you think the answers are useful to other users, you can flag for a mod to clear the question's migration history. This delinks it from the question on the origin site, and makes the question act just as if it was posted on the destination site in the first place. Then, once the question is closed, nothing will happen to the answers.

Of course, this is a bit of a crude solution, as it requires a moderator to intervene, requires the mod to know about this behavior of the system, and wipes out the public history of the fact it was migrated originally.

Another way to solve the issue is to automatically undelete migration stubs (if they were deleted as part of the RemoveMigrationStubs process) if a migration gets rejected. However, this isn't the best solution, since if the question is closed long after migration, it's usually for procedural reasons (such as the "other example" in your bottom paragraph) and the question's pretty much settled in to the new site.