The Messages app is a wonderful way to keep in touch with friends and relatives no matter where they are, and share photos and videos. This article tries to answer the seemingly simple question as to where those are stored, and what this has to do with syndication. I’m grateful to Jack for asking.

Sharing in Messages

If you have more than one Mac or Apple device connected to iMessage, and share that via Messages in iCloud, you’ll no doubt have discovered that shared photos and videos sync across them reasonably well. Delete an image on one, and it should be removed on all the others so long as they’re running, awake and can sync with iCloud.

Those shared photos and videos don’t appear in your System Photo Library, though, unless you save them there. That System Photo Library can share its contents using iCloud Photos, Shared Albums and iCloud Shared Photo Library, but those are separate from sharing in Messages. Turn all Photos sharing off and that doesn’t affect those shared in Messages.

Unfortunately, information about those shared images and videos, and control over them, is primitive in macOS compared with iOS. On an iPhone, you can manage storage for Messages in iCloud in much greater detail, and can view those that are taking up most space. That isn’t offered in macOS 26 Tahoe, only the total space used by Messages in iCloud. Nor is there any Photos library or other location obvious on your Mac that appears to store them.

Syndication Photos Library

Jack isn’t the first to discover this, but if you care to look in ~/Library/Photos/Libraries you’ll find a hidden Photos library named Syndication.photoslibrary that has a similar if not identical structure to a regular photoslibrary. If you look inside that, in the path scopes/syndication/originals you’ll see folders numbered with a single hexadecimal digit, and inside those are many of the shared photos and videos from Messages.

Try copying or duplicating Syndication.photoslibrary into your Picture folder, then launch the Photos app with the Option key held so you’re asked to select a Photos library to open. There pick Syndication.photoslibrary and browse its contents. Although that should look similar to the images and videos still stored in your local Messages, you may well notice there are differences, with the Syndication Photos Library containing more, sometimes a great deal more, than Messages.

But there’s more

Checking on my iPhone, Settings there reports that Messages is currently using 523 MB for photos, 14.7 MB for videos, and 1.1 MB for GIFs and Stickers, making a total of just under 540 MB. Yet on my iMac Pro Syndication.photoslibrary is only 394.1 MB, nearly 150 MB smaller, and on my Mac mini M4 Pro it’s a huge 1.14 GB, although each of them should be storing the same photos and videos. Some users have reported Syndication.photoslibrary of huge size, sometimes tens of GB, suggesting that they either never perform housekeeping on shared images and video in Messages, or theirs have accumulated many orphaned items.

Those Syndication Photos Libraries are the location of photos and videos for Messages, though. Try deleting a photo or two in Messages, and you’ll see each of them update in synchrony.

There’s another puzzle too: if you have some older Photos Libraries, look inside them and you may well see photos and videos in folders in the path scopes/syndication/originals, just as you do in Syndication.photoslibrary. This suggests that the separate Syndication Photos Library may have originally been saved in the current System Photo Library rather than in ~/Library/Photos/Libraries/Syndication.photoslibrary.

My last mystery comes from the list of open files provided by Activity Monitor. With both Messages and Photos apps running, guess which has the database inside Syndication.photoslibrary open? No, not Messages, but Photos.

Conclusions

• ~/Library/Photos/Libraries/Syndication.photoslibrary is the Photos Library now used to store shared photos, videos, GIFs and Stickers for the Messages app.
• Although it syncs changes promptly, some local copies appear to accumulate contents that aren’t removed by Messages.
• As a result, some Syndication Photos Libraries grow far larger than required, but there’s no way to force them to purge unused contents.

President Trump’s failure to ram through a Republican-friendly House map was a new sign that his iron grip on the party has slipped, and was likely to reverberate nationally.

© Jon Cherry for The New York Times