Cross site image link does not work (also for merger sites)

Rev3860, when i add to my ZeroBlog an image linked from external site:

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then image not show up until (i think) i visit that site at least once ?
I hope you can make the zeronet download linked file/site automaticaly when it is linked like that.

It is similar with merger sites i think. For example Millchan discussion board. When i not visit the hub site, the link to the merger site, which points to a content on that hub will show "Not Found" error. I think this is important thing to the TODO list to fix.

The issue names no files, tests, or entry points. Reproduce the external ZeroBlog image and Millchan merger-site cases from the provided examples, then trace how linked sites are fetched when the user has not visited them; done means those linked resources load without a prior visit.

Written by the indexing model from the issue text.