I think - like mentioned above - creating a branch and tag with proper vendaor tags can already be done using the standard fossil commands.

The main problem, deescribed at the beginning was the sync of the checkout file tree and the files in the repository. This can be hanlded with the new commen.

Would the merge work, if we use the cherrypicck option? I cannot test it now, but i'll try it later and i think, it will work.

The only problem, we may have is the fact, that the import command needs to be called from an ceckout. The new command shares most of its code withalready exitant code for and all these ccommands are only implemented, when called from an existing checkout.
It will be complex to extendd it to work with standalone checkouts, and i don't believe, that it's neccesary:

  *  First checkin:<br>fossil new x.fsl;mkdir x;cd x;fossil open ..\x.fsl<br>
     copy source tree to x<br>fossil import<br>fossil commit -m "..."<br>and
     set branches/tagss to whatever you want
  *  further checkins:<br>cd x;fossil update VENDORBRANCH<br>
     remove old data and copy new source tree<br>
     fossil import;fossil commit -m ".."

Merging to main development branch should be possible by using cherrypick

best regards