However, my question is still how to keep discussion contexts (or
history/background).
It seems Zanata history is associated with Zanata internal resource ID.
I am afraid it can be easily lost and we cannot recover it :-(

Yes, Zanata associate our internal resource ID to history. 
But I don't understand why is that an issue given all translators are already registered in Zanata and have their user id. (correct me if I'm wrong about what you mean Akihiro)
I don't think the data can be easily lost as everything is in database. I'm sure infrastructure team have prepared for backup and even restore if anything happens.
Keep in mind if there's possibility of data lost, that would mean same for all translations history.

Another benefit I can see is that their contributions will be included in their statistics.


Japanese team actually maintains it in OpenStack wiki and it works mostly well
except that we need to sync glossary manually, but it might be a small thing
compared to keep "context". Keeping "context" will save time to explain why
we choose THIS in our current glossary. If we do not have it, we need to
explain same things to new contributors again and again, and this will increase
the barrier to new contributors.

This is one of the improvement we want to make as Glossary in Zanata at the moment is global (everyone shares the same glossary).
We might look into levelling Glossary into project level or even concept of context glossary where you can select which group glossary you wish to use.
Please feel free to provide us feedback if such feature is needed.

Another thing you might want to explore is to use our translation memory import export. It has the concept of group (context) and it shows up in translation memory panel.
But only limitation is that it only supports .tmx file. You can access it through "admin" screen and "translation memory"

---------------------------------------------

Alex Eng 
Globalisation Tools Engineering
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Mobile: +614 2335 3457 

Red Hat, Asia-Pacific Pty Ltd 
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