Hi, I was using prodigy for the NER annotation, I labelled some documents then I wanted to modify some in the history, I then clicked to the one I wanted to modify and done some modifications, I THEN CLICKED TO ANOTHER ONE IN THE HISTORY WITHOUT CLICKING THE GREEN VALIDATION BUTTON. Guess what I lose that annotation which was really a long document 
I think it would be maybe better to give some alert here.
Hi! I can't reproduce this 
Which version of Prodigy are you using? An what do you mean by "lose that annotation"? Are the entities you marked not there anymore?
Annotations should be locked in as you make them and clicking a task in the history just moves the example you click on to the front of the queue. If you submit it again, it goes back to the history and you're back at the task you were annotating before, in the same state.
by "lose the annotation" i mean the document was gone like i clicked the ignore button.
I am using version 1.9.9.
For exemple it works as the same if you are proposed a new doc and then you click the one in the history that new doc is gone just if you clicked the ignore button
If I click on an example in the history, that example is moved to the top of the queue, before the one I'm currently annotating. Then I can re-annotate that example (e.g. by clicking accept/reject/ignore) and I'm back at the example I was working on before and can keep working on it and submit it. Once I submit it, it shows up in the history.
Or maybe I'm misunderstanding the question/problem? Do you have a reproducible workflow that shows the problem?
"Then I can re-annotate that example (e.g. by clicking accept/reject/ignore)", so here instead of clicking one of these options, just click to another doc in the history. That will act as if you ignored the document you were modifying.
I tried to explain the scenario in my first post but I am available to show you in a quick call.
So if I don't re-annotate the example I moved to the top of the queue from the history, and click on another history task, it moves that one to the top of the queue. And if I re-annotate the two again, I'm back a the one I previously annotated
I made a quick gif – is that similar to your workflow?
Here is the demo, as you can see when i returned to the first document and then reclicked to the second one the first document was gone.
PS : I couldn't show the gif directly
Thanks for recording! 
The gif is a bit small, but it looks as expected and like it does in my gif? When you click on the entry in the sidebar, it will take that example and move it to the top of the queue. So the history example is now "on top of" your previous example. You can then either change the example or "file" it again and move it back to the history by clicking accept/reject/ignore. And then you should see your work-in-progress example again.
Ah I see, it's not in the history but it's still there. and i have to do action in the actual document to see it back. prodigy will know that it has to show me my old examples instead of a new one. Am I right ?
Yes, I thin the part that might have led to the confusion here is that the current task is not in the history – it only gets added once you submit an answer. But the app always has the state of all current tasks stored on the client and it shouldn't change.
You can also imagine it as a stack of cards. Or, explained in pseudocode:
history = [1, 2, 3]
queue = [4, 5]
current = 4
# You click on 1 in history
history = [2, 3]
queue = [1, 4, 5]
current = 1
# You accept the current task (re-annotated 1 from history)
history = [2, 3, 1]
queue = [4, 5]
current = 4
Humm, but when i clicked to the second article and the first one was no longer in the history, we agree that the first one was not the current one, but still it was no longer in the history.
Is that normal.
The question is whether the first one should be considered as being from history or just in the queue? Because as a user(i.e ME) after these actions in the GIF I am expecting to have the document in the history since i already validated the document. and if i wanna have this behaviour I would just click the ignore button.
Yes, that's intended, because if you click on an item in the history or hit "undo" (which is the same action), the item is moved back onto the annotation queue. So it's no longer part of the completed annotations, because you're asking to re-annotate it again. Clicking on a history item is basically a shortcut for "undo" of a specific annotation task.
ok i see. though not intuitive, since already validated. but ok now it's saved in my brain. thanks for all thee clarifications. reallay appreciated.