how can i set that backpack drop only in pvp area ? rest is pve area ,true pve

I'm not sure off the top of my head. The plugin doesn't have any built in knowledge of PvE since vanilla is PvP.

One way to achieve this would be to disable dropping on death, and write a simple plugin (a few lines of code) which would detect player death, check if area is PvP (ideally the PvE plugin has an API to check this), then call the Backpacks API to drop the backpack. A slightly different approach would be to have another plugin block dropping the backpack if the player dies in a PvE zone, which would work very similar, but instead of calling a Backpacks API, that would use a Backpacks hook.

ufff so it was hard question,even harder answer .. About writing a smiple plugin (never did that so i dont know) . So easiest way(for me) is to put in config/permissions that backpack drop on death ,so players in pve will drop on death bpack, and also in pvp area .. Its kinda bad for me ,but i think that is only solution for me now .. Maybe i can do it with zone permissions,but iam not sure would that work (so in pvp zone i put they dont have permission keep on death bpack ,but they have in their group permission keep bpack on death ) .I rly dont know ... In plugin raidable bases there is option in config "Backpacks Drop At PVP Bases": true,and it works no matter they have permission keep bpack on death.

You could ask the maintainer of the PvE plugin to add a similar option to the one in Raidable Bases.

I'm hesitant to add a PvE option into Backpacks because there can be multiple implementations of PvE and that is a specific game design, whereas Backpacks is a more generic plugin which does not assume game design. Generally I prefer that specific plugins be the ones to integrate with generic ones, but ultimately it could go either way.

I cant ask him bcs when we add zones they dont use no more truepve plugin ... so they are true vanila pvp ... I mean maybe he can pull something ,but not sure ,bcs that plugin just dont exist in zone (pvp zone) ...  If i understund how to make plugins i would just add something like bypass permission so i can add plugin zone permission and just add in that "pvp zone" that bypass permision .. Maybe iam saying wrong ...but iam just mixing all possibilities in my head...

My high level understanding is as follows. Vanilla is PvP. PvE plugins work by altering the outcome of specific events, particularly by blocking the original/vanilla outcome of those events. For instance, they may prevent a specific player from dealing damage to a specific player or object, or prevent a player from looting a specific container. To decide whether to block an event, PvE plugins examine various factors such as who/what performed the action, which player/object was acted on, location, time, and more. Zones, as defined by the plugin Zone Manager, are not strictly necessary for PvE plugins to function, but they are a convenient feature that PvE plugins can consider since they can indicate both location and time.

Since the domain of a PvE plugin is primarily to block events, it stands to reason that the backpack drop event is just one more event that could be blocked. The PvE plugin would simply need to detect the backpack drop event, and evaluate certain criteria to determine whether dropping the backpack is appropriate.

According to your original post, you want to block backpacks from dropping in certain areas. Can you elaborate on how these areas are created, and about which plugin manages them? If a PvE plugin is able to know whether a given area is a PvE area, then it's also able to know whether an area is a PvP area by process of elimination. That means it should be trivial for whichever that plugin manages these areas to either a) block backpacks from dropping in those areas, or b) provide an API for another plugin to query if a given location is a PvE area.

Is this making sense?

Yes Sir ...Thank you for your time ,appreciate it !