can we take diff of stack from history? eg: 1st run of activity vs 3rd run in activity etc?

If you're using the Pulumi Service as your backend stack state storage then there's a Stack Activity view apparently which might be what you're after. See https://www.pulumi.com/docs/intro/pulumi-service/projects-and-stacks/#stack-activity For the Azure backend, there used to be a

history

folder and/or a

backup

folder, but they seem to have stopped receiving any new entries some time at the end of 2020. Instead there's just a single "_state_.json.bak" file next to the "_state._json" file in the

stacks

folder. I'm guessing this feature was removed to become part of the paid for service. Now I've noticed this, I'm wondering if it might be a good idea to create a function with a blob or event grid trigger to copy the bak file into the history folder. Then I'd be able to do a diff file between the states.