This is a good reason to establish clear written communication and to use that as documentation to cover yourself when someone is being insidious.
"Let me confirm, you would like X, and that I should post in Y for X purpose. Can do!" then when they try to say you should have done Z, you just show them what they said and say, I did what we agreed to, happy to make adjustments in the future but let's make sure to establish a common ground/set expectations up front.
"Let me confirm, you would like X, and that I should post in Y for X purpose. Can do!" then when they try to say you should have done Z, you just show them what they said and say, I did what we agreed to, happy to make adjustments in the future but let's make sure to establish a common ground/set expectations up front.