Trying out the new "ephemeral parameters" feature, I made this parameter in my template ephemeral:

data "coder_parameter" "rebuild_devcontainer" {
  name         = "rebuild_devcontainer"
  display_name = "Force devcontainer rebuild"
  type         = "bool"
  ephemeral    = true
  default      = "false"
  mutable      = true
  order        = 7
}

When I select the non-default value "true" for this parameter in the "Build Options" popup under "Restart", my provider's Update method still sees a false value in the plan.

However, this works as expected if I instead go to Settings->Parameters and change the value there.

cc @mtojek