Enhancement: Different environment variables with multiple configuration environments

[tomasfarias]

In my workflow, I use different sets of environment variables depending on which environment I am working on.

While reading about config environments, I assumed the following would be possible: Have multiple .mise.*.toml files with different environment variables, and set different environment variables depending on what I set MISE_ENV to.

However, I tested it out, and noticed that this was not supported:

$ touch .mise.toml
$ touch .mise.prod.toml
$ echo -e '[env]\nTEST_PROD="PRODUCTION"\nTEST="OVERRIDE"' >> .mise.prod.toml
$ echo -e '[env]\nTEST="TEST"' >> .mise.toml
$  MISE_ENV="prod" echo $TEST_PROD

$  MISE_ENV="prod" echo $TEST
TEST
$  MISE_ENV="prod" mise cfg
Path                                                    Tools
~/.config/mise/config.toml                              usage, python
~/mise-test/.mise.toml       (none)
~/mise-test/.mise.prod.toml  (none)

To elaborate: MISE_ENV="prod" echo $TEST_PROD doesn't echo out the TEST_PROD environment variable configured in .mise.prod.toml, and MISE_ENV="prod" echo $TEST echoes back the environment variable configured in the top level .mise.toml, not the override set in .mise.prod.toml.

It would appear that the files are being read in the right order, given mise cfg, and I am not sure if there is any other way to achieve this. So I'd like to know if this would be a wanted enhancement. I'd be happy to contribute some code to mise, the tool is great!