Migrating from confy

amethystate includes a compatibility adapter that reimplements the confy API on top of its own storage backend. You can switch to it by replacing the confy import — existing call sites stay unchanged.

Enabling the adapter

Add the feature flag to your Cargo.toml:

amethystate = { version = "*", default-features = false, features = ["toml", "confy-compat"] }

For projects using confy 0.6:

amethystate = { version = "*", default-features = false, features = ["toml", "confy-compat-0-6"] }

Then replace the import:

// before
use confy;

// after
use amethystate::confy;

The API is the same: confy::load, confy::store, confy::get_configuration_file_path, confy::store_path all work as before.

Coexistence with amethystate state

The adapter writes only to the root section of the file — the flat key-value region that confy manages. amethystate-managed sections ([network], [ui], and so on, corresponding to struct prefixes) are left untouched.

The original confy overwrites the entire file on every store call. amethystate::confy does not — it merges only the root keys, so both can share the same file:

// Initialize amethystate on the same path confy uses
let file_path = confy::get_configuration_file_path("my-app", None)?;
StoreBuilder::new(&file_path).init_global();

// confy write — touches only root keys
confy::store("my-app", None, &legacy_config)?;

// amethystate write — touches only its own prefix
let mut network = NetworkState::load()?;
network.mutate(|n| n.port = 9090)?;

// both reads still work
let cfg: LegacyConfig = confy::load("my-app", None)?;
assert_eq!(network.port, 9090);

Limitations

yaml_conf and basic_toml_conf variants are not supported. The upstream crates behind them (serde_yaml, basic-toml) are archived or unmaintained.

Migrating to native amethystate state

Once you are comfortable with the adapter, you can move individual structs to #[amethystate] one at a time. Use as_root to keep the same flat file layout that confy produced:

#[amethystate(mode = "persistent", as_root)]
pub struct AppConfig {
    #[amestate(default = "Unknown".to_string())]
    pub name: String,

    #[amestate(default = true)]
    pub comfy: bool,

    #[amestate(default = 42i64)]
    pub foo: i64,
}

This reads from and writes to the root section of the file with no prefix namespace — the same layout confy produced. No data migration is needed.

When you are done migrating all structs, drop the confy-compat feature and the confy import entirely.