Derive Macro OutcomeLattice 

#[derive(OutcomeLattice)]
{
    // Attributes available to this derive:
    #[outcome_lattice]
    #[outcome]
}

#[derive(OutcomeLattice)] — auto-implement an OutcomeLattice trait from per-variant severity attributes.

Expected trait shape:

pub trait OutcomeLattice: Clone + PartialEq {
    fn severity(&self) -> u32;
    fn baseline() -> Self;
    fn worst(&self, other: &Self) -> Self { ... }
    fn best(&self, other: &Self) -> Self { ... }
}

The derive emits severity() (from per-variant attrs) + baseline() (returning the single #[outcome(baseline)]-tagged unit variant). worst + best come from the trait’s defaults.

Attributes

• #[outcome_lattice(trait_path = "::path::to::OutcomeLattice")] — fully-qualified trait path (default unqualified OutcomeLattice — consumer must use the_trait::OutcomeLattice in scope).
• Per-variant #[outcome(severity = N)] — severity for this variant (u32; default 0 if unspecified).
• Per-variant #[outcome(baseline)] — marks the unit variant that baseline() returns. Exactly ONE variant must carry this; it must be a unit variant.

Example

use magma_converge::outcome::OutcomeLattice;

#[derive(Clone, PartialEq, gen_platform::OutcomeLattice)]
enum ReadyState {
    #[outcome(severity = 0, baseline)]
    Ready,
    #[outcome(severity = 1)]
    Unknown,
    #[outcome(severity = 2)]
    InProgress { reason: String },
    #[outcome(severity = 3)]
    Failed { reason: String },
}

// Auto-generated:
//   impl OutcomeLattice for ReadyState {
//       fn severity(&self) -> u32 { match self { ... } }
//       fn baseline() -> Self { Self::Ready }
//   }