Module target 

Typed TargetPredicate — conditional-dependency activation.

Every package manager has its own syntax for “only install this dep on platform X” / “only on node 18+” / “only on Linux”:

• Cargo: target.'cfg(unix)'.dependencies
• npm: "engines": { "node": ">=18" } + "os": ["linux"]
• pip: [platform_python_implementation == 'CPython'] markers
• Bundler: platforms :ruby, :mswin
• Composer: "php": ">=8.0"

Adapters normalise their native predicate into the canonical typed shape here. The resolver in gen-engine consults this once + decides per-target whether the dep is active.

Structs

CompoundTargetPredicate

Compound predicate combining atomic TargetPredicates. Kept separate from TargetPredicate to avoid serde recursion- overflow on the derive macros — same trick as crate::CompoundConstraint.

Target

A concrete target the engine evaluates predicates against. Typically derived from the host system the engine is running on, optionally overridden via shikumi config (e.g. --target aarch64-linux cross-build).

Enums

PredicateCombinator

TargetPredicate

Typed conditional-activation predicate. Adapters set this on crate::Dependency when the dep is conditional.