# support — inert cargo across a consumption boundary
A declaration expands where it stands, while some of its generated material belongs only in a test or benchmark target.
Compiling that material in the declaring crate as well as in the target would erase the boundary the declaration asked for.
This home owns the exported carrier that preserves that boundary.
## Responsibilities
The parent retains only declaration and schema-pin vocabulary shared across the crossing.
Carried material, its promotion, and its axes remain distinct from the checked join that assembles them and from the carrier that renders and delivers the result.
That separation prevents rendering machinery from inventing cargo and prevents cargo from bypassing the relationships the join establishes.
## The boundary
Authority enters as one captured declaration, terminal deliveries already proved by the compiler, the producer's published schema expectation, and an optional address chosen by the declaration.
The home admits only cargo read from the delivery that proved it and assembles every carried part under one declaration and one delivery form.
What leaves is an exported macro definition whose body remains inert until a consumption target invokes it.
The carrier is machinery, not a second declaration language.
It owns the vehicle, the coupling of its seats, and the proof that the cargo came from the deliveries it names.
The descriptor adapter owns the material placed in those seats, and the harness owns the gate and the destination vocabulary released on a matching schema.
## One coupled crossing
The schema gate governs the declaration-shaped material and the opaque target cargo together.
A matching publication releases both seats of the selected form, while a mismatch releases neither.
This coupling prevents a target from receiving half of a delivery under a schema that did not admit the other half.
The schema expectation is fixed by the producer rather than supplied by each declaration.
Its independent currency observation compares both published copies with the identity derived from the harness declaration, because agreement between two copies establishes coherence and not freshness.
## Proved cargo only
Opaque cargo is promoted from a closed terminal's own delivery.
The promotion records the terminal, its declaration, its destination, and the digest of the delivered bytes as one informed value.
Assembly then verifies the relationships across every carried axis before any shell can be rendered.
The rendered carrier is named from its plan identity so declarations sharing one crate do not choose competing machinery names.
An author-facing alias may forward to that hidden carrier, but it adds no grammar and changes no cargo.
## Composition
The descriptor doors read first-party declarations, close their generated outputs, and hand this home only proved deliveries and declaration-owned material.
This home composes the carrier and walks it through the same request, rendering, closure, explanation, and binding road as every other generated unit.
The proc host only emits the resulting declaration-site unit beside the item it was given.
At the consumption boundary, the harness gate proves that the supplied harness path reaches the publishing crate and that the producer's schema expectation matches the published one before either seat reaches type checking.
The gate transports opaque cargo without interpreting it.
## Evidence ceiling
An assembled carrier establishes producer-side parentage, singular delivery, one declaration, one form, and the published expectation used to render the shell.
It does not establish that a target invokes the carrier, that the published schema is current, that opaque cargo is semantically correct, or that the consuming target succeeds.
Those claims belong to external carrier-road, schema-currency, compile-refusal, proc, package, and consumption observations.
This home also makes no performance claim.
Generated-token growth, compile cost, packaged outside consumption, renamed paths, and target behavior remain adopter-facing evidence planes rather than constants or prose claims here.