ADR-0003: One parameter registry generates everything

Status: Accepted · 2026-10-08

Context

Parameters appear in at least seven places: generators, validation, VectorCraft manifests, the CLI, SVG attributes, documentation and property tests. When each place restates them by hand they drift apart: a parameter is added in code and never documented, or its documented default goes stale.

Decision

Declare each parameter once, next to its generator, with a params! macro (doc comment = help text). Generate typed structs, validation, manifests, CLI help, SVG mapping, docs pages, JSON Schema and proptest strategies from it. Registry keys are Ink/Stitch attribute names where the meaning matches, and defaults equal Ink/Stitch’s. Details: parameter registry.

Consequences

• Adding a parameter is a one-place change; docs and UIs cannot forget it.
• A macro_rules! macro keeps contributors in plain Rust; if it grows unwieldy (reassessed after M3), a derive macro can replace it without changing the registry’s data model.
• VectorCraft v1’s 64-parameter limit is checked by a test at PR time.

Alternatives considered

• Serde structs + hand-written docs: the drift we are trying to avoid.
• External schema file (YAML) generating Rust: another language and a build step; doc comments next to code are where contributors look.