# Contributing to culvert
Thanks for your interest in contributing. This document covers the basics.
## Getting started
Relevant docs for contributors:
- [`doc/setup.md`](doc/setup.md) — build, test, and coverage commands
- [`doc/testing.md`](doc/testing.md) — testing strategy, transport harness, and CI expectations
- [`doc/architecture.md`](doc/architecture.md) — role, scope, register map, design principles, and the culvert / link training boundary
- [`doc/roadmap.md`](doc/roadmap.md) — SCDC registers deferred to future releases
## Issues and pull requests
**Open an issue first** if you're unsure whether something is a bug or if you want to
discuss a change before implementing it. For small, self-contained fixes a PR on its own
is fine.
- Bug reports: describe which register group is affected, what value the sink returned,
and what culvert did with it.
- Feature requests: a brief description of what you need and why is enough to start a
conversation.
- PRs: keep them focused. One logical change per PR makes review faster and keeps history
readable.
## Coding standards
- Run `cargo fmt` and `cargo clippy -- -D warnings` before pushing.
- Public items need rustdoc comments (`cargo rustdoc -- -D missing_docs` must pass).
- Follow the existing patterns in the codebase — see [`doc/architecture.md`](doc/architecture.md)
for the design principles behind them.
- `#![forbid(unsafe_code)]` is enforced; no unsafe code.
- Keep `no_std` compatibility. `Scdc<T>` and all output types must compile without `alloc`
or `std`.
## Commit and PR expectations
- Write commit messages in the imperative mood ("Add support for …", not "Added …").
- Keep commits logically atomic. A PR that touches three unrelated things should be three
commits (or three PRs).
- Tests are expected for new register coverage. Pre-loading a `TestTransport` and
asserting on the decoded struct is the established pattern; see the existing `client`
modules for examples.
- CI must be green before a PR can merge: fmt, clippy, docs, all test and build targets,
and coverage must not drop more than 0.1% below the baseline (stored in
`.coverage-baseline`). New register coverage without tests will likely trip this.
## Review process
PRs are reviewed on a best-effort basis. Expect feedback within a few days; if you haven't
heard back in a week feel free to ping the thread. Reviews aim to be constructive — if
something needs to change, the reviewer will explain why. Approval from the maintainer is
required to merge.
## Code of Conduct
This project follows the [Contributor Covenant 3.0](CODE_OF_CONDUCT.md). Please read it
before participating.