# Dependency rules

## Use workspace dependency versions

### Rule

Declare Rust dependency versions in the repository root `Cargo.toml` under `[workspace.dependencies]`.
Reference workspace dependencies from package `Cargo.toml` files with `workspace = true`.
Do not declare dependency versions in package `Cargo.toml` files unless the operator explicitly requests a package-local version.
Add package-local dependency features only when the feature set is specific to that package.

### Rationale

The repository has one Cargo workspace and one `Cargo.lock`.
Centralized versions keep package manifests consistent with the workspace lockfile.

## Declare Rust dependencies in each build system

### Rule

Declare each direct crate dependency in each build system that builds the Rust target.
For Cargo, declare the crate in the package `Cargo.toml` file.
Use `workspace = true` for workspace-managed dependencies.
For Bazel, add the crate label to the `deps` of the target that uses it.
Apply this rule to `rust_library`, `rust_binary`, and `rust_test` targets.

### Rationale

Cargo and Bazel resolve Rust dependencies independently.
Complete declarations keep Cargo, Rust Analyzer, and Bazel builds consistent.