rust

name	rust
description	Hermetic Rust crate building, testing, and formatting via Bazel targets. Covers build/test commands through rules_rust, formatting with bazel run //tools:format, test suites defined in root BUILD, and dependency management via MODULE.bazel crates.io integration.

Rust Skill

Description

The Rust skill provides a set of reusable commands for building, testing, and formatting Rust crates in the Moosync repository. All operations use Bazel's hermetic rules_rust toolchain — Cargo is never invoked directly.

Commands

Command	Description	Example
Build crate	Build a specific Rust library or binary target via Bazel.	bazel build //core/player:player
Run tests	Execute unit tests for a crate through Bazel.	bazel test //core/database:database_test
Format files	Run hermetic formatter on staged .rs, .slint, .proto, and Bazel files via the pre-commit target.	bazel run //tools:format -- path/to/file.rs path/to/file.proto

Usage Patterns

1. Quick build of a feature module — identify the target label in the crate's BUILD.bazel file and run the Build crate command.
2. Test after change — run Run tests to catch regressions before committing. Test suites are aggregated under core_tests at the root level.
3. Formatting — invoke Format files as part of a Git pre-commit hook (see .git/hooks/pre-commit). The formatter resolves hermetic rustfmt, slint-lsp, buildifier, and buf through Bazel runfiles.

Example Workflow

# Build the player module
bazel build //core/player:player

# Run tests for the database crate
bazel test //core/database:database_test

# Format specific files (pre-commit hook pattern)
bazel run //tools:format -- core/player/src/lib.rs ui/slint/app.slint

Rules_rust Integration Notes

• All Rust dependencies are declared in modules/crates.MODULE.bazel via the crates.io integration. Do not manually edit lockfiles.
• New crates should use rust_library, rust_binary, or rust_shared_library from @rules_rust//rust:defs.bzl.
• Build scripts (build.rs) are declared with cargo_build_script() from @rules_rust//cargo:cargo_build_script.bzl.