rust-skills

Design Rust library APIs that follow the Rust API Guidelines — naming (C-CASE, C-CONV, C-GETTER), interop traits (C-COMMON-TRAITS, C-CONVERT, C-ITER, C-SERDE), predictability (C-INTUITIVE, C-CONST), flexibility (C-GENERIC, C-NEWTYPE, C-EXT), type safety (C-BOOL, C-NONZERO, C-WRAPPER, C-STR), dependability (C-PANIC, C-UNWRAP), debuggability (C-DEBUG), and future-proofing (C-SEALED, C-STRUCT-FIELD, C-NON-EXHAUSTIVE). Use when users design a public crate API, choose between generics/concrete/newtype, decide trait bounds, hide implementation, avoid breakage, or ask "what is idiomatic Rust API design"; hand semver and publish workflow to rust-semver, lint config to rust-style-clippy, and in-crate layout to rust-module-layout.

Show Rust patterns through short compilable examples — type conversions (From/Into/TryFrom/as/Deref), flow control (if let/while let/match/loop), functions and closures (Fn/FnMut/FnOnce, captures), modules (mod/use/pub/super/self), generics and traits (bounds/associated types/trait objects), error handling (?/Result/thiserror/anyhow), attributes (derive/cfg/inline/allow), unsafe (raw pointers/unions/ABI), procedural macros (derive/attribute/function-like), and inline asm. Use when users ask "how do I write X in Rust", need a concrete pattern with copy-pasteable code, or are migrating from Java/Python/Go/C++ and want the Rust equivalent; hand architecture decisions to rust-api-design/rust-workspace, std API selection to rust-stdlib, and async runtime to rust-concurrency.

Configure, operate, diagnose, and automate Cargo for Rust packages and workspaces. Cover manifests and targets, commands, dependency resolution and features, profiles, build scripts, configuration and environment variables, caches and build diagnostics, cross-compilation, registries, packaging, publishing, metadata, CI reproducibility, and stable-versus-nightly feature gates. Use for Cargo.toml, Cargo.lock, .cargo/config.toml, cargo build/check/run/tree/metadata/package/publish, resolver or feature problems, build output and performance, private registries, and beginner Cargo workflows. Route crate selection and supply-chain audits to rust-dependencies, workspace topology to rust-workspace, test design to rust-testing, documentation design to rust-documentation, lint policy to rust-style-clippy, and API compatibility decisions to rust-semver.

Design, implement, test, and release production Rust command-line applications, including command contracts, subcommands, configuration precedence, stdin/stdout/stderr, exit codes, file safety, daemon IPC, terminal handling, packaging, and process-level tests. Use when users ask for a Rust CLI, command parser, clap integration, Unix-style pipelines, daemon clients, PTY/TUI behavior, shell completion, or CLI release engineering.

Review Rust changes for correctness, memory and thread safety, error semantics, unnecessary allocation or cloning, lock scope, API compatibility, test gaps, documentation, and dependency risk, applying the Rust API Guidelines checklist (C-PANIC, C-UNWRAP, C-TRANSMUTE, C-BOOL, C-NEWTYPE, C-COMMON-TRAITS, C-CONVERT, C-SEALED, C-NON-EXHAUSTIVE). Use when reviewing Rust diffs, pull requests, libraries, unsafe boundaries, or production incidents; report actionable findings by severity before summaries, route automated formatting or lint policy to rust-style-clippy, and route API shape decisions (trait sealing, error taxonomy, newtype design, builder patterns) to rust-api-design.

Design, implement, diagnose, and test Rust concurrency and parallelism with threads, Send and Sync, locks, atomics, channels, Tokio, Rayon, Crossbeam, bounded backpressure, actor ownership, task supervision, graceful shutdown, runtime diagnostics, and Loom model tests. Use when users ask about shared state, deadlocks, async tasks, CPU parallelism, high concurrency, daemon resource budgets, slow consumers, worker pools, lock-free structures, or concurrent correctness.

Discover, evaluate, score, and compare Rust crates for adoption — search crates.io, fetch metadata from 4 sources (crates.io API, docs.rs, GitHub API, RustSec advisory DB), apply a weighted 0-100 scoring model across adoption/maintenance/documentation/maturity/community/license, flag red concerns (unmaintained, advisories, no docs, single-maintainer), and recommend the best fit. Use when users ask "which crate should I use for X", "is this crate maintained/safe/popular", "compare these 3 crates", or need to pick a dependency before adoption; hand post-adoption governance (cargo-deny, license policy, advisory response) to rust-dependencies, semver and breaking-change classification to rust-semver, and manifest mechanics to rust-cargo-build.

Design, implement, migrate, test, and operate Rust database access, including SQLx, Diesel, SeaORM, schema evolution, transaction boundaries, connection pools, retries, type mapping, concurrency control, and real-database verification. Use when users ask about Rust SQL or ORM code, migrations, transactions, PostgreSQL or MySQL integration, connection pools, query safety, or database production readiness.

Manage Rust dependency governance at scale — version requirement strategy, crate and source selection, feature minimization, transitive dependency analysis, cargo-deny license/ban/advisory/source policy, cargo-audit, cargo-outdated, Renovate/Dependabot automation, dependency update cadence, cycle diagnosis, and supply-chain security. Use for dependency strategy, crate approval, license compliance, advisories, allowed sources, automated updates, or dependency-graph governance; hand Cargo manifest and registry configuration, lockfile mechanics, resolvers, and Cargo command behavior to rust-cargo-build, semver compatibility decisions to rust-semver, and lint policy to rust-style-clippy.

Design, write, build, test, and publish Rust documentation with rustdoc, cargo doc, doctests, intra-doc links, crate-level guides, examples, README synchronization, mdBook, docs.rs metadata, link checking, documentation CI, and the Rust API Guidelines Documentation chapter (C-DOC, C-LINK, C-META, C-EXAMPLE). Use when users ask for Rust API docs, a project book, runnable examples, docs.rs readiness, missing-doc policy, API guideline compliance, documentation architecture, or stale documentation repair.

Design, implement, review, and validate embedded Rust firmware, including no_std, targets, runtime and startup, embedded-hal drivers, interrupts, DMA, shared state, async executors, hardware mocks, cross-compilation, flashing, and hardware acceptance evidence. Use when users ask about MCU firmware, portable drivers, HAL versions, bare-metal targets, interrupts, Embassy, RTIC, probe-rs, or embedded testing.

Design, implement, test, and operate resilient Rust outbound HTTP clients with reqwest, hyper, Tower middleware, connection pooling, DNS, proxies, TLS, redirects, deadlines, retries, rate and concurrency limits, streaming bodies, cancellation, SSRF controls, and mock or real-server contract tests. Use when users ask to call REST APIs, download or upload data, configure an HTTP client, diagnose connection failures, or harden service-to-service requests; keep inbound servers in rust-web.

Plan, execute, audit, and verify behavior-preserving migrations from Java Maven or Gradle projects to project-shaped Rust Cargo workspaces, including derived crate boundaries, scale-appropriate topology, 100% lossless source-test/case migration, byte-identical test assets, and complete per-case differential parity. Use when comparing repositories at module, package, object, file, method, parameter, documentation, example, test, fixture/data, dependency-reuse, JavaBean/script-property, concurrency, runtime-behavior, oversized Rust-file, or test-organization level; producing migration documents; continuing an incomplete port; or repairing workspace drift. Enforces source-authoritative inventories, Rust-native APIs, a 500-line cohesion-review threshold and 800-line authored-file blocker, idiomatic unit/integration test placement, strict non-completion states, frozen baselines, and unified verification.

Design, implement, audit, and report lossless Java-to-Rust migration tests without promoting green tests into false completion claims. Use when porting 100% of JUnit tests and concrete parameterized/dynamic cases, SHA-256-verifying source fixtures/resources/scripts/data, requiring complete per-case golden or live differential MATCH results, validating object/test ledgers, reviewing oversized Rust test files, organizing inline unit versus integration tests, adding Rust-specific obligations, comparing coverage, or building property, fuzz, mutation, concurrency, lifecycle, adapter, host, load, security, and rollback evidence. Enforces a 500-line cohesion-review threshold, an 800-line authored-file blocker, and idiomatic Rust test placement.

Use, migrate, and review lombok-macros derives that generate Rust getters, mutable getters, setters, constructors, Debug, and Debug-backed Display implementations. Use when users explicitly mention lombok-macros or Java Lombok, want to remove repetitive accessor or constructor methods, configure generated visibility or conversions, redact fields from Debug, or review generated APIs. Prefer DTOs and data carriers; reject generation that bypasses domain invariants, exposes mutable internals, panics on Option or Result access, or turns Debug into a public display contract.

Design, name, implement, debug, test, and review Rust declarative and procedural macros, including macro_rules matchers and repetition, hygiene, $crate paths, derive, attribute and function-like macros, proc-macro crate naming, syn parsing, quote generation, diagnostics, cargo-expand, doctests, and trybuild. Use when users need compile-time code generation, a Rust DSL, or guidance choosing -derive versus -macros; keep ordinary trait, generic, or handwritten APIs outside macros unless generation has a clear maintenance benefit.

Design and enforce the internal layout of a single Rust crate — lib.rs/main.rs as a thin index, semantically named directory modules, `mod` declarations, `pub` visibility, and targeted re-exports. Use when users ask how to organize src/, write lib.rs, split a growing crate into subdirectories, choose between `foo.rs` and `foo/mod.rs`, name modules, avoid flat lib.rs "index plus glob re-export" anti-patterns, or migrate Java-style or Python-style flat projects to idiomatic Rust module trees.

Instrument, operate, and review Rust applications with tracing spans and events, structured logs, metrics, OpenTelemetry context propagation, Prometheus export, sampling, correlation, redaction, cardinality control, tokio-console diagnostics, and graceful telemetry shutdown. Use when users ask for logging, distributed traces, service metrics, request correlation, async task diagnosis, SLO evidence, or production observability architecture.

Measure, profile, optimize, and regression-test Rust performance across latency, throughput, CPU, allocations, memory, binary size, and compile time using representative workloads, Criterion, iai-callgrind, cargo-flamegraph, samply, DHAT, heap or pprof tools, cargo-bloat, cargo-llvm-lines, and build timings. Use when users report slow Rust code, high memory or CPU, large binaries, noisy benchmarks, tail-latency regressions, or need performance budgets and evidence-backed optimization.

Manage Rust crate semantic versioning — what counts as a public API (visible items + reachable through re-exports), pre-1.0 rules (0.x.y compatibility), breaking change detection via cargo-semver-checks (270+ lints), workspace lockstep publishing with cargo-workspaces, yank/deprecate workflows, RustSec advisories, and the semver implications of `#[non_exhaustive]`, sealed traits, hidden modules, feature flags, and trait impl additions. Use when users ask whether a change is breaking, want to publish a new version safely, run cargo-semver-checks, coordinate multi-crate workspace releases, or handle a yanked/advisory situation; hand Cargo manifest mechanics to rust-cargo-build, API design choices to rust-api-design, and CI config to rust-style-clippy.

Implement and explain stable Rust language semantics with explicit toolchain and MSRV checks — ownership, borrowing, lifetimes, move semantics, traits, generics, associated types, pattern matching, closures, error propagation, and Edition differences. Use as the core Rust language skill when users ask for Rust syntax, compiler-error fixes, ownership/borrowing diagnoses, or version-sensitive stable code; hand std API selection (which collection, which smart pointer, which string type) to rust-stdlib, "how do I write X" pattern questions to rust-by-example, and specialized domains to their dedicated skills.

Select and compose Rust standard-library APIs — collections (HashMap/BTreeMap/Vec/VecDeque/LinkedList/BinaryHeap), smart pointers (Box/Rc/Arc/RefCell/Mutex/OnceLock/LazyLock), string types (String/&str/OsString/PathBuf/Cow), interior mutability (Cell/RefCell/OnceCell/OnceLock), I/O streams (Read/Write/BufRead), iterators, Option/Result combinators, threads and mpsc channels, time (Duration/Instant/SystemTime), paths, env, process, fs, net, and module selection decisions. Use when users ask "which std type should I use", compare collection/pointer/string alternatives, design Option/Result chains, choose Cell vs RefCell vs Mutex, work with std threads/channels, or pick the right std module for a task; hand async runtime to rust-concurrency, language semantics to rust-stable, and application-layer concerns to domain skills.

Apply and diagnose Rust style, rustfmt, Clippy, compiler diagnostics, Edition migrations, lint policy, idiomatic control flow, error handling, allocation behavior, production Rust conventions, and the Rust API Guidelines ↔ Clippy lint mapping. Use when users ask to format or lint Rust, fix warning or error codes, migrate editions, review unwrap or clone usage, improve idioms, map a C-* API guideline rule to the enforcing Clippy lint, or establish CI quality gates. Route API shape decisions (naming conventions, type/trait design, module layout, full C-* guideline review) to the rust-api-design skill.

Design, implement, and validate Rust tests, including unit, integration, doctest, compile-fail, property, fuzz, benchmark, coverage, async, concurrency, process, daemon, IPC, terminal, platform, and hardware-facing test strategies. Use when users ask for Rust test architecture, flaky-test diagnosis, coverage gates, benchmarks, trybuild, cargo-nextest, real-process tests, or failure-path verification.

Build, generate, test, package, and troubleshoot shared Rust components and cross-platform bindings with Mozilla UniFFI. Use automatically when users want to write business logic once in Rust and call or reuse it from Swift, iOS, macOS, Kotlin, Android, JVM, Python, Ruby, JavaScript, browsers, desktop apps, or multiple platforms—even when they do not mention UniFFI; when they ask to bridge, expose, connect, or share Rust with Swift/Kotlin/Android/iOS; or when they need procedural-macro versus UDL selection, records, enums, errors, objects, traits, callbacks, custom types, uniffi.toml, uniffi-bindgen, async exports, generated-binding diagnostics, native-library loading, packaging, ABI, or upgrades. Verify that the locked UniFFI release supports each requested target; route hand-written C ABI work to rust-unsafe-ffi.

Design, implement, audit, and test unsafe Rust and foreign-function boundaries, including raw pointers, validity and aliasing invariants, MaybeUninit, layout, Pin, manual Send and Sync, allocators, C ABI declarations, callbacks, ownership transfer, unwinding, and Edition 2024 unsafe syntax. Use when safe Rust cannot express the required memory or ABI operation; require minimal unsafe blocks, explicit safety contracts, safe wrappers, Miri where applicable, and real platform integration tests.

Design, implement, test, and operate production Rust server-side HTTP services, including axum, Actix Web, routing, extractors, application state, error mapping, middleware order, timeouts, body limits, observability, graceful shutdown, and database boundaries. Use when users ask for Rust REST APIs, web handlers, middleware, server lifecycle, HTTP contracts, or production web-service architecture; hand security controls to rust-web-security.

Threat-model, implement, review, and test Rust web security, including authentication, object and tenant authorization, sessions, cookies, JWT and OIDC validation, CSRF, CORS, SSRF, input limits, secrets, cryptographic dependency boundaries, audit logging, and negative security tests. Use when users ask to secure or audit Rust web services, tokens, browser transport, multi-tenant access, secret handling, or security incident fixes.

Design Rust project topology — single-crate packages, project-sized multi-crate workspaces (small root-flat, hybrid/domain-grouped, contained crates/, nested, or root-package layouts), workspace-level configuration, dependency DAGs, and crate-boundary decisions. Use when users ask how to split a project into crates, choose paths from the resulting project scale instead of copying a source-language module tree, configure a workspace, avoid dependency cycles, refactor a mixed root-package workspace, or decide between modules and crates. For in-crate src/ layout, see rust-module-layout.