rust

A set of recommended practices for writing Rust code with the 2024 edition of the language. It covers project structure, source files, tests, examples, benchmarks, and package configuration.

In plain words
What is it for?
Use it when structuring Rust packages, naming common directories and files, writing integration tests, adding examples, or setting up benchmarks.
Why use it?
It gives a codebase a consistent organization and development approach when the project uses modern Rust conventions.

Cursor rule for Cursor

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/saynaai/sayna/rust
Clone the repo
git clone --depth 1 https://github.com/SaynaAI/sayna

Made for: Cursor.

Per session 4,445 This file is loaded in full into every session.
When invoked 4,445 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.04445 $0.04445
Opus 5 $0.02223 $0.02223
Sonnet 5 $0.00889 $0.00889
Haiku 4.5 $0.00445 $0.00445

Measured 2d ago against content hash d0daef889f1c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

rust scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.cursor/rules/rust.mdc · 362 lines

How it starts

The opening of the file, as written. The whole thing — 362 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Rust Best Practices (2024-2025)

This document outlines a comprehensive set of best practices for Rust development, covering various aspects from code organization to security and tooling. Adhering to these guidelines will help you write idiomatic, efficient, secure, and maintainable Rust code.

Note: This project uses Rust Edition 2024 (released Feb 2025 with Rust 1.85).

1. Code Organization and Structure

1.1. Directory Structure

  • src/: Contains all the Rust source code.
    • main.rs: The entry point for binary crates.
    • lib.rs: The entry point for library crates.
    • bin/: Contains source files for multiple binary executables within the same project. Each file in bin/ will be compiled into a separate executable.
    • modules/ or components/: (Optional) For larger projects, group related modules or components into subdirectories. Use descriptive names.
    • tests/: Integration tests. (See Testing section below for more details.)
    • examples/: Example code that demonstrates how to use the library.
  • benches/: Benchmark tests (using criterion or similar).
  • Cargo.toml: Project manifest file.
  • Cargo.lock: Records the exact versions of dependencies used. Do not manually edit.
  • .gitignore: Specifies intentionally untracked files that Git should ignore.
  • README.md: Project documentation, including usage instructions, build instructions, and license information.

sayna/ ├── Cargo.toml ├── Cargo.lock ├── src/ │ ├── main.rs # Entry point for a binary crate │ ├── lib.rs # Entry point for a library crate │ ├── modules/ │ │ ├── module_a.rs # A module within the crate │ │ └── module_b.rs # Another module │ └── bin/ │ ├── cli_tool.rs # A separate binary executable │ └── worker.rs # Another binary executable ├── tests/ │ └── integration_test.rs # Integration tests ├── benches/ │ └── my_benchmark.rs # Benchmark tests using Criterion ├── examples/ │ └── example_usage.rs # Example code using the library ├── README.md

Read the full file on GitHub · 362 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 362 lines · 4,445 tokens per session scan A d0daef889f1c

Subscribe to this mod's changes

rust is a cursor rule published in the GitHub repository SaynaAI/sayna (311 stars, last pushed 3mo ago), licensed Apache-2.0. It adds 4,445 tokens to every session, about $0.0222 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.