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.
npx agentmods add rules/tyrchen/cursor-rust-rules/single-crategit clone --depth 1 https://github.com/tyrchen/cursor-rust-rulesWhat 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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00000 | $0.03609 |
| Opus 5 | $0.00000 | $0.01804 |
| Sonnet 5 | $0.00000 | $0.00722 |
| Haiku 4.5 | $0.00000 | $0.00361 |
Grade A, and why
single-crate 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.
How it starts
The opening of the file, as written. The whole thing — 594 lines — stays where its author put it; the contents beside it link to each section on GitHub.
📦 SINGLE CRATE PROJECT STRUCTURE
TL;DR: Guidelines for organizing simple Rust projects using a single crate structure with clean separation of concerns and maintainable file organization.
🔍 SINGLE CRATE DESIGN STRATEGY
graph TD
Start["Single Crate Project"] --> CrateType{"Crate<br>Type?"}
CrateType -->|Binary| BinaryStructure["Binary Crate Structure"]
CrateType -->|Library| LibraryStructure["Library Crate Structure"]
CrateType -->|Mixed| MixedStructure["Mixed Crate Structure"]
BinaryStructure --> MinimalMain["Minimal main.rs"]
BinaryStructure --> CoreLib["Core Logic in lib.rs"]
LibraryStructure --> PublicAPI["Public API Design"]
LibraryStructure --> ModuleOrg["Module Organization"]
MixedStructure --> BinaryEntry["Binary Entry Point"]
MixedStructure --> LibraryAPI["Library API"]
MinimalMain --> FeatureModules["Feature-Based Modules"]
CoreLib --> FeatureModules
PublicAPI --> FeatureModules
ModuleOrg --> FeatureModules
BinaryEntry --> FeatureModules
LibraryAPI --> FeatureModules
FeatureModules --> ErrorHandling["Centralized Error Handling"]
ErrorHandling --> Configuration["Configuration Management"]
Configuration --> Testing["Testing Strategy"]
Testing --> Documentation["Documentation"]
Documentation --> Production["Production Single Crate"]
style Start fill:#4da6ff,stroke:#0066cc,color:white
style BinaryStructure fill:#4dbb5f,stroke:#36873f,color:white
style LibraryStructure fill:#ffa64d,stroke:#cc7a30,color:white
style MixedStructure fill:#d94dbb,stroke:#a3378a,color:white
🏗️ PROJECT STRUCTURE OVERVIEW
graph TD
Project["Single Crate Project"] --> Binary["Binary Crate<br>(src/main.rs)"]
Project --> Library["Library Crate<br>(src/lib.rs)"]
Project --> Mixed["Mixed Crate<br>(src/main.rs + src/lib.rs)"]
Binary --> BinStructure["Binary Structure:"]
Library --> LibStructure["Library Structure:"]
Mixed --> MixedStructure["Mixed Structure:"]
BinStructure --> MainRs["src/main.rs<br>(minimal)"]
BinStructure --> AppLib["src/lib.rs<br>(core logic)"]
BinStructure --> Modules["src/modules/<br>(feature modules)"]
LibStructure --> LibRs["src/lib.rs<br>(public API)"]
LibStructure --> LibModules["src/modules/<br>(functionality)"]
LibStructure --> LibErrors["src/errors.rs<br>(centralized errors)"]
MixedStructure --> BothMain["src/main.rs<br>(binary entry)"]
MixedStructure --> BothLib["src/lib.rs<br>(library API)"]
MixedStructure --> SharedMods["src/modules/<br>(shared logic)"]
style Project fill:#4da6ff,stroke:#0066cc,color:white
style Binary fill:#4dbb5f,stroke:#36873f,color:white
style Library fill:#ffa64d,stroke:#cc7a30,color:white
style Mixed fill:#d94dbb,stroke:#a3378a,color:white
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.
- 2d ago First seen · 594 lines · 0 tokens per session scan A 2a203e5f3228
single-crate is a cursor rule published in the GitHub repository tyrchen/cursor-rust-rules (27 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 3,609 tokens. 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.
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