# Neverinfamous Memory Journal MCP Rust > Rust Development & Meta-Cognition - Skill: `tomevault-io/neverinfamous-memory-journal-mcp-rust` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/neverinfamous-memory-journal-mcp-rust` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/neverinfamous-memory-journal-mcp-rust/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: AI & ML - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/neverinfamous-memory-journal-mcp-rust --- # Rust Development & Meta-Cognition When solving Rust problems, **do not immediately write code.** Trace through the cognitive layers first to understand the data's lifecycle, ownership, and constraints. ## 🧠 1. The Meta-Cognition Framework (Before You Code) ### Layer 1: Domain Constraints (WHY) What is the system trying to achieve? - **Web Service:** Concurrent, async, low-latency (Often uses `axum`, `tokio`, `Arc>`). - **CLI Tool:** Fast startup, zero overhead, clean exit codes (Often uses `clap`, `anyhow`, strict error formatting). - **Embedded / Systems:** No heap allocation (Requires `no_std`, specific hardware limitations). ### Layer 2: Design Choices & Ownership (WHAT) Ask the core question: **Who should own this data?** - _Single owner, strictly unique_: Direct value or `Box`. - _Single thread, multiple owners_: `Rc` (use `RefCell` for mutation). - _Multi-thread, multiple owners_: `Arc` (use `Mutex` or `RwLock` for mutation). **Why does it need to mutate?** Avoid slapping `mut` everywhere. Prefer returning new values or using tight, scoped mutability. ### Layer 3: Language Mechanics (HOW) Use the compiler's strictness as a tool, not an obstacle. - Implement standard traits: `Drop`, `Clone`, `Default`, `Display`, `From`, `TryFrom`. - Avoid `unwrap()` or `expect()` in production logic. Propagate errors natively via `?` and `Result`. --- ## 🏗️ 2. Core Ecosystem Defaults Consult [references/ecosystem.md](references/ecosystem.md) for canonical community crates. --- ## 🛡️ 3. Solving Borrow Checker Errors Consult [references/borrow-checker.md](references/borrow-checker.md) for diagnostics and resolution paths for common compiler errors (E0382, E0596, E0499). --- ## ⚡ 4. High-Integrity Code Patterns 1. **Avoid Panic-Driven Development**: `clone()` is an acceptable escape hatch during prototyping, but do not scatter it throughout the code. Revisit the lifetime boundaries as soon as it works. 2. **The Newtype Pattern**: Use tuple structs to prevent invalid state. `struct UserId(u64);` avoids mixing it up with `struct OrderId(u64);`. 3. **Exhaustive Matching**: Prefer `match` over `if let` when handling Enums or State Machines. The compiler will notify you when a new variant is added, preventing silent bugs. 4. **Data-Oriented Modeling**: Prefer small, flat structs that compose over deep, object-oriented inheritance hierarchies. --- ## 🛠️ 5. Standard Commands - **Run Application**: `cargo run` - **Linting / Idioms**: `cargo clippy -- -D warnings` - **Formatting**: `cargo fmt` - **Testing**: `cargo test` **Agent Directive:** When writing or editing Rust code, always invoke `cargo clippy` and `cargo test` dynamically to validate your implementations before concluding your task. --- ## 🔒 6. Security & `unsafe` Blocks Avoid `unsafe` blocks. If you must use `unsafe` for FFI or performance, you MUST thoroughly document the exact safety invariants being upheld inside the block. Require user confirmation before executing any command with external side effects, including `cargo publish` and registry operations. --- > Source: [neverinfamous/memory-journal-mcp](https://github.com/neverinfamous/memory-journal-mcp) — distributed by [TomeVault](https://tomevault.io).