M12 Lifecycle

The m12-lifecycle skill guides developers through designing resource lifecycles in Rust by answering when resources should be created, used, and cleaned up. It covers patterns like RAII, lazy initialization, connection pooling, and scope guards, tracing decisions from domain constraints down to implementation details using ownership and the Drop trait. This skill is for Rust developers designing systems that manage expensive resources like database connections, helping them choose appropriate patterns based on resource cost, scope, and error handling requirements.

skills.sh installs: 764
GitHub stars: 1.3K
last updated: Jul 14, 2026

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Install

$ npx -y skills add zhanghandong/rust-skills --skill m12-lifecycle --agent claude-code

Installs into .claude/skills of the current project.

Files

Resource Lifecycle

Layer 2: Design Choices

Core Question

When should this resource be created, used, and cleaned up?

Before implementing lifecycle:

What's the resource's scope?
Who owns the cleanup responsibility?
What happens on error?

Lifecycle Pattern → Implementation

Pattern	When	Implementation
RAII	Auto cleanup	`Drop` trait
Lazy init	Deferred creation	`OnceLock`, `LazyLock`
Pool	Reuse expensive resources	`r2d2`, `deadpool`
Guard	Scoped access	`MutexGuard` pattern
Scope	Transaction boundary	Custom struct + Drop

Thinking Prompt

Before designing lifecycle:

What's the resource cost?
- Cheap → create per use
- Expensive → pool or cache
- Global → lazy singleton
What's the scope?
- Function-local → stack allocation
- Request-scoped → passed or extracted
- Application-wide → static or Arc
What about errors?
- Cleanup must happen → Drop
- Cleanup is optional → explicit close
- Cleanup can fail → Result from close