PaperclipOrg
Claude Agent Skill · by Zhanghandong

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

Install
Terminal · npx
$npx skills add https://github.com/zhanghandong/rust-skills --skill m12-lifecycle
Works with Paperclip

How M12 Lifecycle fits into a Paperclip company.

M12 Lifecycle drops into any Paperclip agent that handles this kind of work. Assign it to a specialist inside a pre-configured PaperclipOrg company and the skill becomes available on every heartbeat — no prompt engineering, no tool wiring.

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Source file
SKILL.md177 lines
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---name: m12-lifecycledescription: "Use when designing resource lifecycles. Keywords: RAII, Drop, resource lifecycle, connection pool, lazy initialization, connection pool design, resource cleanup patterns, cleanup, scope, OnceCell, Lazy, once_cell, OnceLock, transaction, session management, when is Drop called, cleanup on error, guard pattern, scope guard, 资源生命周期, 连接池, 惰性初始化, 资源清理, RAII 模式"user-invocable: false--- # 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: 1. **What's the resource cost?**   - Cheap → create per use   - Expensive → pool or cache   - Global → lazy singleton 2. **What's the scope?**   - Function-local → stack allocation   - Request-scoped → passed or extracted   - Application-wide → static or Arc 3. **What about errors?**   - Cleanup must happen → Drop   - Cleanup is optional → explicit close   - Cleanup can fail → Result from close --- ## Trace Up ↑ To domain constraints (Layer 3): ```"How should I manage database connections?"    ↑ Ask: What's the connection cost?    ↑ Check: domain-* (latency requirements)    ↑ Check: Infrastructure (connection limits)``` | Question | Trace To | Ask ||----------|----------|-----|| Connection pooling | domain-* | What's acceptable latency? || Resource limits | domain-* | What are infra constraints? || Transaction scope | domain-* | What must be atomic? | --- ## Trace Down ↓ To implementation (Layer 1): ```"Need automatic cleanup"    ↓ m02-resource: Implement Drop    ↓ m01-ownership: Clear owner for cleanup "Need lazy initialization"    ↓ m03-mutability: OnceLock for thread-safe    ↓ m07-concurrency: LazyLock for sync "Need connection pool"    ↓ m07-concurrency: Thread-safe pool    ↓ m02-resource: Arc for sharing``` --- ## Quick Reference | Pattern | Type | Use Case ||---------|------|----------|| RAII | `Drop` trait | Auto cleanup on scope exit || Lazy Init | `OnceLock`, `LazyLock` | Deferred initialization || Pool | `r2d2`, `deadpool` | Connection reuse || Guard | `MutexGuard` | Scoped lock release || Scope | Custom struct | Transaction boundaries | ## Lifecycle Events | Event | Rust Mechanism ||-------|----------------|| Creation | `new()`, `Default` || Lazy Init | `OnceLock::get_or_init` || Usage | `&self`, `&mut self` || Cleanup | `Drop::drop()` | ## Pattern Templates ### RAII Guard ```ruststruct FileGuard {    path: PathBuf,    _handle: File,} impl Drop for FileGuard {    fn drop(&mut self) {        // Cleanup: remove temp file        let _ = std::fs::remove_file(&self.path);    }}``` ### Lazy Singleton ```rustuse std::sync::OnceLock; static CONFIG: OnceLock<Config> = OnceLock::new(); fn get_config() -> &'static Config {    CONFIG.get_or_init(|| {        Config::load().expect("config required")    })}``` --- ## Common Errors | Error | Cause | Fix ||-------|-------|-----|| Resource leak | Forgot Drop | Implement Drop or RAII wrapper || Double free | Manual memory | Let Rust handle || Use after drop | Dangling reference | Check lifetimes || E0509 move out of Drop | Moving owned field | `Option::take()` || Pool exhaustion | Not returned | Ensure Drop returns | --- ## Anti-Patterns | Anti-Pattern | Why Bad | Better ||--------------|---------|--------|| Manual cleanup | Easy to forget | RAII/Drop || `lazy_static!` | External dep | `std::sync::OnceLock` || Global mutable state | Thread unsafety | `OnceLock` or proper sync || Forget to close | Resource leak | Drop impl | --- ## Related Skills | When | See ||------|-----|| Smart pointers | m02-resource || Thread-safe init | m07-concurrency || Domain scopes | m09-domain || Error in cleanup | m06-error-handling |