rust-ownership

rust-ownership is a skill for Claude Code, Codex from heyAyushh/stacc. It costs 44 tokens per session (795 once invoked), scanned A, original, MIT.

A guide to Rust ownership, borrowing, and lifetimes—the rules that decide which part of a program controls data and how long references may be used.

In plain words
What is it for?
Use it when fixing ownership errors or deciding whether data should be owned, borrowed, shared, or returned from a function.
Why use it?
It helps explain compiler errors caused by moving, borrowing, or keeping data alive for the wrong amount of time.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it when fixing ownership errors or deciding whether data should be owned, borrowed, shared, or returned from a function.

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Install with agentmods
npx agentmods add skills/heyayushh/stacc/ownership
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.

Any agent
npx skills add heyAyushh/stacc --skill ownership
Clone the repo
git clone --depth 1 https://github.com/heyAyushh/stacc

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for rust-ownership

README.md
[![agentmods](https://agentmods.dev/badge/skills/heyayushh/stacc/ownership/github.svg)](https://agentmods.dev/skills/heyayushh/stacc/ownership)
Your own site
<a href="https://agentmods.dev/skills/heyayushh/stacc/ownership"><img src="https://agentmods.dev/badge/skills/heyayushh/stacc/ownership/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for rust-ownership

Your own site · 80×15
<a href="https://agentmods.dev/skills/heyayushh/stacc/ownership"><img src="https://agentmods.dev/badge/skills/heyayushh/stacc/ownership.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 795 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00044 $0.00795
Opus 5 $0.00022 $0.00398
Sonnet 5 $0.00009 $0.00159
Haiku 4.5 $0.00004 $0.00080

Measured 9d ago against content hash 13a5b098e5b2, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

rust-ownership 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 9d 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.

configs/stacks/rust/ownership/SKILL.md · 98 lines

How it starts

The opening of the file, as written. The whole thing — 98 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Ownership & Lifetimes

Layer 1: Language Mechanics

Core Question

Who should own this data, and for how long?

Before fixing ownership errors, understand the data's role:

  • Is it shared or exclusive?
  • Is it short-lived or long-lived?
  • Is it transformed or just read?

Error → Design Question

Error Don't Just Say Ask Instead
E0382 "Clone it" Who should own this data?
E0597 "Extend lifetime" Is the scope boundary correct?
E0506 "End borrow first" Should mutation happen elsewhere?
E0507 "Clone before move" Why are we moving from a reference?
E0515 "Return owned" Should caller own the data?
E0716 "Bind to variable" Why is this temporary?
E0106 "Add 'a" What is the actual lifetime relationship?

Thinking Prompt

Before fixing an ownership error, ask:

  1. What is this data's domain role?

    • Entity (unique identity) → owned
    • Value Object (interchangeable) → clone/copy OK
    • Temporary (computation result) → maybe restructure
  2. Is the ownership design intentional?

    • By design → work within constraints
    • Accidental → consider redesign
  3. Fix symptom or redesign?

    • If Strike 3 (3rd attempt) → escalate to design layer

Quick Reference

Pattern Ownership Cost Use When
Move Transfer Zero Caller doesn't need data
&T Borrow Zero Read-only access
&mut T Exclusive borrow Zero Need to modify
clone() Duplicate Alloc + copy Actually need a copy
Rc<T> Shared (single) Ref count Single-thread sharing
Arc<T> Shared (multi) Atomic ref count Multi-thread sharing
Cow<T> Clone-on-write Alloc if mutated Might modify

Error Code Reference

Error Cause Fix
E0382 Value moved Clone, reference, or redesign ownership
E0597 Reference outlives owner Extend owner scope or restructure
E0506 Assign while borrowed End borrow before mutation
E0507 Move out of borrowed Clone or use reference
E0515 Return local reference Return owned value
E0716 Temporary dropped Bind to variable
E0106 Missing lifetime Add 'a annotation

Read the full file on GitHub · 98 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. 9d ago First seen · 98 lines · 44 tokens per session scan A 13a5b098e5b2

Subscribe to this mod's changes

rust-ownership is a skill published in the GitHub repository heyAyushh/stacc (3 stars, last pushed 2mo ago), licensed MIT. It adds 44 tokens to every session and 795 once invoked, about $0.0002 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 2026-09-03.