Rust Ffi Safe Wrappers

What it does

When your agent uses it

• Reviewing unsafe extern blocks
• Panic-safe foreign boundaries

Example prompts

• “/rust-ffi-safe-wrappers”

Requirements

• Compatibility (from SKILL.md): Codex, Claude Code, and other Agent Skills-compatible clients.

Workflow steps

7 steps, taken from the first numbered list in SKILL.md.

1. 1Separate raw declarations from safe wrappers. Put raw unsafe extern
2. 2Verify ABI, type layout, calling convention, ownership, nullability,
3. 3Use unsafe extern "C" blocks for modern Rust, especially Rust 2024 edition
4. 4Use #[repr(C)] for structs and enums that cross the ABI boundary. Do not
5. 5Use CString for owned nul-terminated strings sent to C and CStr for
6. 6Wrap raw handles in Rust types with private fields and Drop cleanup using
7. 7Prevent Rust panics from crossing extern "C" boundaries. Catch panics or

What it can do on your machine

Read from SKILL.md and the folder at commit 9e7b281. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are rust).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  No URLs in SKILL.md.

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

• Compatibility

  Codex, Claude Code, and other Agent Skills-compatible clients.

  From compatibility in the SKILL.md frontmatter.

Context cost

Rust Ffi Safe Wrappers loads about 945 tokens when it runs, and up to ~1.5k if it reads all its reference files. Until then it costs about 88 tokens; SKILL.md has 390 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~88

When it runs · the whole SKILL.md, loaded when a task matches

~945

With references · SKILL.md plus every file in references/, read only if the agent opens them

~1.5k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from hashgraph-online/awesome-codex-plugins at commit 9e7b281, republished under its MIT licence (© hashgraph-online). 390 words, ~945 tokens.

name

rust-ffi-safe-wrappers

description

Design and review Rust FFI boundaries that keep raw declarations isolated behind safe ownership, lifetime, error, and cleanup wrappers. Use when writing, refactoring, or reviewing unsafe extern blocks, C ABI wrappers, repr(C) types, CString, CStr, raw handles, Drop cleanup, bindgen, cbindgen, or panic-safe foreign boundaries.

compatibility

Codex, Claude Code, and other Agent Skills-compatible clients.

license

MIT

metadata.version

0.1.0

metadata.displayName

Rust FFI Safe Wrappers

metadata.category

Rust

metadata.tags

rust,ffi,c-abi,unsafe,bindings

unsafe extern "C" {
    pub fn library_open(path: *const core::ffi::c_char) -> *mut RawHandle;
    pub fn library_close(handle: *mut RawHandle);
    // Mark an item `safe` only when calling it is valid for all Rust inputs:
    // pub safe fn library_version() -> core::ffi::c_int;
}

// SAFETY: This exported symbol name is unique for this library.
#[unsafe(no_mangle)]
pub extern "C" fn plugin_version() -> core::ffi::c_int {
    1
}

© hashgraph-online, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 2 other files (references) in plugins/LVTD-LLC/skills/skills/rust-ffi-safe-wrappers of hashgraph-online/awesome-codex-plugins.

• SKILL.md
• agents/openai.yaml
• references/ffi-boundary-patterns.md

Open the folder on GitHubat commit 9e7b281