webassembly-expert

webassembly-expert is a skill for Claude Code from personamanagmentlayer/pcl. It costs 69 tokens per session (1,211 once invoked), scanned A, original, Apache-2.0.

A guide to WebAssembly, a portable low-level format that lets code from languages such as Rust or C++ run in browsers and on servers. It covers compiling modules, connecting them to JavaScript, and using WASI for access to system resources outside browsers.

In plain words
What is it for?
Use it to create WebAssembly modules, compile Rust or C++ for the browser, connect modules to JavaScript, use WASI, and work on performance-sensitive code.
Why use it?
It helps reuse low-level code across web and server environments without rewriting it in JavaScript. It also clarifies how sandboxed modules handle memory, files, networking, and other resources.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Good fit Use it to create WebAssembly modules, compile Rust or C++ for the browser, connect modules to JavaScript, use WASI, and work on performance-sensitive code.

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Install with agentmods
npx agentmods add skills/personamanagmentlayer/pcl/webassembly-expert
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 personamanagmentlayer/pcl --skill webassembly-expert
Clone the repo
git clone --depth 1 https://github.com/personamanagmentlayer/pcl

Made for: Claude Code.

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 webassembly-expert

README.md
[![agentmods](https://agentmods.dev/badge/skills/personamanagmentlayer/pcl/webassembly-expert.svg)](https://agentmods.dev/skills/personamanagmentlayer/pcl/webassembly-expert)
Your own site
<a href="https://agentmods.dev/skills/personamanagmentlayer/pcl/webassembly-expert"><img src="https://agentmods.dev/badge/skills/personamanagmentlayer/pcl/webassembly-expert.svg" alt="Measured on agentmods" height="20"></a>
Per session 69 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,211 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00069 $0.01211
Opus 5 $0.00034 $0.00606
Sonnet 5 $0.00014 $0.00242
Haiku 4.5 $0.00007 $0.00121

Measured 2d ago against content hash 24fac9797e44, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

webassembly-expert 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 2d 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.

stdlib/domains/webassembly-expert/SKILL.md · 186 lines

How it starts

The opening of the file, as written. The whole thing — 186 lines — stays where its author put it; the contents beside it link to each section on GitHub.

WebAssembly Expert

Create production-ready WebAssembly modules for web and server environments with optimal performance and seamless JavaScript integration.

Learning Objectives

  • Master WebAssembly module development and compilation
  • Build high-performance WASM applications from Rust and C++
  • Implement WASI for system-level capabilities
  • Optimize WASM for size and execution speed
  • Integrate WASM with JavaScript and web browsers

Prerequisites

  • Strong Rust or C++ programming skills
  • Understanding of low-level systems programming
  • Knowledge of web technologies (JavaScript, browsers)
  • Familiarity with compilation toolchains

Core Concepts

WebAssembly (WASM)

Binary instruction format designed as portable compilation target for high-level languages. Provides near-native performance in web browsers and enables code reuse across platforms.

WASI (WebAssembly System Interface)

System interface specification enabling WASM to run outside browsers with access to system resources (files, network, environment) in a secure, sandboxed manner.

Memory Management

Linear memory model where WASM modules access contiguous byte arrays. Requires careful management of memory allocation, deallocation, and sharing between WASM and JavaScript.

Compilation Targets

Languages like Rust, C++, C, Go, and AssemblyScript can compile to WASM. Each provides different toolchains (rustc, Emscripten, TinyGo) with varying levels of optimization.

JavaScript Interop

Bidirectional communication between WASM and JavaScript through imported/exported functions, shared memory, and typed arrays. Requires careful data marshalling and type conversions.

Best Practices

Performance Optimization

  • Minimize data copying between JavaScript and WASM
  • Use shared memory (SharedArrayBuffer) for large datasets
  • Batch operations to reduce boundary crossings
  • Optimize for WASM instruction set (SIMD when available)
  • Profile hot paths and optimize critical loops
  • Use appropriate numeric types (i32, f32 for better performance)
  • Enable compiler optimizations (opt-level, lto)

Read the full file on GitHub · 186 lines

Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 2d ago First seen · 186 lines · 69 tokens per session scan A 24fac9797e44

Subscribe to this mod's changes

webassembly-expert is a skill published in the GitHub repository personamanagmentlayer/pcl (41 stars, last pushed 2d ago), licensed Apache-2.0. It adds 69 tokens to every session and 1,211 once invoked, about $0.0003 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 2026-09-05.

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