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smithery/cosmonic-labs

webassembly-component-development

Comprehensive guide to WebAssembly component development covering WASI fundamentals, component composition patterns, language interoperability, runtime compatibility, and troubleshooting. Use this skill when building WebAssembly components, writing or editing WIT (WebAssembly Interface Types) definitions, composing components with wac or wasm-tools, targeting wasip1/wasip2/wasip3, working with `.wit` or `.wasm` files, or whenever the user mentions WASI, the component model, wkg, wstd, or compon…

Installation

$ npx skills add smithery/cosmonic-labs --skill webassembly-component-development
View on skills.sh ↗ Website ↗

Summary

  • Comprehensive guide to WebAssembly component development covering WASI fundamentals, component composition patterns, language interoperability, runtime compatibility, and troubleshooting.
  • Use this skill when building WebAssembly components, writing or editing WIT (WebAssembly Interface Types) definitions, composing components with wac or wasm-tools, targeting wasip1/wasip2/wasip3, working with `.wit` or `.wasm` files, or whenever the user mentions WASI, the component model, wkg, wstd, or component composition.

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Also in this package

Other skills from smithery/cosmonic-labs.

npx skills add smithery/cosmonic-labs
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More details

Agent compatibility

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Skill metadata

Parsed from SKILL.md frontmatter.

LicenseApache-2.0

Package contents

Files included with this skill beyond the listing page.

  • skill md SKILL.md 3,504 B
  • docs SUMMARY.md 228 B

History

  1. First recorded snapshot · 0 installs

SKILL.md

WebAssembly Component Development

This skill provides comprehensive expertise in developing WebAssembly components, including WASI fundamentals, composition patterns, runtime compatibility, and troubleshooting.

Key Defaults

  • Build: Use wash build when the project has .wash/config.yaml. Use wash build --skip-fetch for plugins (since wasmcloud:wash interface isn't published). Otherwise cargo build --target wasm32-wasip2 --release.
  • Target: wasm32-wasip2 (Rust 1.82+ tier-2 target). WASI 0.2 (wasip2) is the current standard.
  • Async: Pick one — tokio 1.50+ with RUSTFLAGS="--cfg tokio_unstable", or wstd (lighter, Wasm-native). Do not mix.
  • Strings: Always UTF-8 on wasip2. Avoid asencodedbytes().
  • Threading: Unsupported. Design single-threaded. Avoid rayon, threaded tokio, std::thread::spawn.
  • wasmCloud docs: Always use https://wasmcloud.com/docs/ — never /docs/v1/.

Reference Files

Load the relevant file when working on the matching topic:

Topic File
Component Model fundamentals, benefits, WASI (wasip2) basics [core-concepts.md](core-concepts.md)
Composition patterns (simple dependency, adapter, middleware, facade), boundary design, building with wash build / cargo, wac, .wash/config.yaml [composition-and-building.md](composition-and-building.md)
Cross-language composition, supported languages (Rust, Python, JS/TS, Go, C/C++, C#), data type / performance / error handling considerations [language-interop.md](language-interop.md)
WASI gotchas (no threading, UTF-8 string assumptions, network capabilities), unknown-import errors, runtime-specific compatibility (wasmtime flags, wasmCloud), version alignment strategies [gotchas-and-runtime.md](gotchas-and-runtime.md)
Async with tokio on wasip2, wstd (Wasm-native async stdlib), when to choose which [async.md](async.md)
Testing (host harness, mocks, wash integration, feature flags, env setup), debugging workflow, common error patterns, wasm-tools/wash inspect, performance (minimize cross-component calls, streaming, batching) [testing-debugging-performance.md](testing-debugging-performance.md)
Documentation links, development/component-design/runtime-compat best practices, CI/CD examples, common architecture patterns (microservices, plugin, data pipeline) [patterns-and-best-practices.md](patterns-and-best-practices.md)

Summary

  • Component Model enables language-agnostic, composable WebAssembly applications
  • WASI 0.2 (wasip2) is the current standard with full networking and UTF-8 guarantees
  • Design coarse-grained interfaces for better performance
  • Test in target runtime early and often
  • Use wash build for wasmCloud projects — handles compatibility automatically
  • Document runtime requirements and maintain compatibility matrices