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.
npx skills add vinnie357/claude-skills --skill wasmtimegit clone --depth 1 https://github.com/vinnie357/claude-skillsWrote 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.
[](https://agentmods.dev/skills/vinnie357/claude-skills/wasmtime)<a href="https://agentmods.dev/skills/vinnie357/claude-skills/wasmtime"><img src="https://agentmods.dev/badge/skills/vinnie357/claude-skills/wasmtime/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.
<a href="https://agentmods.dev/skills/vinnie357/claude-skills/wasmtime"><img src="https://agentmods.dev/badge/skills/vinnie357/claude-skills/wasmtime.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00043 | $0.01371 |
| Opus 5 | $0.00022 | $0.00685 |
| Sonnet 5 | $0.00009 | $0.00274 |
| Haiku 4.5 | $0.00004 | $0.00137 |
Grade A, and why
wasmtime 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 5d 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.
How it starts
The opening of the file, as written. The whole thing — 86 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Wasmtime Development
Wasmtime is a standalone, fast, secure WebAssembly runtime from the Bytecode Alliance. It implements the WebAssembly standard and extensions including WASI (WebAssembly System Interface) and the Component Model.
Anti-fabrication
This skill follows core:anti-fabrication. Wasmtime ships major-version bumps roughly
monthly, so pinned versions and API paths are high-risk. Verified against wasmtime
47.0.3 (crates.io, claude-skills-204): the host/guest Rust examples were pinned to a
stale "29" and used the pre-reorg wasmtime_wasi API — corrected to the p1::/p2::
submodule layout confirmed against docs.rs/wasmtime-wasi/latest, and WasiView::ctx()
was corrected to return a single WasiCtxView<'_> rather than separate ctx()/table()
methods. WASI 0.3.0 native-async coverage (stream/future in the Component Model,
requires Wasmtime 46+) was added, confirmed against wasi.dev and bytecodealliance.org.
Re-verify against docs.rs/wasmtime/latest before asserting an API this skill doesn't
cover — this crate changes fast enough that a stale example compiles against nothing.
Core Concepts
| Concept | Purpose |
|---|---|
| Engine | Shared compilation environment and configuration |
| Store | Per-instance state container (fuel, epoch, host data) |
| Module | Compiled .wasm binary (core module) |
| Component | Compiled component with typed interfaces (WIT-based) |
| Instance | Runtime instantiation of a module or component |
| Linker | Resolves imports by name, defines host functions |
| WIT | WebAssembly Interface Type language for component contracts |
Authoring WIT interface files continues in /wasm:wit.
Supported Languages
Guest Languages (compile TO wasm)
| Language | Target | Tooling | Reference |
|---|---|---|---|
| Rust | wasm32-wasip1, wasm32-wasip2, wasm32-unknown-unknown |
cargo-component, wit-bindgen |
guest-rust.md |
| Zig | wasm32-wasi, wasm32-freestanding |
zig build, build.zig |
guest-zig.md |
What ships with it
5 files 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.
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.
- 5d ago First seen · 86 lines · 43 tokens per session scan A fae2c2d5919e
wasmtime is a skill published in the GitHub repository vinnie357/claude-skills (25 stars, last pushed 3d ago), licensed MIT. It adds 43 tokens to every session and 1,371 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 2026-09-04.
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