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 sailingnaturali/claude-skills --skill signalk-wasm-librarygit clone --depth 1 https://github.com/sailingnaturali/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/sailingnaturali/claude-skills/signalk-wasm-library)<a href="https://agentmods.dev/skills/sailingnaturali/claude-skills/signalk-wasm-library"><img src="https://agentmods.dev/badge/skills/sailingnaturali/claude-skills/signalk-wasm-library/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/sailingnaturali/claude-skills/signalk-wasm-library"><img src="https://agentmods.dev/badge/skills/sailingnaturali/claude-skills/signalk-wasm-library.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00112 | $0.01858 |
| Opus 5.5 | $0.00045 | $0.00743 |
| Sonnet 5.5 | $0.00022 | $0.00372 |
| Haiku 4.5 | $0.00011 | $0.00186 |
Grade A, and why
signalk-wasm-library 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 today.
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 — 138 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Ship a wasm-pack module inside a SignalK Node plugin
The other way to use WebAssembly in SignalK: keep a normal Node plugin (full
@signalk/server-api, read-only routes, serial ports, the NMEA event bus) and run the heavy
or reused code as a wasm-bindgen module loaded in-process. The reference implementation is
@canboat/wasm — canboat's Rust NMEA 2000
decoder/encoder compiled for wasm32-unknown-unknown and published as an npm package; read it
as the worked example. (For a fully sandboxed plugin written in Rust, see the sibling skill
signalk-wasm-plugin.)
1. Why this pattern exists
- Install scripts never run on app-store installs (
npm --ignore-scripts), and npm 12 skips dependency scripts by default. A native addon built inpostinstallsilently disappears; a.wasmfile that is already in the tarball needs no build step, no toolchain on the boat and no per-arch prebuilds. One artifact runs on x86, arm64 and armv7. - In-process beats a child process.
@canboat/wasmdecodes a line in about 5 µs — roughly 2.8× faster than the pure-JScanboatjsand faster than the native binary behind a pipe. Cost: a bigger package (1.55 MB wasm, ~530 KB gzipped). - One codebase, two targets. The same Rust crate builds the native CLI and the wasm module, so behaviour can't drift — if you keep the wasm crate free of protocol logic and depend on the upstream crate with only its sans-I/O features.
2. Design rule: sans-I/O
wasm32-unknown-unknown has no sockets, files or clock. Put parsing/encoding/state machines
in Rust and leave all I/O in TypeScript (node:net for TCP gateways, serialport,
WebSocket). For byte-stream protocols expose a feed/poll shape — decodeBytes(chunk),
takePendingTx(), tick() called about once a second so timers advance on a quiet link —
rather than callbacks into JS.
3. Build
[lib]
crate-type = ["cdylib", "rlib"] # rlib keeps `cargo test` on the host target
[dependencies]
wasm-bindgen = "0.2"
[profile.release]
opt-level = "z"
lto = true
strip = true
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.
- today First seen · 138 lines · 112 tokens per session scan A 58648d63ab04
signalk-wasm-library is a skill published in the GitHub repository sailingnaturali/claude-skills (3 stars, last pushed yesterday), licensed MIT. It adds 112 tokens to every session and 1,858 once invoked, about $0.0004 per session on Opus 5.5. 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 2026-10-19.
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