engine

engine is a skill for Claude Code, Codex from Generous-Corp/pulp. It costs 43 tokens per session (12,605 once invoked), scanned A, original, MIT.

Query, recommend, and switch the Pulp JS engine backend (QuickJS, JavaScriptCore, V8). Handles "which JS engine", "switch to V8", "engine for Three.js".

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/generous-corp/pulp/engine
Any agent
npx skills add Generous-Corp/pulp --skill engine
Clone the repo
git clone --depth 1 https://github.com/Generous-Corp/pulp

Made for: Claude Code, Codex.

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 engine

README.md
[![agentmods](https://agentmods.dev/badge/skills/generous-corp/pulp/engine.svg)](https://agentmods.dev/skills/generous-corp/pulp/engine)
Your own site
<a href="https://agentmods.dev/skills/generous-corp/pulp/engine"><img src="https://agentmods.dev/badge/skills/generous-corp/pulp/engine.svg" alt="Measured on agentmods" height="20"></a>
Per session 43 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 12,605 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00043 $0.12605
Opus 5 $0.00022 $0.06302
Sonnet 5 $0.00009 $0.02521
Haiku 4.5 $0.00004 $0.01260

Measured today against content hash 6b010cdca137, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

engine 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.

.agents/skills/engine/SKILL.md · 709 lines

How it starts

The opening of the file, as written. The whole thing — 709 lines — stays where its author put it; the contents beside it link to each section on GitHub.

JS Engine Skill

Manage the JavaScript engine backend used by Pulp's scripting layer. Three engines are available:

Engine Platform Strengths License
QuickJS All Portable, small, zero dependencies. Default. MIT
JavaScriptCore Apple only System framework, good JIT, zero-dep on macOS/iOS LGPL-2.1 (system use OK)
V8 Desktop Best JIT, ideal for heavy JS (Three.js), largest footprint BSD-3-Clause

Web-compat preludes shipped with every engine

Every engine boots with the same set of web-compat-*.js preludes embedded into web_compat_preludes_gen.hpp and evaluated in order by WidgetBridge. The current set covers everything React 18 dev (and most similar frameworks) feature-detect on construction:

Surface Where Why
Element.nodeType (=1) / nodeName (=tagName) web-compat-element.js React reconciler walks every node and bails before first commit without DOM-compatible node identity.
Element.ELEMENT_NODE / TEXT_NODE / COMMENT_NODE constants web-compat-element.js node.ELEMENT_NODE === 1 fast-paths in React
Widget tag factories (virtual-list, virtuallist, segmented, stepper, etc.) web-compat-element.js DOM-lite custom tags construct the same native widgets as @pulp/react; keep this table in sync when a new widget tag is routed through _ensureNative. A tag needs FOUR tables in step, not one: this map, the createX factory (factory_api.cpp), make_widget_for_tag() (widget_bridge.cpp, the __domAppend path), and wire_callbacks() (widget_callbacks.cpp). The factory wires its callbacks inline while the tag path takes them from wire_callbacks(), so missing that one builds a real, clickable widget whose changes reach nothing — on the tag path only, from a script that is identical either way.
createTextNode → nodeType=3 + nodeName='#text' + data/nodeValue mirrors web-compat-document.js DOM Level 1 text-node spec; React's text-update path
createComment → nodeType=8, createDocumentFragment → nodeType=11 web-compat-document.js React portal sentinels + batched commits
MutationObserver / IntersectionObserver / ResizeObserver / PerformanceObserver no-ops web-compat-observers.js typeof X === 'function' feature-detects pass; React skips because no events ever fire
XMLHttpRequest no-op + spec readyState constants web-compat-observers.js React dev-mode error-stack lookup probes XHR
Element.scrollTop/scrollLeft/scrollWidth/scrollHeight (returns 0) web-compat-observers.js React dev focus warnings
queueMicrotask (Promise-based shim) web-compat-scheduler.js React 18 concurrent scheduler
MessageChannel + MessagePort (microtask-deferred postMessage) web-compat-scheduler.js React 18 scheduler prefers MC; falls back to setTimeout if missing (perf cliff, not a blocker)
URLSearchParams polyfill web-compat-scheduler.js React error-source URL parsing
requestAnimationFrame / cancelAnimationFrame (driven by native __requestFrame__) web-compat-scheduler.js Bundled-React frameworks reference the standard names; without this each consumer has to carry its own scheduler shim.
setTimeout / clearTimeout / setInterval / clearInterval (driven by native __scheduleTimer__ deadline tracker) web-compat-scheduler.js React's scheduler yield path + plugin code; setTimeout(fn, 0) drains via microtask, positive delays drain in service_frame_callbacks().
performance.now() (driven by native __performanceNow__) web-compat-scheduler.js Bundled-React modules read performance.now at module-eval time before the legacy window.performance shim is reachable.
Mirror block onto window (rAF/cAF/sT/cT/sI/cI/MC/qM/perf) web-compat-scheduler.js React 18's scheduler reads window.setTimeout / window.requestAnimationFrame specifically; the global must be reachable through both names.

Read the full file on GitHub · 709 lines

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. today First seen · 709 lines · 43 tokens per session scan A 6b010cdca137

Subscribe to this mod's changes

engine is a skill published in the GitHub repository Generous-Corp/pulp (16 stars, last pushed today), licensed MIT. It adds 43 tokens to every session and 12,605 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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