policyengine-app

Development guidance for PolicyEngine's website and calculator, which run in a Bun/Turbo monorepo—a repository containing several related projects managed together.

In plain words
What is it for?
Use it when developing, building, or running the PolicyEngine website, calculator, shared packages, or their API connections.
Why use it?
It explains the split between the newer Next.js website and the older Vite calculator during their migration, reducing confusion about where changes belong.

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/policyengine/policyengine-claude/policyengine-app
Any agent
npx skills add PolicyEngine/policyengine-claude --skill policyengine-app
Clone the repo
git clone --depth 1 https://github.com/PolicyEngine/policyengine-claude

Made for: Claude Code, Codex.

Per session 174 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,993 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 2 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 $0.00174 $0.01993
Opus 5 $0.00087 $0.00996
Sonnet 5 $0.00035 $0.00399
Haiku 4.5 $0.00017 $0.00199

Measured 2d ago against content hash efcd2fc6d374, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade C, and why

policyengine-app scanned grade C with 2 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.

Recursive force deletehighDestructive command

rm -rf with a variable or a broad path is one typo away from removing the wrong tree.

- When `bun install` fails, try at most 2 fixes, then ask. Never `rm -rf node_modules`,

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

- **`curl` is NOT verification.** An SPA (and a streamed Next page) returns a 200 HTML shell
skills/policyengine-app/SKILL.md · 140 lines

How it starts

The opening of the file, as written. The whole thing — 140 lines — stays where its author put it; the contents beside it link to each section on GitHub.

PolicyEngine app v2

PolicyEngine/policyengine-app-v2 is the frontend served at policyengine.org. It is mid-migration: a Next.js 15 App Router host lives in website/ and is the live apex, while a legacy Vite SPA in app/ still owns the calculator surface and is being ported page by page. Verify the current stack from package.json files before trusting any summary — this repo moves fast.

Monorepo layout

Bun workspaces + Turbo (packageManager: [email protected], root turbo.json). Workspaces: packages/*, app, website, calculator-app.

Path What Bundler
website/ @policyengine/website — Next.js 15 App Router host (live apex, marketing/research/tools) Next 15 + Turbopack
app/ policyengine-app-v2 — legacy Vite SPA (calculator: policies, households, reports, simulations) Vite 6
calculator-app/ standalone calculator workspace Vite
packages/ shared workspace packages

Root scripts run through Turbo: bun run buildturbo run build; bun run dev runs the Next host (scripts/dev-server-next.mjs); bun run dev:legacy runs the Vite app.

Tech stack (verified from package.json)

There is no third-party component framework — UI is built from radix-ui primitives plus local components. Do not add one.

  • website/: next ^15.3.3, radix-ui ^1.4.3, @tabler/icons-react, tailwindcss v4 (@tailwindcss/postcss), class-variance-authority, react 19, react-plotly.js (maps), framer-motion, fuse.js, react-markdown.
  • app/: vite 6, react-router-dom 7, @tanstack/react-query, @reduxjs/toolkit + react-redux, recharts ^3.7.0, @tabler/icons-react, tailwindcss v4 (@tailwindcss/vite), Storybook.
  • Both pin @policyengine/ui-kit ^0.4.0. See the policyengine-design skill for its API.

useDisclosure / useMediaQuery / useViewportSize in app/src/hooks/ are local reimplementations — not a dependency.

App Router page pattern (website/)

Read the full file on GitHub · 140 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. 2d ago First seen · 140 lines · 174 tokens per session scan C efcd2fc6d374

Subscribe to this mod's changes

policyengine-app is a skill published in the GitHub repository PolicyEngine/policyengine-claude (31 stars, last pushed 8d ago), licensed MIT. It adds 174 tokens to every session and 1,993 once invoked, about $0.0009 per session on Opus 5. A static security scan graded it C with 2 findings (recursive force delete, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

Other skills, from other repositories

systematic-debugging

Use when encountering any bug, test failure, or unexpected behavior, before proposing fixes.

obra/superpowers · 21 tokens

brainstorming

You MUST use this before any creative work - creating features, building components, adding functionality, or modifying behavior. Explores user intent, requirements and design before implementation.

obra/superpowers · 37 tokens

auto-perf-optimize

Run agent-driven VS Code performance or memory investigations. Use when asked to launch Code OSS, automate a VS Code scenario, run the Chat memory smoke runner, capture renderer heap snapshots, take workflow screenshots, compare run summaries, or drive a repeatable scenario before heap-snapshot analysis.

microsoft/vscode · 62 tokens

chat-perf

Run chat perf benchmarks and memory leak checks against the local dev build or any published VS Code version. Use when investigating chat rendering regressions, validating perf-sensitive changes to chat UI, or checking for memory leaks in the chat response pipeline.

microsoft/vscode · 51 tokens

chat-pet-sprite-creation

Use when creating or changing VS Code chat pet sprite art, sprite sheets, state animations, eye treatments, Stable/Insiders variants, or pet transitions under src/vs/workbench/contrib/chat/browser/widget/media/chatPet.

microsoft/vscode · 53 tokens

cpu-profile-analysis

Analyze V8/Chrome CPU profiles (.cpuprofile) and DevTools trace files (Trace-.json). Use when: profiling performance, investigating slow functions, comparing code paths, finding bottlenecks, analyzing timeToRequest, understanding call trees from sampling profiler data, analyzing layout/paint/rendering, investigating…

microsoft/vscode · 71 tokens