astro

Project rules for Astro, a framework for building websites with HTML and optional interactive components called islands.

In plain words
What is it for?
Use them when creating Astro pages, choosing static or server output, adding official integrations, working with content collections, and deciding where interactive components belong.
Why use it?
They prevent Astro projects from being written with patterns from unrelated frameworks and keep client-side JavaScript limited to places that need it.

Cursor rule

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 rules/kleosr/kleosrules/astro
Clone the repo
git clone --depth 1 https://github.com/kleosr/kleosrules
Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 253 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 $0.00000 $0.00253
Opus 5 $0.00000 $0.00127
Sonnet 5 $0.00000 $0.00051
Haiku 4.5 $0.00000 $0.00025

Measured 2d ago against content hash 0d1fdf1217f3, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

astro 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 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.

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.

shared/rules/astro.mdc · 20 lines

What it actually says

Astro

Training is stale (actions, sessions, content collections). Before Write: current Astro docs (Docs MCP if connected, else docs.astro.build). Do not mix Next App Router or Vite-only SPA patterns into .astro pages.

Hard

  • HTML first. Client JS only with an explicit client:* directive. Do not wrap the whole page in React/Vue.
  • Official integrations: pnpm astro add <name>. Do not hand-edit astro.config for those.
  • Content: use Content Collections if this repo already has src/content. Do not invent a parallel glob CMS.
  • Routing and output (static vs server) from this astro.config.*. No getServerSideProps. No app/ directory as Next.
  • Islands: pass only the props the island needs. No fetching in useEffect for data the .astro frontmatter already has.

Subagents inherit this. Do not paste into Task prompts.

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 · 20 lines · 0 tokens per session scan A 0d1fdf1217f3

Subscribe to this mod's changes

astro is a cursor rule published in the GitHub repository kleosr/kleosrules (2 stars, last pushed 2d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 253 tokens. 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 2026-08-31.