effect-atom-rpc

effect-atom-rpc is a skill for Claude Code, Codex from mpsuesser/pi-effect-harness. It costs 48 tokens per session (4,904 once invoked), scanned A, original, MIT.

A reactive client for remote procedure calls in React or other Atom-based interfaces, with cached queries and mutations that update related data.

In plain words
What is it for?
Use it to read and update RPC data in reactive UIs, cache queries, invalidate dependent data after mutations, hydrate server-rendered pages, and consume streaming RPCs.
Why use it?
It removes manual coordination between remote data, UI state, and updates after a change. It also supports restoring query data during server-side rendering, when HTML is prepared on the server.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is import { UsersGroup } from '../shared/users-rpc.ts';.

Good fit Use it to read and update RPC data in reactive UIs, cache queries, invalidate dependent data after mutations, hydrate server-rendered pages, and consume streaming RPCs.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/mpsuesser/pi-effect-harness
agentmods
npx agentmods add skills/mpsuesser/pi-effect-harness/effect-atom-rpc

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 effect-atom-rpc

README.md
[![agentmods](https://agentmods.dev/badge/skills/mpsuesser/pi-effect-harness/effect-atom-rpc.svg)](https://agentmods.dev/skills/mpsuesser/pi-effect-harness/effect-atom-rpc)
Your own site
<a href="https://agentmods.dev/skills/mpsuesser/pi-effect-harness/effect-atom-rpc"><img src="https://agentmods.dev/badge/skills/mpsuesser/pi-effect-harness/effect-atom-rpc.svg" alt="Measured on agentmods" height="20"></a>
Per session 48 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,904 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00048 $0.04904
Opus 5 $0.00024 $0.02452
Sonnet 5 $0.00010 $0.00981
Haiku 4.5 $0.00005 $0.00490

Measured 8d ago against content hash af04606ba23c, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

effect-atom-rpc 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 8d 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.

harnesses/effect/skills/effect-atom-rpc/SKILL.md · 487 lines

How it starts

The opening of the file, as written. The whole thing — 487 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are an Effect TypeScript expert specializing in effect/unstable/reactivity/AtomRpc — the reactive RPC client for Atom-driven frontends.

When to use this skill

AtomRpc sits on top of an RpcGroup and gives you:

  • A Service-style RPC client whose dependencies are wired through an AtomRuntime
  • client.query(tag, payload, options?) — a cached, reactive Atom<AsyncResult<...>>
  • client.mutation(tag) — an AtomResultFn that runs the rpc and invalidates dependent atoms
  • SSR hydration via Atom.serializable when you pass serializationKey
  • Time-to-live caching, reactivity-key invalidation, and stream rpcs surfaced as PullResult atoms

Use this skill when building React (or Atom-based) frontends that consume an existing RpcGroup.

For the underlying RPC definitions, see the effect-rpc-cluster skill. For Atom fundamentals (Atom.make, family, keepAlive, AsyncResult, hydration), see the effect-atom-state and effect-react-vm skills.

Effect Source Reference

  • packages/effect/src/unstable/reactivity/AtomRpc.ts — the whole API (~270 lines)
  • packages/effect/test/reactivity/AtomRpc.test.ts — minimal usage + serialization test
  • packages/effect/src/unstable/reactivity/AtomHttpApi.ts — the cousin pattern for HttpApi (same idea, same options)
  • packages/effect/src/unstable/reactivity/AsyncResult.ts — the AsyncResult type returned by query
  • packages/effect/src/unstable/reactivity/Atom.tsruntime, family, serializable, keepAlive, setIdleTTL
  • packages/effect/src/unstable/reactivity/Hydration.ts — SSR dehydrate/hydrate helpers
  • packages/effect/src/unstable/reactivity/Reactivity.ts — the Reactivity service that powers reactivity keys

Imports

import {
	AsyncResult,
	Atom,
	AtomRpc,
	Hydration,
	Reactivity
} from 'effect/unstable/reactivity';
import { RpcClient, RpcSerialization } from 'effect/unstable/rpc';
import { FetchHttpClient } from 'effect/unstable/http';
import { useAtomValue, useAtomSet } from '@effect/atom-react';

Read the full file on GitHub · 487 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. 8d ago First seen · 487 lines · 48 tokens per session scan A af04606ba23c

Subscribe to this mod's changes

effect-atom-rpc is a skill published in the GitHub repository mpsuesser/pi-effect-harness (24 stars, last pushed 2mo ago), licensed MIT. It adds 48 tokens to every session and 4,904 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 2026-08-30.

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