effect-http-server

effect-http-server is a skill for Claude Code, Codex from mpsuesser/pi-effect-harness. It costs 84 tokens per session (10,602 once invoked), scanned A, original, MIT.

A guide to building HTTP servers with Effect v4, a TypeScript library for structured programs. It covers routes, requests, responses, middleware, file serving, uploads, WebSockets, and server setup.

In plain words
What is it for?
Use it to create HTTP routes, decode request bodies, handle uploads, serve static files, add middleware, upgrade connections to WebSockets, or run tests with in-memory handlers.
Why use it?
It provides a reference for connecting incoming web requests to application code without guessing how Effect's server pieces fit together.

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/mpsuesser/pi-effect-harness/effect-http-server
Any agent
npx skills add mpsuesser/pi-effect-harness --skill effect-http-server
Clone the repo
git clone --depth 1 https://github.com/mpsuesser/pi-effect-harness

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-http-server

README.md
[![agentmods](https://agentmods.dev/badge/skills/mpsuesser/pi-effect-harness/effect-http-server.svg)](https://agentmods.dev/skills/mpsuesser/pi-effect-harness/effect-http-server)
Your own site
<a href="https://agentmods.dev/skills/mpsuesser/pi-effect-harness/effect-http-server"><img src="https://agentmods.dev/badge/skills/mpsuesser/pi-effect-harness/effect-http-server.svg" alt="Measured on agentmods" height="20"></a>
Per session 84 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 10,602 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 $0.00084 $0.10602
Opus 5 $0.00042 $0.05301
Sonnet 5 $0.00017 $0.02120
Haiku 4.5 $0.00008 $0.01060

Measured 4d ago against content hash c798817eed76, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

effect-http-server 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 4d 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-http-server/SKILL.md · 907 lines

How it starts

The opening of the file, as written. The whole thing — 907 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 HTTP servers built with effect/unstable/httpHttpRouter, HttpServer, HttpServerRequest, HttpServerResponse, HttpMiddleware, and the platform server layers.

This skill covers the imperative HTTP server primitives. For the declarative, schema-first HttpApi/OpenAPI layer see the effect-http-api skill; for HTTP clients see effect-http-client; for raw TCP/WebSocket sockets see effect-socket.

Effect Source Reference

The Effect v4 source is at ~/.cache/effect-v4/. Read it directly when in doubt — these modules are unstable and change between betas.

Key files:

  • packages/effect/src/unstable/http/HttpRouter.ts — router service, add/addAll/route/use, serve, toWebHandler, schema decoders, middleware, cors, provideRequest, RouterConfig
  • packages/effect/src/unstable/http/HttpServer.tsHttpServer service, serve/serveEffect, address helpers, layerTestClient, layerServices
  • packages/effect/src/unstable/http/HttpServerRequest.ts — request model, body accessors, schemaBodyJson/schemaBodyForm/etc., ParsedSearchParams, upgrade, MaxBodySize
  • packages/effect/src/unstable/http/HttpServerResponse.ts — every response constructor and combinator, toWeb/fromWeb
  • packages/effect/src/unstable/http/HttpMiddleware.tslogger, tracer, cors, xForwardedHeaders, searchParamsParser, tracing config references
  • packages/effect/src/unstable/http/HttpEffect.tstoWebHandler*, fromWebHandler, toHandled, pre-response handlers, request scope management
  • packages/effect/src/unstable/http/HttpServerError.tsHttpServerError + reasons, causeResponse, ClientAbort
  • packages/effect/src/unstable/http/HttpServerRespondable.ts — the error-to-response protocol
  • packages/effect/src/unstable/http/HttpBody.ts — body variants (Empty/Raw/Uint8Array/FormData/Stream) and constructors
  • packages/effect/src/unstable/http/Headers.ts, Cookies.ts, Multipart.ts — header/cookie/multipart models and limits
  • packages/effect/src/unstable/http/HttpStaticServer.ts — static file serving
  • packages/platform-node/src/NodeHttpServer.ts — Node server adapter, layer, layerTest, graceful shutdown
  • packages/platform-bun/src/BunHttpServer.ts — Bun equivalent
  • packages/platform-node/test/NodeHttpServer.test.ts — the best end-to-end reference for real route/middleware/multipart wiring

Read the full file on GitHub · 907 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. 4d ago First seen · 907 lines · 84 tokens per session scan A c798817eed76

Subscribe to this mod's changes

effect-http-server is a skill published in the GitHub repository mpsuesser/pi-effect-harness (23 stars, last pushed 2mo ago), licensed MIT. It adds 84 tokens to every session and 10,602 once invoked, about $0.0004 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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