ONCE — Exactly-Once Reliability for AI Agent Actions for Claude Code

io.github.gsterlingpress/once

Prevent duplicate AI-agent side effects with idempotency, verification, and durable receipts.

client:Claude Code transport:streamable-http

Install ONCE — Exactly-Once Reliability for AI Agent Actions in Claude Code

run in your project directory

claude mcp add --transport http once https://optimistic-compassion-production.up.railway.app/mcp

Adds it for this project only. Append --scope user to make it available everywhere. Claude Code docs