Show HN: Replay three AI agent approval failures in five seconds, in Python

Call4Agents is a zero-dependency Python library that adds once-only actions, approvals bound to exact arguments, undo, idempotency keys and record/replay/diff to existing agents built on LangGraph, Pydantic AI, the OpenAI Agents SDK, MCP or plain Python. Its `call4agents incident` and `call4agents quickstart` commands reproduce crash-and-resume double actions (e.g. 2 emails without the kit, 1 with it) in real processes, and version 0.6 is Apache-2.0 with an optional PostgreSQL backend for multiple machines.