Crypto Protocol Diagram skill: what it does and how to install it

What it does. Reads protocol source code, RFCs, papers, prose, ProVerif models or Tamarin models to identify parties, messages, cryptographic operations, phases and abort paths. It writes an annotated Mermaid sequenceDiagram to a Markdown file and prints an ASCII sequence diagram with a protocol summary.

When to use it. For visualising handshakes, key exchanges and multi-party cryptographic protocols such as TLS, Noise, Signal, X3DH and FROST. It is not for call graphs, class hierarchies, module dependencies or formal verification.