Hi HN — I just open-sourced Hibana and hibana-agent.

Hibana is an Affine MultiParty Session Types (MPST) runtime for Rust.

It targets protocol drift in distributed systems. Instead of maintaining separate hand-written state machines in each component, you define interaction once as a global choreography and project role-local behavior at compile time. At runtime, only valid protocol transitions are executable, so invalid moves such as skipping, reusing, or taking the wrong branch are rejected by the protocol model.

The practical value is that one global source of truth replaces multiple hand-written state machines and removes a class of protocol-drift bugs.

Core repo: https://github.com/hibanaworks/hibana

One concrete example is hibana-agent, which demonstrates the same model on an AI agent workflow: allowed action paths are defined in choreography, and only those transitions are executable at runtime.

Example app: https://github.com/hibanaworks/hibana-agent