Session type

Source: Wikipedia Topic: Typing communication protocols for concurrent and distributed programs.

Core idea

Session types ensure that messages are exchanged in the expected order and of the expected type, with protocol conformance and communication safety as first-class goals.

Key claims

• Correctness of interaction is a type-level concern, not just an implementation detail.
• Concurrent systems benefit from making protocol structure explicit.
• Deadlock and communication mismatches can be reduced when the global protocol is checkable.

Harness takeaway

Agent-tool-human handoffs should be typed protocols with inspectable states, not improvised prompt rituals.