Protocol
Protocol is the set of rules governing how Agents in a Composition interact along the edges of a Topology. If Topology is who is connected to whom, Protocol is how they communicate. Protocol covers two kinds of rules: infrastructure Protocols (the channels themselves - Slack, email, a weekly standup, reporting lines) and governance Protocols (the rules that constrain what happens on those channels - signing authority, approval thresholds, escalation policies, meeting cadences).
The same Topology with different Protocols produces a different Composition - the connections are the same, but what flows through them and how it is governed changes the collective Boundaries. Protocol is one of the three structural elements of a Composition alongside Topology and Tools. A Protocol that blocks information from reaching an Agent constrains that Agent’s Actual Input (Computational effect) which inherently constrains what the Agent can model (Cognitive effect) and therefore what it can do (Causal effect) - the downstream bleed-through across Boundaries is a structural property of Protocols.