diff --git a/doc/architecture.md b/doc/architecture.md
index 85ccef7..2ee94d1 100644
--- a/doc/architecture.md
+++ b/doc/architecture.md
@@ -54,9 +54,9 @@ An MCP server can remain an optional external dependency. A bridge tool can invo
 
 Capabilities are not compiled into the agent loop as provider-specific or framework-specific tool objects. Tool behavior lives in external executables or metadata-only commands, and toolsrv owns discovery, loading, execution, sandboxing, and process state. See [`architecture-tools.md`](architecture-tools.md) and [`architecture-toolsrv.md`](architecture-toolsrv.md).
 
-### No second coordination protocol
+### No external coordination protocol
 
-Ollie does not add a workflow engine, message bus, actor framework, or master coordinator for multi-agent work. Sessions, agents, `prompt`, `chat`, `statewait`, `feed`, and `ctl` files provide routing, synchronization, observation, and control. Hub-and-spoke, pipeline, scatter-gather, peer, reactive, and self-directed workflows are scripts or agent conventions over those files.
+Ollie does not expose a workflow engine, message bus, actor framework, or master coordinator as an external integration boundary. The runtime does contain an internal session event bus for agent and session observers; it is an implementation detail, not a public coordination API. External multi-agent coordination uses sessions, agents, `prompt`, `chat`, `statewait`, `feed`, and `ctl` files. Hub-and-spoke, pipeline, scatter-gather, peer, reactive, and self-directed workflows are scripts or agent conventions over those files.
 
 ### No separate frontend control plane