dsh-cross-session-messaging: DeepSeek Harness Cross-Session Message Relay

DeepSeek Harness (dsh) provides a cross-process, point-to-point messaging mechanism to enable bidirectional communication between independent sessions. The plugin allows models to discover and exchange messages through tool calls. Messages are injected in a “relay” format, and the recipient must manually approve the tool calls. It supports both local and cross-machine communication and requires TLS configuration as well as a peer node list. Installation requires Node.js >= 24.11, with the plugin to be added to the configuration after building via npm.