The design philosophy of DeepSeek Harness is “everything is a plugin.” When developing agents or orchestrating workflows, it is often necessary to pass messages between different sessions within the same host process. Without a convenient local communication mechanism, developers often have to bypass the standard DSH interface. As a local plugin, DSH Bridge directly solves the problem of session discovery and message sending between sessions within the same host process.

Plugin Positioning

DSH Bridge is a same-host-process, inter-session message-passing plugin for DeepSeek Harness. It is maintained by baixianger and released under the MIT license. The plugin does not rely on cross-host transport tools such as DSH Weave or DSH Chat; it focuses on providing lightweight local message routing.

Core Features

The plugin implements its core capabilities through three tool functions:

  • session_list: lists sessions and displays their current status.
  • session_send: sends a message using an exact session ID or a human-readable title.
  • session_messages: reads the recent message log for a specified session.

Installation and Usage

Installation

Before installing, ensure that the DeepSeek Harness plugin environment is properly configured. Run the following commands to install the plugin:

dsh plugin --profile web add dsh-bridge@latest
dsh web

Usage Flow

After installation, the plugin directly injects the above tool functions into DSH; there is no standalone settings page. A typical workflow is as follows:

  1. Ask the agent to call session_list to retrieve the session list and their status.
  2. Use session_send to send a message to the target session.
    • In session_send, setting mode: auto first attempts to match an exact ID, then matches a title.
    • Setting mode: id or mode: name uses only the corresponding lookup method.
    • Title matching is case-insensitive. If the name is ambiguous, the tool returns candidate IDs without automatically selecting a recipient.

Configuration and Notes

Message Delivery Logic

The plugin handles session status according to the following rules:

  • Status Wakeup: Idle sessions are woken up; running sessions receive work from the queue.
  • Cold Session Handling: When a persisted session is restored, the recorded presets and model are applied. Concurrent requests to a cold session share a single restoration operation. Cancellations remain effective during cold session restoration; even if the shared load completes, no subsequent message is generated.
  • Archive Limitation: Archived sessions reject delivery and are not woken up.
  • Acknowledgment Meaning: Receiving a delivery acknowledgment only means that the session accepted follow-up instructions; it does not mean the model has processed or completed the task.

Runtime Scope and Persistence

  • Process Isolation: Bridge operates only within a single host process. It does not provide cross-process communication capabilities.
  • In-Memory Storage: The recent message log and duplicate ID table maintained by the plugin reside only in memory. When the plugin is unloaded or reloaded, this data is reset; it does not provide a persistent mailbox.
  • Dependencies: DSH Weave provides cross-host transport, and DSH Chat provides rooms and Web views, but neither is a prerequisite for local message passing.

Default Configuration

The plugin provides the following configuration options (no standalone page is required for configuration; they are usually managed by the host or plugin loading logic):

Config Item Default Description
recentMessages 1000 Number of recent messages retained per host
dedupeCapacity 10000 Capacity for remembering external message IDs
maxMessagesPerRead 100 Maximum number of messages returned in a single read operation

Summary

DSH Bridge provides a basic session communication layer for local agent development. It works without cross-host transport and is suitable for scenarios that require fine-grained control of local session interactions.