DeepSeek Harness (DSH) is built around a central design philosophy of plugin architecture, enabling the construction of complex agent workflows. In multi-session collaboration or complex task orchestration, passing context between different sessions is a common requirement. dsh-session-collaboration is a plugin package designed to enable explicit, bidirectional cross-session collaboration.

This plugin is maintained by w210548735-art and is released under the MIT License. It achieves its goals by adding model tools, a host runtime, and a Web card.

Installation

Install the published package using the official installation command:

dsh plugin --profile web add dsh-session-collaboration

Core Features

  1. session_delegate model tool: The model uses this tool to initiate a collaboration request. An explicit session_id must be provided when calling it.
  2. Host Runtime: Uses Agent.steer() to insert relay context into the target session’s next step. Messages do not enter the regular FIFO queue, but are admitted through the target’s steering path.
  3. Web Card: Provides a Web card that records the target session ID and task, and opens the target session in the current view using the existing session service.

Configuration and Usage

Collaboration Mechanism

The relay mechanism records both the sender’s and target session’s IDs, allowing the target session to send a reverse relay without guessing the caller.

Parameter Settings

  • Wait for Reply (wait): Defaults to true. When enabled, the tool waits for the target turn, extracts its assistant text, injects a reply relay, and returns a receipt. If wait: false is set, it can be used for one-way or reverse message passing (for example, when another session is already waiting).
  • Timeout Settings: The default configuration is as follows:
    allowCrossWorkspace: false
    waitTimeoutMs: 120000
  • Cross-Workspace Collaboration: Disabled by default. To enable it, both deployment settings and target authorization conditions must be satisfied.

Limitations and Caveats

  • Self-Delegation: A session cannot delegate to itself.
  • Concurrency Limitation: Each session can have only one collaboration waiting for a reply at a time.
  • Error Handling: Unknown or unavailable targets return typed collaboration errors. Target replies are collected from assistant text blocks; if no text is present, TARGET_REPLY_MISSING is returned.
  • Discovery Limitation: The plugin does not discover sessions by content or title. The caller must provide an opaque session_id.
  • Environment Limitation: The Web card is only available in the Web profile. The host service still works in headless orchestration environments that provide the required DSH services.