dsh-call-session

In-process cross-session communication and workspace shared blackboard for DeepSeek Harness (DSH)

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Overview

DeepSeek Harness sessions are isolated by default, and child tasks exit upon completion.

dsh-call-session adds in-process cross-session communication, peer session creation, and shared blackboard capabilities:

• Inter-session unicast: send directives or hand off tasks between independent long-running sessions.
• Shared blackboard: publish bulky artifacts to a shared board for on-demand retrieval, avoiding context bloat.
• Visual canvas: observe session states, blackboard items, and call trajectories in the DSH Web UI.

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Install

# Add to target profile web
dsh plugin --profile web add dsh-call-session

# List installed plugins
dsh plugin --profile web list

# Remove plugin
dsh plugin --profile web remove dsh-call-session

Note: The --profile option must follow the plugin subcommand, e.g. dsh plugin --profile web ....

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Scenarios

Instruct the agent using plain natural language in the chat; the agent invokes the tools automatically:

Task Handoff

User prompt:

Hand off this task summary to the "audit-session" session.

The agent calls session_call to dispatch a unicast message. If the target session is running, it steers execution; if idle, it wakes a new turn.

Post Results

User prompt:

Publish the review conclusions to the board and notify relevant sessions to pick up tasks.

The agent calls board_post to store the detailed report on the blackboard and obtain a postId. Other sessions retrieve the content on demand via board_list, preventing context window explosion.

Create Session

User prompt:

Create a new session and hand off tasks.

The agent calls session_create to spawn a long-running peer session in the current workspace, automatically inheriting model specifications and presets.

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Canvas

The DSH Web session view exposes a Canvas tab to observe multi-agent collaboration across workspaces:

• Topology: workspace columns, running/idle session nodes, blackboard items with TTL countdowns, and directional call traces.
• Interaction: hovering highlights the 1-hop connected subgraph; double-clicking opens a read-only inspector drawer.
• Read-only boundary: the canvas offers no control inputs; all state changes originate from the agents themselves.

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Tools

Tool	Type	Mode	Common Use Case
session_call	Tool	Push	1:1 unicast call for task dispatch, progress reporting, and handoffs
session_create	Tool	Native	Create long-running peer sessions for parallel multi-role collaboration
session_query	Tool	Read-only	List sessions and check active/idle statuses in or across workspaces
board_post	Tool	Pull	Publish blackboard entries for large artifacts and shared milestones
board_list	Tool	Pull	Query blackboard records by ID, topic, or digest mode
board_clear	Tool	Manage	Dismiss or purge completed and expired blackboard entries

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Comparison

Mechanism	Type	Model	When to Use
subagent	Built-in	Hierarchical delegation, ephemeral child task, exits on completion	Scoped exploration, code search, one-off script execution.
dsh-call-session	Plugin	Peer-to-peer collaboration, in-process unicast messaging and shared board	Directives and status sync between independent top-level sessions, or sharing large outputs.

Selection guidelines:

• Prefer built-in: for isolated, scoped tasks, use DSH built-in subagent directly.
• Use on demand: when multiple independent top-level sessions need to coordinate or share large context via a blackboard, use dsh-call-session.

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Config

The plugin runs with built-in defaults out of the box.

To customize, add property overrides to ~/.dsh/profiles/web/cordis.patch.yml:

- id: dsh-call-session
  config:
    debounceMs: 500
    maxCapacity: 500

Options:

• enabled: boolean, default true. Enable or disable plugin tools.
• debounceMs: number, default 300. Atomic disk write debounce delay in milliseconds.
• maxCapacity: number, default 200. Maximum board entries.
• telemetryCapacity: number, default 200. Maximum call traces retained in canvas data buffer.
• locale: string, default 'auto'. Interaction language preference ('auto', 'zh', 'en').

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Architecture

Technical decisions are recorded as Architecture Decision Records (ADRs):

• Decision catalog: see docs/adrs/README.md.
• Architecture topology: see docs/architecture/.

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Compatibility

Environment	Supported	Verified
DeepSeek Harness	>=0.1.1-rc.1	0.1.2-rc.1, 0.1.5-rc.1, 0.1.5-rc.2
Cordis	^4.0.2	4.0.2+
Node.js	>=20.0.0	20.x, 22.x

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License

This project is licensed under the MIT License.