dsh-tool-session-message

Cross-session messaging for DeepSeek Harness (DSH): send a user message to another session by its session id — ask a separate window what it is doing, or hand it new facts.

给 DSH 加一个工具 session_send(session_id, message, mode?)：把一条 user 消息投递到另一个会话（比如另一个窗口），让对方开始一轮或插话。每条消息自动带上发送方 Session ID，便于多窗口互相认证身份并接续任务。

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Features

• session_send(session_id, message, mode?) — deliver a message to any session in the same DSH host.
• Identity header — every delivered message is automatically prefixed with:

  【跨会话消息 · session_send】
  from: session-xxxxxxxx-...
  reply: session_send(session_id="session-xxxxxxxx-...", message="...")
  

  so the receiver knows who sent it and how to answer back.
• mode: "followup" (default, queued as the target's next user turn) or "steer" (injected into a running turn).
• Returns the host acknowledgement as structured JSON (ok, from, to, mode, requestId, result).

Requirements

• DSH 0.2.1-rc.5 or compatible (uses the sessionController service).
• The target session must live in the same DSH host process (multiple windows of one desktop app satisfy this).

Install

In the DSH desktop app (recommended)

Settings → Plugins → Add plugin, then paste:

github:BigBugy/dsh-tool-session-message

The plugin manager accepts npm package names, GitHub repositories and local directories. This package is not published to npm — use the github: spec (or the local path below).

With the DSH CLI (CLI deployments only)

dsh plugin --profile <profile> add github:BigBugy/dsh-tool-session-message

The desktop app does not ship a dsh command; desktop users install through Settings → Plugins.

Manual (local development)

1. Put this package at <profile>/node_modules/dsh-tool-session-message (<profile> is e.g. ~/.dsh/profiles/desktop).
2. Add it to the profile's package.json:

   {
     "dependencies": { "dsh-tool-session-message": "link:<path-to-this-package>" },
     "dsh": { "profile": { "bundles": [ "...", "dsh-tool-session-message" ] } }
   }
   

3. The package ships its own cordis.patch.yml with dsh.bundle.patch, so the tool is inserted process-wide.
4. Restart DSH (host plugins load at startup).

Usage

Ask the model to call, or call directly:

session_send(session_id="session-0e8596c3-...", message="What are you working on? Reply briefly.")

The receiver sees the decorated message and can answer with:

session_send(session_id="<the id in from:>", message="...")

How it works

• DSH uses the Cordis plugin framework. A plugin is an ESM module exporting { name, inject, apply } (and optionally Config).
• This plugin injects ["tools", "sessionController"] and registers a tool via ctx.tools.register({...}) (plain object — no @deepseek-ai/dsh-tools dependency).
• Delivery calls ctx.sessionController.prompt({ sessionId, content: [{ type: "text", text }], mode, requestId }, signal):
  • requestId is required — without it the host rejects with prompt rejected.
  • Session ids must keep their session- prefix.

Implementation notes / pitfalls

1. parameters must be a complete JSON Schema root. ctx.tools.register() validates only output.schema; parameters is projected to the model as-is. A flat property map without { "type": "object" } makes the whole model request fail with: Invalid schema for function 'session_send': schema must be a JSON Schema of 'type": "object"', got 'type": null'.
2. DSH's supported schema subset: type / oneOf / properties / required / additionalProperties / items / enum / const, plus annotations description / title / default / examples. Property-level required: true is not valid JSON Schema.
3. requestId: generate one per call (crypto.randomUUID()), otherwise the host rejects the prompt.
4. Loading: signature/import errors surface only in the host process log; the plugin is loaded at DSH startup, so code changes require a restart.
5. Bundle metadata: to appear in the plugin manager UI, a third-party plugin should declare dsh.bundle.patch in package.json and be listed in the profile's dependencies + dsh.profile.bundles.

Security notes

• The tool lets a model inject user prompts into other sessions, which can start turns in those sessions. Treat it like any privileged automation: enable it only in profiles you control.
• No network access, no file writes, no shell — it only calls the host's session controller.
• Messages are stored in the target session transcript as ordinary user messages.

Compatibility

DSH version	Status
0.2.1-rc.5	tested
older	unknown — sessionController service may not exist

License

MIT