dsh-plugin-session-fleet

Session Fleet: four model-facing tools that let one DeepSeek Harness agent discover other sessions, start a session, and message a session directly.

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Install

dsh plugin --profile <profile> add dsh-plugin-session-fleet

The bundle patch is opt-in: it inserts the tool-session-fleet row with conservative defaults. Enable Session fleet in the Plugins page after install.

Tools installed per agent

• list_sessions lists visible sessions with status, activity, and working directory, and starts none of them.
• search_sessions runs a literal full-text search across visible session messages.
• create_session creates a session in a given cwd or workspace.
• send_to_session delivers a queued or steered message to another session through the DSH session message queue.

A delivery carries the dedicated session-fleet message source and a peer-agent framing note, so a target never mistakes fleet input for user input. Replies travel back through the same channel.

Compatibility

The plugin declares the host support window >=0.2.0-rc.2 <0.3.0-0. Every 0.2.x host release, candidates included, satisfies it; a 0.3 release needs a new plugin release. pnpm run check:host-support fails when a pin leaves the window or when the host next channel moves past it.

@deepseek-ai/dsh-brand never appears as a dependency. Its brand marker is a unique symbol, so a second physical copy would break every branded identifier type in this plugin.

Configuration

Key	Default	Meaning
allowCrossWorkspace	false	Permit a tool call to reach a session recorded under a different working directory.
maxListRows	50	Upper bound of one list_sessions response.
maxMessageChars	20000	Upper bound of one send_to_session body.
includeSubagents	false	Show subagent-owned sessions in list and search. Delivery to them stays refused.

Safety model

• Delivery reaches ordinary top-level sessions only. Subagent children remain the parent agent's internal delegation, and delivery to them is refused unconditionally, whether or not includeSubagents is set.
• Cross-workspace delivery is refused unless allowCrossWorkspace is true on the plugin row.
• Fleet provides no content read. An agent asks a peer for context through send_to_session, or a profile enables the harness session query tools for audit access.
• An inbound fleet message is untrusted peer input. The framing note tells the receiving agent to confirm consequential actions with the user first.

Development

pnpm install
pnpm run check:refactor   # host support window, typecheck, lint, prettier
pnpm run test             # vitest run
pnpm run build            # declarations plus the bundled entry

Requires Node.js 22 or later.