@deepseek-ai/dsh-tool-subagent-control
The globally named send_message tool: a thin adapter over ctx.subagentControl.sendMessage(). Provider-bound @deepseek-ai/dsh-tool-subagent instances register distinct delegation tools per transport; this separately loaded package registers the one shared control tool, so multiple delegation tools never register duplicate global controls.
The tool performs no lifecycle routing. It attributes every follow-up as { kind: 'coordinator', senderSessionId: parent.id }; the control service preserves that source while deciding between live delivery to the running activation's existing Task and a fresh Task that cold-resumes the durable child. The tool renders which route was taken and the relevant Task id. A control-service throw becomes an errored tool result stating the message was not delivered.
Model Experience
Tool schema
What the model sees
The generated send_message schema: subagent_id and message, with delivery-or-continue semantics and the task_output collection path described.
Token effect
Fixed schema cost per parent request.
KV Cache effect
Prefix-stable; the schema does not change at runtime.
Delivery result
What the model sees
message delivered to running task <taskId> when the message joined the running activation, or message started task <taskId> continuing subagent <subagent_id> when it started a cold-resume activation. Synchronous routing failures — an ownership conflict, a lost steering race, no live-delivery capability — are errored results whose message states the message was not delivered. An absent activation always reports started: lookup runs inside that Task, so an unknown, foreign, or descriptor-less child surfaces as the started Task settling failed (read through task_output), not as an errored send_message result.
Token effect
One short acknowledgement per call; the child's response enters parent history only when collected through task_output (the completion notice is a status line, never the response).
KV Cache effect
Append-only; newly visible content follows the reusable request prefix and does not invalidate existing KV-cache entries.
Known Limitations and Deferred Work
- A delivered message has no independent result — its effect is reflected in the current Task's eventual result; only a started follow-up owns a fresh Task result.
- Delivery can lose timing races — a message racing task settlement, cancellation, or cleanup fails explicitly rather than falling through to cold resume; the model retries after the task settles.