7428cdf41e
- Make host-user authority unforgeable. `{ kind: 'user' }` was a bare
discriminant, so any plugin holding `ctx.subagents` — including
model-generated cordis_mount code, which the advanced ACP composition ships
alongside continuable subagents — could construct it and skip the
direct-parent check for any known child id. It now carries an opaque grant
that only SubagentService.userAuthority() mints, which composition hands to
trusted host adapters; a model-facing tool uses parent authority from its own
execution context.
- Reconcile a delivery discarded inside its own admission window. An enqueue
listener that cancels fires the discard before followup() returns, so the
discard listener could not clear an id it had not seen; submit() retained it
and residency stayed `running` until an explicit drain.
- Recheck the caller signal after materialization. An abort landing between
publication and inbox acceptance still submitted the prompt and returned both
ids; it now rolls the child back.
- Stop promising the model transcript access that no shipped continuable config
mounts. The tools now state only that a background child does not report back.
- Restate the implemented note as shipped state rather than a proposal, so it
works as current authority.
@deepseek-ai/dsh-tool-subagent-control
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The optional, globally named send_message tool: a thin adapter over ctx.subagents.followup(). Provider-bound @deepseek-ai/dsh-tool-subagent instances register distinct delegation tools per transport; this separately loaded package registers one shared follow-up tool, so multiple delegation tools never register duplicate global controls. Its presence does not determine whether a delegation tool starts continuable work.
The tool performs no lifecycle routing — residency and cold resume belong to the subagent service. It supplies exact live parent authority ({ kind: 'parent', agent }) from exec.agent and attributes every message as durable provenance { kind: 'coordinator', senderSessionId: parent.id }, which the service retains but never treats as authority. Every message becomes the subagent's next FIFO turn through Agent.followup(): if the child is still working, the message waits until its current turn finishes, so it cannot redirect work already underway. The tool forwards its execution signal, which owns admission only until inbox acceptance; once the child accepts the message the accepted turn cannot be cancelled through this tool. The child does not reply to the sender — its transcript by that id is the source of what it did. A delivery failure 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, describing that the message becomes the subagent's next turn, that the subagent does not reply, and that a failure means the message was not delivered.
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 queued as the next turn for subagent <subagent_id> on acceptance; the canonical output carries the accepted messageId. A failure — an unauthorized or unknown child, a descriptor-less child that cannot be resumed, or admission rejected — is an errored result whose message states the message was not delivered.
Token effect
One short acknowledgement per call; the child's response never returns through this tool, so its output enters parent history only if a caller reads the child transcript and relays it.
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 queued message has no independent result — acceptance returns only its inbox
messageId; the child's work on that turn lands in the durable child Session, read by its subagent id, and is neither delivered back nor collected through this tool. - No steering of the current turn — every message opens a later FIFO turn, so a message sent while the child is working runs only after its current turn finishes and cannot redirect it.