deepseek-harness/packages/subagent

subagent/ — subagent capability family

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The subagent seam: an agent delegating work to a child agent. Like the bash and llm families this is a capability seam (see capability seams) — but with one defining difference: multiple provider implementations coexist in one context, registered by name, rather than the single-implementation bash shape. The registry mirrors the LLM adapter registry.

Package	Role	ctx key
subagent/	Subagent service: named-provider registry, vocabulary, durable descriptor, and continuable-child orchestration	ctx.subagents
subagent-inprocess/	Shared in-process run driver (no provider; one cleanup effect per run)	—
subagent-spawn/	In-process backend: a fresh child agent, with cold resume	(registers on ctx.subagents)
subagent-fork/	In-process backend: a child seeded with the parent's completed-turn prefix, with cold resume	(registers on ctx.subagents)
subagent-acp/	Out-of-process backend: a child agent in a spawned subprocess, driven over ACP (one-shot)	(registers on ctx.subagents)
subagent-dsh-sdk/	Out-of-process backend: a child harness runtime in a spawned subprocess, driven over stdio JSON-RPC through the TypeScript SDK client	(registers on ctx.subagents)
tool-subagent/	Model-facing subagent delegation tool over ctx.subagents	(registers on ctx.tools)
tool-subagent-control/	The optional, globally named send_message and list_agents tools over ctx.subagents	(registers on ctx.tools)
tool-subagent-report/	Child-scoped report return channel for continuable in-process children	(registers in each child scope)

The interface and continuation orchestration live at subagent/subagent/. One-shot provider start dispatch stays independent of persistence; an internal continuation manager owns each durable continuable child as one Session plus at most one process-local Activation, binding no Task, and exists only while the Agent service is present, resolving persistence per continuation operation. The in-process subagent-spawn / subagent-fork backends share the subagent-inprocess driver (a library with no provider of its own — both depend on it, neither on the other), and the out-of-process subagent-acp / subagent-dsh-sdk backends spawn their children through the subprocess/ seam (the shared credential scrub, tree-scoped teardown, and dispose ladder). Tests replace only the child boundary with package-local fixtures.

The design rationale: .agents/notes/implemented/feature/2026-06-21-subagent-capability-seam.md, .agents/notes/implemented/feature/2026-07-21-continuable-background-subagents.md, and .agents/notes/implemented/simplification/2026-07-26-merge-subagent-control-service.md.