The in-process spawn subagent backend: a SubagentProvider that runs each child as a fresh child Agent on the same cordis context (ctx.agents) — its own session, its own (or the parent's) model, zero inherited conversation. The cheapest transport, reusing the agent factory's quiescent AgentHandle teardown.

The run mechanics live in the shared @deepseek-ai/dsh-subagent-inprocess driver (startInProcessRun); this backend just passes no seed (a fresh child). The fork backend is an independent peer over the same driver — neither knows about the other.

What it does

start(request) delegates to startInProcessRun(ctx, request, {}) with no seed: a fresh child agent with the parent's cwd/parentSession lineage and (by default) the parent's model. The driver creates one run-owner fiber under parent.ctx; parent teardown, this provider's teardown, manual disposal, and cancellation before readiness all converge there before child publication. Its run.started boundary resolves only after the fresh child is published, so subagent/start observers see a live registry entry; a same-tick cancel deactivates the unpublished transaction instead, rejects readiness, resolves the result as aborted, and emits no agent/session or subagent lifecycle. See the driver README for the full lifecycle (depth check, one-shot drive, result read, dispose).

Capabilities

{ outputSchema: true, depthLimit: true, toolFilter: true, persona: true }. It constructs the child, so it enforces a recursion cap and composes the child's persona, global-tool restriction, and structured runtime inside the agent-creation setup window. At apply it registers this one named provider on ctx.subagents; per-run contributions belong to each child's scope.

Config

Key	Meaning
`providerName`	Registry name on `ctx.subagents` (default `spawn`).