deepseek-harness/packages/subagent/subagent-inprocess

@deepseek-ai/dsh-subagent-inprocess

The shared in-process subagent run driver. A pure library (no provider, no registration) that the in-process backends — spawn (a fresh child) and fork (a child seeded with a prefix of the parent's log) — both build on. The backends are thin shells that differ ONLY in the session seed they pass; everything downstream lives here, so neither backend depends on the other.

What it exports

startInProcessRun(ctx, request, options): SubagentRun

Runs a child as a child Agent on the same cordis context (ctx.agents):

1. computes child depth = depthOf(parent) + 1; if request.maxDepth is set and exceeded, throws SubagentDepthError (the depthLimit capability);
2. creates a child via ctx.agents.create with a fresh AgentId/SessionId, the parent's cwd + parentSession lineage, the optional options.seed (fork's completed-turn prefix; omitted for a fresh child), and agentOptions (the child inherits the parent's model by default — a child with no model can't run — overridable via request.agentOptions.model; the system prompt is NOT inherited);
3. drives the one-shot: child.send(prompt) then await child.whenIdle() (ordering matters — send enqueues synchronously, so whenIdle observes the queued work and resolves on the child's running → idle transition, never before the turn starts);
4. reads the result, scoped to the child's OWN events (everything at or after seedLength, so a seeded child that produced no message of its own never returns the seeded parent's last message): the last assistant/message content (deep-cloned — the log is frozen) and the last turn/end.reason mapped to a SubagentStopReason.

dispose() delegates to AgentHandle.dispose() (stop loop → await quiescence → remove session); cancel() cancels the child's in-flight turn. A cancel landing before any turn/end (the pre-turn window) still settles aborted, honoring the cancel contract rather than the generic no-turn error.

InProcessRunOptions

{ providerName: string; seed?: SessionEvent[] } — the per-backend inputs: the provider name (for error context) and the optional child-session seed.

depthOf(agent): number

Delegation depth rides on a merge-extensible AgentOptions.subagentDepth field (0 for a top-level agent, parent + 1 for a child), so a nested spawn reads its parent's depth from parent.options.subagentDepth. depthOf reads it (absent ⇒ 0).

SubagentDepthError

Thrown by startInProcessRun when a spawn would exceed the request's maxDepth cap; carries attemptedDepth and maxDepth.