dsh-subagent-spawn-in-process/packages/subagent/subagent-spawn-in-processOfficial

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The spawn provider creates a fresh child Agent in the current process. The child has its own session, sees no parent conversation history, and reuses the host's agent factory and LLM/tool services.

Behavior

start(request) delegates to startInProcessRun with no seed and awaits publication before returning. The child receives parent working-directory/session lineage and inherits the parent model unless overridden, but starts with an empty conversation.

The shared driver owns depth checking, persona and tool-filter setup, structured output, required-signal cancellation, one-shot execution, result reading, and quiescent disposal. A startup rejection leaves no published child; provider unload after fulfillment does not revoke the holder-owned run.

Capabilities

Spawn advertises { outputSchema: true, depthLimit: true, toolFilter: true, persona: true } because it controls the child's creation window and can enforce all four features.

Config

Model Experience

Child-agent request

What the model sees

The fresh child receives the standalone task content verbatim, inherits the parent model and workspace by default, and sees the global prompt with any configured child-scoped persona shadow. A tool filter removes global wire schemas, executable lookup, and Code Mode SDK bindings for that child but leaves independently registered guidance. It receives zero parent conversation messages; the filter is visibility/composition, not an authority grant inherited from the parent.

Token effect

The child pays for a new independent context and history; no parent-history tokens are duplicated. Persona changes this child's repeated prompt cost, while filtering changes its schema or generated SDK cost.

KV Cache effect

Independent of the parent request cache. Child history grows append-only, while persona, tool-filter, generated-SDK, provider, or model changes establish a different child prefix.

Parent tool result, indirectly

What the model sees

Through dsh-tool-subagent, the parent receives only the child's final output or stop-reason error.

Token effect

Parent input grows by one data-dependent result retained until compaction.

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

• Fresh means no parent transcript — the child inherits cwd, lineage, model, and explicitly configured persona/tool restrictions, but none of the parent's conversation; use the fork provider when completed-turn context is required.