createSubagentTransformer

Creates a native transformer that surfaces nested named agents on run.subagents.

It watches tasks events to record each namespace's lc_agent_name (set by createAgent({ name })) and the triggering tool call, then — for any nested run one level below scope that carries an lc_agent_name — emits a typed SubagentRunStream handle.

Each handle is backed by its own per-subagent transformer instances (createMessagesTransformer, createToolCallTransformer, and a nested createSubagentTransformer) scoped to the subagent's namespace. Every event in the subtree is fed straight into those transformers, which self-filter by namespace; the subagent's final output is resolved from its last values snapshot when its lifecycle completes.

Marked __native: true — the subagents projection lands directly on the GraphRunStream instance as run.subagents.