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Base interface for a single subagent stream. Tracks the lifecycle of a subagent from invocation to completion.
Extends StreamBase to share common properties with UseStream, allowing subagents to be treated similarly to the main stream.
Prefer using SubagentStream which supports passing an agent type directly for automatic type inference.
interface SubagentStreamInterfaceCurrently active subagents (where status === "running").
Use this to track and display subagents that are actively executing. Completed or errored subagents are not included.
// Show loading indicators for active subagents
stream.activeSubagents.map(subagent => (
<SubagentCard
key={subagent.id}
type={subagent.toolCall.args.subagent_type}
isLoading={true}
/>
));Wall-clock timestamp when the task tool terminated (null if running).
Nesting depth from the root (root = 0).
Get subagent stream by tool call ID.
Use this when you have a specific tool call ID and need to access its corresponding subagent stream.
// In a tool call component
const subagent = stream.getSubagent(toolCall.id);
if (subagent) {
return <SubagentProgress subagent={subagent} />;
}Get all subagents triggered by a specific AI message.
Useful for rendering subagent activities grouped by conversation turn. Each AI message that contains subagent tool calls will have its triggered subagents returned by this method.
// Render subagents inline after the AI message that triggered them
{stream.messages.map((msg) => (
<div key={msg.id}>
<MessageBubble message={msg} />
{msg.type === "ai" && "tool_calls" in msg && (
<SubagentPipeline
subagents={stream.getSubagentsByMessage(msg.id)}
/>
)}
</div>
))}Get all subagents of a specific type.
Returns streams with properly inferred state types based on subagent name. When called with a literal string that matches a subagent name, TypeScript will infer the correct state type for that subagent.
// Get all researcher subagents with typed state
const researchers = stream.getSubagentsByType("researcher");
researchers.forEach(researcher => {
// researcher.values is typed based on ResearchMiddleware
console.log("Research messages:", researcher.values.messages.length);
console.log("Status:", researcher.status);
});
// Get all writer subagents
const writers = stream.getSubagentsByType("writer");
// writers have different state type based on WriterMiddlewareGet tool calls for a specific AI message.
Use this to find which tool calls were initiated by a particular assistant message, useful for rendering tool calls inline with messages.
messages.map(message => {
if (message.type === "ai") {
const calls = stream.getToolCalls(message);
return (
<>
<MessageBubble message={message} />
{calls.map(tc => <ToolCallCard key={tc.call.id} {...tc} />)}
</>
);
}
return <MessageBubble message={message} />;
});Current interrupt, if the stream is interrupted.
Convenience alias for interrupts[0].
For workflows with multiple concurrent interrupts, use interrupts instead.
Interrupt payloads collected during the run, if any.
Mirrors the in-process run.interrupts.
Whether the stream is currently running.
true while streaming, false when idle or completed.
Parent subagent id, or null if spawned from the root.
Wall-clock timestamp when the task tool started.
Switch to a different thread, clearing the current stream state.
Pass null to reset to no thread (a new thread will be created on next submit).
Currently active subagents (where status === "running").
Get subagent stream by tool call ID.
Get all subagents triggered by a specific AI message.
Get all subagents of a specific type.
Get tool calls for a specific AI message.
Current interrupt, if the stream is interrupted.
Interrupt payloads collected during the run, if any.
Whether the stream is currently running.
Switch to a different thread, clearing the current stream state.