Silo

Interface: AgentBackgroundTask ​

Defined in: packages/sdk/src/agents-service.ts:1004

Beta

One backgrounded command's lifecycle — a shell command that detached from the agent's turn, and later reported how it ended.

The shell counterpart to AgentDelegation, and the resolution for AgentToolCall.backgrounded: that flag says a tool call's "completed" described only the hand-off, and this says what became of the command itself.

Unlike delegated work, this resolves. A subagent dispatch gets no finish signal on the tool-call stream at all, which is why a UI can only count dispatches. A backgrounded command reports an identified terminal state, so a row can settle and a count of outstanding work can come down.

It outlives its turn, and that is the normal case, not an edge. In the 2026-10-08 capture the turn ended 24 seconds before the command did, with the session reading idle throughout. So never gate the rendering of this on whether the agent is currently working — the quiet window is exactly when it matters.

Not every agent reports this. Where the connected agent doesn't, AgentSessionUpdate.backgroundTask is simply never set. Treat its absence as "this agent doesn't say", never as "nothing is running".

Properties ​

asyncTaskId ​

ts
readonly asyncTaskId: string;

Defined in: packages/sdk/src/agents-service.ts:1014

Beta

The command this event is about — the primary key, stable for the task's whole life, and the only field always present.

Key on this rather than on toolCallId: the announcing frame carries no tool call at all (see toolCallId), so a consumer keyed on the call would drop the announcement and with it name, taskType and canStop.

state? ​

ts
readonly optional state?: AgentBackgroundTaskState;

Defined in: packages/sdk/src/agents-service.ts:1023

Beta

Where the command is in its life, when this frame reported it.

Absent on a frame that carried only metadata — which is a distinction worth preserving rather than collapsing to "running": a metadata frame can arrive after a terminal one, and reading it as "running" would resurrect a finished command.

toolCallId? ​

ts
readonly optional toolCallId?: string;

Defined in: packages/sdk/src/agents-service.ts:1032

Beta

The tool call this command belongs to — the join that puts the lifecycle on the right row.

Learned, not given. The announcing frame does not carry it; it first arrives on a later frame, once the agent correlates the two. Accumulate it, and expect a window in which a task is known but its row is not.

name? ​

ts
readonly optional name?: string;

Defined in: packages/sdk/src/agents-service.ts:1036

Beta

Human-readable label, e.g. "Sleep for 30 seconds". Carried on the announcement, not on later state changes, so accumulate it rather than expecting it on the terminal event.

taskType? ​

ts
readonly optional taskType?: string;

Defined in: packages/sdk/src/agents-service.ts:1039

Beta

The agent's coarse category for the work, e.g. "shell". Same accumulation caveat as name.

canStop? ​

ts
readonly optional canStop?: boolean;

Defined in: packages/sdk/src/agents-service.ts:1042

Beta

Whether the agent would honour a request to stop this command. Same accumulation caveat as name.

summary? ​

ts
readonly optional summary?: string;

Defined in: packages/sdk/src/agents-service.ts:1044

Beta

The agent's own closing summary, when it sent one.