Silo

Interface: AgentDelegation ​

Defined in: packages/sdk/src/agents-service.ts:923

Beta

One delegated worker's lifecycle — a named subagent appearing, and later reporting how it ended.

This is the signal that lets a transcript stop guessing about delegated work. AgentToolCall.handedOff says a dispatch's "completed" was only a hand-off; this says when the handed-off work actually finished, and which worker's it was. A UI can therefore show a per-agent result and a count of outstanding work that comes down — neither of which is derivable from the tool-call stream, which never revisits a dispatch.

Not every agent reports this. Where the connected agent doesn't, AgentSessionUpdate.delegation is simply never set and a UI falls back to counting dispatches. Treat its absence as "this agent doesn't say", never as "nothing is running".

Properties ​

subagentId ​

ts
readonly subagentId: string;

Defined in: packages/sdk/src/agents-service.ts:935

Beta

The worker this event is about — the same id that appears on AgentToolCall.subagentId for the dispatch that started it and on AgentSessionUpdate.subagentId for every frame it produces.

Stable across every event for one worker, including the repeat announcements some agents send when a worker resumes: Silo normalises the vendor's generation suffix away, so a consumer keyed on this id counts one worker once. The un-normalised form stays in AgentSessionUpdate.raw for anyone who wants it.

name? ​

ts
readonly optional name?: string;

Defined in: packages/sdk/src/agents-service.ts:939

Beta

The worker's human-readable name, e.g. "Background sleep task" — carried on the announcement, not on later state changes, so accumulate it rather than expecting it on the terminal event.

task? ​

ts
readonly optional task?: string;

Defined in: packages/sdk/src/agents-service.ts:942

Beta

The prompt the worker was given. Same accumulation caveat as name, and it can be long — agents put structured payloads here.

state ​

ts
readonly state: AgentDelegationState;

Defined in: packages/sdk/src/agents-service.ts:944

Beta

Where the worker is in its life. See AgentDelegationState.