Module ids 

String-backed identifier newtypes.

Why these wrap String and not Uuid

AG-UI identifiers are opaque strings. Nothing in the protocol requires a UUID, and real producers routinely send values that are not one: LangGraph emits thread ids like "thread-abc" and run ids that are plain integers, and several adapters reuse provider-side ids verbatim.

An earlier community Rust SDK typed these fields as Uuid, which made every LangGraph payload fail to deserialize (ag-ui-protocol/ag-ui#2195, #2196). These newtypes therefore accept any string, including the empty one, and round-trip it byte-for-byte. Callers that want UUIDs can generate one and pass its string form.

Structs

AgentId

Identifies an agent, for multi-agent routing and discovery UIs.

MessageId

Identifies a message within a thread.

RunId

Identifies a single agent run within a thread.

StepName

Names a step inside a run, as carried by STEP_STARTED / STEP_FINISHED.

SubagentRunId

Identifies one invocation of a subagent.

ThreadId

Identifies a conversation thread across runs.

ToolCallId

Identifies one tool invocation.