Enhancement Request for AgentEvent.RunPath to Uniquely Identify Multiple Runs of Nested Agents under EmitInternalEvents

**Is your feature request related to a problem? Please describe.**

no

**Describe the solution you'd like**

Currently, with the EmitInternalEvents feature enabled, events from sub-agents can be propagated to the main agent. However, in complex invocation chains involving nested agents, there is no clear way to distinguish which specific run a given event originated from.

While the AgentEvent provides a RunPath field, it has the following limitations:

- Identification Conflict: When multiple sub-agents of different types exist (e.g., a "General-Purpose Agent" and a "Tool Call Agent"), they may share the same RunPath identifier (e.g., both named Task), making them indistinguishable in the event stream.

- Lack of Run-specific Distinction: A single sub-agent can be invoked multiple times within a session. The current RunPath lacks a round or counter flag to differentiate between these successive runs of the same agent.

Expected Solution:
To display sub-agent messages and their historical runs clearly in a monitoring UI, I propose enhancing the RunPath mechanism or adding supplementary fields. This would allow each event to be uniquely and traceably linked to its specific agent instance and invocation round.

**Describe alternatives you've considered**

no

**Additional context**

no