> ## Documentation Index
> Fetch the complete documentation index at: https://traceroot.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Live Tracing

> Watch spans stream into the trace viewer in real time while your agent is still running

When you open a trace whose root span hasn't ended yet, TraceRoot streams new spans into the viewer as they arrive. There is no toggle and no SDK flag — live tracing is on by default for every in-flight trace.

<Frame>
  <img src="https://mintcdn.com/tracerootai/m31pHxp8MDg6-cT0/images/trace_live_v1.png?fit=max&auto=format&n=m31pHxp8MDg6-cT0&q=85&s=22788300964a17948b37bfb6b3f5b659" alt="TraceRoot trace viewer streaming new spans live while an agent runs" width="3452" height="1866" data-path="images/trace_live_v1.png" />
</Frame>

## How spans arrive

Spans are merged into the existing tree by span ID, so they can arrive in any order:

* Newly started spans appear as **pending** rows (greyed out, no duration yet).
* When a pending span finishes, its end time fills in and the row renders normally.
* The [Timeline View](/tracing/timeline) updates in step — bars extend and new bars appear.

Once the root span completes, the viewer makes a final consistency pass and stops streaming.