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

# Trace a room session

> Tutorial for capturing protocol and replay evidence from one collaborative room workflow.

## Outcome

By the end of this tutorial you will have:

* a filtered protocol trace snippet from `protocol-inspector`
* replay snapshot windows from `replay-lab`
* a mapped timeline from user action to runtime message patterns

## Setup

1. Start host and app surfaces from `developer-experience/apps`.
2. Open two browser windows for `infinite-room-workspace`.
3. Open one window each for `protocol-inspector` and `replay-lab`.
4. Set all windows to the same room id.

## Step 1: Establish baseline session

In first workspace window:

* connect in `npm sdk + wasm`
* apply shared document action once

In second workspace window:

* connect in `npm sdk + wasm`
* publish presence

Expected:

* peer lifecycle and presence events appear in protocol inspector.

## Step 2: Capture protocol evidence

In `protocol-inspector`:

1. apply preset `Peer lifecycle`
2. apply preset `Presence`
3. export trace snippet

Record:

* timestamp, event types, and message ordering

## Step 3: Capture replay evidence

In `replay-lab`:

1. capture snapshot before new action
2. perform new workspace action (text update or signal)
3. capture snapshot after action
4. use range controls to inspect event windows around the change

Record:

* before/after snapshot event windows

## Step 4: Build your action-to-runtime map

Create a short mapping:

* **Action**: what user did
* **Protocol message types**: what you observed
* **Replay window evidence**: what changed in captured event ranges

## Related docs

* `protocol/websocket-messages`
* `api-reference/websocket-commands`
* `guides/replay-debugging`