Sessions

How a Sedata-instrumented MCP server tracks a session lifecycle.

A session in @sedata-ai/mcp is a single instrumented process. It begins when instrumentServer is called and ends when telemetry.shutdown() runs.

Session id

TelemetryManager mints one UUID per process and adds it to every span and every metric as mcp.session.id.

mcp.session.id = "f3a4b9c2-..." // constant for the lifetime of the process

You’ll see this attribute on:

• every span produced by tool calls
• every metric data point
• every custom span you record via telemetry.startActiveSpan

Session start

Implicit. Created when you construct the TelemetryManager:

const telemetry = instrumentServer(server, telemetryConfig)
// ↑ session begins here

Session duration

When you call telemetry.shutdown(), the package records a histogram:

Metric	Unit	Tag
mcp.server.session.duration	seconds	mcp.session.id

Wire it up to your process exit:

const exit = async (code = 0) => {
  await telemetry.shutdown()
  process.exit(code)
}

process.on('SIGINT', () => exit(0))
process.on('SIGTERM', () => exit(0))
process.on('uncaughtException', () => exit(1))

Skipping shutdown() means the final batch of metrics never leaves your process — including session.duration. Always wire it.

What “session” doesn’t mean

• It’s not a per-client session. If two MCP clients connect to the same server process, they share one mcp.session.id. Use mcp.request.id for per-call correlation, and client.address to differentiate.
• It’s not a transport-level connection. A stdio server has one logical client; an HTTP server may have many.

Per-call ids

For correlating logs to a single tool call:

Attribute	Where it comes from
mcp.request.id	UUID generated for each tools/call invocation.
mcp.session.id	UUID per process.
mcp.tool.name	Tool that was called.

Combine (mcp.session.id, mcp.request.id) for unique-per-call identity.