A field guide by Foglamp

AI observability,
illustrated.

Follow a request through an AI app. See how traces, evaluations, and alerts help you understand what happened, and whether the answer was good.

A small world. The whole picture.8 stops along the way
Inside an AI app
A hand-drawn workshop with an agent at a desk, an order clerk, a counting room, an inspection bench, and a bell tower. Messages travel between its rooms.
Your app does the work. Foglamp helps you see it.
The request’s pathRecorded activityIllustrative data
01A request

It starts with a question.

Someone asks your app, ‘Where’s my order?’ Behind that little message, an agent calls a model, looks up the order, and writes an answer.

A customer asks

Where’s my order?

Sent

Think of your app as a workshop. Each station has a job. A request moves between them until the work is done.

Connect your app
02Traces

Follow the work inside.

Foglamp records each AI call as a trace. Inside it, smaller steps called spans show the model calls and tools, with their inputs, outputs, and timing.

One trace, three steps1.8 s
Read the question0.4 s
Look up the order0.6 s
Write the answer0.8 s
Tool result DelayedAnswer Arrives today

The order lookup says ‘delayed.’ The answer says ‘arrives today.’ Following the trace shows where those two stopped agreeing.

Explore traces
03Agents

Meet the agent doing the work.

An agent uses instructions, models, and tools to work on a task. Give it a name, and Foglamp brings its runs, costs, and errors together.

The agent’s instructionsPrompt versions

Help the customer with their order. Keep your answer short.

Select version 2 to see what changed.

Instructions change, too. Foglamp finds prompt versions in your recorded runs, so you can compare what changed and see which runs used each version.

Get to know your agents
04Workflows

Some jobs take a team.

One agent sorts the question. Another checks the order. A workflow run groups the AI calls that belong to one job, even when different agents do the work.

Order supportOne workflow run
1Triage agentSort the question
2Order agentCheck and answer
Two traces, connected by the same run ID.

Your code controls the steps and branches. Add a workflow name and run ID, and Foglamp brings the recorded calls into one view.

See how workflows connect
05Sessions

A conversation keeps going.

The customer asks a follow-up. A session connects the traces in the same conversation, so you can understand the experience across several messages.

One sessionTwo messages
Where’s my order?

Your order arrives today.

Are you sure? Tracking says it’s delayed.
The next message gives the first answer more context.

Workflows group calls for a job. Sessions group calls for a conversation. The same trace can belong to both.

See the whole conversation
06Costs

Small calls add up.

Each model call takes time and uses tokens, the pieces of text a model reads and writes. Foglamp tracks usage, cost, and latency so you can see where they go.

A day in the workshopExample data
2,400AI calls
$12.80Total cost
1.8 sp95 latency
Order agent · $9.60Triage agent · $3.20
p95 means 95% of steps finished within this time.

Pull back to see patterns by model, agent, or customer. Then open an individual trace to understand an expensive or slow run.

Explore cost intelligence
07Evals

An answer can work and still be wrong.

Evaluations check the quality of an answer. Code checks test clear rules, like valid JSON. LLM judges assess things like helpfulness or whether an answer agrees with its sources.

At the inspection benchExample checks
Agrees with order dataFail · 0.18 / 1

The answer promises delivery today, but the order data says it is delayed.

The inspection bench checks copies of recorded traffic. Choose which traces or steps to sample, review their scores, and open the ones that failed.

Explore evaluations
08Alerts

Know when something needs you.

Set a limit for cost, latency, error rate, or an eval’s pass rate. Foglamp checks recent traffic every minute and sends an email when a rule fires.

Answer qualityHealthy
97%pass rate
Alert below 85% over 1 hour

The pass rate is above your threshold. All quiet at the watchtower.

Start with the alert, inspect its context and relevant traces, then follow the work back to the problem. The rule returns to healthy when the metric recovers.

Explore alerts

Now you can see the whole picture.

A little light on
your AI app.

Follow the work. Check the answers.
Know when something needs your attention.

See it in Foglamp
Open source. Built for the Vercel AI SDK.