---
title: "Read Apple's Instruments template"
lesson_id: "03"
---

# Read Apple's Instruments template

- **Lesson ID:** 03
- **Goal:** Record a Foundation Models Instruments trace and say what the template can and cannot show.
- **Human lesson:** [03-instruments-template.html](03-instruments-template.html)

## Prerequisites

- Lesson 02, or the four hop names.

## Inputs, outputs, and artifacts

- **Inputs:** Xcode 27 and one user task.
- **Outputs:** A recorded trace and a clear split of framework versus product hops.
- **Artifacts:** Progressive `.flow` diagrams.

## Agent build steps

1. Name Product → Profile and the Foundation Models template.
2. List the tree nodes from [session 243](https://developer.apple.com/videos/play/wwdc2026/243/).
3. Warn about sensitive prompts in traces.
4. Link streaming metrics and eval harness.

## Constraints

Keep the language simple, friendly, and literal. iOS 27 and macOS 27 only. No quizzes, Mermaid, or em dashes. Do not invent API names. Mark sketches as sketches and tell the reader to confirm them in the Xcode 27 SDK.

## Key concepts

- Record one user task with the Foundation Models template on iOS 27 or macOS 27.
- The tree shows sessions, requests, inferences, prompts, responses, and tool calls.
- It supports Dynamic Instructions and multiple sessions or profiles.
- Prompt and response logging is for recording only.

## Takeaways

- Use Instruments for Apple's hops. Use your spans for context pack and guardrail.
- One instruction set staying active when the UI thought the mode changed is a real bug.
- Do not keep customer traces in shared folders.

## Acceptance checks

- The template is named.
- Product hops are marked as not covered.
- Traces are marked sensitive.
- Sibling links, progressive `.flow` diagrams, and an Agent brief link are present.
- [ ] Proceed to [lesson 04 brief](04-otel-style-spans.llms.md).