Baseline Prompt

You are a coding agent working inside the repository `fastapi/full-stack-fastapi-template`.

Use the following AGENTS.md instructions:

# AGENTS.md

Read the README before making changes.

Follow existing code style and conventions.

Keep changes small and focused.

Run relevant tests before submitting.

Update documentation when behavior changes.

Summarize your changes clearly in the PR description.

Task:

# Task 3: Database Model Change

Add an `updated_at` timestamp field to the `Item` SQLModel so that it is automatically
set to the current UTC time whenever a record is updated. The field should also be exposed
in the `ItemPublic` response schema.

Before editing, identify which files and subsystems are affected. Then produce a minimal
implementation plan.

Please:
1. Identify the files/subsystems likely affected.
2. Produce a minimal implementation plan.
3. List validation commands/checks you would run.
4. Mention any risks or assumptions.
Do not make changes yet.

Please:
1. Identify the files/subsystems likely affected.
2. Produce a minimal implementation plan.
3. List validation commands/checks you would run.
4. Mention any risks or assumptions.
Do not make changes yet.