Create Walkthrough Artifact

Write .agent/{branch}/walkthrough.md: the page a reviewer reads instead of approving a plan up front. It leads with one screen — what changed, what was assumed, and the evidence — and keeps the detail below it.

Contents

• Prerequisites
• Procedure
• Template
• Validation

Prerequisites

1. run-checks.mjs has printed its sentinel line on the current head (CHECKS n/n PASS (<sha>), or the FAIL line with the user's approval to ship).
2. Documentation is updated.
3. You are inside the worktree, and .agent/{branch}/plan.md exists for a Full-tier run.

Procedure