---
title: Reviewing Stacks
description: A reviewer's guide to navigating and reviewing stacked pull requests.
---

import { Image } from 'astro:assets';
import StackComment from '../../images/stack-comment.png';

Stacked PRs look and feel like regular pull requests, just smaller. You don't
need to install anything or learn new tools to review them.

## What You'll See

Each stacked PR contains a single commit's worth of changes. At the top of
every PR, a stack comment shows the full chain and highlights the current PR:

<Image src={StackComment} alt="Stack comment showing the current PR in the chain" style={{ maxWidth: '66%' }} />

The comment includes links to every PR in the stack, so you can jump between
them.

## How to Review

### Start from the Bottom

Review the stack in order, starting with the first PR (the one targeting
`main`). Each subsequent PR builds on the previous one, so reviewing in order
gives you the narrative of the change.

### Each PR Shows Only Its Own Changes

Unlike a single large PR, each stacked PR's diff contains only the changes from
its corresponding commit, not the accumulated changes of the entire branch:

- PR #1 shows the data model changes
- PR #2 shows only the API endpoint, not the model + endpoint
- PR #3 shows only the tests, not everything combined

You review small, focused diffs instead of trying to parse hundreds of lines at
once.

### Navigate Between PRs

Use the links in the stack comment to move between PRs. The current PR is
marked in the list so you always know where you are in the chain.

## Leaving Feedback

Review comments work exactly like any other PR:

- Leave inline comments on specific lines
- Request changes or approve
- Use GitHub's review features normally

When the author addresses your feedback, they'll rebase and push. The PR updates
in place, and your review comments stay attached to the relevant lines.

## Merging Stacked PRs

Stacked PRs merge bottom-up. The first PR in the stack (targeting `main`)
merges first. Once it lands, the next PR's base automatically updates to `main`,
and you can review and merge that one. Each PR in turn, working up the chain.

:::tip
  Stacks work well with [Merge Queue](/merge-queue). Each stacked PR can enter
  the queue independently as its dependencies land, keeping your merge pipeline
  flowing.
:::

You don't need to merge the entire stack at once. If the first two PRs are
approved but the third needs more work, merge the first two and let the author
continue iterating on the rest.