pr-screenshots

PR Screenshots

Embed before/after screenshots in pull request descriptions so reviewers can see the visual change without checking out the branch.

When to Use This Skill

Use this skill when a PR changes something visible:

• Layout, styling, CSS
• Charts, dashboards, data visualizations
• UI components, forms, modals
• Error messages, CLI output, log formatting

PR Description Pattern

Place screenshots directly in the PR description body. Avoid wrapping them in <details> collapse — reviewers are more likely to look at images they can see without clicking.

**Before** — brief description of the problem:
 
![before](url-to-before-image)
 
**After** — brief description of the fix:
 
![after](url-to-after-image)

Keep the text brief. A sentence or two per image describing what the reader should notice. Let the image carry most of the communication.

Multiple changes

For PRs with several visual changes, use separate before/after pairs with headings:

Image Sizing

• Take screenshots at native 1x resolution — don't resize with PIL (creates artifacts)
• Control display size in HTML when images are too large:

  <img src="url" width="600" alt="description">
• Before/after pairs must use the same viewport width and crop — otherwise the comparison is meaningless

Uploading Images

Azure DevOps

Upload images as PR attachments via the REST API:

$token = az account get-access-token `
    --resource "499b84ac-1321-427f-aa17-267ca6975798" `
    --query accessToken -o tsv
 
$base = "https://{org}.visualstudio.com/{projectId}/_apis/git/repositories/{repoId}"
$url = "$base/pullRequests/{prId}/attachments/screenshot.png?api-version=7.1-preview.1"
 
# Use HttpClient — Invoke-RestMethod can corrupt binary data
$client = New-Object System.Net.Http.HttpClient
$client.DefaultRequestHeaders.Authorization = `
    New-Object System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", $token)
$content = New-Object System.Net.Http.ByteArrayContent(
    , [System.IO.File]::ReadAllBytes("screenshot.png")
)
$content.Headers.ContentType = `
    [System.Net.Http.Headers.MediaTypeHeaderValue]::new("application/octet-stream")
$resp = $client.PostAsync($url, $content).Result

Reference in the PR description:

![description](https://{org}.visualstudio.com/{projectId}/_apis/git/repositories/{repoId}/pullRequests/{prId}/attachments/screenshot.png)

Azure DevOps gotchas:

• Use {org}.visualstudio.com NOT dev.azure.com/{org} — AzDO's markdown renderer uses .visualstudio.com. The dev.azure.com format loads noticeably slower
• Use POST not PUT (PUT returns 405)
• API version must be 7.1-preview.1
• Can't re-upload with the same filename — use a new name (e.g. screenshot-v2.png)
• Use HttpClient not Invoke-RestMethod — IRM can corrupt binary data
• Repo-relative paths don't work in PR descriptions — must use full URLs
• Don't commit images to the branch just for PR screenshots

GitHub

⚠️ Work in progress. GitHub's drag-and-drop image upload uses internal endpoints that require browser cookies. There's no clean public API for uploading images to PR descriptions yet.

Current workaround: Commit images to a pr-assets orphan branch and reference via blob URLs (github.com/{owner}/{repo}/blob/pr-assets/{file}?raw=true). It works but is clunky — contributions for a better approach are welcome.

Guidelines

1. Capture before state BEFORE making changes — it's easy to forget, and reconstructing the original state later is slow and error-prone
2. Keep descriptions brief — a sentence or two per image pointing out what changed is enough
3. Prefer visible images over collapsed sections — screenshots behind <details> tags are easy to skip
4. Annotate when the change is subtle — use the image-annotations skill to add callouts when the difference isn't immediately obvious
5. Match viewport and crop between before/after pairs so the comparison is meaningful

Limitations

• GitHub image upload requires workarounds (no public API for PR description images)
• Azure DevOps attachment filenames can't be reused — plan naming ahead
• Very large images (>10MB) may not render inline on some platforms