test: regenerate screenshot expectations (#9442)

The pixels fade, the tests turn red,
Old screenshots haunt us from the dead.
A branch is born, a label placed,
And golden images are replaced.

The shards spin up, four workers strong,
To right what rendering got wrong.
When CI turns green, the deed is done—
New expectations, freshly won.

---------

Co-authored-by: Amp <amp@ampcode.com>
Co-authored-by: GitHub Action <action@github.com>
Co-authored-by: github-actions <github-actions@github.com>

.claude/skills/regenerating-screenshots/SKILL.md

@@ -0,0 +1,83 @@
+---
+name: regenerating-screenshots
+description: 'Creates a PR to regenerate Playwright screenshot expectations. Use when screenshot tests are failing on main or PRs due to stale golden images. Triggers on: regen screenshots, regenerate screenshots, update expectations, fix screenshot tests.'
+---
+
+# Regenerating Playwright Screenshot Expectations
+
+Automates the process of triggering the `PR: Update Playwright Expectations`
+GitHub Action by creating a labeled PR from `origin/main`.
+
+## Steps
+
+1. **Fetch latest main**
+
+   ```bash
+   git fetch origin main
+   ```
+
+2. **Create a timestamped branch** from `origin/main`
+
+   Format: `regen-screenshots/YYYY-MM-DDTHH` (hour resolution, local time)
+
+   ```bash
+   git checkout -b regen-screenshots/<datetime> origin/main
+   ```
+
+3. **Create an empty commit**
+
+   ```bash
+   git commit --allow-empty -m "test: regenerate screenshot expectations"
+   ```
+
+4. **Push the branch**
+
+   ```bash
+   git push origin regen-screenshots/<datetime>
+   ```
+
+5. **Generate a poem** about regenerating screenshots. Be creative — a
+   new, unique poem every time. Short (4–8 lines). Can be funny, wistful,
+   epic, haiku-style, limerick, sonnet fragment — vary the form.
+
+6. **Create the PR** with the poem as the body (no label yet).
+
+   Write the poem to a temp file and use `--body-file`:
+
+   ```bash
+   # Write poem to temp file
+   # Create PR:
+   gh pr create \
+     --base main \
+     --head regen-screenshots/<datetime> \
+     --title "test: regenerate screenshot expectations" \
+     --body-file <temp-file>
+   ```
+
+7. **Add the label** as a separate step to trigger the GitHub Action.
+
+   The `labeled` event only fires when a label is added after PR
+   creation, not when applied during creation via `--label`.
+
+   Use the GitHub API directly (`gh pr edit --add-label` fails due to
+   deprecated Projects Classic GraphQL errors):
+
+   ```bash
+   gh api repos/{owner}/{repo}/issues/<pr-number>/labels \
+     -f "labels[]=New Browser Test Expectations" --method POST
+   ```
+
+8. **Report the result** to the user:
+   - PR URL
+   - Branch name
+   - Note that the GitHub Action will run automatically and commit
+     updated screenshots to the branch.
+
+## Notes
+
+- The `New Browser Test Expectations` label triggers the
+  `pr-update-playwright-expectations.yaml` workflow.
+- The workflow runs Playwright with `--update-snapshots`, commits results
+  back to the PR branch, then removes the label.
+- This is fire-and-forget — no need to wait for or monitor the Action.
+- Always return to the original branch/worktree state after pushing.