fix: scroll back to position 0 after an element screenshot

[theluckystrike]

Fixes #1229

checkElement(), saveElement() and toMatchElementSnapshot() with autoElementScroll (the default) scroll the element into view and then restore the old position. The restore in packages/image-comparison-core/src/methods/takeElementScreenshots.ts checked options.autoElementScroll && currentPosition, so a page at the top (scrollY 0) was never scrolled back. A later checkScreen() then captured a scrolled page.

The three restore guards (BiDi document origin, BiDi viewport origin, WebDriver classic) now check typeof currentPosition === 'number'. An undefined result still skips the restore. screenshots.ts restores scrollY without a truthiness check, so it stays unchanged. A patch changeset covers @wdio/image-comparison-core.

Tests I ran on macOS, Node 25.9.0, pnpm 11.28.2

$ npx vitest --run packages/image-comparison-core/src/methods/takeElementScreenshots.test.ts
main 187e0767e   Tests  3 failed | 25 passed (28)
this branch      Tests  28 passed (28)

$ pnpm run build && pnpm run test:lint && pnpm run test:types   all exit 0
$ pnpm run test:unit   1071 passed, 1 timeout in processDiffPixels.test.ts (6M pixel case, 5000 ms under load), passes when rerun alone

End to end with the reporter's long.html and spec, headless Chrome 155, @wdio/visual-service built from this workspace

main 187e0767e   E2E start 0: after checkElement 1206
                 E2E start 100: after checkElement 100
this branch      E2E start 0: after checkElement 0
                 E2E start 100: after checkElement 100

The cloud provider suites and test.local.chrome.v10 were not run.

[changeset-bot]

🦋 Changeset detected

Latest commit: 45f1d88

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@wdio/image-comparison-core	Patch
@wdio/visual-service	Patch

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[greptile-apps]

Confidence Score: 5/5

[Medium risk] Fixes scroll restoration logic in element screenshot capture.

This PR appears safe to merge.

What we checked:

• Scroll restoration stays optional: Each path reads the position only when autoElementScroll is enabled. The new guards require both that option and a numeric position.

Summary

Restores the page’s previous scroll position after an element screenshot, including position zero.

• Updates the guards for BiDi document, BiDi viewport, and WebDriver Classic screenshots.
• Adds a zero-position regression test for each path.
• Adds a patch changeset for @wdio/image-comparison-core.

_{Reviews (1) · Last reviewed commit: "fix: scroll back to position 0 after an ..." · Reviewed by Greptile}