fix: rotate landscape screenshots in the pixels, not with an exif tag

[mobile-kevin]

Summary

In landscape, device.screenshot returned an image that disagreed with the UI tree and with tap coordinates.

XCTest hands a rotated screen back as the panel's portrait pixels plus an orientation, and both encoders wrote that orientation as an EXIF tag (8, "rotate 270"). A decoder that ignores the tag (Go's image packages in mobilecli, among others) sees a 1206x2622 portrait image, while device.dump.ui and device.io.tap work in the rotated 874x402 space. Coordinates read off the screenshot land somewhere else.

• Screenshot.swift: when the captured image carries an orientation, it is redrawn upright before encoding, so the rotation is in the pixels. No EXIF rotation is left for the viewer to apply.
• Portrait screenshots take the same path as before (pngRepresentation / jpegData on the original image).

Result on iPhone 17 Pro simulator (iOS 26.0), Safari in landscape

	Before	After
PNG size	1206x2622	2622x1206
JPEG size	1206x2622	2622x1206
EXIF orientation	8 (rotate 270)	1 (normal)
App rect in device.dump.ui	874x402	874x402

Through mobilecli with this runner, mobilecli screenshot in landscape is 2622x1206, and cropping it at the rectangle dump ui reports for a button (x3) lands exactly on that button.

Testing

• New tests in tests/rpc.test.ts ("device.screenshot in landscape"), for png and jpeg:
  • the screenshot is as wide and as tall as the foreground app's rect times the device scale
  • the screenshot does not ask its viewer to rotate it (EXIF orientation absent or 1)
• tests/image.ts: a small png/jpeg reader for the size and the orientation tag, so the tests need no image library.
• All four failed before the fix and pass after.
• Full suite: 56 passed, 1 failed. The failure is device.io.swipe › swipes over an explicit duration, which passes on its own and fails when it runs after another swipe (about 1390ms against a 1400ms floor); it does not involve the screenshot handler.
• swiftlint lint --strict reports nothing on the added lines.

Not covered

The MJPEG stream has no orientation handling either; it is not changed or tested here.

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: 92af5124-29f3-4f48-946a-21ed2deea757

📥 Commits

Reviewing files that changed from the base of the PR and between 5d499ae and 249fba3.

📒 Files selected for processing (3)

• DeviceKitTests/JSONRPC/Handlers/Screenshot.swift
• tests/image.ts
• tests/rpc.test.ts

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Walkthrough

The screenshot handler now rotates image pixels upright before PNG or JPEG encoding, with fallback behavior when rotation is unavailable. New test helpers parse PNG and JPEG dimensions and EXIF orientation. RPC tests capture landscape screenshots and check their dimensions and upright EXIF orientation.

Priority: ⬇️ Low

Merge Risk: ⚪ Minimal · up to 249fb

The screenshot rotation change is mergeable subject to normal checks. The supplied evidence establishes no actionable defect in screenshot encoding or the landscape tests.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 35.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 20 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: rotating landscape screenshots in the pixel data instead of relying on an EXIF orientation tag.
Description check	✅ Passed	The description directly explains the screenshot orientation problem, the implementation, test coverage, reported results, and the unchanged MJPEG scope.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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🧪 Generate unit tests (beta)

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