fix(seg): prevent viewport orientation change when loading SEG in manual grid layout

[GhadeerAlbattarni]

Context

Fixes #6012

When a user switches from 3D four up layout to a manual grid layout (e.g. 3×2) and then drags a SEG into an empty viewport, all viewports reset to axial orientation and the segmentation loads in the wrong viewport.

Changes & Results

• hydrationUtils.ts: skip mergeVolumeSharingViewports when isHangingProtocolLayout=false.
• SEGHydrationFrom3DFourUp.spec.ts: add playwright test covering SEG hydration after switching from 3D four up to a manual 3x2 grid layout.
• MainToolbarPageObject.ts: add grid(cols, rows) helper for selecting custom grid layouts by column and row count

load-seg-3DfourUp-to-3By2.mov

Testing

1. Open a study that has SEG (e.g., StudyInstanceUIDs=1.3.6.1.4.1.14519.5.2.1.256467663913010332776401703474716742458)
2. Switch to 3D four up
3. Switch to 3x2
4. Drag SEG series into the 3rd Viewport

• Verify the segmentation is loaded only to the target viewport (3rd) and all other viewports remain unchanged

5. Switch back to 3D four up

• Verify no segmentation in the viewports

Checklist

PR

• My Pull Request title is descriptive, accurate and follows the
  semantic-release format and guidelines.

Code

• [] My code has been well-documented (function documentation, inline comments,
  etc.)

Public Documentation Updates

• [] The documentation page has been updated as necessary for any public API
  additions or removals.

Tested Environment

• OS: macOS 10.15.4
• Node version: v22.13.0
• Browser: Chrome 83.0.4103.116

Greptile Summary

Prevents viewport orientation resets when a SEG is dragged into a viewport under a manually-selected grid layout. The root cause was mergeVolumeSharingViewports propagating updates to all volume-sharing viewports regardless of layout type; a single guard now skips that merge when isHangingProtocolLayout is false.

• hydrationUtils.ts: adds || !isHangingProtocolLayout to the early-return condition so mergeVolumeSharingViewports is only invoked for hanging-protocol-driven layouts, not manual grids.
• SEGHydrationFrom3DFourUp.spec.ts: new describe block verifies that hydrating a SEG into a specific viewport in a 3×2 grid leaves other viewports unchanged, then confirms no segmentation appears after switching back to 3D four-up.
• MainToolbarPageObject.ts: adds grid(cols, rows) helper to select custom grid layouts by column/row count, consistent with the existing layout-selector pattern.

Confidence Score: 5/5

Safe to merge; the core change is a one-line guard that only affects the manual-grid code path.

The fix is minimal and targeted: it skips mergeVolumeSharingViewports exclusively when isHangingProtocolLayout is false, leaving the hanging-protocol path unchanged. The accompanying test exercises the exact scenario described in the bug report.

No files require special attention; test quality notes were already raised in prior review threads.

Important Files Changed

Filename	Overview
extensions/cornerstone/src/utils/hydrationUtils.ts	Single-line guard added to skip mergeVolumeSharingViewports when isHangingProtocolLayout=false; fix is focused and correct
tests/SEGHydrationFrom3DFourUp.spec.ts	New describe block tests the SEG hydration after layout switch; uses correct render-cycle pattern but skips { renderedTimeout: 180000 } for backTo3DFourUp screenshot (already discussed in review threads)
tests/pages/MainToolbarPageObject.ts	Adds grid(cols, rows) helper method consistent with the existing layout-selector pattern; test-ID convention (Layout-${cols-1}-${rows-1}) matches usage in other spec files
tests/utils/screenShotPaths.ts	Adds segHydrationAfterLayoutSwitchTo3By2 entry; filenames are unique within the spec's screenshot directory

_{Reviews (5): Last reviewed commit: "add small change to the test" | Re-trigger Greptile}

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[jbocce]

@claude review

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[jbocce]

See the one suggestion from AI and let me know how it goes. Thanks for this.

[jbocce]

Looks awesome.