fix(rtstruct): prevent viewport from becoming blank on second load

[Belbin-GK]

Context

Hydration was being triggered before the viewport was fully initialized, which could lead to rendering issues such as a blank viewport, especially when loading RTSTRUCT multiple times.

Changes & Results

• Removed the use of setTimeout for delaying hydration
• Introduced a mechanism to wait for actual viewport readiness

5996-rtstruct-viewport-blank-on-second-load.mp4

Testing

• Load a study with RT Struct.
• Drag and drop the RT Struct.
• Close the RT struct from the segmentation panel.
• Drag and drop the RT Struct again.
• Observe that RT struct is not loaded in the viewport and the segmentation panel.

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: Windows 11
• Node version: 22.20
• Browser: Chrome 147.0.7727.138

Summary by CodeRabbit

• Bug Fixes

  • Improved reliability of SEG and RTSTRUCT hydration by waiting for the matching viewport to become ready before triggering hydration, using a 5-second timeout safeguard. If readiness fails or hydration throws/rejects, the operation now rejects instead of continuing.

• Tests

  • Updated the hydration test to align with the new viewport-ready async behavior, removing reliance on immediate deferral while still validating the expected SEG hydration payload.

Greptile Summary

This PR fixes blank viewport regressions when loading RTSTRUCT (and SEG) a second time by replacing the setTimeout(0) deferral with a proper readiness check: if getCornerstoneViewport returns null, hydration now waits for the VIEWPORT_DATA_CHANGED event (with a 5-second timeout) before invoking hydrateCallback.

• The waitForViewportDataChange helper subscribes to VIEWPORT_DATA_CHANGED and properly rejects on timeout; the outer async executor wraps the await in a try/catch so timeout rejections correctly propagate to callers.
• The VIEWPORT_DATA_CHANGED payload shape { viewportData, viewportId } is consistent with how other subscribers in the codebase, confirming the viewport-ID comparison is correct.
• The test suite does not include cornerstoneViewportService in its mock, so the new waiting branch is never exercised; the vestigial window.setTimeout spy in beforeEach is also left over from the old implementation.

Confidence Score: 5/5

The runtime fix is correct and the event payload shape is consistent with existing usage; the only gaps are missing test coverage for the new branch.

The core logic is sound: the event used to detect viewport readiness is the same one used throughout the codebase, the timeout/reject wiring is correct, and no prior-thread issues remain unaddressed. The test file does not cover the new code path, but this does not introduce a runtime defect.

extensions/cornerstone/src/utils/promptHydrationDialog.test.ts — the mock services manager should be extended to exercise the new waitForViewportDataChange branch.

Important Files Changed

Filename	Overview
extensions/cornerstone/src/utils/promptHydrationDialog.ts	Replaces setTimeout(0) for SEG/RTSTRUCT hydration with a VIEWPORT_DATA_CHANGED subscription that waits for the viewport to be ready; timeout and reject handling are correctly wired. Event payload shape ({ viewportId }) confirmed consistent with other subscribers in the codebase.
extensions/cornerstone/src/utils/promptHydrationDialog.test.ts	Removes the setTimeout assertion, but the new waitForViewportDataChange branch is never exercised because cornerstoneViewportService is absent from mockServicesManager; vestigial window.setTimeout spy remains.

_{Reviews (13): Last reviewed commit: "Merge branch 'master' into rtstruct-view..." | Re-trigger Greptile}

[netlify]

❌ Deploy Preview for ohif-dev failed. Why did it fail? →

Name	Link
🔨 Latest commit	74ff9d8
🔍 Latest deploy log	https://app.netlify.com/projects/ohif-dev/deploys/6a3c2e6a2afb700008ef01e1

[Belbin-GK]

@wayfarer3130 Could you please review the changes?

[sen-trenser]

@wayfarer3130 We have updated the review comments. Could you please take a look at the changes?

[coderabbitai]

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📝 Walkthrough

Walkthrough

promptHydrationDialog now waits for Cornerstone viewport readiness before hydrating SEG and RTSTRUCT display sets. The SEG test no longer checks window.setTimeout and still verifies the hydration callback payload.

Changes

Viewport-driven hydration for SEG/RTSTRUCT

Layer / File(s)	Summary
Helper docs and service wiring extensions/cornerstone/src/utils/promptHydrationDialog.ts	Inline documentation is added for the callback and helper functions, and cornerstoneViewportService is destructured from servicesManager.services.
Async viewport-driven hydration flow extensions/cornerstone/src/utils/promptHydrationDialog.ts	SEG and RTSTRUCT hydration now waits for VIEWPORT_DATA_CHANGED on the target viewportId, with a 5-second timeout, before invoking hydrateCallback.
Test update for async flow extensions/cornerstone/src/utils/promptHydrationDialog.test.ts	The window.setTimeout assertion is removed from the SEG hydration test, leaving the callback payload assertion intact.

🎯 2 (Simple) | ⏱️ ~12 minutes

🐰 I hop through viewports, wait and see,
No timeout jingle for SEG or RT.
When data changes, I bounce along,
And hydration sings its async song.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is concise, specific, and accurately reflects the main RTSTRUCT viewport fix.
Description check	✅ Passed	The description matches the template with context, changes, testing steps, and completed checklist items.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
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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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[greptile-apps]

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[Devu-trenser]

The Netlify builds for this PR are currently failing with the following error:

sh: 1: cross-env: Permission denied

Based on the build logs, the failure occurs before the application build starts and appears to be related to the CI/build environment rather than the changes introduced in this PR.

@sedghi , could you please take a look at this when you get a chance?

cc: @sen-trenser