fix: avoid scene initialization after Strict Mode cleanup

[akn966]

Summary

• defer scene initialization by one microtask so React Strict Mode can clean up its discarded effect before addScene() starts
• skip initialization when that effect has already been cleaned up
• add a Strict Mode regression test that verifies the SDK initializes exactly once

Why

In a Next.js App Router application, navigating client-side to a route containing a scene could trigger this SDK error:

TypeError: Cannot read properties of null (reading 'canvas')
    at setInitialFlattenedPlaneUniforms

The first Strict Mode effect started addScene() synchronously. React then cleaned up that discarded effect and the wrapper destroyed the scene, while asynchronous SDK initialization callbacks were still running. Those callbacks later accessed the destroyed scene's null curtain.

Yielding one microtask before touching the SDK lets the Strict Mode cleanup set ignore, preventing the discarded effect from starting a scene at all.

Checks

• npm test — 124 passed
• npm run lint
• npm run type-check
• npm run build

Summary by CodeRabbit

• Bug Fixes
  • Improved scene initialization reliability when the app is rendered under React Strict Mode.
  • Prevented scenes from being initialized more than once or unintentionally destroyed during startup.
  • Improved handling when scene properties change while initialization is still in progress.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 9c089e95-5c09-48c1-9a6b-e1a15ac35f0d

📥 Commits

Reviewing files that changed from the base of the PR and between cee51fb and e4b3f93.

📒 Files selected for processing (2)

• src/__tests__/useUnicornScene.test.ts
• src/shared/hooks.ts

Included review availability: Your plan provides up to 1 included review per hour; 0 remain after this review.

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📝 Walkthrough

Walkthrough

The scene initialization hook now waits for one microtask before SDK startup. It skips initialization when Strict Mode cleanup invalidates the effect. Tests cover single initialization, scene retention, and pending rerender behavior.

Changes

Scene initialization

Layer / File(s)	Summary
Strict Mode initialization guard src/shared/hooks.ts, src/__tests__/useUnicornScene.test.ts	initializeScene yields before SDK startup and exits when cleanup occurs during the delay. Tests verify that Strict Mode does not duplicate addScene, does not destroy the created scene, and flushes pending initialization before rerendering.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to e4b3f

The change defers scene initialization to avoid starting discarded Strict Mode effects and adds regression coverage; no actionable merge-blocking risk remains after normal checks and review.

Suggested reviewers: diegopeixoto

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the fix that prevents scene initialization after React Strict Mode cleanup.
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.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[diegopeixoto]

@GeorgeHastings