fix: streaming race condition

[schiller-manuel]

Summary by CodeRabbit

• Bug Fixes
  • Fixed a race condition in server-side rendering where injected HTML could appear in incorrect order relative to app content. Enhanced buffering logic ensures proper content sequencing during streaming.

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[coderabbitai]

📝 Walkthrough

Walkthrough

The change modifies the buffering condition in the onInjectedHtml listener within the SSR stream transformer to buffer injected HTML not only during app rendering but also when leftover content is pending flush, preventing a race condition where injected HTML could appear before buffered app content.

Changes

Cohort / File(s)	Summary
SSR Stream Buffering Logic packages/router-core/src/ssr/transformStreamWithRouter.ts	Expanded the buffering condition to include leftover content pending flush alongside the existing rendering state check, ensuring injected HTML is buffered to pendingRouterHtmlParts until a safe insertion point is found.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Possibly related PRs

• fix: fix streaming #5994: Modifies the same SSR stream transformer file to address injected-HTML buffering and leftover-flush race conditions.
• fix: more robust stream handling #5996: Updates the same file with changes to injected-HTML buffering and stream cleanup guard logic.
• fix: cleanup references #5965: Alters how the injectedHtml listener processes and buffers HTML content in the same SSR transformer.

Suggested labels

package: router-core

Poem

🐰 A rabbit hops through buffered streams,
Where HTML flows in orderly schemes,
No racing left, no jumbled fate,
Each piece waits patiently at the gate!

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'fix: streaming race condition' is clear, concise, and directly describes the main change in the pull request. It identifies both the nature of the fix and the specific issue being addressed.

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✨ Finishing touches

• 📝 Generate docstrings

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[nx-cloud]

View your CI Pipeline Execution ↗ for commit f7bb020

Command	Status	Duration	Result
nx affected --targets=test:eslint,test:unit,tes...	✅ Succeeded	12m 13s	View ↗
nx run-many --target=build --exclude=examples/*...	✅ Succeeded	1m 44s	View ↗

---

☁️ Nx Cloud last updated this comment at 2026-01-24 20:36:50 UTC

[pkg-pr-new]

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commit: f7bb020