[linkdotnet]

Summary

Nodes cached a parse of the old markup when a render (e.g. timer) finished mid-parse; Find then served stale nodes with removed event handler IDs → UnknownEventHandlerIdException.

test thread                          dispatcher (UpdateMarkup)
latestRenderNodes is null
read Markup (old)                    latestRenderNodes = null
parse old markup...                  write new Markup
latestRenderNodes = old nodes  ← stale until next render

Nodes are now cached with the markup string they were parsed from and re-parsed when it no longer matches:

 Nodes
-  return latestRenderNodes ??= Parse(Markup)
+  current = Markup
+  if cached is null or cached.Markup is not current
+    cached = (current, Parse(current))
+  return cached.Nodes

Not needed in v3: #1910 (shared render tree) replaces this with immutable markup snapshots — take its side on conflict.

Evidence

Test030 (deterministic): render <p>1</p> without reading Nodes; hold BunitHtmlParser's parse lock so a reader thread pauses after capturing the old markup; render <p>2</p>; release; cut.Find("p").TextContent.ShouldBe("2").

• Before (original getter): failed 5/5 — should be "2" but was "1"
  After: passed 5/5; full net10.0 suite 2274/2274 passed

Merge Danger

Door: two-way

Blast Radius: small

Only RenderedComponent.Nodes changes; same instance/new-instance semantics as before (Test006–008 unchanged).

[Copilot]

🟡 Changes recommended

The regression test needs controlled synchronization to reliably detect the original race.

1 open issue

• Make stale-cache race regression test deterministic · New

What changed in this PR

Fixes stale DOM-node caching in bUnit when rendering overlaps HTML parsing.

Changes:

• Associates cached nodes with their markup snapshot.
• Adds a cross-thread rendering regression test.
• Documents the fix in the changelog.

File	Description
tests/​bunit.tests/​Rendering/​RenderedComponentTest.cs	Adds concurrent rendering coverage.
src/​bunit/​Rendering/​RenderedComponent.cs	Validates cached nodes against current markup.
CHANGELOG.md	Records the stale-node fix.

_{Review effort: Balanced}