Custom markdown input not streamed correctly in PlaygroundEditor

[aradhyacp]

Bug Description

When using the PlaygroundEditor, typing custom markdown in the left panel and clicking Simulate Stream does not stream the typed content. Instead, it either streams the default markdown or fails to update correctly.

Steps to Reproduce

1. Open the PlaygroundEditor and type custom markdown in the left panel.
2. Click the Simulate Stream button.
3. Observe that the streamed output does not match the typed content.

Screen Recording

Screen.Recording.2026-03-12.at.2.10.49.AM.mov

Expected Behavior

The streamed output should reflect the current content in the markdown input field, animating exactly what the user typed.

Actual Behavior

The stream either uses stale default content or does not update correctly when custom markdown is typed.

Code Sample

Streamdown Version

2.4.0

React Version

^19.2.3

Node.js Version

No response

Browser(s)

Not applicable (Node.js)

Operating System

macOS

Additional Context

While testing the PlaygroundEditor, I noticed that streaming always started from the default markdown rather than the current input.