feat: Conditionally handle incompletes

[2hu12]

Description

This PR introduces the following changes:

Added the extraIncompleteHandles option

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Performance improvement
• Refactoring (no functional changes)

Related Issues

Fixes #159 #108
Closes #
Related to #159 #108

Changes Made

• Added the extraIncompleteHandles option: This new option allows users to configure how unterminated Markdown blocks are handled, providing greater flexibility for custom remarkPlugins configurations. Re-enable support for the ⁠singleDollarTextMath option, as requested in Streamdown is not working properly only in rendering the mathematical equations. Rest is working fine and perfect. #159.

Testing

• All existing tests pass
• Added new tests for the changes
• Manually tested the changes

Test Coverage

Screenshots/Demos

Checklist

• My code follows the project's code style
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings or errors
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have created a changeset (pnpm changeset)

Changeset

• I have created a changeset for these changes

Additional Notes

[vercel]

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[vercel]

Block component memo comparison only checks content but ignores extraIncompleteHandles, causing stale renders when extraIncompleteHandles changes.

View Details

📝 Patch Details

diff --git a/packages/streamdown/index.tsx b/packages/streamdown/index.tsx
index 8921f60..a7636b6 100644
--- a/packages/streamdown/index.tsx
+++ b/packages/streamdown/index.tsx
@@ -103,7 +103,10 @@ const Block = memo(
 
     return <ReactMarkdown {...props}>{parsedContent}</ReactMarkdown>;
   },
-  (prevProps, nextProps) => prevProps.content === nextProps.content
+  (prevProps, nextProps) => 
+    prevProps.content === nextProps.content && 
+    prevProps.shouldParseIncompleteMarkdown === nextProps.shouldParseIncompleteMarkdown &&
+    prevProps.extraIncompleteHandles === nextProps.extraIncompleteHandles
 );
 
 Block.displayName = "Block";
@@ -165,6 +168,7 @@ export const Streamdown = memo(
   (prevProps, nextProps) =>
     prevProps.children === nextProps.children &&
     prevProps.shikiTheme === nextProps.shikiTheme &&
-    prevProps.isAnimating === nextProps.isAnimating
+    prevProps.isAnimating === nextProps.isAnimating &&
+    prevProps.extraIncompleteHandles === nextProps.extraIncompleteHandles
 );
 Streamdown.displayName = "Streamdown";

Analysis

Block component memo comparison ignores extraIncompleteHandles causing stale renders

What fails: The Block component's React.memo comparison function only checks content prop, ignoring extraIncompleteHandles and shouldParseIncompleteMarkdown dependencies used in the component's useMemo hook.

How to reproduce:

1. Render <Streamdown extraIncompleteHandles={[handler1]}>content</Streamdown>
2. Re-render with different handlers: <Streamdown extraIncompleteHandles={[handler2]}>content</Streamdown>
3. Same content, different handlers - component should re-render but doesn't

Result: Block component shows stale parsed content when extraIncompleteHandles changes, because memo comparison returns true (no re-render needed) even though the useMemo dependencies have changed.

Expected: Component should re-render when any useMemo dependency changes, producing different parsed output when handlers change.

Root cause: Both Streamdown and Block memo functions were incomplete:

• Block memo only checked content but ignored extraIncompleteHandles and shouldParseIncompleteMarkdown
• Streamdown memo only checked children, shikiTheme, and isAnimating but ignored extraIncompleteHandles