* feat: support custom starting line number in code blocks
Add support for specifying a custom starting line number via the code
fence meta string, e.g.:
```js startLine=10
const x = 1;
```
Implementation:
- Add `remarkCodeMeta` remark plugin that forwards the fenced-code meta
string to hast as the `metastring` property so it is available to the
custom React code component.
- Update the rehype-sanitize default schema to allow the `metastring`
attribute on `code` elements.
- Parse `startLine=N` from the meta string in `CodeComponent` and pass
the value down as a `startLine` prop.
- In `CodeBlockBody`, apply `counter-reset: line N-1` as an inline style
when `startLine > 1`, which overrides the Tailwind counter-reset class
and makes CSS counters begin from the specified number.
- Pass `startLine` through the `CodeBlock` and
`HighlightedCodeBlockBody` call chains.
- Add 12 tests covering the remark plugin, CodeBlockBody prop, and
CodeBlock integration.
Closes: resolves#287
* fix: lint errors — use literal keys, hoist regex, sort imports
* feat: allow customizing icons via icons prop
Add an IconContext-based system that lets users override any of the
built-in icons (CheckIcon, CopyIcon, DownloadIcon, etc.) by passing
a Partial<IconMap> via the new `icons` prop on <Streamdown>.
- Created lib/icon-context.tsx with IconMap type, IconProvider, and useIcons hook
- Updated all sub-components to consume icons via useIcons() instead of direct imports
- Added icons prop to StreamdownProps with IconProvider wrapper
- Exported IconMap type from package entry
Closes#412
* style: fix biome lint and formatting errors
* Merge branch 'main' into feat/custom-icons
* fix: review fixes for icons and startLine features
- Add missing changeset for icons feature (minor)
- Fix IconComponent type to include size prop matching actual usage
- Fix IconProvider memoization: use shallow comparison instead of
referential equality so inline icon objects don't cause re-renders
- Move START_LINE_PATTERN constant below all imports
- Add bounds checking for startLine (must be >= 1)
- Convert dynamic imports to top-level imports in startLine tests
- Add icon-context tests (5 tests)
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---------
Co-authored-by: Dmitrii Troitskii <jsleitor@gmail.com>
Co-authored-by: Hayden Bleasel <hello@haydenbleasel.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Dmitrii