## I have read the
[CONTRIBUTING.md](https://github.com/supabase/supabase/blob/master/CONTRIBUTING.md)
file.
YES
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **Behavior Changes**
* Partial directives now render unprovided variables as empty strings
instead of throwing validation errors
* Escaped placeholders (preceded by backslash) are preserved and not
substituted
* Unused provided variables are silently ignored
* **Tests**
* Updated test coverage to validate the new permissive variable
substitution behavior and removed prior error-focused assertions
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
- Add validation for missing required variables
- Add validation for unexpected variables
- Provide detailed error messages showing expected vs provided variables
- Include partial path in error messages for better debugging
- Add comprehensive tests for new error scenarios
Error messages now clearly indicate:
- Which variables are missing
- Which variables are unexpected
- What variables were expected vs provided
Co-authored-by: Claude <noreply@anthropic.com>
Partials are currently defined via MDX includes. This PR switches to pre-compile-time partials, which have a new syntax:
```
<$Partial path="path/to/file.mdx" />
```
## Rationale
This produces two improvements:
1. Partial substitution can occur in pipelines that don't use MDX compilation. For example, we can now do partial substitution before building the search index, so partial content will also be indexed.
2. After the App Router migration, the MDXProviders should've been deprecated, but were kept around for the sole reason of making partials work, and leading to us shipping unnecessary client-side code. We get a minor decrease in overall client bundle size (5.74 MB to 5.6 MB) by getting rid of the Providers.
## Breaking changes
Besides the change to partial syntax, the arguments are also less powerful than before because we are doing string substitution and don't have the full power of JS. Defining string variables is still possible (documented in the Contributing guide), and since that's all we actually do in practice, this shouldn't be too cumbersome. There is always the escape hatch of making a custom component for more complex content reuse cases.
