legacy remark

Author: nojaf

_blogposts/2025-11-11-introducing-rewatch.mdx

@@ -314,7 +314,7 @@ We're continuing to test compatibility across different environments and configu
 
 ## Using the Legacy Build System
 
-For projects that need it, the legacy bsb build system remains available through the `rescript-legacy` command. This is a separate binary, not a subcommand.
+For projects that need it, the legacy bsb build system remains available throughout the v12 release cycle through the `rescript-legacy` command. This is a separate binary, not a subcommand. We expect to remove the legacy build system in v13, so we encourage migrating to ReWatch when possible.
 
 ```bash
 # Build your project