Sync open source content 🐝 (from 3630ea3d4506e7f0335d36235f3c111f87c64711)

Author: beezythebot

docs/speakeasy-reference/generation/gen-yaml.mdx

@@ -187,3 +187,16 @@ Controls how `allOf` constructs in OpenAPI schemas are merged. For detailed info
   schemas:
     allOfMergeStrategy: deepMerge
 ```
+
+### multipartArrayFormat
+
+Controls how arrays are serialized in multipart/form-data requests. This option determines whether array field names include brackets (`[]`) or use the RFC 7578-compliant approach of repeating the same field name.
+
+- `legacy` (default for existing SDKs): Appends `[]` to array field names (e.g., `files[]`). This maintains backward compatibility with existing SDKs but is non-compliant with RFC 7578.
+- `standard` (default for new SDKs): Uses the RFC 7578-compliant format by repeating the same field name for each array element (e.g., multiple `files` fields). This is the correct multipart/form-data encoding according to RFC 7578 Section 4.3.
+
+```yaml
+  multipartArrayFormat: standard
+```
+
+**Migration note**: Changing from `legacy` to `standard` is a breaking change. APIs expecting field names with `[]` suffixes will need to be updated to handle the RFC-compliant format.