developers: stone: v1: payload-subheader: Document

Author: livingsilver94

astro.config.mjs

@@ -213,6 +213,7 @@ export default defineConfig({
                   items: [
                     { slug: "developers/stone/v1" },
                     { slug: "developers/stone/v1/header" },
+                    { slug: "developers/stone/v1/payload-subheader" },
                     {
                       label: "Records",
                       items: [

src/content/docs/Developers/Stone/V1/payload-subheader.mdx

@@ -0,0 +1,79 @@
+---
+title: Payload's sub-header
+lastUpdated: 2026-04-22T00:00:00Z
+description: The content of Payload's sub-header
+---
+
+Described below is the format of the 32-byte-long payload sub-header. This format is unique to v1.
+
+<table>
+  <tr>
+    <th>Field</th>
+    <th>Type</th>
+    <th>Size (bytes)</th>
+    <th>Description</th>
+  </tr>
+  <tr>
+    <td>stored_size</td>
+    <td>uint</td>
+    <td>8</td>
+    <td>
+        Compressed size, in bytes, of the records.
+        If records are not compressed, stored_size is equal to plain_size.
+    </td>
+  </tr>
+  <tr>
+    <td>plain_size</td>
+    <td>uint</td>
+    <td>8</td>
+    <td>Uncompressed size, in bytes, of records.</td>
+  </tr>
+  <tr>
+    <td>checksum</td>
+    <td>blob</td>
+    <td>8</td>
+    <td>Checksum of records, computed using <a href="https://xxhash.com">XXH3_64bits</a>.</td>
+  </tr>
+  <tr>
+    <td>num_records</td>
+    <td>uint</td>
+    <td>4</td>
+    <td>Number of records contained in the payload.</td>
+  </tr>
+  <tr>
+    <td>version</td>
+    <td>uint</td>
+    <td>2</td>
+    <td>Version of the payload data format. Unused.</td>
+  </tr>
+  <tr>
+    <td>record_kind</td>
+    <td>uint</td>
+    <td>1</td>
+    <td>Kind of records that the payload contains.</td>
+  </tr>
+  <tr>
+    <td>compression</td>
+    <td>uint</td>
+    <td>1</td>
+    <td>Compression algorithm used for the records.</td>
+  </tr>
+</table>
+
+### record_kind
+
+`record_kind` is an enum. The following table lists all possible values:
+
+|Value|Name|
+|---|---|
+|1|<a href="/developers/stone/v1/record/meta">Meta</a>|
+|2|<a href="/developers/stone/v1/record/content">Content</a>|
+|3|<a href="/developers/stone/v1/record/layout">Layout</a>|
+|4|<a href="/developers/stone/v1/record/index">Index</a>|
+|5|<a href="/developers/stone/v1/record/attributes">Attributes</a>
+
+### compression
+|Value|Name|
+|---|---|
+|1|Uncompressed|
+|2|Zstd|