diff --git a/changelog.mdx b/changelog.mdx
index 7ee8bff..dce2b62 100644
--- a/changelog.mdx
+++ b/changelog.mdx
@@ -4,6 +4,15 @@ description: "New features, improvements, and fixes across the Sendmux platform.
 rss: true
 ---
 
+<Update label="16 July 2026" tags={["Bug fixes"]} rss={{ title: "Agent attachment uploads are more reliable" }}>
+  ## Bug fixes
+
+AI tool workflows can now upload and download mailbox attachments through hosted MCP without hitting an unintended permission block.
+
+Short-lived Sending API upload links now reject invalid tokens or mismatched upload headers before reading file bytes, keeping delegated uploads safer and more predictable.
+
+</Update>
+
 <Update label="14 July 2026" tags={["Bug fixes"]} rss={{ title: "Inbox thread lists load more reliably" }}>
   ## Bug fixes