diff --git a/changelog.mdx b/changelog.mdx
index b965396ee..2cfe31051 100644
--- a/changelog.mdx
+++ b/changelog.mdx
@@ -7,6 +7,20 @@ keywords: ["changelog", "API updates", "release notes", "what's new", "API chang
 
 To subscribe to updates, please [**“Turn on notifications”**](https://help.x.com/en/managing-your-account/notifications-on-mobile-devices#:~:text=In%20the%20top%20menu,%20you,you%20would%20like%20to%20receive) for [**@API**](https://x.com/api). You can also follow this changelog in your feed reader via the [**RSS feed**](https://docs.x.com/changelog/rss.xml).
 
+<Update label="Sep 4, 2026" description="X API v2">
+  ### User-context authentication for webhook and X Activity API management
+
+  Webhook management endpoints ([`GET /2/webhooks`](/x-api/webhooks/get-webhook), [`POST /2/webhooks`](/x-api/webhooks/create-webhook), [`DELETE /2/webhooks/{webhook_id}`](/x-api/webhooks/delete-webhook), and [`PUT /2/webhooks/{webhook_id}`](/x-api/webhooks/validate-webhook)) now accept **OAuth 2.0 user-context** authentication, and `GET /2/webhooks` additionally accepts OAuth 1.0a.
+
+  The [X Activity API](/x-api/activity/introduction) subscription endpoints [`PUT /2/activity/subscriptions/{subscription_id}`](/x-api/activity/update-x-activity-subscription) and [`DELETE /2/activity/subscriptions/{subscription_id}`](/x-api/activity/deletes-x-activity-subscription) now accept **OAuth 2.0 user-context** and **OAuth 1.0a** authentication in addition to app-only Bearer Tokens.
+
+  You can now manage webhooks and Activity API subscriptions with the same user-context credentials your app already uses, instead of switching to an app-only Bearer Token.
+
+  ### Faster streaming delivery
+
+  We improved delivery latency on the hydrated streaming endpoints, including [Filtered Stream](/x-api/posts/filtered-stream/introduction) and the volume streams. P99 latency is now **approximately 4-5 seconds**, down from ~6-7 seconds. No changes are required on your side. See [consuming streaming data](/x-api/fundamentals/consuming-streaming-data) for delivery guarantees, or [Powerstream](/x-api/powerstream/introduction) if you need the lowest possible latency.
+</Update>
+
 <Update label="Sep 1, 2026" description="X API v2">
   ### Media upload and Post-create size and duration limits