Draft changelog: OAuth 2.0 webhook auth and faster streaming

[mintlify]

Summary

Adds a Sep 4, 2026 changelog entry covering product changes shipped since the Sep 1 entry.

Changes

• New: OAuth 2.0 user-context authentication now accepted on webhook management endpoints and X Activity API subscription endpoints (previously app-only Bearer, or OAuth 1.0a on some webhook endpoints).
• Update: volume streaming endpoints (including Filtered Stream) improved P99 latency from ~6-7 seconds to ~4-5 seconds.

Context

Sourced from the OpenAPI spec security changes and the streaming latency update merged to main this week. Docs-only changes (media page cleanups) were excluded.

[mintlify]

Preview deployment for your docs. Learn more about Mintlify Previews.

Project	Status	Preview	Updated
x-corp	🟢 Ready	View Preview	Sep 4, 2026, 2:18 AM

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}