Draft changelog: Sep 25, 2026 weekly updates

[mintlify]

Summary

Adds a weekly changelog entry for product changes shipped since the Sep 21, 2026 entry.

Changes

• New features: Activity API subscription expires_at, OAuth 2.0 client secret webhook signatures, is_moderator on broadcast.chat
• Updates: broadcast scopes in OAuth 1.0a token exchange, Chat join request approval, Livestream API access for whitelisted apps (no Enterprise plan needed)
• Bug fixes: batch compliance upload limit corrected to 128 MB, deprecated source removed from tweet.fields

Context

Based on PRs #441, #443, #445, #448, #450, #451, #454 and OpenAPI spec updates.

[mintlify]

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

Project	Status	Preview	Updated
x-corp	🟢 Ready	View Preview	Sep 25, 2026, 2:12 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.}