AIG-1532: Add BYOK-only changelog

Author: superhighfives

src/content/changelog/ai-gateway/2026-09-14-require-provider-credentials.mdx

@@ -0,0 +1,19 @@
+---
+title: AI Gateway can require provider credentials
+description: Prevent third-party provider requests from falling back to Unified Billing when provider credentials are unavailable.
+date: 2026-09-14
+---
+
+AI Gateway can now require credentials for third-party provider requests. Credentials must accompany the request or be stored on the gateway. This setting prevents fallback to Unified Billing with Cloudflare-managed credentials.
+
+Turn on **Require provider credentials** in your gateway settings. To use the API, set `byok_only` to `true`:
+
+```json
+{
+	"byok_only": true
+}
+```
+
+Requests without applicable credentials then return an HTTP `400` response. Workers AI requests remain allowed. They continue to use standard Workers AI account billing.
+
+For configuration details and request-level controls, refer to [Require provider credentials](/ai-gateway/features/unified-billing/#require-provider-credentials).