chore: update backend changelog

changelog/backend.mdx

@@ -1,13 +1,73 @@
 ---
 title: "Backend"
-sidebarTitle: "Backend [1.26.0]"
+sidebarTitle: "Backend [1.28.0]"
 rss: true
 ---
 
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 </Card>
 
+<Update label="1.28.0" description="2026-09-28">
+
+## v1.28.0
+---
+
+### Log Exports
+- **Deployment filter**: Log exports support filtering by `deployment_slug`
+- **Leaner export listing**: The list exports API now returns a trimmed set of fields per export
+  - [Documentation](/product/observability/logs-export)
+
+### Model Catalog
+- **Model and pricing refresh**: Updated model definitions and pricing from the Portkey Models repository for Anthropic, Bedrock, Vertex AI, Google, Azure AI, OpenRouter, Lightning AI, and others
+  - [Documentation](/product/model-catalog/portkey-models)
+
+### Fixes and Improvements
+- **User search**: Users can now be searched by first and last name
+- **Deployments**: The deployment list API supports filtering by `workspace_id`
+- Updated dependencies to patch security vulnerabilities.
+
+</Update>
+
+<Update label="1.27.0" description="2026-09-21">
+
+## v1.27.0
+---
+
+### New Providers
+- **SCX.ai**: Added to the Model Catalog (`scx-ai`) as an OpenAI-compatible provider
+  - [Documentation](/integrations/llms)
+
+### Pricing
+- **Model-level pricing adjustments**: Pricing multipliers can now be set on individual models within an integration, overriding the integration-level adjustment for that model
+  - [Documentation](/product/model-catalog/pricing-adjustments#per-model-pricing-adjustments)
+
+<Note>Per-model adjustments require Gateway version 2.22.0 or higher.</Note>
+
+### Model Catalog
+- **Auto-sync new models**: Newly added base models are now synced to existing integrations automatically, respecting each integration's "allow all models" setting
+  - [Documentation](/product/model-catalog)
+
+### Analytics
+- **Guardrails analytics**: New endpoints for guardrail summary, trend, and grouped data
+- **Top MCP and A2A**: Analytics groups now include breakdowns for top MCP and A2A usage
+- **Multi-value metadata filters**: Metadata filters accept multiple values per key, as a comma-separated string (`{"env":"prod,staging"}`) or an array, matched with OR
+  - [Documentation](/product/observability/analytics)
+
+### Guardrails Updates
+- **Azure PII**: Added a `piiCategories` parameter to restrict detection to selected PII categories
+  - [Documentation](/integrations/guardrails/azure-guardrails#azure-pii-detection)
+- **Alibaba Cloud AI Guardrails**: Added new check types
+  - [Documentation](/product/guardrails)
+
+### Fixes and Improvements
+- **Not found responses**: GET lookups for missing resources (virtual keys, configs, and others) now return `404` instead of `403`, so tools like Terraform can detect out-of-band deletions
+- **SCIM**: Correct status returned for SCIM user `PATCH` requests
+  - [Documentation](/product/enterprise-offering/org-management/scim/scim)
+- **API keys**: Added filters to the API key list endpoint
+
+</Update>
+
 <Update label="1.26.0" description="2026-09-06">
 
 ## v1.26.0