diff --git a/README.md b/README.md
index 433f7cf..4accec8 100644
--- a/README.md
+++ b/README.md
@@ -55,6 +55,7 @@ This document serves as the master index for the SCADA system design. The system
 | 19 | CLI | [docs/requirements/Component-CLI.md](docs/requirements/Component-CLI.md) | Standalone command-line tool, System.CommandLine, HTTP transport via Management API, JSON/table output, mirrors all Management Service operations. |
 | 20 | Traefik Proxy | [docs/requirements/Component-TraefikProxy.md](docs/requirements/Component-TraefikProxy.md) | Reverse proxy/load balancer fronting central cluster, active node routing via `/health/active`, automatic failover. |
 | 21 | Notification Outbox | [docs/requirements/Component-NotificationOutbox.md](docs/requirements/Component-NotificationOutbox.md) | Central component ingesting store-and-forwarded notifications into the `Notifications` audit table, with `NotificationOutboxActor` singleton dispatcher, per-type delivery adapters, retry/parking, status tracking, daily purge, and delivery KPIs. |
+| 22 | Site Call Audit | [docs/requirements/Component-SiteCallAudit.md](docs/requirements/Component-SiteCallAudit.md) | Central component auditing site cached calls (`ExternalSystem.CachedCall`/`Database.CachedWrite`) into the `SiteCalls` audit table, with `SiteCallAuditActor` singleton, telemetry ingest, periodic reconciliation, point-in-time KPIs, daily purge, and central→site Retry/Discard relay for parked calls. |
 
 ### Reference Documentation