diff --git a/messages/en-US.json b/messages/en-US.json
index 29e904416..299e64044 100644
--- a/messages/en-US.json
+++ b/messages/en-US.json
@@ -1450,8 +1450,11 @@
     "alertingSelectRoles": "Select roles…",
     "alertingRolesSelected": "{count} roles selected",
     "alertingSummarySites": "Sites ({count})",
+    "alertingSummaryAllSites": "All sites",
     "alertingSummaryHealthChecks": "Health checks ({count})",
+    "alertingSummaryAllHealthChecks": "All health checks",
     "alertingSummaryResources": "Resources ({count})",
+    "alertingSummaryAllResources": "All resources",
     "alertingErrorNameRequired": "Enter a name",
     "alertingErrorActionsMin": "Add at least one action",
     "alertingErrorPickSites": "Select at least one site",
diff --git a/src/components/AlertingRulesTable.tsx b/src/components/AlertingRulesTable.tsx
index 3ddcc4c13..9ee70b205 100644
--- a/src/components/AlertingRulesTable.tsx
+++ b/src/components/AlertingRulesTable.tsx
@@ -18,6 +18,11 @@ import { usePaidStatus } from "@app/hooks/usePaidStatus";
 import { createApiClient, formatAxiosError } from "@app/lib/api";
 import { orgQueries } from "@app/lib/queries";
 import { getNextSortOrder, getSortDirection } from "@app/lib/sortColumn";
+import {
+    alertRuleAllHealthChecksSelected,
+    alertRuleAllResourcesSelected,
+    alertRuleAllSitesSelected
+} from "@app/lib/alertRuleForm";
 import { tierMatrix } from "@server/lib/billing/tierMatrix";
 import {
     ArrowDown01Icon,
@@ -71,6 +76,9 @@ function sourceSummary(
     rule: AlertRuleRow,
     t: (k: string, o?: Record<string, number | string>) => string
 ) {
+    if (alertRuleAllSitesSelected(rule.eventType, rule.siteIds)) {
+        return t("alertingSummaryAllSites");
+    }
     if (
         rule.eventType === "site_online" ||
         rule.eventType === "site_offline" ||
@@ -78,11 +86,17 @@ function sourceSummary(
     ) {
         return t("alertingSummarySites", { count: rule.siteIds.length });
     }
+    if (alertRuleAllResourcesSelected(rule.eventType, rule.resourceIds)) {
+        return t("alertingSummaryAllResources");
+    }
     if (rule.eventType.startsWith("resource_")) {
         return t("alertingSummaryResources", {
             count: rule.resourceIds.length
         });
     }
+    if (alertRuleAllHealthChecksSelected(rule.eventType, rule.healthCheckIds)) {
+        return t("alertingSummaryAllHealthChecks");
+    }
     return t("alertingSummaryHealthChecks", {
         count: rule.healthCheckIds.length
     });
diff --git a/src/lib/alertRuleForm.ts b/src/lib/alertRuleForm.ts
index 426a6d309..f4bcf9cee 100644
--- a/src/lib/alertRuleForm.ts
+++ b/src/lib/alertRuleForm.ts
@@ -321,6 +321,43 @@ export function defaultFormValues(): AlertRuleFormValues {
     };
 }
 
+// ---------------------------------------------------------------------------
+// List/API row semantics: empty ID arrays mean "all" for that source kind
+// ---------------------------------------------------------------------------
+
+export function alertRuleAllSitesSelected(
+    eventType: string,
+    siteIds: number[]
+): boolean {
+    const siteEvent =
+        eventType === "site_online" ||
+        eventType === "site_offline" ||
+        eventType === "site_toggle";
+    return siteEvent && siteIds.length === 0;
+}
+
+export function alertRuleAllResourcesSelected(
+    eventType: string,
+    resourceIds: number[] | undefined
+): boolean {
+    return eventType.startsWith("resource_") && (resourceIds?.length ?? 0) === 0;
+}
+
+export function alertRuleAllHealthChecksSelected(
+    eventType: string,
+    healthCheckIds: number[]
+): boolean {
+    if (
+        eventType === "site_online" ||
+        eventType === "site_offline" ||
+        eventType === "site_toggle" ||
+        eventType.startsWith("resource_")
+    ) {
+        return false;
+    }
+    return healthCheckIds.length === 0;
+}
+
 // ---------------------------------------------------------------------------
 // API response → form values
 // ---------------------------------------------------------------------------
@@ -372,11 +409,15 @@ export function apiResponseToFormValues(
         });
     }
 
-    const allSites = sourceType === "site" && rule.siteIds.length === 0;
-    const allHealthChecks =
-        sourceType === "health_check" && rule.healthCheckIds.length === 0;
-    const allResources =
-        sourceType === "resource" && (rule.resourceIds?.length ?? 0) === 0;
+    const allSites = alertRuleAllSitesSelected(rule.eventType, rule.siteIds);
+    const allHealthChecks = alertRuleAllHealthChecksSelected(
+        rule.eventType,
+        rule.healthCheckIds
+    );
+    const allResources = alertRuleAllResourcesSelected(
+        rule.eventType,
+        rule.resourceIds
+    );
 
     return {
         name: rule.name,