diff --git a/internal/unifiedresources/health.go b/internal/unifiedresources/health.go
index ca20899f3..48eeff063 100644
--- a/internal/unifiedresources/health.go
+++ b/internal/unifiedresources/health.go
@@ -89,6 +89,13 @@ func EvaluateResourceHealth(resource Resource, alerts []ResourceHealthAlert, now
 
 	switch strings.ToLower(strings.TrimSpace(string(resource.Status))) {
 	case "online", "running", "ready", "healthy", "available", "active", "up":
+		// A positive provider status without an observation timestamp is not
+		// enough to prove current health. Some compatibility and synthetic
+		// producers do not populate SourceStatus, so keep this guard at the
+		// canonical verdict boundary rather than relying on that map alone.
+		if resource.LastSeen.IsZero() {
+			return healthWithReason(HealthUnknown, "telemetry_missing", "")
+		}
 		return ResourceHealth{Verdict: HealthOK, Reasons: []ResourceHealthReason{}}
 	case "warning", "degraded", "unhealthy", "pending":
 		return healthWithReason(HealthAttention, "degraded", "")
diff --git a/internal/unifiedresources/health_test.go b/internal/unifiedresources/health_test.go
index 3898a94a6..c51de693e 100644
--- a/internal/unifiedresources/health_test.go
+++ b/internal/unifiedresources/health_test.go
@@ -59,6 +59,11 @@ func TestEvaluateResourceHealthPrecedenceAndVerdicts(t *testing.T) {
 			resource: Resource{ID: "host-3", Type: ResourceTypeAgent, Status: StatusOnline, LastSeen: now},
 			want:     HealthOK,
 		},
+		{
+			name:     "positive status without telemetry cannot be healthy",
+			resource: Resource{ID: "host-missing", Type: ResourceTypeAgent, Status: StatusOnline},
+			want:     HealthUnknown, code: "telemetry_missing",
+		},
 		{
 			name:     "informational alert does not invent attention",
 			resource: Resource{ID: "host-info", Type: ResourceTypeAgent, Status: StatusOnline, LastSeen: now},