diff --git a/internal/api/tenant_org_binding_test.go b/internal/api/tenant_org_binding_test.go
new file mode 100644
index 000000000..47d0881fa
--- /dev/null
+++ b/internal/api/tenant_org_binding_test.go
@@ -0,0 +1,56 @@
+package api
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/rcourtman/pulse-go-rewrite/internal/config"
+)
+
+func TestTenantMiddlewareBlocksOrgBoundTokenFromOtherOrg(t *testing.T) {
+	defer SetMultiTenantEnabled(false)
+	SetMultiTenantEnabled(true)
+	// Dev mode enables license checks for multi-tenant features.
+	t.Setenv("PULSE_DEV", "true")
+
+	rawToken := "org-bound-token-123.12345678"
+	record := newTokenRecord(t, rawToken, []string{config.ScopeMonitoringRead}, nil)
+	record.OrgID = "org-a"
+	cfg := newTestConfigWithTokens(t, record)
+
+	// Ensure orgs exist to avoid 400 invalid_org.
+	baseDir := cfg.DataPath
+	for _, orgID := range []string{"org-a", "org-b"} {
+		if err := os.MkdirAll(filepath.Join(baseDir, "orgs", orgID), 0o755); err != nil {
+			t.Fatalf("create org dir: %v", err)
+		}
+	}
+
+	router := NewRouter(cfg, nil, nil, nil, nil, "1.0.0")
+
+	req := httptest.NewRequest(http.MethodGet, "/api/config", nil)
+	req.Header.Set("X-Pulse-Org-ID", "org-b")
+	req.Header.Set("X-API-Token", rawToken)
+	rec := httptest.NewRecorder()
+	router.Handler().ServeHTTP(rec, req)
+
+	if rec.Code != http.StatusForbidden {
+		t.Fatalf("expected 403 for org-bound token access to another org, got %d", rec.Code)
+	}
+
+	var payload map[string]string
+	if err := json.Unmarshal(rec.Body.Bytes(), &payload); err != nil {
+		t.Fatalf("decode response: %v", err)
+	}
+	if payload["error"] != "access_denied" {
+		t.Fatalf("expected error=access_denied, got %q", payload["error"])
+	}
+	if msg := payload["message"]; msg == "" || !strings.Contains(msg, "authorized") {
+		t.Fatalf("expected access denied message, got %q", msg)
+	}
+}