diff --git a/internal/httpapi/registry_add_test.go b/internal/httpapi/registry_add_test.go
index 2f872267c..df4291a5f 100644
--- a/internal/httpapi/registry_add_test.go
+++ b/internal/httpapi/registry_add_test.go
@@ -54,3 +54,21 @@ func TestAddFromRegistry_SlashServerIDUnescaped(t *testing.T) {
 	assert.Equal(t, "microsoft/markitdown", controller.gotServerID, "serverId must be percent-decoded before registry lookup")
 	assert.Equal(t, "github-mcp", controller.gotRegistryID, "registry id must be percent-decoded before lookup")
 }
+
+// TestAddFromRegistry_NilConfigIsAnError pins the nil-tolerance of the success
+// branch: a controller that returns no config and no error yields a JSON 500,
+// never a recovered nil-pointer panic (which corrupts the heap on
+// windows/amd64 under Go 1.26 — golang/go#81238 — and took the whole test
+// binary down with it).
+func TestAddFromRegistry_NilConfigIsAnError(t *testing.T) {
+	ctrl := &adminConfigController{ServerController: &MockServerController{}, apiKey: "admin-secret"}
+	srv := NewServer(ctrl, zaptest.NewLogger(t).Sugar(), nil)
+
+	req := httptest.NewRequest(http.MethodPost, "/api/v1/registries/reg1/servers/srv1/add", nil)
+	req.Header.Set("X-API-Key", "admin-secret")
+	w := httptest.NewRecorder()
+	srv.ServeHTTP(w, req)
+
+	assert.Equal(t, http.StatusInternalServerError, w.Code)
+	assert.Contains(t, w.Body.String(), "no server configuration")
+}
diff --git a/internal/httpapi/server.go b/internal/httpapi/server.go
index 749651e0d..6f059693c 100644
--- a/internal/httpapi/server.go
+++ b/internal/httpapi/server.go
@@ -5836,6 +5836,17 @@ func (s *Server) handleAddFromRegistry(w http.ResponseWriter, r *http.Request) {
 		s.writeRegistryAddError(w, r, status, rerr)
 		return
 	}
+	if cfg == nil {
+		// A controller that reports success without a server config (the
+		// test doubles do) used to be dereferenced here; chi's recoverer
+		// turned that into a bare 500 — and on windows/amd64 the recovered
+		// hardware fault corrupts the Go heap under Go 1.26 (golang/go#81238),
+		// so the httpapi test binary then died in a later GC. Same
+		// nil-tolerance as redactedRegistrySummary.
+		logger.Errorw("Add from registry returned no server config", "registry", registryID, "server", serverID)
+		s.writeError(w, r, http.StatusInternalServerError, "registry returned no server configuration")
+		return
+	}
 
 	// Issue #1148, round 8: the MCP twin of this handler
 	// (`upstream_servers add_from_registry`) has sourced this echo from the
diff --git a/internal/security/scanner/service_test.go b/internal/security/scanner/service_test.go
index dc4dd3926..1f730e627 100644
--- a/internal/security/scanner/service_test.go
+++ b/internal/security/scanner/service_test.go
@@ -2505,11 +2505,36 @@ func TestServiceStartScanDeepOnRunsSourceResolutionAndPass2(t *testing.T) {
 		t.Errorf("deep scan on: Pass 2 (ResolveFullSource) must run, got %d call(s)", got)
 	}
 
-	// Drain the engine so the background Pass-2 goroutine finishes before the
-	// test tears down its temp dirs (keeps -race teardown quiet).
+	// Drain Pass 2 before the test tears down its temp dirs. Waiting for the
+	// engine to go idle is not enough: the Pass-2 goroutine writes tools.json
+	// into workDir (exportToolDefinitions) AFTER ResolveFullSource returns and
+	// BEFORE it registers its job with the engine, so an idle engine can mean
+	// "Pass 1 cleared, Pass 2 not yet started" — and TempDir's RemoveAll then
+	// raced the write ("directory not empty", flaky on ubuntu CI). The Pass-2
+	// job is saved to storage on every exit path (completed, or the failed
+	// placeholder), so that is the terminal signal.
+	waitForPass2Saved(t, store, "srv-on")
 	waitForScanIdle(t, svc, "srv-on")
 }
 
+// waitForPass2Saved polls storage until a Pass-2 job for server has reached a
+// terminal status — the goroutine's last write, on every path startPass2 can
+// take.
+func waitForPass2Saved(t *testing.T, store *mockStorage, server string) {
+	t.Helper()
+	deadline := time.Now().Add(10 * time.Second)
+	for time.Now().Before(deadline) {
+		jobs, _ := store.ListScanJobs(server)
+		for _, j := range jobs {
+			if j.ScanPass == ScanPassSupplyChainAudit && j.Status != ScanJobStatusRunning && j.Status != ScanJobStatusPending {
+				return
+			}
+		}
+		time.Sleep(20 * time.Millisecond)
+	}
+	t.Fatalf("Pass 2 for %s did not reach a terminal status in time", server)
+}
+
 // TestApplySecurityConfigDefaultConfigGatesDeepScanOff locks the audit's FIX-1
 // invariant against the real default config: config.DefaultConfig() never
 // initializes Config.Security (it stays nil), and the server wiring passes