fix(ollama): guard nil filter in galleryop.ListModels (#9817) (#9836)

The Ollama /api/tags handler passes a nil filter to galleryop.ListModels.
When ModelsPath contains any non-skipped loose file the function then
calls filter(name, nil) and panics, which Echo surfaces to clients as
"Server disconnected without sending a response" - the exact failure
Home Assistant's Ollama integration reports against LocalAI.

Mirror the nil guard already present in
ModelConfigLoader.GetModelConfigsByFilter so every caller is safe, and
add a regression test that exercises the loose-file path with a nil
filter.

Assisted-by: claude:claude-opus-4-7 [Claude Code]

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>
Co-authored-by: Ettore Di Giacinto <mudler@localai.io>

core/services/galleryop/list_models.go

@@ -16,6 +16,14 @@ const (
 
 func ListModels(bcl *config.ModelConfigLoader, ml *model.ModelLoader, filter config.ModelConfigFilterFn, looseFilePolicy LooseFilePolicy) ([]string, error) {
 
+	// Callers (e.g. the Ollama /api/tags handler) pass nil to mean "no
+	// filtering". Without this guard the loose-file loop below dereferences
+	// filter and panics, which Echo surfaces to clients as a dropped
+	// connection (see issue #9817).
+	if filter == nil {
+		filter = config.NoFilterFn
+	}
+
 	skipMap := map[string]struct{}{}
 
 	dataModels := []string{}

core/services/galleryop/list_models_test.go

@@ -0,0 +1,64 @@
+package galleryop_test
+
+import (
+	"os"
+	"path/filepath"
+
+	"github.com/mudler/LocalAI/core/config"
+	"github.com/mudler/LocalAI/core/services/galleryop"
+	"github.com/mudler/LocalAI/pkg/model"
+	"github.com/mudler/LocalAI/pkg/system"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+// Regression test for issue #9817: the Ollama /api/tags handler calls
+// ListModels with a nil filter, which used to panic as soon as a loose file
+// existed under ModelsPath. The panic surfaced to Ollama clients (e.g. Home
+// Assistant) as "Server disconnected without sending a response".
+var _ = Describe("ListModels", func() {
+	var (
+		tempDir     string
+		bcl         *config.ModelConfigLoader
+		ml          *model.ModelLoader
+		systemState *system.SystemState
+	)
+
+	BeforeEach(func() {
+		var err error
+		tempDir, err = os.MkdirTemp("", "list-models-test-*")
+		Expect(err).NotTo(HaveOccurred())
+
+		systemState, err = system.GetSystemState(system.WithModelPath(tempDir))
+		Expect(err).NotTo(HaveOccurred())
+		ml = model.NewModelLoader(systemState)
+		bcl = config.NewModelConfigLoader(tempDir)
+	})
+
+	AfterEach(func() {
+		os.RemoveAll(tempDir)
+	})
+
+	It("does not panic with a nil filter when loose files exist", func() {
+		// ListFilesInModelPath skips well-known weight-file extensions
+		// (.gguf, .bin, ...) so use an extension-less file to ensure the
+		// filter path is exercised.
+		Expect(os.WriteFile(filepath.Join(tempDir, "loose-model"), []byte("x"), 0o644)).To(Succeed())
+
+		var names []string
+		var err error
+		Expect(func() {
+			names, err = galleryop.ListModels(bcl, ml, nil, galleryop.SKIP_IF_CONFIGURED)
+		}).ToNot(Panic())
+		Expect(err).ToNot(HaveOccurred())
+		Expect(names).To(ContainElement("loose-model"))
+	})
+
+	It("does not panic with a nil filter when ModelsPath is empty", func() {
+		Expect(func() {
+			_, err := galleryop.ListModels(bcl, ml, nil, galleryop.SKIP_IF_CONFIGURED)
+			Expect(err).ToNot(HaveOccurred())
+		}).ToNot(Panic())
+	})
+})