feat(api): Return 404 when model is not found except for model names in HF format

Signed-off-by: Richard Palethorpe <io@richiejp.com>

Author: richiejp

core/http/app_test.go

@@ -1065,7 +1065,7 @@ parameters:
 		It("returns errors", func() {
 			_, err := client.CreateCompletion(context.TODO(), openai.CompletionRequest{Model: "foomodel", Prompt: testPrompt})
 			Expect(err).To(HaveOccurred())
-			Expect(err.Error()).To(ContainSubstring("error, status code: 500, status: 500 Internal Server Error, message: could not load model - all backends returned error:"))
+			Expect(err.Error()).To(ContainSubstring("error, status code: 404, status: 404 Not Found"))
 		})
 
 		It("shows the external backend", func() {

core/http/middleware/request.go

@@ -140,13 +140,31 @@ func (re *RequestExtractor) SetModelAndConfig(initializer func() schema.LocalAIR
 				}
 			}
 
-			cfg, err := re.modelConfigLoader.LoadModelConfigFileByNameDefaultOptions(input.ModelName(nil), re.applicationConfig)
+			modelName := input.ModelName(nil)
+			cfg, err := re.modelConfigLoader.LoadModelConfigFileByNameDefaultOptions(modelName, re.applicationConfig)
 
 			if err != nil {
-				xlog.Warn("Model Configuration File not found", "model", input.ModelName(nil), "error", err)
-			} else if cfg.Model == "" && input.ModelName(nil) != "" {
-				xlog.Debug("config does not include model, using input", "input.ModelName", input.ModelName(nil))
-				cfg.Model = input.ModelName(nil)
+				xlog.Warn("Model Configuration File not found", "model", modelName, "error", err)
+			} else if cfg.Model == "" && modelName != "" {
+				xlog.Debug("config does not include model, using input", "input.ModelName", modelName)
+				cfg.Model = modelName
+			}
+
+			// If a model name was specified, verify it actually exists before proceeding.
+			// Check both configured models and loose model files in the model path.
+			// Skip the check for HuggingFace model IDs (contain "/") since backends
+			// like diffusers may download these on the fly.
+			if modelName != "" && !strings.Contains(modelName, "/") {
+				exists, existsErr := services.CheckIfModelExists(re.modelConfigLoader, re.modelLoader, modelName, services.ALWAYS_INCLUDE)
+				if existsErr == nil && !exists {
+					return c.JSON(http.StatusNotFound, schema.ErrorResponse{
+						Error: &schema.APIError{
+							Message: fmt.Sprintf("model %q not found. To see available models, call GET /v1/models", modelName),
+							Code:    http.StatusNotFound,
+							Type:    "invalid_request_error",
+						},
+					})
+				}
 			}
 
 			c.Set(CONTEXT_LOCALS_KEY_LOCALAI_REQUEST, input)

core/http/middleware/request_test.go

@@ -0,0 +1,152 @@
+package middleware_test
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/labstack/echo/v4"
+	"github.com/mudler/LocalAI/core/config"
+	. "github.com/mudler/LocalAI/core/http/middleware"
+	"github.com/mudler/LocalAI/core/schema"
+	"github.com/mudler/LocalAI/pkg/model"
+	"github.com/mudler/LocalAI/pkg/system"
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+// newRequestApp creates a minimal Echo app with SetModelAndConfig middleware.
+func newRequestApp(re *RequestExtractor) *echo.Echo {
+	e := echo.New()
+	e.POST("/v1/chat/completions",
+		func(c echo.Context) error {
+			return c.String(http.StatusOK, "ok")
+		},
+		re.SetModelAndConfig(func() schema.LocalAIRequest {
+			return new(schema.OpenAIRequest)
+		}),
+	)
+	return e
+}
+
+func postJSON(e *echo.Echo, path, body string) *httptest.ResponseRecorder {
+	req := httptest.NewRequest(http.MethodPost, path, strings.NewReader(body))
+	req.Header.Set("Content-Type", "application/json")
+	rec := httptest.NewRecorder()
+	e.ServeHTTP(rec, req)
+	return rec
+}
+
+var _ = Describe("SetModelAndConfig middleware", func() {
+	var (
+		app      *echo.Echo
+		modelDir string
+	)
+
+	BeforeEach(func() {
+		var err error
+		modelDir, err = os.MkdirTemp("", "localai-test-models-*")
+		Expect(err).ToNot(HaveOccurred())
+
+		ss := &system.SystemState{
+			Model: system.Model{ModelsPath: modelDir},
+		}
+		appConfig := config.NewApplicationConfig()
+		appConfig.SystemState = ss
+
+		mcl := config.NewModelConfigLoader(modelDir)
+		ml := model.NewModelLoader(ss)
+
+		re := NewRequestExtractor(mcl, ml, appConfig)
+		app = newRequestApp(re)
+	})
+
+	AfterEach(func() {
+		os.RemoveAll(modelDir)
+	})
+
+	Context("when the model does not exist", func() {
+		It("returns 404 with a helpful error message", func() {
+			rec := postJSON(app, "/v1/chat/completions",
+				`{"model":"nonexistent-model","messages":[{"role":"user","content":"hi"}]}`)
+
+			Expect(rec.Code).To(Equal(http.StatusNotFound))
+
+			var resp schema.ErrorResponse
+			Expect(json.Unmarshal(rec.Body.Bytes(), &resp)).To(Succeed())
+			Expect(resp.Error).ToNot(BeNil())
+			Expect(resp.Error.Message).To(ContainSubstring("nonexistent-model"))
+			Expect(resp.Error.Message).To(ContainSubstring("not found"))
+			Expect(resp.Error.Type).To(Equal("invalid_request_error"))
+		})
+	})
+
+	Context("when the model exists as a config file", func() {
+		BeforeEach(func() {
+			cfgContent := []byte("name: test-model\nbackend: llama-cpp\n")
+			err := os.WriteFile(filepath.Join(modelDir, "test-model.yaml"), cfgContent, 0644)
+			Expect(err).ToNot(HaveOccurred())
+		})
+
+		It("passes through to the handler", func() {
+			rec := postJSON(app, "/v1/chat/completions",
+				`{"model":"test-model","messages":[{"role":"user","content":"hi"}]}`)
+
+			Expect(rec.Code).To(Equal(http.StatusOK))
+		})
+	})
+
+	Context("when the model exists as a pre-loaded config", func() {
+		var mcl *config.ModelConfigLoader
+
+		BeforeEach(func() {
+			// Simulate a model installed via gallery: config is loaded in memory
+			// (not just a YAML file on disk). Recreate the app with the pre-loaded config.
+			ss := &system.SystemState{
+				Model: system.Model{ModelsPath: modelDir},
+			}
+			appConfig := config.NewApplicationConfig()
+			appConfig.SystemState = ss
+
+			mcl = config.NewModelConfigLoader(modelDir)
+			// Pre-load a config as if installed via gallery
+			cfgContent := []byte("name: gallery-model\nbackend: llama-cpp\nmodel: gallery-model\n")
+			err := os.WriteFile(filepath.Join(modelDir, "gallery-model.yaml"), cfgContent, 0644)
+			Expect(err).ToNot(HaveOccurred())
+			Expect(mcl.ReadModelConfig(filepath.Join(modelDir, "gallery-model.yaml"))).To(Succeed())
+
+			ml := model.NewModelLoader(ss)
+			re := NewRequestExtractor(mcl, ml, appConfig)
+			app = newRequestApp(re)
+		})
+
+		It("passes through to the handler", func() {
+			rec := postJSON(app, "/v1/chat/completions",
+				`{"model":"gallery-model","messages":[{"role":"user","content":"hi"}]}`)
+
+			Expect(rec.Code).To(Equal(http.StatusOK))
+		})
+	})
+
+	Context("when the model name contains a slash (HuggingFace ID)", func() {
+		It("skips the existence check and passes through", func() {
+			rec := postJSON(app, "/v1/chat/completions",
+				`{"model":"stabilityai/stable-diffusion-xl-base-1.0","messages":[{"role":"user","content":"hi"}]}`)
+
+			Expect(rec.Code).To(Equal(http.StatusOK))
+		})
+	})
+
+	Context("when no model is specified", func() {
+		It("passes through without checking", func() {
+			rec := postJSON(app, "/v1/chat/completions",
+				`{"messages":[{"role":"user","content":"hi"}]}`)
+
+			// No model name → middleware doesn't reject, handler runs
+			Expect(rec.Code).To(Equal(http.StatusOK))
+		})
+	})
+})

core/services/galleryop/list_models.go

@@ -59,5 +59,16 @@ func CheckIfModelExists(bcl *config.ModelConfigLoader, ml *model.ModelLoader, mo
 	if err != nil {
 		return false, err
 	}
-	return (len(models) > 0), nil
+	if len(models) > 0 {
+		return true, nil
+	}
+
+	// ListModels may not find raw model weight files (e.g. .ggml, .gguf)
+	// because ListFilesInModelPath skips known weight-file extensions.
+	// Fall back to checking if the file exists directly in the model path.
+	if ml.ExistsInModelPath(modelName) {
+		return true, nil
+	}
+
+	return false, nil
 }