feat(cli): add interactive chat mode (#10226)

Add an opt-in `local-ai chat` command for testing chat models directly from the terminal without manually sending curl requests.

The command connects to a running LocalAI server, lists available models through the existing OpenAI-compatible API, streams chat completions, and supports interactive commands such as `/models`, `/model`, `/clear`, and `/exit`.

Keep `local-ai run` focused on the server lifecycle so the web UI, API clients, and multiple chat terminals can coexist against the same server.

Document the new command and terminal workflow in the README and CLI docs.

Tests:
- go test -count=1 ./core/cli/chat
- go test -count=1 ./core/cli

Assisted-by: Codex:GPT-5

Signed-off-by: Ching Kao <0980124jim@gmail.com>

Author: Oceankj

README.md

@@ -149,6 +149,16 @@ local-ai run https://gist.githubusercontent.com/.../phi-2.yaml
 local-ai run oci://localai/phi-2:latest
 ```
 
+To test a running LocalAI server from the terminal, open an interactive chat session from another shell. Inside the prompt, `/models` lists installed models and `/model <name>` switches between them.
+
+```bash
+# Terminal 1
+local-ai run llama-3.2-1b-instruct:q4_k_m
+
+# Terminal 2
+local-ai chat --model llama-3.2-1b-instruct:q4_k_m
+```
+
 > **Automatic Backend Detection**: LocalAI automatically detects your GPU capabilities and downloads the appropriate backend. For advanced options, see [GPU Acceleration](https://localai.io/features/gpu-acceleration/).
 
 For more details, see the [Getting Started guide](https://localai.io/basics/getting_started/).

core/cli/chat/chat.go

@@ -0,0 +1,30 @@
+package chat
+
+import (
+	"context"
+	"io"
+	"strings"
+)
+
+type Options struct {
+	Model   string
+	BaseURL string
+	APIKey  string
+	In      io.Reader
+	Out     io.Writer
+}
+
+func Run(ctx context.Context, opts Options) error {
+	if opts.In == nil {
+		opts.In = strings.NewReader("")
+	}
+	if opts.Out == nil {
+		opts.Out = io.Discard
+	}
+
+	session, err := newChatSession(ctx, newLocalAIChatClient(opts.BaseURL, opts.APIKey), opts.Model)
+	if err != nil {
+		return err
+	}
+	return runTerminalChat(ctx, session, opts.In, opts.Out)
+}

core/cli/chat/chat_suite_test.go

@@ -0,0 +1,13 @@
+package chat
+
+import (
+	"testing"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+func TestChat(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Chat Suite")
+}

core/cli/chat/chat_test.go

@@ -0,0 +1,161 @@
+package chat
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("Run chat", func() {
+	It("streams a single chat response", func() {
+		var capturedModel string
+		var capturedAuth string
+		server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if r.URL.Path == "/v1/models" {
+				w.Header().Set("Content-Type", "application/json")
+				fmt.Fprint(w, `{"object":"list","data":[{"id":"test-model","object":"model"}]}`)
+				return
+			}
+
+			Expect(r.URL.Path).To(Equal("/v1/chat/completions"))
+			capturedAuth = r.Header.Get("Authorization")
+
+			var body struct {
+				Model    string `json:"model"`
+				Messages []struct {
+					Role    string `json:"role"`
+					Content string `json:"content"`
+				} `json:"messages"`
+			}
+			Expect(json.NewDecoder(r.Body).Decode(&body)).To(Succeed())
+			capturedModel = body.Model
+			Expect(body.Messages).To(HaveLen(1))
+			Expect(body.Messages[0].Role).To(Equal("user"))
+			Expect(body.Messages[0].Content).To(Equal("hello"))
+
+			w.Header().Set("Content-Type", "text/event-stream")
+			fmt.Fprint(w, "data: {\"choices\":[{\"index\":0,\"delta\":{\"content\":\"hi\"}}]}\n\n")
+			fmt.Fprint(w, "data: {\"choices\":[{\"index\":0,\"delta\":{\"content\":\"!\"}}]}\n\n")
+			fmt.Fprint(w, "data: [DONE]\n\n")
+		}))
+		defer server.Close()
+
+		var out bytes.Buffer
+		err := Run(GinkgoT().Context(), Options{
+			Model:   "test-model",
+			BaseURL: server.URL + "/v1",
+			APIKey:  "secret",
+			In:      strings.NewReader("hello\n/exit\n"),
+			Out:     &out,
+		})
+
+		Expect(err).ToNot(HaveOccurred())
+		Expect(capturedModel).To(Equal("test-model"))
+		Expect(capturedAuth).To(Equal("Bearer secret"))
+		Expect(out.String()).To(ContainSubstring("assistant: hi!"))
+		Expect(out.String()).To(ContainSubstring("bye"))
+	})
+
+	It("auto-selects the only available model", func() {
+		server := chatTestServer([]string{"solo"}, nil)
+		defer server.Close()
+
+		var out bytes.Buffer
+		err := Run(GinkgoT().Context(), Options{
+			BaseURL: server.URL + "/v1",
+			In:      strings.NewReader("/exit\n"),
+			Out:     &out,
+		})
+
+		Expect(err).ToNot(HaveOccurred())
+		Expect(out.String()).To(ContainSubstring("LocalAI chat (solo)"))
+	})
+
+	It("returns an actionable error when no models are installed", func() {
+		server := chatTestServer(nil, nil)
+		defer server.Close()
+
+		err := Run(GinkgoT().Context(), Options{
+			BaseURL: server.URL + "/v1",
+			In:      strings.NewReader(""),
+		})
+
+		Expect(err).To(HaveOccurred())
+		Expect(err.Error()).To(ContainSubstring("no chat models are installed"))
+		Expect(err.Error()).To(ContainSubstring("local-ai models install <model>"))
+	})
+
+	It("returns an actionable error when multiple models are available without a selection", func() {
+		server := chatTestServer([]string{"alpha", "beta"}, nil)
+		defer server.Close()
+
+		err := Run(GinkgoT().Context(), Options{
+			BaseURL: server.URL + "/v1",
+			In:      strings.NewReader(""),
+		})
+
+		Expect(err).To(HaveOccurred())
+		Expect(err.Error()).To(ContainSubstring("multiple models are available"))
+		Expect(err.Error()).To(ContainSubstring("--model"))
+		Expect(err.Error()).To(ContainSubstring("alpha"))
+		Expect(err.Error()).To(ContainSubstring("beta"))
+	})
+
+	It("lists and switches models inside the chat", func() {
+		requestedModels := []string{}
+		server := chatTestServer([]string{"alpha", "beta"}, func(model string) {
+			requestedModels = append(requestedModels, model)
+		})
+		defer server.Close()
+
+		var out bytes.Buffer
+		err := Run(GinkgoT().Context(), Options{
+			Model:   "alpha",
+			BaseURL: server.URL + "/v1",
+			In:      strings.NewReader("/models\n/model beta\nhello\n/exit\n"),
+			Out:     &out,
+		})
+
+		Expect(err).ToNot(HaveOccurred())
+		Expect(out.String()).To(ContainSubstring("* alpha"))
+		Expect(out.String()).To(ContainSubstring("  beta"))
+		Expect(out.String()).To(ContainSubstring("switched to beta; conversation cleared"))
+		Expect(requestedModels).To(Equal([]string{"beta"}))
+	})
+})
+
+func chatTestServer(models []string, onChat func(model string)) *httptest.Server {
+	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		switch r.URL.Path {
+		case "/v1/models":
+			w.Header().Set("Content-Type", "application/json")
+			fmt.Fprint(w, `{"object":"list","data":[`)
+			for i, model := range models {
+				if i > 0 {
+					fmt.Fprint(w, ",")
+				}
+				fmt.Fprintf(w, `{"id":%q,"object":"model"}`, model)
+			}
+			fmt.Fprint(w, `]}`)
+		case "/v1/chat/completions":
+			var body struct {
+				Model string `json:"model"`
+			}
+			Expect(json.NewDecoder(r.Body).Decode(&body)).To(Succeed())
+			if onChat != nil {
+				onChat(body.Model)
+			}
+			w.Header().Set("Content-Type", "text/event-stream")
+			fmt.Fprint(w, "data: {\"choices\":[{\"index\":0,\"delta\":{\"content\":\"ok\"}}]}\n\n")
+			fmt.Fprint(w, "data: [DONE]\n\n")
+		default:
+			w.WriteHeader(http.StatusNotFound)
+		}
+	}))
+}

core/cli/chat/client.go

@@ -0,0 +1,112 @@
+package chat
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"sort"
+	"strings"
+
+	openai "github.com/sashabaranov/go-openai"
+)
+
+type chatClient interface {
+	ListModels(ctx context.Context) ([]string, error)
+	StreamChat(ctx context.Context, model string, messages []chatMessage, out io.Writer) (string, error)
+}
+
+type localAIChatClient struct {
+	client *openai.Client
+}
+
+func newLocalAIChatClient(baseURL string, apiKey string) *localAIChatClient {
+	cfg := openai.DefaultConfig(apiKey)
+	cfg.BaseURL = baseURL
+	return &localAIChatClient{client: openai.NewClientWithConfig(cfg)}
+}
+
+func (c *localAIChatClient) ListModels(ctx context.Context) ([]string, error) {
+	resp, err := c.client.ListModels(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	models := make([]string, 0, len(resp.Models))
+	for _, model := range resp.Models {
+		if model.ID != "" {
+			models = append(models, model.ID)
+		}
+	}
+	sort.Strings(models)
+	return models, nil
+}
+
+func (c *localAIChatClient) StreamChat(ctx context.Context, model string, messages []chatMessage, out io.Writer) (string, error) {
+	stream, err := c.client.CreateChatCompletionStream(ctx, openai.ChatCompletionRequest{
+		Model:    model,
+		Messages: openAIChatMessages(messages),
+	})
+	if err != nil {
+		return "", friendlyChatError(err, model)
+	}
+	defer stream.Close()
+
+	var answer strings.Builder
+	for {
+		resp, err := stream.Recv()
+		if errors.Is(err, io.EOF) {
+			break
+		}
+		if err != nil {
+			return answer.String(), friendlyChatError(err, model)
+		}
+		if len(resp.Choices) == 0 {
+			continue
+		}
+
+		token := resp.Choices[0].Delta.Content
+		if token == "" {
+			continue
+		}
+		answer.WriteString(token)
+		if _, err := fmt.Fprint(out, token); err != nil {
+			return answer.String(), err
+		}
+	}
+
+	return answer.String(), nil
+}
+
+func openAIChatMessages(messages []chatMessage) []openai.ChatCompletionMessage {
+	converted := make([]openai.ChatCompletionMessage, len(messages))
+	for i, message := range messages {
+		converted[i] = openai.ChatCompletionMessage{
+			Role:    message.Role,
+			Content: message.Content,
+		}
+	}
+	return converted
+}
+
+func friendlyChatError(err error, model string) error {
+	var apiErr *openai.APIError
+	if errors.As(err, &apiErr) {
+		switch apiErr.HTTPStatusCode {
+		case 404:
+			return fmt.Errorf("model %q is not available. Run `local-ai models list`, install a model with `local-ai models install <model>`, or switch with `/model <name>`", model)
+		case 403:
+			return fmt.Errorf("model %q is disabled. Enable it from LocalAI settings or choose another model with `/model <name>`", model)
+		}
+		if apiErr.Message != "" {
+			return errors.New(apiErr.Message)
+		}
+	}
+
+	msg := err.Error()
+	if strings.Contains(msg, "model") && strings.Contains(msg, "not found") {
+		return fmt.Errorf("model %q is not available. Run `local-ai models list`, install a model with `local-ai models install <model>`, or switch with `/model <name>`", model)
+	}
+
+	return err
+}

core/cli/chat/models.go

@@ -0,0 +1,17 @@
+package chat
+
+import "strings"
+
+func formatChatModelList(models []string, current string) string {
+	var b strings.Builder
+	for _, model := range models {
+		prefix := "  "
+		if model == current {
+			prefix = "* "
+		}
+		b.WriteString(prefix)
+		b.WriteString(model)
+		b.WriteByte('\n')
+	}
+	return b.String()
+}