cmd: ollama config command to help configure integrations to use Ollama (#13712)

cmd/cmd.go

@@ -35,6 +35,7 @@ import (
 	"golang.org/x/term"
 
 	"github.com/ollama/ollama/api"
+	"github.com/ollama/ollama/cmd/config"
 	"github.com/ollama/ollama/envconfig"
 	"github.com/ollama/ollama/format"
 	"github.com/ollama/ollama/parser"
@@ -2026,6 +2027,7 @@ func NewCLI() *cobra.Command {
 		copyCmd,
 		deleteCmd,
 		runnerCmd,
+		config.ConfigCmd(checkServerHeartbeat),
 	)
 
 	return rootCmd

cmd/config/claude.go

@@ -0,0 +1,36 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+)
+
+// Claude implements Runner for Claude Code integration
+type Claude struct{}
+
+func (c *Claude) String() string { return "Claude Code" }
+
+func (c *Claude) args(model string) []string {
+	if model != "" {
+		return []string{"--model", model}
+	}
+	return nil
+}
+
+func (c *Claude) Run(model string) error {
+	if _, err := exec.LookPath("claude"); err != nil {
+		return fmt.Errorf("claude is not installed, install from https://code.claude.com/docs/en/quickstart")
+	}
+
+	cmd := exec.Command("claude", c.args(model)...)
+	cmd.Stdin = os.Stdin
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	cmd.Env = append(os.Environ(),
+		"ANTHROPIC_BASE_URL=http://localhost:11434",
+		"ANTHROPIC_API_KEY=",
+		"ANTHROPIC_AUTH_TOKEN=ollama",
+	)
+	return cmd.Run()
+}

cmd/config/claude_test.go

@@ -0,0 +1,42 @@
+package config
+
+import (
+	"slices"
+	"testing"
+)
+
+func TestClaudeIntegration(t *testing.T) {
+	c := &Claude{}
+
+	t.Run("String", func(t *testing.T) {
+		if got := c.String(); got != "Claude Code" {
+			t.Errorf("String() = %q, want %q", got, "Claude Code")
+		}
+	})
+
+	t.Run("implements Runner", func(t *testing.T) {
+		var _ Runner = c
+	})
+}
+
+func TestClaudeArgs(t *testing.T) {
+	c := &Claude{}
+
+	tests := []struct {
+		name  string
+		model string
+		want  []string
+	}{
+		{"with model", "llama3.2", []string{"--model", "llama3.2"}},
+		{"empty model", "", nil},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := c.args(tt.model)
+			if !slices.Equal(got, tt.want) {
+				t.Errorf("args(%q) = %v, want %v", tt.model, got, tt.want)
+			}
+		})
+	}
+}

cmd/config/codex.go

@@ -0,0 +1,61 @@
+package config
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+
+	"golang.org/x/mod/semver"
+)
+
+// Codex implements Runner for Codex integration
+type Codex struct{}
+
+func (c *Codex) String() string { return "Codex" }
+
+func (c *Codex) args(model string) []string {
+	args := []string{"--oss"}
+	if model != "" {
+		args = append(args, "-m", model)
+	}
+	return args
+}
+
+func (c *Codex) Run(model string) error {
+	if err := checkCodexVersion(); err != nil {
+		return err
+	}
+
+	cmd := exec.Command("codex", c.args(model)...)
+	cmd.Stdin = os.Stdin
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	return cmd.Run()
+}
+
+func checkCodexVersion() error {
+	if _, err := exec.LookPath("codex"); err != nil {
+		return fmt.Errorf("codex is not installed, install with: npm install -g @openai/codex")
+	}
+
+	out, err := exec.Command("codex", "--version").Output()
+	if err != nil {
+		return fmt.Errorf("failed to get codex version: %w", err)
+	}
+
+	// Parse output like "codex-cli 0.87.0"
+	fields := strings.Fields(strings.TrimSpace(string(out)))
+	if len(fields) < 2 {
+		return fmt.Errorf("unexpected codex version output: %s", string(out))
+	}
+
+	version := "v" + fields[len(fields)-1]
+	minVersion := "v0.81.0"
+
+	if semver.Compare(version, minVersion) < 0 {
+		return fmt.Errorf("codex version %s is too old, minimum required is %s, update with: npm update -g @openai/codex", fields[len(fields)-1], "0.81.0")
+	}
+
+	return nil
+}

cmd/config/codex_test.go

@@ -0,0 +1,28 @@
+package config
+
+import (
+	"slices"
+	"testing"
+)
+
+func TestCodexArgs(t *testing.T) {
+	c := &Codex{}
+
+	tests := []struct {
+		name  string
+		model string
+		want  []string
+	}{
+		{"with model", "llama3.2", []string{"--oss", "-m", "llama3.2"}},
+		{"empty model", "", []string{"--oss"}},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := c.args(tt.model)
+			if !slices.Equal(got, tt.want) {
+				t.Errorf("args(%q) = %v, want %v", tt.model, got, tt.want)
+			}
+		})
+	}
+}

cmd/config/config.go

@@ -0,0 +1,115 @@
+// Package config provides integration configuration for external coding tools
+// (Claude Code, Codex, Droid, OpenCode) to use Ollama models.
+package config
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+type integration struct {
+	Models []string `json:"models"`
+}
+
+type config struct {
+	Integrations map[string]*integration `json:"integrations"`
+}
+
+func configPath() (string, error) {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(home, ".ollama", "config", "config.json"), nil
+}
+
+func load() (*config, error) {
+	path, err := configPath()
+	if err != nil {
+		return nil, err
+	}
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return &config{Integrations: make(map[string]*integration)}, nil
+		}
+		return nil, err
+	}
+
+	var cfg config
+	if err := json.Unmarshal(data, &cfg); err != nil {
+		return nil, fmt.Errorf("failed to parse config: %w, at: %s", err, path)
+	}
+	if cfg.Integrations == nil {
+		cfg.Integrations = make(map[string]*integration)
+	}
+	return &cfg, nil
+}
+
+func save(cfg *config) error {
+	path, err := configPath()
+	if err != nil {
+		return err
+	}
+
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		return err
+	}
+
+	data, err := json.MarshalIndent(cfg, "", "  ")
+	if err != nil {
+		return err
+	}
+
+	return writeWithBackup(path, data)
+}
+
+func saveIntegration(appName string, models []string) error {
+	if appName == "" {
+		return errors.New("app name cannot be empty")
+	}
+
+	cfg, err := load()
+	if err != nil {
+		return err
+	}
+
+	cfg.Integrations[strings.ToLower(appName)] = &integration{
+		Models: models,
+	}
+
+	return save(cfg)
+}
+
+func loadIntegration(appName string) (*integration, error) {
+	cfg, err := load()
+	if err != nil {
+		return nil, err
+	}
+
+	ic, ok := cfg.Integrations[strings.ToLower(appName)]
+	if !ok {
+		return nil, os.ErrNotExist
+	}
+
+	return ic, nil
+}
+
+func listIntegrations() ([]integration, error) {
+	cfg, err := load()
+	if err != nil {
+		return nil, err
+	}
+
+	result := make([]integration, 0, len(cfg.Integrations))
+	for _, ic := range cfg.Integrations {
+		result = append(result, *ic)
+	}
+
+	return result, nil
+}

cmd/config/config_test.go

@@ -0,0 +1,373 @@
+package config
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+// setTestHome sets both HOME (Unix) and USERPROFILE (Windows) for cross-platform tests
+func setTestHome(t *testing.T, dir string) {
+	t.Setenv("HOME", dir)
+	t.Setenv("USERPROFILE", dir)
+}
+
+// editorPaths is a test helper that safely calls Paths if the runner implements Editor
+func editorPaths(r Runner) []string {
+	if editor, ok := r.(Editor); ok {
+		return editor.Paths()
+	}
+	return nil
+}
+
+func TestIntegrationConfig(t *testing.T) {
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	t.Run("save and load round-trip", func(t *testing.T) {
+		models := []string{"llama3.2", "mistral", "qwen2.5"}
+		if err := saveIntegration("claude", models); err != nil {
+			t.Fatal(err)
+		}
+
+		config, err := loadIntegration("claude")
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if len(config.Models) != len(models) {
+			t.Errorf("expected %d models, got %d", len(models), len(config.Models))
+		}
+		for i, m := range models {
+			if config.Models[i] != m {
+				t.Errorf("model %d: expected %s, got %s", i, m, config.Models[i])
+			}
+		}
+	})
+
+	t.Run("defaultModel returns first model", func(t *testing.T) {
+		saveIntegration("codex", []string{"model-a", "model-b"})
+
+		config, _ := loadIntegration("codex")
+		defaultModel := ""
+		if len(config.Models) > 0 {
+			defaultModel = config.Models[0]
+		}
+		if defaultModel != "model-a" {
+			t.Errorf("expected model-a, got %s", defaultModel)
+		}
+	})
+
+	t.Run("defaultModel returns empty for no models", func(t *testing.T) {
+		config := &integration{Models: []string{}}
+		defaultModel := ""
+		if len(config.Models) > 0 {
+			defaultModel = config.Models[0]
+		}
+		if defaultModel != "" {
+			t.Errorf("expected empty string, got %s", defaultModel)
+		}
+	})
+
+	t.Run("app name is case-insensitive", func(t *testing.T) {
+		saveIntegration("Claude", []string{"model-x"})
+
+		config, err := loadIntegration("claude")
+		if err != nil {
+			t.Fatal(err)
+		}
+		defaultModel := ""
+		if len(config.Models) > 0 {
+			defaultModel = config.Models[0]
+		}
+		if defaultModel != "model-x" {
+			t.Errorf("expected model-x, got %s", defaultModel)
+		}
+	})
+
+	t.Run("multiple integrations in single file", func(t *testing.T) {
+		saveIntegration("app1", []string{"model-1"})
+		saveIntegration("app2", []string{"model-2"})
+
+		config1, _ := loadIntegration("app1")
+		config2, _ := loadIntegration("app2")
+
+		defaultModel1 := ""
+		if len(config1.Models) > 0 {
+			defaultModel1 = config1.Models[0]
+		}
+		defaultModel2 := ""
+		if len(config2.Models) > 0 {
+			defaultModel2 = config2.Models[0]
+		}
+		if defaultModel1 != "model-1" {
+			t.Errorf("expected model-1, got %s", defaultModel1)
+		}
+		if defaultModel2 != "model-2" {
+			t.Errorf("expected model-2, got %s", defaultModel2)
+		}
+	})
+}
+
+func TestListIntegrations(t *testing.T) {
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	t.Run("returns empty when no integrations", func(t *testing.T) {
+		configs, err := listIntegrations()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if len(configs) != 0 {
+			t.Errorf("expected 0 integrations, got %d", len(configs))
+		}
+	})
+
+	t.Run("returns all saved integrations", func(t *testing.T) {
+		saveIntegration("claude", []string{"model-1"})
+		saveIntegration("droid", []string{"model-2"})
+
+		configs, err := listIntegrations()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if len(configs) != 2 {
+			t.Errorf("expected 2 integrations, got %d", len(configs))
+		}
+	})
+}
+
+func TestEditorPaths(t *testing.T) {
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	t.Run("returns empty for claude (no Editor)", func(t *testing.T) {
+		r := integrations["claude"]
+		paths := editorPaths(r)
+		if len(paths) != 0 {
+			t.Errorf("expected no paths for claude, got %v", paths)
+		}
+	})
+
+	t.Run("returns empty for codex (no Editor)", func(t *testing.T) {
+		r := integrations["codex"]
+		paths := editorPaths(r)
+		if len(paths) != 0 {
+			t.Errorf("expected no paths for codex, got %v", paths)
+		}
+	})
+
+	t.Run("returns empty for droid when no config exists", func(t *testing.T) {
+		r := integrations["droid"]
+		paths := editorPaths(r)
+		if len(paths) != 0 {
+			t.Errorf("expected no paths, got %v", paths)
+		}
+	})
+
+	t.Run("returns path for droid when config exists", func(t *testing.T) {
+		settingsDir, _ := os.UserHomeDir()
+		settingsDir = filepath.Join(settingsDir, ".factory")
+		os.MkdirAll(settingsDir, 0o755)
+		os.WriteFile(filepath.Join(settingsDir, "settings.json"), []byte(`{}`), 0o644)
+
+		r := integrations["droid"]
+		paths := editorPaths(r)
+		if len(paths) != 1 {
+			t.Errorf("expected 1 path, got %d", len(paths))
+		}
+	})
+
+	t.Run("returns paths for opencode when configs exist", func(t *testing.T) {
+		home, _ := os.UserHomeDir()
+		configDir := filepath.Join(home, ".config", "opencode")
+		stateDir := filepath.Join(home, ".local", "state", "opencode")
+		os.MkdirAll(configDir, 0o755)
+		os.MkdirAll(stateDir, 0o755)
+		os.WriteFile(filepath.Join(configDir, "opencode.json"), []byte(`{}`), 0o644)
+		os.WriteFile(filepath.Join(stateDir, "model.json"), []byte(`{}`), 0o644)
+
+		r := integrations["opencode"]
+		paths := editorPaths(r)
+		if len(paths) != 2 {
+			t.Errorf("expected 2 paths, got %d: %v", len(paths), paths)
+		}
+	})
+}
+
+func TestLoadIntegration_CorruptedJSON(t *testing.T) {
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	// Create corrupted config.json file
+	dir := filepath.Join(tmpDir, ".ollama", "config")
+	os.MkdirAll(dir, 0o755)
+	os.WriteFile(filepath.Join(dir, "config.json"), []byte(`{corrupted json`), 0o644)
+
+	// Corrupted file is treated as empty, so loadIntegration returns not found
+	_, err := loadIntegration("test")
+	if err == nil {
+		t.Error("expected error for nonexistent integration in corrupted file")
+	}
+}
+
+func TestSaveIntegration_NilModels(t *testing.T) {
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	if err := saveIntegration("test", nil); err != nil {
+		t.Fatalf("saveIntegration with nil models failed: %v", err)
+	}
+
+	config, err := loadIntegration("test")
+	if err != nil {
+		t.Fatalf("loadIntegration failed: %v", err)
+	}
+
+	if config.Models == nil {
+		// nil is acceptable
+	} else if len(config.Models) != 0 {
+		t.Errorf("expected empty or nil models, got %v", config.Models)
+	}
+}
+
+func TestSaveIntegration_EmptyAppName(t *testing.T) {
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	err := saveIntegration("", []string{"model"})
+	if err == nil {
+		t.Error("expected error for empty app name, got nil")
+	}
+	if err != nil && !strings.Contains(err.Error(), "app name cannot be empty") {
+		t.Errorf("expected 'app name cannot be empty' error, got: %v", err)
+	}
+}
+
+func TestLoadIntegration_NonexistentIntegration(t *testing.T) {
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	_, err := loadIntegration("nonexistent")
+	if err == nil {
+		t.Error("expected error for nonexistent integration, got nil")
+	}
+	if !os.IsNotExist(err) {
+		t.Logf("error type is os.ErrNotExist as expected: %v", err)
+	}
+}
+
+func TestConfigPath(t *testing.T) {
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	path, err := configPath()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expected := filepath.Join(tmpDir, ".ollama", "config", "config.json")
+	if path != expected {
+		t.Errorf("expected %s, got %s", expected, path)
+	}
+}
+
+func TestLoad(t *testing.T) {
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	t.Run("returns empty config when file does not exist", func(t *testing.T) {
+		cfg, err := load()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if cfg == nil {
+			t.Fatal("expected non-nil config")
+		}
+		if cfg.Integrations == nil {
+			t.Error("expected non-nil Integrations map")
+		}
+		if len(cfg.Integrations) != 0 {
+			t.Errorf("expected empty Integrations, got %d", len(cfg.Integrations))
+		}
+	})
+
+	t.Run("loads existing config", func(t *testing.T) {
+		path, _ := configPath()
+		os.MkdirAll(filepath.Dir(path), 0o755)
+		os.WriteFile(path, []byte(`{"integrations":{"test":{"models":["model-a"]}}}`), 0o644)
+
+		cfg, err := load()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if cfg.Integrations["test"] == nil {
+			t.Fatal("expected test integration")
+		}
+		if len(cfg.Integrations["test"].Models) != 1 {
+			t.Errorf("expected 1 model, got %d", len(cfg.Integrations["test"].Models))
+		}
+	})
+
+	t.Run("returns error for corrupted JSON", func(t *testing.T) {
+		path, _ := configPath()
+		os.MkdirAll(filepath.Dir(path), 0o755)
+		os.WriteFile(path, []byte(`{corrupted`), 0o644)
+
+		_, err := load()
+		if err == nil {
+			t.Error("expected error for corrupted JSON")
+		}
+	})
+}
+
+func TestSave(t *testing.T) {
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	t.Run("creates config file", func(t *testing.T) {
+		cfg := &config{
+			Integrations: map[string]*integration{
+				"test": {Models: []string{"model-a", "model-b"}},
+			},
+		}
+
+		if err := save(cfg); err != nil {
+			t.Fatal(err)
+		}
+
+		path, _ := configPath()
+		if _, err := os.Stat(path); os.IsNotExist(err) {
+			t.Error("config file was not created")
+		}
+	})
+
+	t.Run("round-trip preserves data", func(t *testing.T) {
+		cfg := &config{
+			Integrations: map[string]*integration{
+				"claude": {Models: []string{"llama3.2", "mistral"}},
+				"codex":  {Models: []string{"qwen2.5"}},
+			},
+		}
+
+		if err := save(cfg); err != nil {
+			t.Fatal(err)
+		}
+
+		loaded, err := load()
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if len(loaded.Integrations) != 2 {
+			t.Errorf("expected 2 integrations, got %d", len(loaded.Integrations))
+		}
+		if loaded.Integrations["claude"] == nil {
+			t.Error("missing claude integration")
+		}
+		if len(loaded.Integrations["claude"].Models) != 2 {
+			t.Errorf("expected 2 models for claude, got %d", len(loaded.Integrations["claude"].Models))
+		}
+	})
+}

cmd/config/droid.go

@@ -0,0 +1,174 @@
+package config
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"slices"
+	"strings"
+)
+
+// Droid implements Runner and Editor for Droid integration
+type Droid struct{}
+
+// droidModelEntry represents a custom model entry in Droid's settings.json
+type droidModelEntry struct {
+	Model           string `json:"model"`
+	DisplayName     string `json:"displayName"`
+	BaseURL         string `json:"baseUrl"`
+	APIKey          string `json:"apiKey"`
+	Provider        string `json:"provider"`
+	MaxOutputTokens int    `json:"maxOutputTokens"`
+	SupportsImages  bool   `json:"supportsImages"`
+	ID              string `json:"id"`
+	Index           int    `json:"index"`
+}
+
+func (d *Droid) String() string { return "Droid" }
+
+func (d *Droid) Run(model string) error {
+	if _, err := exec.LookPath("droid"); err != nil {
+		return fmt.Errorf("droid is not installed, install from https://docs.factory.ai/cli/getting-started/quickstart")
+	}
+
+	// Call Edit() to ensure config is up-to-date before launch
+	models := []string{model}
+	if config, err := loadIntegration("droid"); err == nil && len(config.Models) > 0 {
+		models = config.Models
+	}
+	if err := d.Edit(models); err != nil {
+		return fmt.Errorf("setup failed: %w", err)
+	}
+
+	cmd := exec.Command("droid")
+	cmd.Stdin = os.Stdin
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	return cmd.Run()
+}
+
+func (d *Droid) Paths() []string {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return nil
+	}
+	p := filepath.Join(home, ".factory", "settings.json")
+	if _, err := os.Stat(p); err == nil {
+		return []string{p}
+	}
+	return nil
+}
+
+func (d *Droid) Edit(models []string) error {
+	if len(models) == 0 {
+		return nil
+	}
+
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return err
+	}
+
+	settingsPath := filepath.Join(home, ".factory", "settings.json")
+	if err := os.MkdirAll(filepath.Dir(settingsPath), 0o755); err != nil {
+		return err
+	}
+
+	settings := make(map[string]any)
+	if data, err := os.ReadFile(settingsPath); err == nil {
+		if err := json.Unmarshal(data, &settings); err != nil {
+			return fmt.Errorf("failed to parse settings file: %w, at: %s", err, settingsPath)
+		}
+	}
+
+	customModels, _ := settings["customModels"].([]any)
+
+	// Keep only non-Ollama models (we'll rebuild Ollama models fresh)
+	nonOllamaModels := slices.DeleteFunc(slices.Clone(customModels), isOllamaModelEntry)
+
+	// Build new Ollama model entries with sequential indices (0, 1, 2, ...)
+	var ollamaModels []any
+	var defaultModelID string
+	for i, model := range models {
+		modelID := fmt.Sprintf("custom:%s-[Ollama]-%d", model, i)
+		ollamaModels = append(ollamaModels, droidModelEntry{
+			Model:           model,
+			DisplayName:     model,
+			BaseURL:         "http://localhost:11434/v1",
+			APIKey:          "ollama",
+			Provider:        "generic-chat-completion-api",
+			MaxOutputTokens: 64000,
+			SupportsImages:  false,
+			ID:              modelID,
+			Index:           i,
+		})
+		if i == 0 {
+			defaultModelID = modelID
+		}
+	}
+
+	settings["customModels"] = append(ollamaModels, nonOllamaModels...)
+
+	sessionSettings, ok := settings["sessionDefaultSettings"].(map[string]any)
+	if !ok {
+		sessionSettings = make(map[string]any)
+	}
+	sessionSettings["model"] = defaultModelID
+
+	if effort, ok := sessionSettings["reasoningEffort"].(string); !ok || !isValidReasoningEffort(effort) {
+		sessionSettings["reasoningEffort"] = "none"
+	}
+
+	settings["sessionDefaultSettings"] = sessionSettings
+
+	data, err := json.MarshalIndent(settings, "", "  ")
+	if err != nil {
+		return err
+	}
+	return writeWithBackup(settingsPath, data)
+}
+
+func (d *Droid) Models() []string {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return nil
+	}
+	settings, err := readJSONFile(filepath.Join(home, ".factory", "settings.json"))
+	if err != nil {
+		return nil
+	}
+
+	customModels, _ := settings["customModels"].([]any)
+
+	var result []string
+	for _, m := range customModels {
+		if !isOllamaModelEntry(m) {
+			continue
+		}
+		entry, ok := m.(map[string]any)
+		if !ok {
+			continue
+		}
+		if model, _ := entry["model"].(string); model != "" {
+			result = append(result, model)
+		}
+	}
+	return result
+}
+
+var validReasoningEfforts = []string{"high", "medium", "low", "none"}
+
+func isValidReasoningEffort(effort string) bool {
+	return slices.Contains(validReasoningEfforts, effort)
+}
+
+func isOllamaModelEntry(m any) bool {
+	entry, ok := m.(map[string]any)
+	if !ok {
+		return false
+	}
+	id, _ := entry["id"].(string)
+	return strings.Contains(id, "-[Ollama]-")
+}

cmd/config/droid_test.go

@@ -0,0 +1,454 @@
+package config
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestDroidIntegration(t *testing.T) {
+	d := &Droid{}
+
+	t.Run("String", func(t *testing.T) {
+		if got := d.String(); got != "Droid" {
+			t.Errorf("String() = %q, want %q", got, "Droid")
+		}
+	})
+
+	t.Run("implements Runner", func(t *testing.T) {
+		var _ Runner = d
+	})
+
+	t.Run("implements Editor", func(t *testing.T) {
+		var _ Editor = d
+	})
+}
+
+func TestDroidEdit(t *testing.T) {
+	d := &Droid{}
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	settingsDir := filepath.Join(tmpDir, ".factory")
+	settingsPath := filepath.Join(settingsDir, "settings.json")
+
+	cleanup := func() {
+		os.RemoveAll(settingsDir)
+	}
+
+	readSettings := func() map[string]any {
+		data, _ := os.ReadFile(settingsPath)
+		var settings map[string]any
+		json.Unmarshal(data, &settings)
+		return settings
+	}
+
+	getCustomModels := func(settings map[string]any) []map[string]any {
+		models, ok := settings["customModels"].([]any)
+		if !ok {
+			return nil
+		}
+		var result []map[string]any
+		for _, m := range models {
+			if entry, ok := m.(map[string]any); ok {
+				result = append(result, entry)
+			}
+		}
+		return result
+	}
+
+	t.Run("fresh install creates models with sequential indices", func(t *testing.T) {
+		cleanup()
+		if err := d.Edit([]string{"model-a", "model-b"}); err != nil {
+			t.Fatal(err)
+		}
+
+		settings := readSettings()
+		models := getCustomModels(settings)
+
+		if len(models) != 2 {
+			t.Fatalf("expected 2 models, got %d", len(models))
+		}
+
+		// Check first model
+		if models[0]["model"] != "model-a" {
+			t.Errorf("expected model-a, got %s", models[0]["model"])
+		}
+		if models[0]["id"] != "custom:model-a-[Ollama]-0" {
+			t.Errorf("expected custom:model-a-[Ollama]-0, got %s", models[0]["id"])
+		}
+		if models[0]["index"] != float64(0) {
+			t.Errorf("expected index 0, got %v", models[0]["index"])
+		}
+
+		// Check second model
+		if models[1]["model"] != "model-b" {
+			t.Errorf("expected model-b, got %s", models[1]["model"])
+		}
+		if models[1]["id"] != "custom:model-b-[Ollama]-1" {
+			t.Errorf("expected custom:model-b-[Ollama]-1, got %s", models[1]["id"])
+		}
+		if models[1]["index"] != float64(1) {
+			t.Errorf("expected index 1, got %v", models[1]["index"])
+		}
+	})
+
+	t.Run("sets sessionDefaultSettings.model to first model ID", func(t *testing.T) {
+		cleanup()
+		if err := d.Edit([]string{"model-a", "model-b"}); err != nil {
+			t.Fatal(err)
+		}
+
+		settings := readSettings()
+		session, ok := settings["sessionDefaultSettings"].(map[string]any)
+		if !ok {
+			t.Fatal("sessionDefaultSettings not found")
+		}
+		if session["model"] != "custom:model-a-[Ollama]-0" {
+			t.Errorf("expected custom:model-a-[Ollama]-0, got %s", session["model"])
+		}
+	})
+
+	t.Run("re-indexes when models removed", func(t *testing.T) {
+		cleanup()
+		// Add three models
+		d.Edit([]string{"model-a", "model-b", "model-c"})
+
+		// Remove middle model
+		d.Edit([]string{"model-a", "model-c"})
+
+		settings := readSettings()
+		models := getCustomModels(settings)
+
+		if len(models) != 2 {
+			t.Fatalf("expected 2 models, got %d", len(models))
+		}
+
+		// Check indices are sequential 0, 1
+		if models[0]["index"] != float64(0) {
+			t.Errorf("expected index 0, got %v", models[0]["index"])
+		}
+		if models[1]["index"] != float64(1) {
+			t.Errorf("expected index 1, got %v", models[1]["index"])
+		}
+
+		// Check IDs match new indices
+		if models[0]["id"] != "custom:model-a-[Ollama]-0" {
+			t.Errorf("expected custom:model-a-[Ollama]-0, got %s", models[0]["id"])
+		}
+		if models[1]["id"] != "custom:model-c-[Ollama]-1" {
+			t.Errorf("expected custom:model-c-[Ollama]-1, got %s", models[1]["id"])
+		}
+	})
+
+	t.Run("preserves non-Ollama custom models", func(t *testing.T) {
+		cleanup()
+		os.MkdirAll(settingsDir, 0o755)
+		// Pre-existing non-Ollama model
+		os.WriteFile(settingsPath, []byte(`{
+			"customModels": [
+				{"model": "gpt-4", "displayName": "GPT-4", "provider": "openai"}
+			]
+		}`), 0o644)
+
+		d.Edit([]string{"model-a"})
+
+		settings := readSettings()
+		models := getCustomModels(settings)
+
+		if len(models) != 2 {
+			t.Fatalf("expected 2 models (1 Ollama + 1 non-Ollama), got %d", len(models))
+		}
+
+		// Ollama model should be first
+		if models[0]["model"] != "model-a" {
+			t.Errorf("expected Ollama model first, got %s", models[0]["model"])
+		}
+
+		// Non-Ollama model should be preserved at end
+		if models[1]["model"] != "gpt-4" {
+			t.Errorf("expected gpt-4 preserved, got %s", models[1]["model"])
+		}
+	})
+
+	t.Run("preserves other settings", func(t *testing.T) {
+		cleanup()
+		os.MkdirAll(settingsDir, 0o755)
+		os.WriteFile(settingsPath, []byte(`{
+			"theme": "dark",
+			"enableHooks": true,
+			"sessionDefaultSettings": {"autonomyMode": "auto-high"}
+		}`), 0o644)
+
+		d.Edit([]string{"model-a"})
+
+		settings := readSettings()
+
+		if settings["theme"] != "dark" {
+			t.Error("theme was not preserved")
+		}
+		if settings["enableHooks"] != true {
+			t.Error("enableHooks was not preserved")
+		}
+
+		session := settings["sessionDefaultSettings"].(map[string]any)
+		if session["autonomyMode"] != "auto-high" {
+			t.Error("autonomyMode was not preserved")
+		}
+	})
+
+	t.Run("required fields present", func(t *testing.T) {
+		cleanup()
+		d.Edit([]string{"test-model"})
+
+		settings := readSettings()
+		models := getCustomModels(settings)
+
+		if len(models) != 1 {
+			t.Fatal("expected 1 model")
+		}
+
+		model := models[0]
+		requiredFields := []string{"model", "displayName", "baseUrl", "apiKey", "provider", "maxOutputTokens", "id", "index"}
+		for _, field := range requiredFields {
+			if model[field] == nil {
+				t.Errorf("missing required field: %s", field)
+			}
+		}
+
+		if model["baseUrl"] != "http://localhost:11434/v1" {
+			t.Errorf("unexpected baseUrl: %s", model["baseUrl"])
+		}
+		if model["apiKey"] != "ollama" {
+			t.Errorf("unexpected apiKey: %s", model["apiKey"])
+		}
+		if model["provider"] != "generic-chat-completion-api" {
+			t.Errorf("unexpected provider: %s", model["provider"])
+		}
+	})
+
+	t.Run("fixes invalid reasoningEffort", func(t *testing.T) {
+		cleanup()
+		os.MkdirAll(settingsDir, 0o755)
+		// Pre-existing settings with invalid reasoningEffort
+		os.WriteFile(settingsPath, []byte(`{
+			"sessionDefaultSettings": {"reasoningEffort": "off"}
+		}`), 0o644)
+
+		d.Edit([]string{"model-a"})
+
+		settings := readSettings()
+		session := settings["sessionDefaultSettings"].(map[string]any)
+
+		if session["reasoningEffort"] != "none" {
+			t.Errorf("expected reasoningEffort to be fixed to 'none', got %s", session["reasoningEffort"])
+		}
+	})
+
+	t.Run("preserves valid reasoningEffort", func(t *testing.T) {
+		cleanup()
+		os.MkdirAll(settingsDir, 0o755)
+		os.WriteFile(settingsPath, []byte(`{
+			"sessionDefaultSettings": {"reasoningEffort": "high"}
+		}`), 0o644)
+
+		d.Edit([]string{"model-a"})
+
+		settings := readSettings()
+		session := settings["sessionDefaultSettings"].(map[string]any)
+
+		if session["reasoningEffort"] != "high" {
+			t.Errorf("expected reasoningEffort to remain 'high', got %s", session["reasoningEffort"])
+		}
+	})
+}
+
+// Edge case tests for droid.go
+
+func TestDroidEdit_CorruptedJSON(t *testing.T) {
+	d := &Droid{}
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	settingsDir := filepath.Join(tmpDir, ".factory")
+	settingsPath := filepath.Join(settingsDir, "settings.json")
+
+	os.MkdirAll(settingsDir, 0o755)
+	os.WriteFile(settingsPath, []byte(`{corrupted json content`), 0o644)
+
+	// Corrupted JSON should return an error so user knows something is wrong
+	err := d.Edit([]string{"model-a"})
+	if err == nil {
+		t.Fatal("expected error for corrupted JSON, got nil")
+	}
+
+	// Original corrupted file should be preserved (not overwritten)
+	data, _ := os.ReadFile(settingsPath)
+	if string(data) != `{corrupted json content` {
+		t.Errorf("corrupted file was modified: got %s", string(data))
+	}
+}
+
+func TestDroidEdit_WrongTypeCustomModels(t *testing.T) {
+	d := &Droid{}
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	settingsDir := filepath.Join(tmpDir, ".factory")
+	settingsPath := filepath.Join(settingsDir, "settings.json")
+
+	os.MkdirAll(settingsDir, 0o755)
+	// customModels is a string instead of array
+	os.WriteFile(settingsPath, []byte(`{"customModels": "not an array"}`), 0o644)
+
+	// Should not panic - wrong type should be handled gracefully
+	err := d.Edit([]string{"model-a"})
+	if err != nil {
+		t.Fatalf("Edit failed with wrong type customModels: %v", err)
+	}
+
+	// Verify models were added correctly
+	data, _ := os.ReadFile(settingsPath)
+	var settings map[string]any
+	json.Unmarshal(data, &settings)
+
+	customModels, ok := settings["customModels"].([]any)
+	if !ok {
+		t.Fatalf("customModels should be array after setup, got %T", settings["customModels"])
+	}
+	if len(customModels) != 1 {
+		t.Errorf("expected 1 model, got %d", len(customModels))
+	}
+}
+
+func TestDroidEdit_EmptyModels(t *testing.T) {
+	d := &Droid{}
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	settingsDir := filepath.Join(tmpDir, ".factory")
+	settingsPath := filepath.Join(settingsDir, "settings.json")
+
+	os.MkdirAll(settingsDir, 0o755)
+	originalContent := `{"customModels": [{"model": "existing"}]}`
+	os.WriteFile(settingsPath, []byte(originalContent), 0o644)
+
+	// Empty models should be no-op
+	err := d.Edit([]string{})
+	if err != nil {
+		t.Fatalf("Edit with empty models failed: %v", err)
+	}
+
+	// Original content should be preserved (file not modified)
+	data, _ := os.ReadFile(settingsPath)
+	if string(data) != originalContent {
+		t.Errorf("empty models should not modify file, but content changed")
+	}
+}
+
+func TestDroidEdit_DuplicateModels(t *testing.T) {
+	d := &Droid{}
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	settingsDir := filepath.Join(tmpDir, ".factory")
+	settingsPath := filepath.Join(settingsDir, "settings.json")
+
+	// Add same model twice
+	err := d.Edit([]string{"model-a", "model-a"})
+	if err != nil {
+		t.Fatalf("Edit with duplicates failed: %v", err)
+	}
+
+	settings, err := readJSONFile(settingsPath)
+	if err != nil {
+		t.Fatalf("readJSONFile failed: %v", err)
+	}
+
+	customModels, _ := settings["customModels"].([]any)
+	// Document current behavior: duplicates are kept as separate entries
+	if len(customModels) != 2 {
+		t.Logf("Note: duplicates result in %d entries (documenting behavior)", len(customModels))
+	}
+}
+
+func TestDroidEdit_MalformedModelEntry(t *testing.T) {
+	d := &Droid{}
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	settingsDir := filepath.Join(tmpDir, ".factory")
+	settingsPath := filepath.Join(settingsDir, "settings.json")
+
+	os.MkdirAll(settingsDir, 0o755)
+	// Model entry is a string instead of a map
+	os.WriteFile(settingsPath, []byte(`{"customModels": ["not a map", 123]}`), 0o644)
+
+	err := d.Edit([]string{"model-a"})
+	if err != nil {
+		t.Fatalf("Edit with malformed entries failed: %v", err)
+	}
+
+	// Malformed entries should be preserved in nonOllamaModels
+	settings, _ := readJSONFile(settingsPath)
+	customModels, _ := settings["customModels"].([]any)
+
+	// Should have: 1 new Ollama model + 2 preserved malformed entries
+	if len(customModels) != 3 {
+		t.Errorf("expected 3 entries (1 new + 2 preserved malformed), got %d", len(customModels))
+	}
+}
+
+func TestDroidEdit_WrongTypeSessionSettings(t *testing.T) {
+	d := &Droid{}
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	settingsDir := filepath.Join(tmpDir, ".factory")
+	settingsPath := filepath.Join(settingsDir, "settings.json")
+
+	os.MkdirAll(settingsDir, 0o755)
+	// sessionDefaultSettings is a string instead of map
+	os.WriteFile(settingsPath, []byte(`{"sessionDefaultSettings": "not a map"}`), 0o644)
+
+	err := d.Edit([]string{"model-a"})
+	if err != nil {
+		t.Fatalf("Edit with wrong type sessionDefaultSettings failed: %v", err)
+	}
+
+	// Should create proper sessionDefaultSettings
+	settings, _ := readJSONFile(settingsPath)
+	session, ok := settings["sessionDefaultSettings"].(map[string]any)
+	if !ok {
+		t.Fatalf("sessionDefaultSettings should be map after setup, got %T", settings["sessionDefaultSettings"])
+	}
+	if session["model"] == nil {
+		t.Error("expected model to be set in sessionDefaultSettings")
+	}
+}
+
+func TestIsValidReasoningEffort(t *testing.T) {
+	tests := []struct {
+		effort string
+		valid  bool
+	}{
+		{"high", true},
+		{"medium", true},
+		{"low", true},
+		{"none", true},
+		{"off", false},
+		{"", false},
+		{"HIGH", false}, // case sensitive
+		{"max", false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.effort, func(t *testing.T) {
+			got := isValidReasoningEffort(tt.effort)
+			if got != tt.valid {
+				t.Errorf("isValidReasoningEffort(%q) = %v, want %v", tt.effort, got, tt.valid)
+			}
+		})
+	}
+}

cmd/config/files.go

@@ -0,0 +1,99 @@
+package config
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"time"
+)
+
+func readJSONFile(path string) (map[string]any, error) {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+	var result map[string]any
+	if err := json.Unmarshal(data, &result); err != nil {
+		return nil, err
+	}
+	return result, nil
+}
+
+func copyFile(src, dst string) error {
+	info, err := os.Stat(src)
+	if err != nil {
+		return err
+	}
+	data, err := os.ReadFile(src)
+	if err != nil {
+		return err
+	}
+	return os.WriteFile(dst, data, info.Mode().Perm())
+}
+
+func backupDir() string {
+	return filepath.Join(os.TempDir(), "ollama-backups")
+}
+
+func backupToTmp(srcPath string) (string, error) {
+	dir := backupDir()
+	if err := os.MkdirAll(dir, 0o755); err != nil {
+		return "", err
+	}
+
+	backupPath := filepath.Join(dir, fmt.Sprintf("%s.%d", filepath.Base(srcPath), time.Now().Unix()))
+	if err := copyFile(srcPath, backupPath); err != nil {
+		return "", err
+	}
+	return backupPath, nil
+}
+
+// writeWithBackup writes data to path via temp file + rename, backing up any existing file first
+func writeWithBackup(path string, data []byte) error {
+	var backupPath string
+	// backup must be created before any writes to the target file
+	if existingContent, err := os.ReadFile(path); err == nil {
+		if !bytes.Equal(existingContent, data) {
+			backupPath, err = backupToTmp(path)
+			if err != nil {
+				return fmt.Errorf("backup failed: %w", err)
+			}
+		}
+	} else if !os.IsNotExist(err) {
+		return fmt.Errorf("read existing file: %w", err)
+	}
+
+	dir := filepath.Dir(path)
+	tmp, err := os.CreateTemp(dir, ".tmp-*")
+	if err != nil {
+		return fmt.Errorf("create temp failed: %w", err)
+	}
+	tmpPath := tmp.Name()
+
+	if _, err := tmp.Write(data); err != nil {
+		_ = tmp.Close()
+		_ = os.Remove(tmpPath)
+		return fmt.Errorf("write failed: %w", err)
+	}
+	if err := tmp.Sync(); err != nil {
+		_ = tmp.Close()
+		_ = os.Remove(tmpPath)
+		return fmt.Errorf("sync failed: %w", err)
+	}
+	if err := tmp.Close(); err != nil {
+		_ = os.Remove(tmpPath)
+		return fmt.Errorf("close failed: %w", err)
+	}
+
+	if err := os.Rename(tmpPath, path); err != nil {
+		_ = os.Remove(tmpPath)
+		if backupPath != "" {
+			_ = copyFile(backupPath, path)
+		}
+		return fmt.Errorf("rename failed: %w", err)
+	}
+
+	return nil
+}

cmd/config/files_test.go

@@ -0,0 +1,502 @@
+package config
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"runtime"
+	"testing"
+)
+
+func mustMarshal(t *testing.T, v any) []byte {
+	t.Helper()
+	data, err := json.MarshalIndent(v, "", "  ")
+	if err != nil {
+		t.Fatal(err)
+	}
+	return data
+}
+
+func TestWriteWithBackup(t *testing.T) {
+	tmpDir := t.TempDir()
+
+	t.Run("creates file", func(t *testing.T) {
+		path := filepath.Join(tmpDir, "new.json")
+		data := mustMarshal(t, map[string]string{"key": "value"})
+
+		if err := writeWithBackup(path, data); err != nil {
+			t.Fatal(err)
+		}
+
+		content, err := os.ReadFile(path)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		var result map[string]string
+		if err := json.Unmarshal(content, &result); err != nil {
+			t.Fatal(err)
+		}
+		if result["key"] != "value" {
+			t.Errorf("expected value, got %s", result["key"])
+		}
+	})
+
+	t.Run("creates backup in /tmp/ollama-backups", func(t *testing.T) {
+		path := filepath.Join(tmpDir, "backup.json")
+
+		os.WriteFile(path, []byte(`{"original": true}`), 0o644)
+
+		data := mustMarshal(t, map[string]bool{"updated": true})
+		if err := writeWithBackup(path, data); err != nil {
+			t.Fatal(err)
+		}
+
+		entries, err := os.ReadDir(backupDir())
+		if err != nil {
+			t.Fatal("backup directory not created")
+		}
+
+		var foundBackup bool
+		for _, entry := range entries {
+			if filepath.Ext(entry.Name()) != ".json" {
+				name := entry.Name()
+				if len(name) > len("backup.json.") && name[:len("backup.json.")] == "backup.json." {
+					backupPath := filepath.Join(backupDir(), name)
+					backup, err := os.ReadFile(backupPath)
+					if err == nil {
+						var backupData map[string]bool
+						json.Unmarshal(backup, &backupData)
+						if backupData["original"] {
+							foundBackup = true
+							os.Remove(backupPath)
+							break
+						}
+					}
+				}
+			}
+		}
+
+		if !foundBackup {
+			t.Error("backup file not created in /tmp/ollama-backups")
+		}
+
+		current, _ := os.ReadFile(path)
+		var currentData map[string]bool
+		json.Unmarshal(current, &currentData)
+		if !currentData["updated"] {
+			t.Error("file doesn't contain updated data")
+		}
+	})
+
+	t.Run("no backup for new file", func(t *testing.T) {
+		path := filepath.Join(tmpDir, "nobak.json")
+
+		data := mustMarshal(t, map[string]string{"new": "file"})
+		if err := writeWithBackup(path, data); err != nil {
+			t.Fatal(err)
+		}
+
+		entries, _ := os.ReadDir(backupDir())
+		for _, entry := range entries {
+			if len(entry.Name()) > len("nobak.json.") && entry.Name()[:len("nobak.json.")] == "nobak.json." {
+				t.Error("backup should not exist for new file")
+			}
+		}
+	})
+
+	t.Run("no backup when content unchanged", func(t *testing.T) {
+		path := filepath.Join(tmpDir, "unchanged.json")
+
+		data := mustMarshal(t, map[string]string{"key": "value"})
+
+		if err := writeWithBackup(path, data); err != nil {
+			t.Fatal(err)
+		}
+
+		entries1, _ := os.ReadDir(backupDir())
+		countBefore := 0
+		for _, e := range entries1 {
+			if len(e.Name()) > len("unchanged.json.") && e.Name()[:len("unchanged.json.")] == "unchanged.json." {
+				countBefore++
+			}
+		}
+
+		if err := writeWithBackup(path, data); err != nil {
+			t.Fatal(err)
+		}
+
+		entries2, _ := os.ReadDir(backupDir())
+		countAfter := 0
+		for _, e := range entries2 {
+			if len(e.Name()) > len("unchanged.json.") && e.Name()[:len("unchanged.json.")] == "unchanged.json." {
+				countAfter++
+			}
+		}
+
+		if countAfter != countBefore {
+			t.Errorf("backup was created when content unchanged (before=%d, after=%d)", countBefore, countAfter)
+		}
+	})
+
+	t.Run("backup filename contains unix timestamp", func(t *testing.T) {
+		path := filepath.Join(tmpDir, "timestamped.json")
+
+		os.WriteFile(path, []byte(`{"v": 1}`), 0o644)
+		data := mustMarshal(t, map[string]int{"v": 2})
+		if err := writeWithBackup(path, data); err != nil {
+			t.Fatal(err)
+		}
+
+		entries, _ := os.ReadDir(backupDir())
+		var found bool
+		for _, entry := range entries {
+			name := entry.Name()
+			if len(name) > len("timestamped.json.") && name[:len("timestamped.json.")] == "timestamped.json." {
+				timestamp := name[len("timestamped.json."):]
+				for _, c := range timestamp {
+					if c < '0' || c > '9' {
+						t.Errorf("backup filename timestamp contains non-numeric character: %s", name)
+					}
+				}
+				found = true
+				os.Remove(filepath.Join(backupDir(), name))
+				break
+			}
+		}
+		if !found {
+			t.Error("backup file with timestamp not found")
+		}
+	})
+}
+
+// Edge case tests for files.go
+
+// TestWriteWithBackup_FailsIfBackupFails documents critical behavior: if backup fails, we must not proceed.
+// User could lose their config with no way to recover.
+func TestWriteWithBackup_FailsIfBackupFails(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("permission tests unreliable on Windows")
+	}
+
+	tmpDir := t.TempDir()
+	path := filepath.Join(tmpDir, "config.json")
+
+	// Create original file
+	originalContent := []byte(`{"original": true}`)
+	os.WriteFile(path, originalContent, 0o644)
+
+	// Make backup directory read-only to force backup failure
+	backupDir := backupDir()
+	os.MkdirAll(backupDir, 0o755)
+	os.Chmod(backupDir, 0o444) // Read-only
+	defer os.Chmod(backupDir, 0o755)
+
+	newContent := []byte(`{"updated": true}`)
+	err := writeWithBackup(path, newContent)
+
+	// Should fail because backup couldn't be created
+	if err == nil {
+		t.Error("expected error when backup fails, got nil")
+	}
+
+	// Original file should be preserved
+	current, _ := os.ReadFile(path)
+	if string(current) != string(originalContent) {
+		t.Errorf("original file was modified despite backup failure: got %s", string(current))
+	}
+}
+
+// TestWriteWithBackup_PermissionDenied verifies clear error when target file has wrong permissions.
+// Common issue when config owned by root or wrong perms.
+func TestWriteWithBackup_PermissionDenied(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("permission tests unreliable on Windows")
+	}
+
+	tmpDir := t.TempDir()
+
+	// Create a read-only directory
+	readOnlyDir := filepath.Join(tmpDir, "readonly")
+	os.MkdirAll(readOnlyDir, 0o755)
+	os.Chmod(readOnlyDir, 0o444)
+	defer os.Chmod(readOnlyDir, 0o755)
+
+	path := filepath.Join(readOnlyDir, "config.json")
+	err := writeWithBackup(path, []byte(`{"test": true}`))
+
+	if err == nil {
+		t.Error("expected permission error, got nil")
+	}
+}
+
+// TestWriteWithBackup_DirectoryDoesNotExist verifies behavior when target directory doesn't exist.
+// writeWithBackup doesn't create directories - caller is responsible.
+func TestWriteWithBackup_DirectoryDoesNotExist(t *testing.T) {
+	tmpDir := t.TempDir()
+	path := filepath.Join(tmpDir, "nonexistent", "subdir", "config.json")
+
+	err := writeWithBackup(path, []byte(`{"test": true}`))
+
+	// Should fail because directory doesn't exist
+	if err == nil {
+		t.Error("expected error for nonexistent directory, got nil")
+	}
+}
+
+// TestWriteWithBackup_SymlinkTarget documents behavior when target is a symlink.
+// Documents what happens if user symlinks their config file.
+func TestWriteWithBackup_SymlinkTarget(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("symlink tests may require admin on Windows")
+	}
+
+	tmpDir := t.TempDir()
+	realFile := filepath.Join(tmpDir, "real.json")
+	symlink := filepath.Join(tmpDir, "link.json")
+
+	// Create real file and symlink
+	os.WriteFile(realFile, []byte(`{"v": 1}`), 0o644)
+	os.Symlink(realFile, symlink)
+
+	// Write through symlink
+	err := writeWithBackup(symlink, []byte(`{"v": 2}`))
+	if err != nil {
+		t.Fatalf("writeWithBackup through symlink failed: %v", err)
+	}
+
+	// The real file should be updated (symlink followed for temp file creation)
+	content, _ := os.ReadFile(symlink)
+	if string(content) != `{"v": 2}` {
+		t.Errorf("symlink target not updated correctly: got %s", string(content))
+	}
+}
+
+// TestBackupToTmp_SpecialCharsInFilename verifies backup works with special characters.
+// User may have config files with unusual names.
+func TestBackupToTmp_SpecialCharsInFilename(t *testing.T) {
+	tmpDir := t.TempDir()
+
+	// File with spaces and special chars
+	path := filepath.Join(tmpDir, "my config (backup).json")
+	os.WriteFile(path, []byte(`{"test": true}`), 0o644)
+
+	backupPath, err := backupToTmp(path)
+	if err != nil {
+		t.Fatalf("backupToTmp with special chars failed: %v", err)
+	}
+
+	// Verify backup exists and has correct content
+	content, err := os.ReadFile(backupPath)
+	if err != nil {
+		t.Fatalf("could not read backup: %v", err)
+	}
+	if string(content) != `{"test": true}` {
+		t.Errorf("backup content mismatch: got %s", string(content))
+	}
+
+	os.Remove(backupPath)
+}
+
+// TestCopyFile_PreservesPermissions verifies that copyFile preserves file permissions.
+func TestCopyFile_PreservesPermissions(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("permission preservation tests unreliable on Windows")
+	}
+
+	tmpDir := t.TempDir()
+	src := filepath.Join(tmpDir, "src.json")
+	dst := filepath.Join(tmpDir, "dst.json")
+
+	// Create source with specific permissions
+	os.WriteFile(src, []byte(`{"test": true}`), 0o600)
+
+	err := copyFile(src, dst)
+	if err != nil {
+		t.Fatalf("copyFile failed: %v", err)
+	}
+
+	srcInfo, _ := os.Stat(src)
+	dstInfo, _ := os.Stat(dst)
+
+	if srcInfo.Mode().Perm() != dstInfo.Mode().Perm() {
+		t.Errorf("permissions not preserved: src=%v, dst=%v", srcInfo.Mode().Perm(), dstInfo.Mode().Perm())
+	}
+}
+
+// TestCopyFile_SourceNotFound verifies clear error when source doesn't exist.
+func TestCopyFile_SourceNotFound(t *testing.T) {
+	tmpDir := t.TempDir()
+	src := filepath.Join(tmpDir, "nonexistent.json")
+	dst := filepath.Join(tmpDir, "dst.json")
+
+	err := copyFile(src, dst)
+	if err == nil {
+		t.Error("expected error for nonexistent source, got nil")
+	}
+}
+
+// TestWriteWithBackup_TargetIsDirectory verifies error when path points to a directory.
+func TestWriteWithBackup_TargetIsDirectory(t *testing.T) {
+	tmpDir := t.TempDir()
+	dirPath := filepath.Join(tmpDir, "actualdir")
+	os.MkdirAll(dirPath, 0o755)
+
+	err := writeWithBackup(dirPath, []byte(`{"test": true}`))
+	if err == nil {
+		t.Error("expected error when target is a directory, got nil")
+	}
+}
+
+// TestWriteWithBackup_EmptyData verifies writing zero bytes works correctly.
+func TestWriteWithBackup_EmptyData(t *testing.T) {
+	tmpDir := t.TempDir()
+	path := filepath.Join(tmpDir, "empty.json")
+
+	err := writeWithBackup(path, []byte{})
+	if err != nil {
+		t.Fatalf("writeWithBackup with empty data failed: %v", err)
+	}
+
+	content, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("could not read file: %v", err)
+	}
+	if len(content) != 0 {
+		t.Errorf("expected empty file, got %d bytes", len(content))
+	}
+}
+
+// TestWriteWithBackup_FileUnreadableButDirWritable verifies behavior when existing file
+// cannot be read (for backup comparison) but directory is writable.
+func TestWriteWithBackup_FileUnreadableButDirWritable(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("permission tests unreliable on Windows")
+	}
+
+	tmpDir := t.TempDir()
+	path := filepath.Join(tmpDir, "unreadable.json")
+
+	// Create file and make it unreadable
+	os.WriteFile(path, []byte(`{"original": true}`), 0o644)
+	os.Chmod(path, 0o000)
+	defer os.Chmod(path, 0o644)
+
+	// Should fail because we can't read the file to compare/backup
+	err := writeWithBackup(path, []byte(`{"updated": true}`))
+	if err == nil {
+		t.Error("expected error when file is unreadable, got nil")
+	}
+}
+
+// TestWriteWithBackup_RapidSuccessiveWrites verifies backup works with multiple writes
+// within the same second (timestamp collision scenario).
+func TestWriteWithBackup_RapidSuccessiveWrites(t *testing.T) {
+	tmpDir := t.TempDir()
+	path := filepath.Join(tmpDir, "rapid.json")
+
+	// Create initial file
+	os.WriteFile(path, []byte(`{"v": 0}`), 0o644)
+
+	// Rapid successive writes
+	for i := 1; i <= 3; i++ {
+		data := []byte(fmt.Sprintf(`{"v": %d}`, i))
+		if err := writeWithBackup(path, data); err != nil {
+			t.Fatalf("write %d failed: %v", i, err)
+		}
+	}
+
+	// Verify final content
+	content, _ := os.ReadFile(path)
+	if string(content) != `{"v": 3}` {
+		t.Errorf("expected final content {\"v\": 3}, got %s", string(content))
+	}
+
+	// Verify at least one backup exists
+	entries, _ := os.ReadDir(backupDir())
+	var backupCount int
+	for _, e := range entries {
+		if len(e.Name()) > len("rapid.json.") && e.Name()[:len("rapid.json.")] == "rapid.json." {
+			backupCount++
+		}
+	}
+	if backupCount == 0 {
+		t.Error("expected at least one backup file from rapid writes")
+	}
+}
+
+// TestWriteWithBackup_BackupDirIsFile verifies error when backup directory path is a file.
+func TestWriteWithBackup_BackupDirIsFile(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("test modifies system temp directory")
+	}
+
+	// Create a file at the backup directory path
+	backupPath := backupDir()
+	// Clean up any existing directory first
+	os.RemoveAll(backupPath)
+	// Create a file instead of directory
+	os.WriteFile(backupPath, []byte("not a directory"), 0o644)
+	defer func() {
+		os.Remove(backupPath)
+		os.MkdirAll(backupPath, 0o755)
+	}()
+
+	tmpDir := t.TempDir()
+	path := filepath.Join(tmpDir, "test.json")
+	os.WriteFile(path, []byte(`{"original": true}`), 0o644)
+
+	err := writeWithBackup(path, []byte(`{"updated": true}`))
+	if err == nil {
+		t.Error("expected error when backup dir is a file, got nil")
+	}
+}
+
+// TestWriteWithBackup_NoOrphanTempFiles verifies temp files are cleaned up on failure.
+func TestWriteWithBackup_NoOrphanTempFiles(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("permission tests unreliable on Windows")
+	}
+
+	tmpDir := t.TempDir()
+
+	// Count existing temp files
+	countTempFiles := func() int {
+		entries, _ := os.ReadDir(tmpDir)
+		count := 0
+		for _, e := range entries {
+			if len(e.Name()) > 4 && e.Name()[:4] == ".tmp" {
+				count++
+			}
+		}
+		return count
+	}
+
+	before := countTempFiles()
+
+	// Create a file, then make directory read-only to cause rename failure
+	path := filepath.Join(tmpDir, "orphan.json")
+	os.WriteFile(path, []byte(`{"v": 1}`), 0o644)
+
+	// Make a subdirectory and try to write there after making parent read-only
+	subDir := filepath.Join(tmpDir, "subdir")
+	os.MkdirAll(subDir, 0o755)
+	subPath := filepath.Join(subDir, "config.json")
+	os.WriteFile(subPath, []byte(`{"v": 1}`), 0o644)
+
+	// Make subdir read-only after creating temp file would succeed but rename would fail
+	// This is tricky to test - the temp file is created in the same dir, so if we can't
+	// rename, we also couldn't create. Let's just verify normal failure cleanup works.
+
+	// Force a failure by making the target a directory
+	badPath := filepath.Join(tmpDir, "isdir")
+	os.MkdirAll(badPath, 0o755)
+
+	_ = writeWithBackup(badPath, []byte(`{"test": true}`))
+
+	after := countTempFiles()
+	if after > before {
+		t.Errorf("orphan temp files left behind: before=%d, after=%d", before, after)
+	}
+}

cmd/config/integrations.go

@@ -0,0 +1,361 @@
+package config
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"maps"
+	"os"
+	"os/exec"
+	"runtime"
+	"slices"
+	"strings"
+	"time"
+
+	"github.com/ollama/ollama/api"
+	"github.com/spf13/cobra"
+)
+
+// Runners execute the launching of a model with the integration - claude, codex
+// Editors can edit config files (supports multi-model selection) - opencode, droid
+// They are composable interfaces where in some cases an editor is also a runner - opencode, droid
+// Runner can run an integration with a model.
+
+type Runner interface {
+	Run(model string) error
+	// String returns the human-readable name of the integration
+	String() string
+}
+
+// Editor can edit config files (supports multi-model selection)
+type Editor interface {
+	// Paths returns the paths to the config files for the integration
+	Paths() []string
+	// Edit updates the config files for the integration with the given models
+	Edit(models []string) error
+	// Models returns the models currently configured for the integration
+	Models() []string
+}
+
+// integrations is the registry of available integrations.
+var integrations = map[string]Runner{
+	"claude":   &Claude{},
+	"codex":    &Codex{},
+	"droid":    &Droid{},
+	"opencode": &OpenCode{},
+}
+
+func selectIntegration() (string, error) {
+	if len(integrations) == 0 {
+		return "", fmt.Errorf("no integrations available")
+	}
+
+	names := slices.Sorted(maps.Keys(integrations))
+	var items []selectItem
+	for _, name := range names {
+		r := integrations[name]
+		description := r.String()
+		if conn, err := loadIntegration(name); err == nil && len(conn.Models) > 0 {
+			description = fmt.Sprintf("%s (%s)", r.String(), conn.Models[0])
+		}
+		items = append(items, selectItem{Name: name, Description: description})
+	}
+
+	return selectPrompt("Select integration:", items)
+}
+
+// selectModels lets the user select models for an integration
+func selectModels(ctx context.Context, name, current string) ([]string, error) {
+	r, ok := integrations[name]
+	if !ok {
+		return nil, fmt.Errorf("unknown integration: %s", name)
+	}
+
+	client, err := api.ClientFromEnvironment()
+	if err != nil {
+		return nil, err
+	}
+
+	models, err := client.List(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(models.Models) == 0 {
+		return nil, fmt.Errorf("no models available, run 'ollama pull <model>' first")
+	}
+
+	var items []selectItem
+	cloudModels := make(map[string]bool)
+	for _, m := range models.Models {
+		if m.RemoteModel != "" {
+			cloudModels[m.Name] = true
+		}
+		items = append(items, selectItem{Name: m.Name})
+	}
+
+	if len(items) == 0 {
+		return nil, fmt.Errorf("no local models available, run 'ollama pull <model>' first")
+	}
+
+	// Get previously configured models (saved config takes precedence)
+	var preChecked []string
+	if saved, err := loadIntegration(name); err == nil {
+		preChecked = saved.Models
+	} else if editor, ok := r.(Editor); ok {
+		preChecked = editor.Models()
+	}
+	checked := make(map[string]bool, len(preChecked))
+	for _, n := range preChecked {
+		checked[n] = true
+	}
+
+	// Resolve current to full name (e.g., "llama3.2" -> "llama3.2:latest")
+	for _, item := range items {
+		if item.Name == current || strings.HasPrefix(item.Name, current+":") {
+			current = item.Name
+			break
+		}
+	}
+
+	// If current model is configured, move to front of preChecked
+	if checked[current] {
+		preChecked = append([]string{current}, slices.DeleteFunc(preChecked, func(m string) bool { return m == current })...)
+	}
+
+	// Sort: checked first, then alphabetical
+	slices.SortFunc(items, func(a, b selectItem) int {
+		ac, bc := checked[a.Name], checked[b.Name]
+		if ac != bc {
+			if ac {
+				return -1
+			}
+			return 1
+		}
+		return strings.Compare(strings.ToLower(a.Name), strings.ToLower(b.Name))
+	})
+
+	var selected []string
+	// only editors support multi-model selection
+	if _, ok := r.(Editor); ok {
+		selected, err = multiSelectPrompt(fmt.Sprintf("Select models for %s:", r), items, preChecked)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		model, err := selectPrompt(fmt.Sprintf("Select model for %s:", r), items)
+		if err != nil {
+			return nil, err
+		}
+		selected = []string{model}
+	}
+
+	// if any model in selected is a cloud model, ensure signed in
+	var selectedCloudModels []string
+	for _, m := range selected {
+		if cloudModels[m] {
+			selectedCloudModels = append(selectedCloudModels, m)
+		}
+	}
+	if len(selectedCloudModels) > 0 {
+		// ensure user is signed in
+		user, err := client.Whoami(ctx)
+		if err == nil && user != nil && user.Name != "" {
+			return selected, nil
+		}
+
+		var aErr api.AuthorizationError
+		if !errors.As(err, &aErr) || aErr.SigninURL == "" {
+			return nil, err
+		}
+
+		modelList := strings.Join(selectedCloudModels, ", ")
+		yes, err := confirmPrompt(fmt.Sprintf("sign in to use %s?", modelList))
+		if err != nil || !yes {
+			return nil, fmt.Errorf("%s requires sign in", modelList)
+		}
+
+		fmt.Fprintf(os.Stderr, "\nTo sign in, navigate to:\n    %s\n\n", aErr.SigninURL)
+
+		// TODO(parthsareen): extract into auth package for cmd
+		// Auto-open browser (best effort, fail silently)
+		switch runtime.GOOS {
+		case "darwin":
+			_ = exec.Command("open", aErr.SigninURL).Start()
+		case "linux":
+			_ = exec.Command("xdg-open", aErr.SigninURL).Start()
+		case "windows":
+			_ = exec.Command("rundll32", "url.dll,FileProtocolHandler", aErr.SigninURL).Start()
+		}
+
+		spinnerFrames := []string{"|", "/", "-", "\\"}
+		frame := 0
+
+		fmt.Fprintf(os.Stderr, "\033[90mwaiting for sign in to complete... %s\033[0m", spinnerFrames[0])
+
+		ticker := time.NewTicker(200 * time.Millisecond)
+		defer ticker.Stop()
+
+		for {
+			select {
+			case <-ctx.Done():
+				fmt.Fprintf(os.Stderr, "\r\033[K")
+				return nil, ctx.Err()
+			case <-ticker.C:
+				frame++
+				fmt.Fprintf(os.Stderr, "\r\033[90mwaiting for sign in to complete... %s\033[0m", spinnerFrames[frame%len(spinnerFrames)])
+
+				// poll every 10th frame (~2 seconds)
+				if frame%10 == 0 {
+					u, err := client.Whoami(ctx)
+					if err == nil && u != nil && u.Name != "" {
+						fmt.Fprintf(os.Stderr, "\r\033[K\033[A\r\033[K\033[1msigned in:\033[0m %s\n", u.Name)
+						return selected, nil
+					}
+				}
+			}
+		}
+	}
+
+	return selected, nil
+}
+
+func runIntegration(name, modelName string) error {
+	r, ok := integrations[name]
+	if !ok {
+		return fmt.Errorf("unknown integration: %s", name)
+	}
+	fmt.Fprintf(os.Stderr, "\nLaunching %s with %s...\n", r, modelName)
+	return r.Run(modelName)
+}
+
+// ConfigCmd returns the cobra command for configuring integrations.
+func ConfigCmd(checkServerHeartbeat func(cmd *cobra.Command, args []string) error) *cobra.Command {
+	var modelFlag string
+	var launchFlag bool
+
+	cmd := &cobra.Command{
+		Use:   "config [INTEGRATION]",
+		Short: "Configure an external integration to use Ollama",
+		Long: `Configure an external application to use Ollama models.
+
+Supported integrations:
+  claude    Claude Code
+  codex     Codex
+  droid     Droid
+  opencode  OpenCode
+
+Examples:
+  ollama config
+  ollama config claude
+  ollama config droid --launch`,
+		Args:    cobra.MaximumNArgs(1),
+		PreRunE: checkServerHeartbeat,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			var name string
+			if len(args) > 0 {
+				name = args[0]
+			} else {
+				var err error
+				name, err = selectIntegration()
+				if errors.Is(err, errCancelled) {
+					return nil
+				}
+				if err != nil {
+					return err
+				}
+			}
+
+			r, ok := integrations[strings.ToLower(name)]
+			if !ok {
+				return fmt.Errorf("unknown integration: %s", name)
+			}
+
+			// If --launch without --model, use saved config if available
+			if launchFlag && modelFlag == "" {
+				if config, err := loadIntegration(name); err == nil && len(config.Models) > 0 {
+					return runIntegration(name, config.Models[0])
+				}
+			}
+
+			var models []string
+			if modelFlag != "" {
+				// When --model is specified, merge with existing models (new model becomes default)
+				models = []string{modelFlag}
+				if existing, err := loadIntegration(name); err == nil && len(existing.Models) > 0 {
+					for _, m := range existing.Models {
+						if m != modelFlag {
+							models = append(models, m)
+						}
+					}
+				}
+			} else {
+				var err error
+				models, err = selectModels(cmd.Context(), name, "")
+				if errors.Is(err, errCancelled) {
+					return nil
+				}
+				if err != nil {
+					return err
+				}
+			}
+
+			if editor, isEditor := r.(Editor); isEditor {
+				paths := editor.Paths()
+				if len(paths) > 0 {
+					fmt.Fprintf(os.Stderr, "This will modify your %s configuration:\n", r)
+					for _, p := range paths {
+						fmt.Fprintf(os.Stderr, "  %s\n", p)
+					}
+					fmt.Fprintf(os.Stderr, "Backups will be saved to %s/\n\n", backupDir())
+
+					if ok, _ := confirmPrompt("Proceed?"); !ok {
+						return nil
+					}
+				}
+			}
+
+			if err := saveIntegration(name, models); err != nil {
+				return fmt.Errorf("failed to save: %w", err)
+			}
+
+			if editor, isEditor := r.(Editor); isEditor {
+				if err := editor.Edit(models); err != nil {
+					return fmt.Errorf("setup failed: %w", err)
+				}
+			}
+
+			if _, isEditor := r.(Editor); isEditor {
+				if len(models) == 1 {
+					fmt.Fprintf(os.Stderr, "Added %s to %s\n", models[0], r)
+				} else {
+					fmt.Fprintf(os.Stderr, "Added %d models to %s (default: %s)\n", len(models), r, models[0])
+				}
+			}
+
+			if slices.ContainsFunc(models, func(m string) bool {
+				return !strings.HasSuffix(m, "cloud")
+			}) {
+				fmt.Fprintln(os.Stderr)
+				fmt.Fprintln(os.Stderr, "Coding agents work best with at least 64k context. Either:")
+				fmt.Fprintln(os.Stderr, "  - Set the context slider in Ollama app settings")
+				fmt.Fprintln(os.Stderr, "  - Run: OLLAMA_CONTEXT_LENGTH=64000 ollama serve")
+			}
+
+			if launchFlag {
+				return runIntegration(name, models[0])
+			}
+
+			if launch, _ := confirmPrompt(fmt.Sprintf("\nLaunch %s now?", r)); launch {
+				return runIntegration(name, models[0])
+			}
+
+			fmt.Fprintf(os.Stderr, "Run 'ollama config %s --launch' to start with %s\n", strings.ToLower(name), models[0])
+			return nil
+		},
+	}
+
+	cmd.Flags().StringVar(&modelFlag, "model", "", "Model to use")
+	cmd.Flags().BoolVar(&launchFlag, "launch", false, "Launch the integration after configuring")
+	return cmd
+}

cmd/config/integrations_test.go

@@ -0,0 +1,188 @@
+package config
+
+import (
+	"slices"
+	"strings"
+	"testing"
+
+	"github.com/spf13/cobra"
+)
+
+func TestIntegrationLookup(t *testing.T) {
+	tests := []struct {
+		name      string
+		input     string
+		wantFound bool
+		wantName  string
+	}{
+		{"claude lowercase", "claude", true, "Claude Code"},
+		{"claude uppercase", "CLAUDE", true, "Claude Code"},
+		{"claude mixed case", "Claude", true, "Claude Code"},
+		{"codex", "codex", true, "Codex"},
+		{"droid", "droid", true, "Droid"},
+		{"opencode", "opencode", true, "OpenCode"},
+		{"unknown integration", "unknown", false, ""},
+		{"empty string", "", false, ""},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			r, found := integrations[strings.ToLower(tt.input)]
+			if found != tt.wantFound {
+				t.Errorf("integrations[%q] found = %v, want %v", tt.input, found, tt.wantFound)
+			}
+			if found && r.String() != tt.wantName {
+				t.Errorf("integrations[%q].String() = %q, want %q", tt.input, r.String(), tt.wantName)
+			}
+		})
+	}
+}
+
+func TestIntegrationRegistry(t *testing.T) {
+	expectedIntegrations := []string{"claude", "codex", "droid", "opencode"}
+
+	for _, name := range expectedIntegrations {
+		t.Run(name, func(t *testing.T) {
+			r, ok := integrations[name]
+			if !ok {
+				t.Fatalf("integration %q not found in registry", name)
+			}
+			if r.String() == "" {
+				t.Error("integration.String() should not be empty")
+			}
+		})
+	}
+}
+
+func TestHasLocalModel(t *testing.T) {
+	tests := []struct {
+		name   string
+		models []string
+		want   bool
+	}{
+		{"empty list", []string{}, false},
+		{"single local model", []string{"llama3.2"}, true},
+		{"single cloud model", []string{"cloud-model"}, false},
+		{"mixed models", []string{"cloud-model", "llama3.2"}, true},
+		{"multiple local models", []string{"llama3.2", "qwen2.5"}, true},
+		{"multiple cloud models", []string{"cloud-a", "cloud-b"}, false},
+		{"local model first", []string{"llama3.2", "cloud-model"}, true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := slices.ContainsFunc(tt.models, func(m string) bool {
+				return !strings.Contains(m, "cloud")
+			})
+			if got != tt.want {
+				t.Errorf("hasLocalModel(%v) = %v, want %v", tt.models, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestConfigCmd(t *testing.T) {
+	// Mock checkServerHeartbeat that always succeeds
+	mockCheck := func(cmd *cobra.Command, args []string) error {
+		return nil
+	}
+
+	cmd := ConfigCmd(mockCheck)
+
+	t.Run("command structure", func(t *testing.T) {
+		if cmd.Use != "config [INTEGRATION]" {
+			t.Errorf("Use = %q, want %q", cmd.Use, "config [INTEGRATION]")
+		}
+		if cmd.Short == "" {
+			t.Error("Short description should not be empty")
+		}
+		if cmd.Long == "" {
+			t.Error("Long description should not be empty")
+		}
+	})
+
+	t.Run("flags exist", func(t *testing.T) {
+		modelFlag := cmd.Flags().Lookup("model")
+		if modelFlag == nil {
+			t.Error("--model flag should exist")
+		}
+
+		launchFlag := cmd.Flags().Lookup("launch")
+		if launchFlag == nil {
+			t.Error("--launch flag should exist")
+		}
+	})
+
+	t.Run("PreRunE is set", func(t *testing.T) {
+		if cmd.PreRunE == nil {
+			t.Error("PreRunE should be set to checkServerHeartbeat")
+		}
+	})
+}
+
+func TestRunIntegration_UnknownIntegration(t *testing.T) {
+	err := runIntegration("unknown-integration", "model")
+	if err == nil {
+		t.Error("expected error for unknown integration, got nil")
+	}
+	if !strings.Contains(err.Error(), "unknown integration") {
+		t.Errorf("error should mention 'unknown integration', got: %v", err)
+	}
+}
+
+func TestHasLocalModel_DocumentsHeuristic(t *testing.T) {
+	tests := []struct {
+		name   string
+		models []string
+		want   bool
+		reason string
+	}{
+		{"empty list", []string{}, false, "empty list has no local models"},
+		{"contains-cloud-substring", []string{"deepseek-r1:cloud"}, false, "model with 'cloud' substring is considered cloud"},
+		{"cloud-in-name", []string{"my-cloud-model"}, false, "'cloud' anywhere in name = cloud model"},
+		{"cloudless", []string{"cloudless-model"}, false, "'cloudless' still contains 'cloud'"},
+		{"local-model", []string{"llama3.2"}, true, "no 'cloud' = local"},
+		{"mixed", []string{"cloud-model", "llama3.2"}, true, "one local model = hasLocalModel true"},
+		{"all-cloud", []string{"cloud-a", "cloud-b"}, false, "all contain 'cloud'"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := slices.ContainsFunc(tt.models, func(m string) bool {
+				return !strings.Contains(m, "cloud")
+			})
+			if got != tt.want {
+				t.Errorf("hasLocalModel(%v) = %v, want %v (%s)", tt.models, got, tt.want, tt.reason)
+			}
+		})
+	}
+}
+
+func TestConfigCmd_NilHeartbeat(t *testing.T) {
+	// This should not panic - cmd creation should work even with nil
+	cmd := ConfigCmd(nil)
+	if cmd == nil {
+		t.Fatal("ConfigCmd returned nil")
+	}
+
+	// PreRunE should be nil when passed nil
+	if cmd.PreRunE != nil {
+		t.Log("Note: PreRunE is set even when nil is passed (acceptable)")
+	}
+}
+
+func TestAllIntegrations_HaveRequiredMethods(t *testing.T) {
+	for name, r := range integrations {
+		t.Run(name, func(t *testing.T) {
+			// Test String() doesn't panic and returns non-empty
+			displayName := r.String()
+			if displayName == "" {
+				t.Error("String() should not return empty")
+			}
+
+			// Test Run() exists (we can't call it without actually running the command)
+			// Just verify the method is available
+			var _ func(string) error = r.Run
+		})
+	}
+}

cmd/config/opencode.go

@@ -0,0 +1,203 @@
+package config
+
+import (
+	"encoding/json"
+	"fmt"
+	"maps"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"slices"
+	"strings"
+)
+
+// OpenCode implements Runner and Editor for OpenCode integration
+type OpenCode struct{}
+
+func (o *OpenCode) String() string { return "OpenCode" }
+
+func (o *OpenCode) Run(model string) error {
+	if _, err := exec.LookPath("opencode"); err != nil {
+		return fmt.Errorf("opencode is not installed, install from https://opencode.ai")
+	}
+
+	// Call Edit() to ensure config is up-to-date before launch
+	models := []string{model}
+	if config, err := loadIntegration("opencode"); err == nil && len(config.Models) > 0 {
+		models = config.Models
+	}
+	if err := o.Edit(models); err != nil {
+		return fmt.Errorf("setup failed: %w", err)
+	}
+
+	cmd := exec.Command("opencode")
+	cmd.Stdin = os.Stdin
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	return cmd.Run()
+}
+
+func (o *OpenCode) Paths() []string {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return nil
+	}
+
+	var paths []string
+	p := filepath.Join(home, ".config", "opencode", "opencode.json")
+	if _, err := os.Stat(p); err == nil {
+		paths = append(paths, p)
+	}
+	sp := filepath.Join(home, ".local", "state", "opencode", "model.json")
+	if _, err := os.Stat(sp); err == nil {
+		paths = append(paths, sp)
+	}
+	return paths
+}
+
+func (o *OpenCode) Edit(modelList []string) error {
+	if len(modelList) == 0 {
+		return nil
+	}
+
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return err
+	}
+
+	configPath := filepath.Join(home, ".config", "opencode", "opencode.json")
+	if err := os.MkdirAll(filepath.Dir(configPath), 0o755); err != nil {
+		return err
+	}
+
+	config := make(map[string]any)
+	if data, err := os.ReadFile(configPath); err == nil {
+		_ = json.Unmarshal(data, &config) // Ignore parse errors; treat missing/corrupt files as empty
+	}
+
+	config["$schema"] = "https://opencode.ai/config.json"
+
+	provider, ok := config["provider"].(map[string]any)
+	if !ok {
+		provider = make(map[string]any)
+	}
+
+	ollama, ok := provider["ollama"].(map[string]any)
+	if !ok {
+		ollama = map[string]any{
+			"npm":  "@ai-sdk/openai-compatible",
+			"name": "Ollama (local)",
+			"options": map[string]any{
+				"baseURL": "http://localhost:11434/v1",
+			},
+		}
+	}
+
+	models, ok := ollama["models"].(map[string]any)
+	if !ok {
+		models = make(map[string]any)
+	}
+
+	selectedSet := make(map[string]bool)
+	for _, m := range modelList {
+		selectedSet[m] = true
+	}
+
+	for name, cfg := range models {
+		if cfgMap, ok := cfg.(map[string]any); ok {
+			if displayName, ok := cfgMap["name"].(string); ok {
+				if strings.HasSuffix(displayName, "[Ollama]") && !selectedSet[name] {
+					delete(models, name)
+				}
+			}
+		}
+	}
+
+	for _, model := range modelList {
+		models[model] = map[string]any{
+			"name": fmt.Sprintf("%s [Ollama]", model),
+		}
+	}
+
+	ollama["models"] = models
+	provider["ollama"] = ollama
+	config["provider"] = provider
+
+	configData, err := json.MarshalIndent(config, "", "  ")
+	if err != nil {
+		return err
+	}
+	if err := writeWithBackup(configPath, configData); err != nil {
+		return err
+	}
+
+	statePath := filepath.Join(home, ".local", "state", "opencode", "model.json")
+	if err := os.MkdirAll(filepath.Dir(statePath), 0o755); err != nil {
+		return err
+	}
+
+	state := map[string]any{
+		"recent":   []any{},
+		"favorite": []any{},
+		"variant":  map[string]any{},
+	}
+	if data, err := os.ReadFile(statePath); err == nil {
+		_ = json.Unmarshal(data, &state) // Ignore parse errors; use defaults
+	}
+
+	recent, _ := state["recent"].([]any)
+
+	modelSet := make(map[string]bool)
+	for _, m := range modelList {
+		modelSet[m] = true
+	}
+
+	// Filter out existing Ollama models we're about to re-add
+	newRecent := slices.DeleteFunc(slices.Clone(recent), func(entry any) bool {
+		e, ok := entry.(map[string]any)
+		if !ok || e["providerID"] != "ollama" {
+			return false
+		}
+		modelID, _ := e["modelID"].(string)
+		return modelSet[modelID]
+	})
+
+	// Prepend models in reverse order so first model ends up first
+	for _, model := range slices.Backward(modelList) {
+		newRecent = slices.Insert(newRecent, 0, any(map[string]any{
+			"providerID": "ollama",
+			"modelID":    model,
+		}))
+	}
+
+	const maxRecentModels = 10
+	newRecent = newRecent[:min(len(newRecent), maxRecentModels)]
+
+	state["recent"] = newRecent
+
+	stateData, err := json.MarshalIndent(state, "", "  ")
+	if err != nil {
+		return err
+	}
+	return writeWithBackup(statePath, stateData)
+}
+
+func (o *OpenCode) Models() []string {
+	home, err := os.UserHomeDir()
+	if err != nil {
+		return nil
+	}
+	config, err := readJSONFile(filepath.Join(home, ".config", "opencode", "opencode.json"))
+	if err != nil {
+		return nil
+	}
+	provider, _ := config["provider"].(map[string]any)
+	ollama, _ := provider["ollama"].(map[string]any)
+	models, _ := ollama["models"].(map[string]any)
+	if len(models) == 0 {
+		return nil
+	}
+	keys := slices.Collect(maps.Keys(models))
+	slices.Sort(keys)
+	return keys
+}

cmd/config/opencode_test.go

@@ -0,0 +1,437 @@
+package config
+
+import (
+	"encoding/json"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestOpenCodeIntegration(t *testing.T) {
+	o := &OpenCode{}
+
+	t.Run("String", func(t *testing.T) {
+		if got := o.String(); got != "OpenCode" {
+			t.Errorf("String() = %q, want %q", got, "OpenCode")
+		}
+	})
+
+	t.Run("implements Runner", func(t *testing.T) {
+		var _ Runner = o
+	})
+
+	t.Run("implements Editor", func(t *testing.T) {
+		var _ Editor = o
+	})
+}
+
+func TestOpenCodeEdit(t *testing.T) {
+	o := &OpenCode{}
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	configDir := filepath.Join(tmpDir, ".config", "opencode")
+	configPath := filepath.Join(configDir, "opencode.json")
+	stateDir := filepath.Join(tmpDir, ".local", "state", "opencode")
+	statePath := filepath.Join(stateDir, "model.json")
+
+	cleanup := func() {
+		os.RemoveAll(configDir)
+		os.RemoveAll(stateDir)
+	}
+
+	t.Run("fresh install", func(t *testing.T) {
+		cleanup()
+		if err := o.Edit([]string{"llama3.2"}); err != nil {
+			t.Fatal(err)
+		}
+		assertOpenCodeModelExists(t, configPath, "llama3.2")
+		assertOpenCodeRecentModel(t, statePath, 0, "ollama", "llama3.2")
+	})
+
+	t.Run("preserve other providers", func(t *testing.T) {
+		cleanup()
+		os.MkdirAll(configDir, 0o755)
+		os.WriteFile(configPath, []byte(`{"provider":{"anthropic":{"apiKey":"xxx"}}}`), 0o644)
+		if err := o.Edit([]string{"llama3.2"}); err != nil {
+			t.Fatal(err)
+		}
+		data, _ := os.ReadFile(configPath)
+		var cfg map[string]any
+		json.Unmarshal(data, &cfg)
+		provider := cfg["provider"].(map[string]any)
+		if provider["anthropic"] == nil {
+			t.Error("anthropic provider was removed")
+		}
+		assertOpenCodeModelExists(t, configPath, "llama3.2")
+	})
+
+	t.Run("preserve other models", func(t *testing.T) {
+		cleanup()
+		os.MkdirAll(configDir, 0o755)
+		os.WriteFile(configPath, []byte(`{"provider":{"ollama":{"models":{"mistral":{"name":"Mistral"}}}}}`), 0o644)
+		if err := o.Edit([]string{"llama3.2"}); err != nil {
+			t.Fatal(err)
+		}
+		assertOpenCodeModelExists(t, configPath, "mistral")
+		assertOpenCodeModelExists(t, configPath, "llama3.2")
+	})
+
+	t.Run("update existing model", func(t *testing.T) {
+		cleanup()
+		o.Edit([]string{"llama3.2"})
+		o.Edit([]string{"llama3.2"})
+		assertOpenCodeModelExists(t, configPath, "llama3.2")
+	})
+
+	t.Run("preserve top-level keys", func(t *testing.T) {
+		cleanup()
+		os.MkdirAll(configDir, 0o755)
+		os.WriteFile(configPath, []byte(`{"theme":"dark","keybindings":{}}`), 0o644)
+		if err := o.Edit([]string{"llama3.2"}); err != nil {
+			t.Fatal(err)
+		}
+		data, _ := os.ReadFile(configPath)
+		var cfg map[string]any
+		json.Unmarshal(data, &cfg)
+		if cfg["theme"] != "dark" {
+			t.Error("theme was removed")
+		}
+		if cfg["keybindings"] == nil {
+			t.Error("keybindings was removed")
+		}
+	})
+
+	t.Run("model state - insert at index 0", func(t *testing.T) {
+		cleanup()
+		os.MkdirAll(stateDir, 0o755)
+		os.WriteFile(statePath, []byte(`{"recent":[{"providerID":"anthropic","modelID":"claude"}],"favorite":[],"variant":{}}`), 0o644)
+		if err := o.Edit([]string{"llama3.2"}); err != nil {
+			t.Fatal(err)
+		}
+		assertOpenCodeRecentModel(t, statePath, 0, "ollama", "llama3.2")
+		assertOpenCodeRecentModel(t, statePath, 1, "anthropic", "claude")
+	})
+
+	t.Run("model state - preserve favorites and variants", func(t *testing.T) {
+		cleanup()
+		os.MkdirAll(stateDir, 0o755)
+		os.WriteFile(statePath, []byte(`{"recent":[],"favorite":[{"providerID":"x","modelID":"y"}],"variant":{"a":"b"}}`), 0o644)
+		if err := o.Edit([]string{"llama3.2"}); err != nil {
+			t.Fatal(err)
+		}
+		data, _ := os.ReadFile(statePath)
+		var state map[string]any
+		json.Unmarshal(data, &state)
+		if len(state["favorite"].([]any)) != 1 {
+			t.Error("favorite was modified")
+		}
+		if state["variant"].(map[string]any)["a"] != "b" {
+			t.Error("variant was modified")
+		}
+	})
+
+	t.Run("model state - deduplicate on re-add", func(t *testing.T) {
+		cleanup()
+		os.MkdirAll(stateDir, 0o755)
+		os.WriteFile(statePath, []byte(`{"recent":[{"providerID":"ollama","modelID":"llama3.2"},{"providerID":"anthropic","modelID":"claude"}],"favorite":[],"variant":{}}`), 0o644)
+		if err := o.Edit([]string{"llama3.2"}); err != nil {
+			t.Fatal(err)
+		}
+		data, _ := os.ReadFile(statePath)
+		var state map[string]any
+		json.Unmarshal(data, &state)
+		recent := state["recent"].([]any)
+		if len(recent) != 2 {
+			t.Errorf("expected 2 recent entries, got %d", len(recent))
+		}
+		assertOpenCodeRecentModel(t, statePath, 0, "ollama", "llama3.2")
+	})
+
+	t.Run("remove model", func(t *testing.T) {
+		cleanup()
+		// First add two models
+		o.Edit([]string{"llama3.2", "mistral"})
+		assertOpenCodeModelExists(t, configPath, "llama3.2")
+		assertOpenCodeModelExists(t, configPath, "mistral")
+
+		// Then remove one by only selecting the other
+		o.Edit([]string{"llama3.2"})
+		assertOpenCodeModelExists(t, configPath, "llama3.2")
+		assertOpenCodeModelNotExists(t, configPath, "mistral")
+	})
+
+	t.Run("remove model preserves non-ollama models", func(t *testing.T) {
+		cleanup()
+		os.MkdirAll(configDir, 0o755)
+		// Add a non-Ollama model manually
+		os.WriteFile(configPath, []byte(`{"provider":{"ollama":{"models":{"external":{"name":"External Model"}}}}}`), 0o644)
+
+		o.Edit([]string{"llama3.2"})
+		assertOpenCodeModelExists(t, configPath, "llama3.2")
+		assertOpenCodeModelExists(t, configPath, "external") // Should be preserved
+	})
+}
+
+func assertOpenCodeModelExists(t *testing.T, path, model string) {
+	t.Helper()
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var cfg map[string]any
+	if err := json.Unmarshal(data, &cfg); err != nil {
+		t.Fatal(err)
+	}
+	provider, ok := cfg["provider"].(map[string]any)
+	if !ok {
+		t.Fatal("provider not found")
+	}
+	ollama, ok := provider["ollama"].(map[string]any)
+	if !ok {
+		t.Fatal("ollama provider not found")
+	}
+	models, ok := ollama["models"].(map[string]any)
+	if !ok {
+		t.Fatal("models not found")
+	}
+	if models[model] == nil {
+		t.Errorf("model %s not found", model)
+	}
+}
+
+func assertOpenCodeModelNotExists(t *testing.T, path, model string) {
+	t.Helper()
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var cfg map[string]any
+	if err := json.Unmarshal(data, &cfg); err != nil {
+		t.Fatal(err)
+	}
+	provider, ok := cfg["provider"].(map[string]any)
+	if !ok {
+		return // No provider means no model
+	}
+	ollama, ok := provider["ollama"].(map[string]any)
+	if !ok {
+		return // No ollama means no model
+	}
+	models, ok := ollama["models"].(map[string]any)
+	if !ok {
+		return // No models means no model
+	}
+	if models[model] != nil {
+		t.Errorf("model %s should not exist but was found", model)
+	}
+}
+
+func assertOpenCodeRecentModel(t *testing.T, path string, index int, providerID, modelID string) {
+	t.Helper()
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	var state map[string]any
+	if err := json.Unmarshal(data, &state); err != nil {
+		t.Fatal(err)
+	}
+	recent, ok := state["recent"].([]any)
+	if !ok {
+		t.Fatal("recent not found")
+	}
+	if index >= len(recent) {
+		t.Fatalf("index %d out of range (len=%d)", index, len(recent))
+	}
+	entry, ok := recent[index].(map[string]any)
+	if !ok {
+		t.Fatal("entry is not a map")
+	}
+	if entry["providerID"] != providerID {
+		t.Errorf("expected providerID %s, got %s", providerID, entry["providerID"])
+	}
+	if entry["modelID"] != modelID {
+		t.Errorf("expected modelID %s, got %s", modelID, entry["modelID"])
+	}
+}
+
+// Edge case tests for opencode.go
+
+func TestOpenCodeEdit_CorruptedConfigJSON(t *testing.T) {
+	o := &OpenCode{}
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	configDir := filepath.Join(tmpDir, ".config", "opencode")
+	configPath := filepath.Join(configDir, "opencode.json")
+
+	os.MkdirAll(configDir, 0o755)
+	os.WriteFile(configPath, []byte(`{corrupted json content`), 0o644)
+
+	// Should not panic - corrupted JSON should be treated as empty
+	err := o.Edit([]string{"llama3.2"})
+	if err != nil {
+		t.Fatalf("Edit failed with corrupted config: %v", err)
+	}
+
+	// Verify valid JSON was created
+	data, _ := os.ReadFile(configPath)
+	var cfg map[string]any
+	if err := json.Unmarshal(data, &cfg); err != nil {
+		t.Errorf("resulting config is not valid JSON: %v", err)
+	}
+}
+
+func TestOpenCodeEdit_CorruptedStateJSON(t *testing.T) {
+	o := &OpenCode{}
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	stateDir := filepath.Join(tmpDir, ".local", "state", "opencode")
+	statePath := filepath.Join(stateDir, "model.json")
+
+	os.MkdirAll(stateDir, 0o755)
+	os.WriteFile(statePath, []byte(`{corrupted state`), 0o644)
+
+	err := o.Edit([]string{"llama3.2"})
+	if err != nil {
+		t.Fatalf("Edit failed with corrupted state: %v", err)
+	}
+
+	// Verify valid state was created
+	data, _ := os.ReadFile(statePath)
+	var state map[string]any
+	if err := json.Unmarshal(data, &state); err != nil {
+		t.Errorf("resulting state is not valid JSON: %v", err)
+	}
+}
+
+func TestOpenCodeEdit_WrongTypeProvider(t *testing.T) {
+	o := &OpenCode{}
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	configDir := filepath.Join(tmpDir, ".config", "opencode")
+	configPath := filepath.Join(configDir, "opencode.json")
+
+	os.MkdirAll(configDir, 0o755)
+	os.WriteFile(configPath, []byte(`{"provider": "not a map"}`), 0o644)
+
+	err := o.Edit([]string{"llama3.2"})
+	if err != nil {
+		t.Fatalf("Edit with wrong type provider failed: %v", err)
+	}
+
+	// Verify provider is now correct type
+	data, _ := os.ReadFile(configPath)
+	var cfg map[string]any
+	json.Unmarshal(data, &cfg)
+
+	provider, ok := cfg["provider"].(map[string]any)
+	if !ok {
+		t.Fatalf("provider should be map after setup, got %T", cfg["provider"])
+	}
+	if provider["ollama"] == nil {
+		t.Error("ollama provider should be created")
+	}
+}
+
+func TestOpenCodeEdit_WrongTypeRecent(t *testing.T) {
+	o := &OpenCode{}
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	stateDir := filepath.Join(tmpDir, ".local", "state", "opencode")
+	statePath := filepath.Join(stateDir, "model.json")
+
+	os.MkdirAll(stateDir, 0o755)
+	os.WriteFile(statePath, []byte(`{"recent": "not an array", "favorite": [], "variant": {}}`), 0o644)
+
+	err := o.Edit([]string{"llama3.2"})
+	if err != nil {
+		t.Fatalf("Edit with wrong type recent failed: %v", err)
+	}
+
+	// The function should handle this gracefully
+	data, _ := os.ReadFile(statePath)
+	var state map[string]any
+	json.Unmarshal(data, &state)
+
+	// recent should be properly set after setup
+	recent, ok := state["recent"].([]any)
+	if !ok {
+		t.Logf("Note: recent type after setup is %T (documenting behavior)", state["recent"])
+	} else if len(recent) == 0 {
+		t.Logf("Note: recent is empty (documenting behavior)")
+	}
+}
+
+func TestOpenCodeEdit_EmptyModels(t *testing.T) {
+	o := &OpenCode{}
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	configDir := filepath.Join(tmpDir, ".config", "opencode")
+	configPath := filepath.Join(configDir, "opencode.json")
+
+	os.MkdirAll(configDir, 0o755)
+	originalContent := `{"provider":{"ollama":{"models":{"existing":{}}}}}`
+	os.WriteFile(configPath, []byte(originalContent), 0o644)
+
+	// Empty models should be no-op
+	err := o.Edit([]string{})
+	if err != nil {
+		t.Fatalf("Edit with empty models failed: %v", err)
+	}
+
+	// Original content should be preserved (file not modified)
+	data, _ := os.ReadFile(configPath)
+	if string(data) != originalContent {
+		t.Errorf("empty models should not modify file, but content changed")
+	}
+}
+
+func TestOpenCodeEdit_SpecialCharsInModelName(t *testing.T) {
+	o := &OpenCode{}
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	// Model name with special characters (though unusual)
+	specialModel := `model-with-"quotes"`
+
+	err := o.Edit([]string{specialModel})
+	if err != nil {
+		t.Fatalf("Edit with special chars failed: %v", err)
+	}
+
+	// Verify it was stored correctly
+	configDir := filepath.Join(tmpDir, ".config", "opencode")
+	configPath := filepath.Join(configDir, "opencode.json")
+	data, _ := os.ReadFile(configPath)
+
+	var cfg map[string]any
+	if err := json.Unmarshal(data, &cfg); err != nil {
+		t.Fatalf("resulting config is invalid JSON: %v", err)
+	}
+
+	// Model should be accessible
+	provider, _ := cfg["provider"].(map[string]any)
+	ollama, _ := provider["ollama"].(map[string]any)
+	models, _ := ollama["models"].(map[string]any)
+
+	if models[specialModel] == nil {
+		t.Errorf("model with special chars not found in config")
+	}
+}
+
+func TestOpenCodeModels_NoConfig(t *testing.T) {
+	o := &OpenCode{}
+	tmpDir := t.TempDir()
+	setTestHome(t, tmpDir)
+
+	models := o.Models()
+	if len(models) > 0 {
+		t.Errorf("expected nil/empty for missing config, got %v", models)
+	}
+}

cmd/config/selector.go

@@ -0,0 +1,499 @@
+package config
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+
+	"golang.org/x/term"
+)
+
+// ANSI escape sequences for terminal formatting.
+const (
+	ansiHideCursor = "\033[?25l"
+	ansiShowCursor = "\033[?25h"
+	ansiBold       = "\033[1m"
+	ansiReset      = "\033[0m"
+	ansiGray       = "\033[37m"
+	ansiClearDown  = "\033[J"
+)
+
+const maxDisplayedItems = 10
+
+var errCancelled = errors.New("cancelled")
+
+type selectItem struct {
+	Name        string
+	Description string
+}
+
+type inputEvent int
+
+const (
+	eventNone inputEvent = iota
+	eventEnter
+	eventEscape
+	eventUp
+	eventDown
+	eventTab
+	eventBackspace
+	eventChar
+)
+
+type selectState struct {
+	items        []selectItem
+	filter       string
+	selected     int
+	scrollOffset int
+}
+
+func newSelectState(items []selectItem) *selectState {
+	return &selectState{items: items}
+}
+
+func (s *selectState) filtered() []selectItem {
+	return filterItems(s.items, s.filter)
+}
+
+func (s *selectState) handleInput(event inputEvent, char byte) (done bool, result string, err error) {
+	filtered := s.filtered()
+
+	switch event {
+	case eventEnter:
+		if len(filtered) > 0 && s.selected < len(filtered) {
+			return true, filtered[s.selected].Name, nil
+		}
+	case eventEscape:
+		return true, "", errCancelled
+	case eventBackspace:
+		if len(s.filter) > 0 {
+			s.filter = s.filter[:len(s.filter)-1]
+			s.selected = 0
+			s.scrollOffset = 0
+		}
+	case eventUp:
+		if s.selected > 0 {
+			s.selected--
+			if s.selected < s.scrollOffset {
+				s.scrollOffset = s.selected
+			}
+		}
+	case eventDown:
+		if s.selected < len(filtered)-1 {
+			s.selected++
+			if s.selected >= s.scrollOffset+maxDisplayedItems {
+				s.scrollOffset = s.selected - maxDisplayedItems + 1
+			}
+		}
+	case eventChar:
+		s.filter += string(char)
+		s.selected = 0
+		s.scrollOffset = 0
+	}
+
+	return false, "", nil
+}
+
+type multiSelectState struct {
+	items         []selectItem
+	itemIndex     map[string]int
+	filter        string
+	highlighted   int
+	scrollOffset  int
+	checked       map[int]bool
+	checkOrder    []int
+	focusOnButton bool
+}
+
+func newMultiSelectState(items []selectItem, preChecked []string) *multiSelectState {
+	s := &multiSelectState{
+		items:     items,
+		itemIndex: make(map[string]int, len(items)),
+		checked:   make(map[int]bool),
+	}
+
+	for i, item := range items {
+		s.itemIndex[item.Name] = i
+	}
+
+	for _, name := range preChecked {
+		if idx, ok := s.itemIndex[name]; ok {
+			s.checked[idx] = true
+			s.checkOrder = append(s.checkOrder, idx)
+		}
+	}
+
+	return s
+}
+
+func (s *multiSelectState) filtered() []selectItem {
+	return filterItems(s.items, s.filter)
+}
+
+func (s *multiSelectState) toggleItem() {
+	filtered := s.filtered()
+	if len(filtered) == 0 || s.highlighted >= len(filtered) {
+		return
+	}
+
+	item := filtered[s.highlighted]
+	origIdx := s.itemIndex[item.Name]
+
+	if s.checked[origIdx] {
+		delete(s.checked, origIdx)
+		for i, idx := range s.checkOrder {
+			if idx == origIdx {
+				s.checkOrder = append(s.checkOrder[:i], s.checkOrder[i+1:]...)
+				break
+			}
+		}
+	} else {
+		s.checked[origIdx] = true
+		s.checkOrder = append(s.checkOrder, origIdx)
+	}
+}
+
+func (s *multiSelectState) handleInput(event inputEvent, char byte) (done bool, result []string, err error) {
+	filtered := s.filtered()
+
+	switch event {
+	case eventEnter:
+		if s.focusOnButton && len(s.checkOrder) > 0 {
+			var res []string
+			for _, idx := range s.checkOrder {
+				res = append(res, s.items[idx].Name)
+			}
+			return true, res, nil
+		} else if !s.focusOnButton {
+			s.toggleItem()
+		}
+	case eventTab:
+		if len(s.checkOrder) > 0 {
+			s.focusOnButton = !s.focusOnButton
+		}
+	case eventEscape:
+		return true, nil, errCancelled
+	case eventBackspace:
+		if len(s.filter) > 0 {
+			s.filter = s.filter[:len(s.filter)-1]
+			s.highlighted = 0
+			s.scrollOffset = 0
+			s.focusOnButton = false
+		}
+	case eventUp:
+		if s.focusOnButton {
+			s.focusOnButton = false
+		} else if s.highlighted > 0 {
+			s.highlighted--
+			if s.highlighted < s.scrollOffset {
+				s.scrollOffset = s.highlighted
+			}
+		}
+	case eventDown:
+		if s.focusOnButton {
+			s.focusOnButton = false
+		} else if s.highlighted < len(filtered)-1 {
+			s.highlighted++
+			if s.highlighted >= s.scrollOffset+maxDisplayedItems {
+				s.scrollOffset = s.highlighted - maxDisplayedItems + 1
+			}
+		}
+	case eventChar:
+		s.filter += string(char)
+		s.highlighted = 0
+		s.scrollOffset = 0
+		s.focusOnButton = false
+	}
+
+	return false, nil, nil
+}
+
+func (s *multiSelectState) selectedCount() int {
+	return len(s.checkOrder)
+}
+
+// Terminal I/O handling
+
+type terminalState struct {
+	fd       int
+	oldState *term.State
+}
+
+func enterRawMode() (*terminalState, error) {
+	fd := int(os.Stdin.Fd())
+	oldState, err := term.MakeRaw(fd)
+	if err != nil {
+		return nil, err
+	}
+	fmt.Fprint(os.Stderr, ansiHideCursor)
+	return &terminalState{fd: fd, oldState: oldState}, nil
+}
+
+func (t *terminalState) restore() {
+	fmt.Fprint(os.Stderr, ansiShowCursor)
+	term.Restore(t.fd, t.oldState)
+}
+
+func clearLines(n int) {
+	if n > 0 {
+		fmt.Fprintf(os.Stderr, "\033[%dA", n)
+		fmt.Fprint(os.Stderr, ansiClearDown)
+	}
+}
+
+func parseInput(r io.Reader) (inputEvent, byte, error) {
+	buf := make([]byte, 3)
+	n, err := r.Read(buf)
+	if err != nil {
+		return 0, 0, err
+	}
+
+	switch {
+	case n == 1 && buf[0] == 13:
+		return eventEnter, 0, nil
+	case n == 1 && (buf[0] == 3 || buf[0] == 27):
+		return eventEscape, 0, nil
+	case n == 1 && buf[0] == 9:
+		return eventTab, 0, nil
+	case n == 1 && buf[0] == 127:
+		return eventBackspace, 0, nil
+	case n == 3 && buf[0] == 27 && buf[1] == 91 && buf[2] == 65:
+		return eventUp, 0, nil
+	case n == 3 && buf[0] == 27 && buf[1] == 91 && buf[2] == 66:
+		return eventDown, 0, nil
+	case n == 1 && buf[0] >= 32 && buf[0] < 127:
+		return eventChar, buf[0], nil
+	}
+
+	return eventNone, 0, nil
+}
+
+// Rendering
+
+func renderSelect(w io.Writer, prompt string, s *selectState) int {
+	filtered := s.filtered()
+
+	fmt.Fprintf(w, "%s %s\r\n", prompt, s.filter)
+	lineCount := 1
+
+	if len(filtered) == 0 {
+		fmt.Fprintf(w, "  %s(no matches)%s\r\n", ansiGray, ansiReset)
+		lineCount++
+	} else {
+		displayCount := min(len(filtered), maxDisplayedItems)
+
+		for i := range displayCount {
+			idx := s.scrollOffset + i
+			if idx >= len(filtered) {
+				break
+			}
+			item := filtered[idx]
+			prefix := "    "
+			if idx == s.selected {
+				prefix = "  " + ansiBold + "> "
+			}
+			if item.Description != "" {
+				fmt.Fprintf(w, "%s%s%s %s- %s%s\r\n", prefix, item.Name, ansiReset, ansiGray, item.Description, ansiReset)
+			} else {
+				fmt.Fprintf(w, "%s%s%s\r\n", prefix, item.Name, ansiReset)
+			}
+			lineCount++
+		}
+
+		if remaining := len(filtered) - s.scrollOffset - displayCount; remaining > 0 {
+			fmt.Fprintf(w, "  %s... and %d more%s\r\n", ansiGray, remaining, ansiReset)
+			lineCount++
+		}
+	}
+
+	return lineCount
+}
+
+func renderMultiSelect(w io.Writer, prompt string, s *multiSelectState) int {
+	filtered := s.filtered()
+
+	fmt.Fprintf(w, "%s %s\r\n", prompt, s.filter)
+	lineCount := 1
+
+	if len(filtered) == 0 {
+		fmt.Fprintf(w, "  %s(no matches)%s\r\n", ansiGray, ansiReset)
+		lineCount++
+	} else {
+		displayCount := min(len(filtered), maxDisplayedItems)
+
+		for i := range displayCount {
+			idx := s.scrollOffset + i
+			if idx >= len(filtered) {
+				break
+			}
+			item := filtered[idx]
+			origIdx := s.itemIndex[item.Name]
+
+			checkbox := "[ ]"
+			if s.checked[origIdx] {
+				checkbox = "[x]"
+			}
+
+			prefix := "  "
+			suffix := ""
+			if idx == s.highlighted && !s.focusOnButton {
+				prefix = "> "
+			}
+			if len(s.checkOrder) > 0 && s.checkOrder[0] == origIdx {
+				suffix = " " + ansiGray + "(default)" + ansiReset
+			}
+
+			if idx == s.highlighted && !s.focusOnButton {
+				fmt.Fprintf(w, "  %s%s %s %s%s%s\r\n", ansiBold, prefix, checkbox, item.Name, ansiReset, suffix)
+			} else {
+				fmt.Fprintf(w, "  %s %s %s%s\r\n", prefix, checkbox, item.Name, suffix)
+			}
+			lineCount++
+		}
+
+		if remaining := len(filtered) - s.scrollOffset - displayCount; remaining > 0 {
+			fmt.Fprintf(w, "  %s... and %d more%s\r\n", ansiGray, remaining, ansiReset)
+			lineCount++
+		}
+	}
+
+	fmt.Fprintf(w, "\r\n")
+	lineCount++
+	count := s.selectedCount()
+	switch {
+	case count == 0:
+		fmt.Fprintf(w, "  %sSelect at least one model.%s\r\n", ansiGray, ansiReset)
+	case s.focusOnButton:
+		fmt.Fprintf(w, "  %s> [ Continue ]%s %s(%d selected)%s\r\n", ansiBold, ansiReset, ansiGray, count, ansiReset)
+	default:
+		fmt.Fprintf(w, "    %s[ Continue ] (%d selected) - press Tab%s\r\n", ansiGray, count, ansiReset)
+	}
+	lineCount++
+
+	return lineCount
+}
+
+// selectPrompt prompts the user to select a single item from a list.
+func selectPrompt(prompt string, items []selectItem) (string, error) {
+	if len(items) == 0 {
+		return "", fmt.Errorf("no items to select from")
+	}
+
+	ts, err := enterRawMode()
+	if err != nil {
+		return "", err
+	}
+	defer ts.restore()
+
+	state := newSelectState(items)
+	var lastLineCount int
+
+	render := func() {
+		clearLines(lastLineCount)
+		lastLineCount = renderSelect(os.Stderr, prompt, state)
+	}
+
+	render()
+
+	for {
+		event, char, err := parseInput(os.Stdin)
+		if err != nil {
+			return "", err
+		}
+
+		done, result, err := state.handleInput(event, char)
+		if done {
+			clearLines(lastLineCount)
+			if err != nil {
+				return "", err
+			}
+			return result, nil
+		}
+
+		render()
+	}
+}
+
+// multiSelectPrompt prompts the user to select multiple items from a list.
+func multiSelectPrompt(prompt string, items []selectItem, preChecked []string) ([]string, error) {
+	if len(items) == 0 {
+		return nil, fmt.Errorf("no items to select from")
+	}
+
+	ts, err := enterRawMode()
+	if err != nil {
+		return nil, err
+	}
+	defer ts.restore()
+
+	state := newMultiSelectState(items, preChecked)
+	var lastLineCount int
+
+	render := func() {
+		clearLines(lastLineCount)
+		lastLineCount = renderMultiSelect(os.Stderr, prompt, state)
+	}
+
+	render()
+
+	for {
+		event, char, err := parseInput(os.Stdin)
+		if err != nil {
+			return nil, err
+		}
+
+		done, result, err := state.handleInput(event, char)
+		if done {
+			clearLines(lastLineCount)
+			if err != nil {
+				return nil, err
+			}
+			return result, nil
+		}
+
+		render()
+	}
+}
+
+func confirmPrompt(prompt string) (bool, error) {
+	fd := int(os.Stdin.Fd())
+	oldState, err := term.MakeRaw(fd)
+	if err != nil {
+		return false, err
+	}
+	defer term.Restore(fd, oldState)
+
+	fmt.Fprintf(os.Stderr, "%s [y/n] ", prompt)
+
+	buf := make([]byte, 1)
+	for {
+		if _, err := os.Stdin.Read(buf); err != nil {
+			return false, err
+		}
+
+		switch buf[0] {
+		case 'Y', 'y', 13:
+			fmt.Fprintf(os.Stderr, "yes\r\n")
+			return true, nil
+		case 'N', 'n', 27, 3:
+			fmt.Fprintf(os.Stderr, "no\r\n")
+			return false, nil
+		}
+	}
+}
+
+func filterItems(items []selectItem, filter string) []selectItem {
+	if filter == "" {
+		return items
+	}
+	var result []selectItem
+	filterLower := strings.ToLower(filter)
+	for _, item := range items {
+		if strings.Contains(strings.ToLower(item.Name), filterLower) {
+			result = append(result, item)
+		}
+	}
+	return result
+}

cmd/config/selector_test.go

@@ -0,0 +1,913 @@
+package config
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+)
+
+func TestFilterItems(t *testing.T) {
+	items := []selectItem{
+		{Name: "llama3.2:latest"},
+		{Name: "qwen2.5:7b"},
+		{Name: "deepseek-v3:cloud"},
+		{Name: "GPT-OSS:20b"},
+	}
+
+	t.Run("EmptyFilter_ReturnsAllItems", func(t *testing.T) {
+		result := filterItems(items, "")
+		if len(result) != len(items) {
+			t.Errorf("expected %d items, got %d", len(items), len(result))
+		}
+	})
+
+	t.Run("CaseInsensitive_UppercaseFilterMatchesLowercase", func(t *testing.T) {
+		result := filterItems(items, "LLAMA")
+		if len(result) != 1 || result[0].Name != "llama3.2:latest" {
+			t.Errorf("expected llama3.2:latest, got %v", result)
+		}
+	})
+
+	t.Run("CaseInsensitive_LowercaseFilterMatchesUppercase", func(t *testing.T) {
+		result := filterItems(items, "gpt")
+		if len(result) != 1 || result[0].Name != "GPT-OSS:20b" {
+			t.Errorf("expected GPT-OSS:20b, got %v", result)
+		}
+	})
+
+	t.Run("PartialMatch", func(t *testing.T) {
+		result := filterItems(items, "deep")
+		if len(result) != 1 || result[0].Name != "deepseek-v3:cloud" {
+			t.Errorf("expected deepseek-v3:cloud, got %v", result)
+		}
+	})
+
+	t.Run("NoMatch_ReturnsEmpty", func(t *testing.T) {
+		result := filterItems(items, "nonexistent")
+		if len(result) != 0 {
+			t.Errorf("expected 0 items, got %d", len(result))
+		}
+	})
+}
+
+func TestSelectState(t *testing.T) {
+	items := []selectItem{
+		{Name: "item1"},
+		{Name: "item2"},
+		{Name: "item3"},
+	}
+
+	t.Run("InitialState", func(t *testing.T) {
+		s := newSelectState(items)
+		if s.selected != 0 {
+			t.Errorf("expected selected=0, got %d", s.selected)
+		}
+		if s.filter != "" {
+			t.Errorf("expected empty filter, got %q", s.filter)
+		}
+		if s.scrollOffset != 0 {
+			t.Errorf("expected scrollOffset=0, got %d", s.scrollOffset)
+		}
+	})
+
+	t.Run("Enter_SelectsCurrentItem", func(t *testing.T) {
+		s := newSelectState(items)
+		done, result, err := s.handleInput(eventEnter, 0)
+		if !done || result != "item1" || err != nil {
+			t.Errorf("expected (true, item1, nil), got (%v, %v, %v)", done, result, err)
+		}
+	})
+
+	t.Run("Enter_WithFilter_SelectsFilteredItem", func(t *testing.T) {
+		s := newSelectState(items)
+		s.filter = "item3"
+		done, result, err := s.handleInput(eventEnter, 0)
+		if !done || result != "item3" || err != nil {
+			t.Errorf("expected (true, item3, nil), got (%v, %v, %v)", done, result, err)
+		}
+	})
+
+	t.Run("Enter_EmptyFilteredList_DoesNothing", func(t *testing.T) {
+		s := newSelectState(items)
+		s.filter = "nonexistent"
+		done, result, err := s.handleInput(eventEnter, 0)
+		if done || result != "" || err != nil {
+			t.Errorf("expected (false, '', nil), got (%v, %v, %v)", done, result, err)
+		}
+	})
+
+	t.Run("Escape_ReturnsCancelledError", func(t *testing.T) {
+		s := newSelectState(items)
+		done, result, err := s.handleInput(eventEscape, 0)
+		if !done || result != "" || err != errCancelled {
+			t.Errorf("expected (true, '', errCancelled), got (%v, %v, %v)", done, result, err)
+		}
+	})
+
+	t.Run("Down_MovesSelection", func(t *testing.T) {
+		s := newSelectState(items)
+		s.handleInput(eventDown, 0)
+		if s.selected != 1 {
+			t.Errorf("expected selected=1, got %d", s.selected)
+		}
+	})
+
+	t.Run("Down_AtBottom_StaysAtBottom", func(t *testing.T) {
+		s := newSelectState(items)
+		s.selected = 2
+		s.handleInput(eventDown, 0)
+		if s.selected != 2 {
+			t.Errorf("expected selected=2 (stayed at bottom), got %d", s.selected)
+		}
+	})
+
+	t.Run("Up_MovesSelection", func(t *testing.T) {
+		s := newSelectState(items)
+		s.selected = 2
+		s.handleInput(eventUp, 0)
+		if s.selected != 1 {
+			t.Errorf("expected selected=1, got %d", s.selected)
+		}
+	})
+
+	t.Run("Up_AtTop_StaysAtTop", func(t *testing.T) {
+		s := newSelectState(items)
+		s.handleInput(eventUp, 0)
+		if s.selected != 0 {
+			t.Errorf("expected selected=0 (stayed at top), got %d", s.selected)
+		}
+	})
+
+	t.Run("Char_AppendsToFilter", func(t *testing.T) {
+		s := newSelectState(items)
+		s.handleInput(eventChar, 'i')
+		s.handleInput(eventChar, 't')
+		s.handleInput(eventChar, 'e')
+		s.handleInput(eventChar, 'm')
+		s.handleInput(eventChar, '2')
+		if s.filter != "item2" {
+			t.Errorf("expected filter='item2', got %q", s.filter)
+		}
+		filtered := s.filtered()
+		if len(filtered) != 1 || filtered[0].Name != "item2" {
+			t.Errorf("expected [item2], got %v", filtered)
+		}
+	})
+
+	t.Run("Char_ResetsSelectionToZero", func(t *testing.T) {
+		s := newSelectState(items)
+		s.selected = 2
+		s.handleInput(eventChar, 'x')
+		if s.selected != 0 {
+			t.Errorf("expected selected=0 after typing, got %d", s.selected)
+		}
+	})
+
+	t.Run("Backspace_RemovesLastFilterChar", func(t *testing.T) {
+		s := newSelectState(items)
+		s.filter = "test"
+		s.handleInput(eventBackspace, 0)
+		if s.filter != "tes" {
+			t.Errorf("expected filter='tes', got %q", s.filter)
+		}
+	})
+
+	t.Run("Backspace_EmptyFilter_DoesNothing", func(t *testing.T) {
+		s := newSelectState(items)
+		s.handleInput(eventBackspace, 0)
+		if s.filter != "" {
+			t.Errorf("expected filter='', got %q", s.filter)
+		}
+	})
+
+	t.Run("Backspace_ResetsSelectionToZero", func(t *testing.T) {
+		s := newSelectState(items)
+		s.filter = "test"
+		s.selected = 2
+		s.handleInput(eventBackspace, 0)
+		if s.selected != 0 {
+			t.Errorf("expected selected=0 after backspace, got %d", s.selected)
+		}
+	})
+
+	t.Run("Scroll_DownPastVisibleItems_ScrollsViewport", func(t *testing.T) {
+		// maxDisplayedItems is 10, so with 15 items we need to scroll
+		manyItems := make([]selectItem, 15)
+		for i := range manyItems {
+			manyItems[i] = selectItem{Name: string(rune('a' + i))}
+		}
+		s := newSelectState(manyItems)
+
+		// move down 12 times (past the 10-item viewport)
+		for range 12 {
+			s.handleInput(eventDown, 0)
+		}
+
+		if s.selected != 12 {
+			t.Errorf("expected selected=12, got %d", s.selected)
+		}
+		if s.scrollOffset != 3 {
+			t.Errorf("expected scrollOffset=3 (12-10+1), got %d", s.scrollOffset)
+		}
+	})
+
+	t.Run("Scroll_UpPastScrollOffset_ScrollsViewport", func(t *testing.T) {
+		manyItems := make([]selectItem, 15)
+		for i := range manyItems {
+			manyItems[i] = selectItem{Name: string(rune('a' + i))}
+		}
+		s := newSelectState(manyItems)
+		s.selected = 5
+		s.scrollOffset = 5
+
+		s.handleInput(eventUp, 0)
+
+		if s.selected != 4 {
+			t.Errorf("expected selected=4, got %d", s.selected)
+		}
+		if s.scrollOffset != 4 {
+			t.Errorf("expected scrollOffset=4, got %d", s.scrollOffset)
+		}
+	})
+}
+
+func TestMultiSelectState(t *testing.T) {
+	items := []selectItem{
+		{Name: "item1"},
+		{Name: "item2"},
+		{Name: "item3"},
+	}
+
+	t.Run("InitialState_NoPrechecked", func(t *testing.T) {
+		s := newMultiSelectState(items, nil)
+		if s.highlighted != 0 {
+			t.Errorf("expected highlighted=0, got %d", s.highlighted)
+		}
+		if s.selectedCount() != 0 {
+			t.Errorf("expected 0 selected, got %d", s.selectedCount())
+		}
+		if s.focusOnButton {
+			t.Error("expected focusOnButton=false initially")
+		}
+	})
+
+	t.Run("InitialState_WithPrechecked", func(t *testing.T) {
+		s := newMultiSelectState(items, []string{"item2", "item3"})
+		if s.selectedCount() != 2 {
+			t.Errorf("expected 2 selected, got %d", s.selectedCount())
+		}
+		if !s.checked[1] || !s.checked[2] {
+			t.Error("expected item2 and item3 to be checked")
+		}
+	})
+
+	t.Run("Prechecked_PreservesSelectionOrder", func(t *testing.T) {
+		// order matters: first checked = default model
+		s := newMultiSelectState(items, []string{"item3", "item1"})
+		if len(s.checkOrder) != 2 {
+			t.Fatalf("expected 2 in checkOrder, got %d", len(s.checkOrder))
+		}
+		if s.checkOrder[0] != 2 || s.checkOrder[1] != 0 {
+			t.Errorf("expected checkOrder=[2,0] (item3 first), got %v", s.checkOrder)
+		}
+	})
+
+	t.Run("Prechecked_IgnoresInvalidNames", func(t *testing.T) {
+		s := newMultiSelectState(items, []string{"item1", "nonexistent"})
+		if s.selectedCount() != 1 {
+			t.Errorf("expected 1 selected (nonexistent ignored), got %d", s.selectedCount())
+		}
+	})
+
+	t.Run("Toggle_ChecksUncheckedItem", func(t *testing.T) {
+		s := newMultiSelectState(items, nil)
+		s.toggleItem()
+		if !s.checked[0] {
+			t.Error("expected item1 to be checked after toggle")
+		}
+	})
+
+	t.Run("Toggle_UnchecksCheckedItem", func(t *testing.T) {
+		s := newMultiSelectState(items, []string{"item1"})
+		s.toggleItem()
+		if s.checked[0] {
+			t.Error("expected item1 to be unchecked after toggle")
+		}
+	})
+
+	t.Run("Toggle_RemovesFromCheckOrder", func(t *testing.T) {
+		s := newMultiSelectState(items, []string{"item1", "item2", "item3"})
+		s.highlighted = 1 // toggle item2
+		s.toggleItem()
+
+		if len(s.checkOrder) != 2 {
+			t.Fatalf("expected 2 in checkOrder, got %d", len(s.checkOrder))
+		}
+		// should be [0, 2] (item1, item3) with item2 removed
+		if s.checkOrder[0] != 0 || s.checkOrder[1] != 2 {
+			t.Errorf("expected checkOrder=[0,2], got %v", s.checkOrder)
+		}
+	})
+
+	t.Run("Enter_TogglesWhenNotOnButton", func(t *testing.T) {
+		s := newMultiSelectState(items, nil)
+		s.handleInput(eventEnter, 0)
+		if !s.checked[0] {
+			t.Error("expected item1 to be checked after enter")
+		}
+	})
+
+	t.Run("Enter_OnButton_ReturnsSelection", func(t *testing.T) {
+		s := newMultiSelectState(items, []string{"item2", "item1"})
+		s.focusOnButton = true
+
+		done, result, err := s.handleInput(eventEnter, 0)
+
+		if !done || err != nil {
+			t.Errorf("expected done=true, err=nil, got done=%v, err=%v", done, err)
+		}
+		// result should preserve selection order
+		if len(result) != 2 || result[0] != "item2" || result[1] != "item1" {
+			t.Errorf("expected [item2, item1], got %v", result)
+		}
+	})
+
+	t.Run("Enter_OnButton_EmptySelection_DoesNothing", func(t *testing.T) {
+		s := newMultiSelectState(items, nil)
+		s.focusOnButton = true
+		done, result, err := s.handleInput(eventEnter, 0)
+		if done || result != nil || err != nil {
+			t.Errorf("expected (false, nil, nil), got (%v, %v, %v)", done, result, err)
+		}
+	})
+
+	t.Run("Tab_SwitchesToButton_WhenHasSelection", func(t *testing.T) {
+		s := newMultiSelectState(items, []string{"item1"})
+		s.handleInput(eventTab, 0)
+		if !s.focusOnButton {
+			t.Error("expected focus on button after tab")
+		}
+	})
+
+	t.Run("Tab_DoesNothing_WhenNoSelection", func(t *testing.T) {
+		s := newMultiSelectState(items, nil)
+		s.handleInput(eventTab, 0)
+		if s.focusOnButton {
+			t.Error("tab should not focus button when nothing selected")
+		}
+	})
+
+	t.Run("Tab_TogglesButtonFocus", func(t *testing.T) {
+		s := newMultiSelectState(items, []string{"item1"})
+		s.handleInput(eventTab, 0)
+		if !s.focusOnButton {
+			t.Error("expected focus on button after first tab")
+		}
+		s.handleInput(eventTab, 0)
+		if s.focusOnButton {
+			t.Error("expected focus back on list after second tab")
+		}
+	})
+
+	t.Run("Escape_ReturnsCancelledError", func(t *testing.T) {
+		s := newMultiSelectState(items, []string{"item1"})
+		done, result, err := s.handleInput(eventEscape, 0)
+		if !done || result != nil || err != errCancelled {
+			t.Errorf("expected (true, nil, errCancelled), got (%v, %v, %v)", done, result, err)
+		}
+	})
+
+	t.Run("IsDefault_TrueForFirstChecked", func(t *testing.T) {
+		s := newMultiSelectState(items, []string{"item2", "item1"})
+		if !(len(s.checkOrder) > 0 && s.checkOrder[0] == 1) {
+			t.Error("expected item2 (idx 1) to be default (first checked)")
+		}
+		if len(s.checkOrder) > 0 && s.checkOrder[0] == 0 {
+			t.Error("expected item1 (idx 0) to NOT be default")
+		}
+	})
+
+	t.Run("IsDefault_FalseWhenNothingChecked", func(t *testing.T) {
+		s := newMultiSelectState(items, nil)
+		if len(s.checkOrder) > 0 && s.checkOrder[0] == 0 {
+			t.Error("expected isDefault=false when nothing checked")
+		}
+	})
+
+	t.Run("Down_MovesHighlight", func(t *testing.T) {
+		s := newMultiSelectState(items, nil)
+		s.handleInput(eventDown, 0)
+		if s.highlighted != 1 {
+			t.Errorf("expected highlighted=1, got %d", s.highlighted)
+		}
+	})
+
+	t.Run("Up_MovesHighlight", func(t *testing.T) {
+		s := newMultiSelectState(items, nil)
+		s.highlighted = 1
+		s.handleInput(eventUp, 0)
+		if s.highlighted != 0 {
+			t.Errorf("expected highlighted=0, got %d", s.highlighted)
+		}
+	})
+
+	t.Run("Arrow_ReturnsFocusFromButton", func(t *testing.T) {
+		s := newMultiSelectState(items, []string{"item1"})
+		s.focusOnButton = true
+		s.handleInput(eventDown, 0)
+		if s.focusOnButton {
+			t.Error("expected focus to return to list on arrow key")
+		}
+	})
+
+	t.Run("Char_AppendsToFilter", func(t *testing.T) {
+		s := newMultiSelectState(items, nil)
+		s.handleInput(eventChar, 'x')
+		if s.filter != "x" {
+			t.Errorf("expected filter='x', got %q", s.filter)
+		}
+	})
+
+	t.Run("Char_ResetsHighlightAndScroll", func(t *testing.T) {
+		manyItems := make([]selectItem, 15)
+		for i := range manyItems {
+			manyItems[i] = selectItem{Name: string(rune('a' + i))}
+		}
+		s := newMultiSelectState(manyItems, nil)
+		s.highlighted = 10
+		s.scrollOffset = 5
+
+		s.handleInput(eventChar, 'x')
+
+		if s.highlighted != 0 {
+			t.Errorf("expected highlighted=0, got %d", s.highlighted)
+		}
+		if s.scrollOffset != 0 {
+			t.Errorf("expected scrollOffset=0, got %d", s.scrollOffset)
+		}
+	})
+
+	t.Run("Backspace_RemovesLastFilterChar", func(t *testing.T) {
+		s := newMultiSelectState(items, nil)
+		s.filter = "test"
+		s.handleInput(eventBackspace, 0)
+		if s.filter != "tes" {
+			t.Errorf("expected filter='tes', got %q", s.filter)
+		}
+	})
+
+	t.Run("Backspace_RemovesFocusFromButton", func(t *testing.T) {
+		s := newMultiSelectState(items, []string{"item1"})
+		s.filter = "x"
+		s.focusOnButton = true
+		s.handleInput(eventBackspace, 0)
+		if s.focusOnButton {
+			t.Error("expected focusOnButton=false after backspace")
+		}
+	})
+}
+
+func TestParseInput(t *testing.T) {
+	t.Run("Enter", func(t *testing.T) {
+		event, char, err := parseInput(bytes.NewReader([]byte{13}))
+		if err != nil || event != eventEnter || char != 0 {
+			t.Errorf("expected (eventEnter, 0, nil), got (%v, %v, %v)", event, char, err)
+		}
+	})
+
+	t.Run("Escape", func(t *testing.T) {
+		event, _, err := parseInput(bytes.NewReader([]byte{27}))
+		if err != nil || event != eventEscape {
+			t.Errorf("expected eventEscape, got %v", event)
+		}
+	})
+
+	t.Run("CtrlC_TreatedAsEscape", func(t *testing.T) {
+		event, _, err := parseInput(bytes.NewReader([]byte{3}))
+		if err != nil || event != eventEscape {
+			t.Errorf("expected eventEscape for Ctrl+C, got %v", event)
+		}
+	})
+
+	t.Run("Tab", func(t *testing.T) {
+		event, _, err := parseInput(bytes.NewReader([]byte{9}))
+		if err != nil || event != eventTab {
+			t.Errorf("expected eventTab, got %v", event)
+		}
+	})
+
+	t.Run("Backspace", func(t *testing.T) {
+		event, _, err := parseInput(bytes.NewReader([]byte{127}))
+		if err != nil || event != eventBackspace {
+			t.Errorf("expected eventBackspace, got %v", event)
+		}
+	})
+
+	t.Run("UpArrow", func(t *testing.T) {
+		event, _, err := parseInput(bytes.NewReader([]byte{27, 91, 65}))
+		if err != nil || event != eventUp {
+			t.Errorf("expected eventUp, got %v", event)
+		}
+	})
+
+	t.Run("DownArrow", func(t *testing.T) {
+		event, _, err := parseInput(bytes.NewReader([]byte{27, 91, 66}))
+		if err != nil || event != eventDown {
+			t.Errorf("expected eventDown, got %v", event)
+		}
+	})
+
+	t.Run("PrintableChars", func(t *testing.T) {
+		tests := []struct {
+			name string
+			char byte
+		}{
+			{"lowercase", 'a'},
+			{"uppercase", 'Z'},
+			{"digit", '5'},
+			{"space", ' '},
+			{"tilde", '~'},
+		}
+		for _, tt := range tests {
+			t.Run(tt.name, func(t *testing.T) {
+				event, char, err := parseInput(bytes.NewReader([]byte{tt.char}))
+				if err != nil || event != eventChar || char != tt.char {
+					t.Errorf("expected (eventChar, %q), got (%v, %q)", tt.char, event, char)
+				}
+			})
+		}
+	})
+}
+
+func TestRenderSelect(t *testing.T) {
+	items := []selectItem{
+		{Name: "item1", Description: "first item"},
+		{Name: "item2"},
+	}
+
+	t.Run("ShowsPromptAndItems", func(t *testing.T) {
+		s := newSelectState(items)
+		var buf bytes.Buffer
+		lineCount := renderSelect(&buf, "Select:", s)
+
+		output := buf.String()
+		if !strings.Contains(output, "Select:") {
+			t.Error("expected prompt in output")
+		}
+		if !strings.Contains(output, "item1") {
+			t.Error("expected item1 in output")
+		}
+		if !strings.Contains(output, "first item") {
+			t.Error("expected description in output")
+		}
+		if !strings.Contains(output, "item2") {
+			t.Error("expected item2 in output")
+		}
+		if lineCount != 3 { // 1 prompt + 2 items
+			t.Errorf("expected 3 lines, got %d", lineCount)
+		}
+	})
+
+	t.Run("EmptyFilteredList_ShowsNoMatches", func(t *testing.T) {
+		s := newSelectState(items)
+		s.filter = "xyz"
+		var buf bytes.Buffer
+		renderSelect(&buf, "Select:", s)
+
+		if !strings.Contains(buf.String(), "no matches") {
+			t.Error("expected 'no matches' message")
+		}
+	})
+
+	t.Run("LongList_ShowsRemainingCount", func(t *testing.T) {
+		manyItems := make([]selectItem, 15)
+		for i := range manyItems {
+			manyItems[i] = selectItem{Name: string(rune('a' + i))}
+		}
+		s := newSelectState(manyItems)
+		var buf bytes.Buffer
+		renderSelect(&buf, "Select:", s)
+
+		// 15 items - 10 displayed = 5 more
+		if !strings.Contains(buf.String(), "5 more") {
+			t.Error("expected '5 more' indicator")
+		}
+	})
+}
+
+func TestRenderMultiSelect(t *testing.T) {
+	items := []selectItem{
+		{Name: "item1"},
+		{Name: "item2"},
+	}
+
+	t.Run("ShowsCheckboxes", func(t *testing.T) {
+		s := newMultiSelectState(items, []string{"item1"})
+		var buf bytes.Buffer
+		renderMultiSelect(&buf, "Select:", s)
+
+		output := buf.String()
+		if !strings.Contains(output, "[x]") {
+			t.Error("expected checked checkbox [x]")
+		}
+		if !strings.Contains(output, "[ ]") {
+			t.Error("expected unchecked checkbox [ ]")
+		}
+	})
+
+	t.Run("ShowsDefaultMarker", func(t *testing.T) {
+		s := newMultiSelectState(items, []string{"item1"})
+		var buf bytes.Buffer
+		renderMultiSelect(&buf, "Select:", s)
+
+		if !strings.Contains(buf.String(), "(default)") {
+			t.Error("expected (default) marker for first checked item")
+		}
+	})
+
+	t.Run("ShowsSelectedCount", func(t *testing.T) {
+		s := newMultiSelectState(items, []string{"item1", "item2"})
+		var buf bytes.Buffer
+		renderMultiSelect(&buf, "Select:", s)
+
+		if !strings.Contains(buf.String(), "2 selected") {
+			t.Error("expected '2 selected' in output")
+		}
+	})
+
+	t.Run("NoSelection_ShowsHelperText", func(t *testing.T) {
+		s := newMultiSelectState(items, nil)
+		var buf bytes.Buffer
+		renderMultiSelect(&buf, "Select:", s)
+
+		if !strings.Contains(buf.String(), "Select at least one") {
+			t.Error("expected 'Select at least one' helper text")
+		}
+	})
+}
+
+func TestErrCancelled(t *testing.T) {
+	t.Run("NotNil", func(t *testing.T) {
+		if errCancelled == nil {
+			t.Error("errCancelled should not be nil")
+		}
+	})
+
+	t.Run("Message", func(t *testing.T) {
+		if errCancelled.Error() != "cancelled" {
+			t.Errorf("expected 'cancelled', got %q", errCancelled.Error())
+		}
+	})
+}
+
+// Edge case tests for selector.go
+
+// TestSelectState_SingleItem verifies that single item list works without crash.
+// List with only one item should still work.
+func TestSelectState_SingleItem(t *testing.T) {
+	items := []selectItem{{Name: "only-one"}}
+
+	s := newSelectState(items)
+
+	// Down should do nothing (already at bottom)
+	s.handleInput(eventDown, 0)
+	if s.selected != 0 {
+		t.Errorf("down on single item: expected selected=0, got %d", s.selected)
+	}
+
+	// Up should do nothing (already at top)
+	s.handleInput(eventUp, 0)
+	if s.selected != 0 {
+		t.Errorf("up on single item: expected selected=0, got %d", s.selected)
+	}
+
+	// Enter should select the only item
+	done, result, err := s.handleInput(eventEnter, 0)
+	if !done || result != "only-one" || err != nil {
+		t.Errorf("enter on single item: expected (true, 'only-one', nil), got (%v, %q, %v)", done, result, err)
+	}
+}
+
+// TestSelectState_ExactlyMaxItems verifies boundary condition at maxDisplayedItems.
+// List with exactly maxDisplayedItems items should not scroll.
+func TestSelectState_ExactlyMaxItems(t *testing.T) {
+	items := make([]selectItem, maxDisplayedItems)
+	for i := range items {
+		items[i] = selectItem{Name: string(rune('a' + i))}
+	}
+
+	s := newSelectState(items)
+
+	// Move to last item
+	for range maxDisplayedItems - 1 {
+		s.handleInput(eventDown, 0)
+	}
+
+	if s.selected != maxDisplayedItems-1 {
+		t.Errorf("expected selected=%d, got %d", maxDisplayedItems-1, s.selected)
+	}
+
+	// Should not scroll when exactly at max
+	if s.scrollOffset != 0 {
+		t.Errorf("expected scrollOffset=0 for exactly maxDisplayedItems, got %d", s.scrollOffset)
+	}
+
+	// One more down should do nothing
+	s.handleInput(eventDown, 0)
+	if s.selected != maxDisplayedItems-1 {
+		t.Errorf("down at max: expected selected=%d, got %d", maxDisplayedItems-1, s.selected)
+	}
+}
+
+// TestFilterItems_RegexSpecialChars verifies that filter is literal, not regex.
+// User typing "model.v1" shouldn't match "modelsv1".
+func TestFilterItems_RegexSpecialChars(t *testing.T) {
+	items := []selectItem{
+		{Name: "model.v1"},
+		{Name: "modelsv1"},
+		{Name: "model-v1"},
+	}
+
+	// Filter with dot should only match literal dot
+	result := filterItems(items, "model.v1")
+	if len(result) != 1 {
+		t.Errorf("expected 1 exact match, got %d", len(result))
+	}
+	if len(result) > 0 && result[0].Name != "model.v1" {
+		t.Errorf("expected 'model.v1', got %s", result[0].Name)
+	}
+
+	// Other regex special chars should be literal too
+	items2 := []selectItem{
+		{Name: "test[0]"},
+		{Name: "test0"},
+		{Name: "test(1)"},
+	}
+
+	result2 := filterItems(items2, "test[0]")
+	if len(result2) != 1 || result2[0].Name != "test[0]" {
+		t.Errorf("expected only 'test[0]', got %v", result2)
+	}
+}
+
+// TestMultiSelectState_DuplicateNames documents handling of duplicate item names.
+// itemIndex uses name as key - duplicates cause collision. This documents
+// the current behavior: the last index for a duplicate name is stored
+func TestMultiSelectState_DuplicateNames(t *testing.T) {
+	// Duplicate names - this is an edge case that shouldn't happen in practice
+	items := []selectItem{
+		{Name: "duplicate"},
+		{Name: "duplicate"},
+		{Name: "unique"},
+	}
+
+	s := newMultiSelectState(items, nil)
+
+	// DOCUMENTED BEHAVIOR: itemIndex maps name to LAST index
+	// When there are duplicates, only the last occurrence's index is stored
+	if s.itemIndex["duplicate"] != 1 {
+		t.Errorf("itemIndex should map 'duplicate' to last index (1), got %d", s.itemIndex["duplicate"])
+	}
+
+	// Toggle item at highlighted=0 (first "duplicate")
+	// Due to name collision, toggleItem uses itemIndex["duplicate"] = 1
+	// So it actually toggles the SECOND duplicate item, not the first
+	s.toggleItem()
+
+	// This documents the potentially surprising behavior:
+	// We toggled at highlighted=0, but itemIndex lookup returned 1
+	if !s.checked[1] {
+		t.Error("toggle should check index 1 (due to name collision in itemIndex)")
+	}
+	if s.checked[0] {
+		t.Log("Note: index 0 is NOT checked, even though highlighted=0 (name collision behavior)")
+	}
+}
+
+// TestSelectState_FilterReducesBelowSelection verifies selection resets when filter reduces list.
+// Prevents index-out-of-bounds on next keystroke
+func TestSelectState_FilterReducesBelowSelection(t *testing.T) {
+	items := []selectItem{
+		{Name: "apple"},
+		{Name: "banana"},
+		{Name: "cherry"},
+	}
+
+	s := newSelectState(items)
+	s.selected = 2 // Select "cherry"
+
+	// Type a filter that removes cherry from results
+	s.handleInput(eventChar, 'a') // Filter to "a" - matches "apple" and "banana"
+
+	// Selection should reset to 0
+	if s.selected != 0 {
+		t.Errorf("expected selected=0 after filter, got %d", s.selected)
+	}
+
+	filtered := s.filtered()
+	if len(filtered) != 2 {
+		t.Errorf("expected 2 filtered items, got %d", len(filtered))
+	}
+}
+
+// TestFilterItems_UnicodeCharacters verifies filtering works with UTF-8.
+// Model names might contain unicode characters
+func TestFilterItems_UnicodeCharacters(t *testing.T) {
+	items := []selectItem{
+		{Name: "llama-日本語"},
+		{Name: "模型-chinese"},
+		{Name: "émoji-🦙"},
+		{Name: "regular-model"},
+	}
+
+	t.Run("filter japanese", func(t *testing.T) {
+		result := filterItems(items, "日本")
+		if len(result) != 1 || result[0].Name != "llama-日本語" {
+			t.Errorf("expected llama-日本語, got %v", result)
+		}
+	})
+
+	t.Run("filter chinese", func(t *testing.T) {
+		result := filterItems(items, "模型")
+		if len(result) != 1 || result[0].Name != "模型-chinese" {
+			t.Errorf("expected 模型-chinese, got %v", result)
+		}
+	})
+
+	t.Run("filter emoji", func(t *testing.T) {
+		result := filterItems(items, "🦙")
+		if len(result) != 1 || result[0].Name != "émoji-🦙" {
+			t.Errorf("expected émoji-🦙, got %v", result)
+		}
+	})
+
+	t.Run("filter accented char", func(t *testing.T) {
+		result := filterItems(items, "émoji")
+		if len(result) != 1 || result[0].Name != "émoji-🦙" {
+			t.Errorf("expected émoji-🦙, got %v", result)
+		}
+	})
+}
+
+// TestMultiSelectState_FilterReducesBelowHighlight verifies highlight resets when filter reduces list.
+func TestMultiSelectState_FilterReducesBelowHighlight(t *testing.T) {
+	items := []selectItem{
+		{Name: "apple"},
+		{Name: "banana"},
+		{Name: "cherry"},
+	}
+
+	s := newMultiSelectState(items, nil)
+	s.highlighted = 2 // Highlight "cherry"
+
+	// Type a filter that removes cherry
+	s.handleInput(eventChar, 'a')
+
+	if s.highlighted != 0 {
+		t.Errorf("expected highlighted=0 after filter, got %d", s.highlighted)
+	}
+}
+
+// TestMultiSelectState_EmptyItems verifies handling of empty item list.
+// Empty list should be handled gracefully.
+func TestMultiSelectState_EmptyItems(t *testing.T) {
+	s := newMultiSelectState([]selectItem{}, nil)
+
+	// Toggle should not panic on empty list
+	s.toggleItem()
+
+	if s.selectedCount() != 0 {
+		t.Errorf("expected 0 selected for empty list, got %d", s.selectedCount())
+	}
+
+	// Render should handle empty list
+	var buf bytes.Buffer
+	lineCount := renderMultiSelect(&buf, "Select:", s)
+	if lineCount == 0 {
+		t.Error("renderMultiSelect should produce output even for empty list")
+	}
+	if !strings.Contains(buf.String(), "no matches") {
+		t.Error("expected 'no matches' for empty list")
+	}
+}
+
+// TestSelectState_RenderWithDescriptions verifies rendering items with descriptions.
+func TestSelectState_RenderWithDescriptions(t *testing.T) {
+	items := []selectItem{
+		{Name: "item1", Description: "First item description"},
+		{Name: "item2", Description: ""},
+		{Name: "item3", Description: "Third item"},
+	}
+
+	s := newSelectState(items)
+	var buf bytes.Buffer
+	renderSelect(&buf, "Select:", s)
+
+	output := buf.String()
+	if !strings.Contains(output, "First item description") {
+		t.Error("expected description to be rendered")
+	}
+	if !strings.Contains(output, "item2") {
+		t.Error("expected item without description to be rendered")
+	}
+}