Handle missing config files codex and claude

internal/harnesses/claude.go

@@ -101,7 +101,7 @@ func (c *ClaudeHarness) Configure(opts ConfigureOptions) error {
 func (c *ClaudeHarness) configureMerge(opts ConfigureOptions) error {
 	settingsPath := c.settingsPath()
 
-	settings, err := mergeJSONConfigFile(settingsPath, map[string]any{
+	settings, err := mergeOrCreateJSONConfigFile(settingsPath, map[string]any{
 		"env": map[string]any{
 			"ANTHROPIC_BASE_URL":   c.config.RouterBaseURL,
 			"ANTHROPIC_AUTH_TOKEN": c.config.APIKey,

internal/harnesses/claude_test.go

@@ -40,6 +40,30 @@ func TestClaudeHarnessRoundTrip(t *testing.T) {
 	assert.Equal(t, true, status.Configured)
 }
 
+func TestClaudeHarnessConfigureCreatesMissingConfig(t *testing.T) {
+	config := config.Config{
+		RouterBaseURL: "https://router.requesty.ai",
+		APIKey:        "my-api-key",
+	}
+	configDir := t.TempDir()
+	settingsPath := filepath.Join(configDir, "settings.json")
+	harness := NewClaudeHarness(config, configDir)
+
+	require.NoError(t, harness.Configure(ConfigureOptions{
+		Model: "anthropic/claude-fable-5",
+	}))
+
+	settings, err := os.ReadFile(settingsPath)
+	require.NoError(t, err)
+	assert.JSONEq(t, `{
+		"env": {
+			"ANTHROPIC_BASE_URL": "https://router.requesty.ai",
+			"ANTHROPIC_AUTH_TOKEN": "my-api-key",
+			"ANTHROPIC_MODEL": "anthropic/claude-fable-5"
+		}
+	}`, string(settings))
+}
+
 func TestClaudeHarnessDefaultConfigDir(t *testing.T) {
 	homePath, err := os.UserHomeDir()
 	require.NoError(t, err)

internal/harnesses/codex.go

@@ -125,7 +125,7 @@ func (c *CodexHarness) Configure(opts ConfigureOptions) error {
 func (c *CodexHarness) configureMerge(opts ConfigureOptions) error {
 	configPath := c.configPath()
 
-	config, err := mergeTOMLConfigFile(configPath, map[string]any{
+	config, err := mergeOrCreateTOMLConfigFile(configPath, map[string]any{
 		"model":                              opts.Model,
 		"model_provider":                     codexModelProvider,
 		"model_reasoning_effort":             "high",
@@ -148,7 +148,7 @@ func (c *CodexHarness) configureMerge(opts ConfigureOptions) error {
 
 	authPath := c.authPath()
 
-	auth, err := mergeJSONConfigFile(authPath, map[string]any{
+	auth, err := mergeOrCreateJSONConfigFile(authPath, map[string]any{
 		"auth_mode":      "apikey",
 		"OPENAI_API_KEY": c.config.APIKey,
 	})

internal/harnesses/codex_test.go

@@ -5,6 +5,7 @@ import (
 	"path/filepath"
 	"testing"
 
+	"github.com/pelletier/go-toml/v2"
 	"github.com/requestyai/cli/internal/config"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -43,6 +44,36 @@ func TestCodexIntegrationRoundTrip(t *testing.T) {
 	assert.Equal(t, true, status.Configured)
 }
 
+func TestCodexHarnessConfigureCreatesMissingConfig(t *testing.T) {
+	config := config.Config{
+		RouterBaseURL: "https://router.requesty.ai",
+		APIKey:        "my-api-key",
+	}
+	configDir := t.TempDir()
+	configPath := filepath.Join(configDir, "config.toml")
+	authPath := filepath.Join(configDir, "auth.json")
+	harness := NewCodexHarness(config, configDir)
+
+	require.NoError(t, harness.Configure(ConfigureOptions{
+		Model: "openai-responses/gpt-5.5",
+	}))
+
+	configBytes, err := os.ReadFile(configPath)
+	require.NoError(t, err)
+	var parsedConfig codexConfig
+	require.NoError(t, toml.Unmarshal(configBytes, &parsedConfig))
+	assert.Equal(t, "openai-responses/gpt-5.5", parsedConfig.Model)
+	assert.Equal(t, codexModelProvider, parsedConfig.ModelProvider)
+	assert.Equal(t, "https://router.requesty.ai/v1", parsedConfig.ModelProviders[codexModelProvider].BaseURL)
+
+	auth, err := os.ReadFile(authPath)
+	require.NoError(t, err)
+	assert.JSONEq(t, `{
+		"auth_mode": "apikey",
+		"OPENAI_API_KEY": "my-api-key"
+	}`, string(auth))
+}
+
 func TestCodexHarnessDefaultConfigDir(t *testing.T) {
 	homePath, err := os.UserHomeDir()
 	require.NoError(t, err)

internal/harnesses/merge.go

@@ -53,9 +53,23 @@ func mergeJSONConfigFileWithOptions(path string, patch map[string]any, options m
 	return data, nil
 }
 
+func mergeOrCreateTOMLConfigFile(path string, patch map[string]any) (map[string]any, error) {
+	return mergeTOMLConfigFileWithOptions(path, patch, mergeOptions{
+		AllowFileNotExists: true,
+	})
+}
+
 func mergeTOMLConfigFile(path string, patch map[string]any) (map[string]any, error) {
+	return mergeTOMLConfigFileWithOptions(path, patch, mergeOptions{
+		AllowFileNotExists: false,
+	})
+}
+
+func mergeTOMLConfigFileWithOptions(path string, patch map[string]any, options mergeOptions) (map[string]any, error) {
 	dataBytes, err := os.ReadFile(path)
-	if err != nil {
+	if errors.Is(err, os.ErrNotExist) && options.AllowFileNotExists {
+		dataBytes = []byte{}
+	} else if err != nil {
 		return nil, fmt.Errorf("failed to read file: %w", err)
 	}