feat(config): support local config file override

Add support for reading local config files (e.g., config.local.toml) that override base config settings. This allows developers to maintain personal settings without modifying the version-controlled config file.

- Extract file extension properly to support different config formats
- Merge local config settings on top of base config
- Add comprehensive tests for the new functionality

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: AnnatarHe

model/config.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"os"
+	"path/filepath"
 	"strings"
 
 	"github.com/pelletier/go-toml/v2"
@@ -25,6 +26,41 @@ func NewConfigService(configFilePath string) ConfigService {
 	}
 }
 
+// mergeConfig merges local config settings into the base config
+// Local settings override base settings when they are non-zero values
+func mergeConfig(base, local *ShellTimeConfig) {
+	if local.Token != "" {
+		base.Token = local.Token
+	}
+	if local.APIEndpoint != "" {
+		base.APIEndpoint = local.APIEndpoint
+	}
+	if local.WebEndpoint != "" {
+		base.WebEndpoint = local.WebEndpoint
+	}
+	if local.FlushCount > 0 {
+		base.FlushCount = local.FlushCount
+	}
+	if local.GCTime > 0 {
+		base.GCTime = local.GCTime
+	}
+	if local.DataMasking != nil {
+		base.DataMasking = local.DataMasking
+	}
+	if local.EnableMetrics != nil {
+		base.EnableMetrics = local.EnableMetrics
+	}
+	if local.Encrypted != nil {
+		base.Encrypted = local.Encrypted
+	}
+	if local.AI != nil {
+		base.AI = local.AI
+	}
+	if len(local.Endpoints) > 0 {
+		base.Endpoints = local.Endpoints
+	}
+}
+
 func (cs *configService) ReadConfigFile(ctx context.Context) (config ShellTimeConfig, err error) {
 	ctx, span := modelTracer.Start(ctx, "config.read")
 	defer span.End()
@@ -42,6 +78,25 @@ func (cs *configService) ReadConfigFile(ctx context.Context) (config ShellTimeCo
 		return
 	}
 
+	// Check for local config file and merge if exists
+	// Extract the file extension and construct local config filename
+	ext := filepath.Ext(configFile)
+	if ext != "" {
+		// Get the base name without extension
+		baseName := strings.TrimSuffix(configFile, ext)
+		// Construct local config filename: baseName + ".local" + ext
+		localConfigFile := baseName + ".local" + ext
+		
+		if localConfig, localErr := os.ReadFile(localConfigFile); localErr == nil {
+			// Parse local config and merge with base config
+			var localSettings ShellTimeConfig
+			if unmarshalErr := toml.Unmarshal(localConfig, &localSettings); unmarshalErr == nil {
+				// Merge local settings into base config
+				mergeConfig(&config, &localSettings)
+			}
+		}
+	}
+
 	// default 10 and at least 3 for performance reason
 	if config.FlushCount == 0 {
 		config.FlushCount = 10

model/config_test.go

@@ -0,0 +1,144 @@
+package model
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestReadConfigFileWithLocal(t *testing.T) {
+	// Create a temporary directory for test configs
+	tmpDir, err := os.MkdirTemp("", "shelltime-test-*")
+	require.NoError(t, err)
+	defer os.RemoveAll(tmpDir)
+
+	// Create base config file
+	baseConfigPath := filepath.Join(tmpDir, "config.toml")
+	baseConfig := `Token = 'base-token'
+APIEndpoint = 'https://api.base.com'
+WebEndpoint = 'https://base.com'
+FlushCount = 5
+GCTime = 7
+dataMasking = false
+enableMetrics = false
+encrypted = false`
+	err = os.WriteFile(baseConfigPath, []byte(baseConfig), 0644)
+	require.NoError(t, err)
+
+	// Create local config file that overrides some settings
+	localConfigPath := filepath.Join(tmpDir, "config.local.toml")
+	localConfig := `Token = 'local-token'
+APIEndpoint = 'https://api.local.com'
+FlushCount = 10
+dataMasking = true`
+	err = os.WriteFile(localConfigPath, []byte(localConfig), 0644)
+	require.NoError(t, err)
+
+	// Test reading config with local override
+	cs := NewConfigService(baseConfigPath)
+	config, err := cs.ReadConfigFile(context.Background())
+	require.NoError(t, err)
+
+	// Verify local config overrides base config
+	assert.Equal(t, "local-token", config.Token, "Token should be overridden by local config")
+	assert.Equal(t, "https://api.local.com", config.APIEndpoint, "APIEndpoint should be overridden by local config")
+	assert.Equal(t, 10, config.FlushCount, "FlushCount should be overridden by local config")
+	assert.True(t, *config.DataMasking, "DataMasking should be overridden by local config")
+
+	// Verify base config values that weren't overridden
+	assert.Equal(t, "https://base.com", config.WebEndpoint, "WebEndpoint should keep base value")
+	assert.Equal(t, 7, config.GCTime, "GCTime should keep base value")
+	assert.False(t, *config.EnableMetrics, "EnableMetrics should keep base value")
+	assert.False(t, *config.Encrypted, "Encrypted should keep base value")
+}
+
+func TestReadConfigFileWithoutLocal(t *testing.T) {
+	// Create a temporary directory for test configs
+	tmpDir, err := os.MkdirTemp("", "shelltime-test-*")
+	require.NoError(t, err)
+	defer os.RemoveAll(tmpDir)
+
+	// Create only base config file (no local file)
+	baseConfigPath := filepath.Join(tmpDir, "config.toml")
+	baseConfig := `Token = 'base-token'
+APIEndpoint = 'https://api.base.com'
+WebEndpoint = 'https://base.com'
+FlushCount = 5
+GCTime = 7`
+	err = os.WriteFile(baseConfigPath, []byte(baseConfig), 0644)
+	require.NoError(t, err)
+
+	// Test reading config without local file
+	cs := NewConfigService(baseConfigPath)
+	config, err := cs.ReadConfigFile(context.Background())
+	require.NoError(t, err)
+
+	// Verify base config values are used
+	assert.Equal(t, "base-token", config.Token)
+	assert.Equal(t, "https://api.base.com", config.APIEndpoint)
+	assert.Equal(t, "https://base.com", config.WebEndpoint)
+	assert.Equal(t, 5, config.FlushCount)
+	assert.Equal(t, 7, config.GCTime)
+}
+
+func TestReadConfigFileWithDifferentExtensions(t *testing.T) {
+	testCases := []struct {
+		name       string
+		configFile string
+		localFile  string
+	}{
+		{
+			name:       "TOML files",
+			configFile: "config.toml",
+			localFile:  "config.local.toml",
+		},
+		{
+			name:       "Custom config name",
+			configFile: "shelltime-config.toml",
+			localFile:  "shelltime-config.local.toml",
+		},
+		{
+			name:       "Different extension",
+			configFile: "settings.conf",
+			localFile:  "settings.local.conf",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			// Create a temporary directory for test configs
+			tmpDir, err := os.MkdirTemp("", "shelltime-test-*")
+			require.NoError(t, err)
+			defer os.RemoveAll(tmpDir)
+
+			// Create base config file
+			baseConfigPath := filepath.Join(tmpDir, tc.configFile)
+			baseConfig := `Token = 'base-token'
+APIEndpoint = 'https://api.base.com'
+FlushCount = 5`
+			err = os.WriteFile(baseConfigPath, []byte(baseConfig), 0644)
+			require.NoError(t, err)
+
+			// Create local config file
+			localConfigPath := filepath.Join(tmpDir, tc.localFile)
+			localConfig := `Token = 'local-token'
+FlushCount = 10`
+			err = os.WriteFile(localConfigPath, []byte(localConfig), 0644)
+			require.NoError(t, err)
+
+			// Test reading config with local override
+			cs := NewConfigService(baseConfigPath)
+			config, err := cs.ReadConfigFile(context.Background())
+			require.NoError(t, err)
+
+			// Verify local config overrides base config
+			assert.Equal(t, "local-token", config.Token, "Token should be overridden by local config for %s", tc.name)
+			assert.Equal(t, 10, config.FlushCount, "FlushCount should be overridden by local config for %s", tc.name)
+			assert.Equal(t, "https://api.base.com", config.APIEndpoint, "APIEndpoint should keep base value for %s", tc.name)
+		})
+	}
+}