chore(docs): add and refine package-level comments across modules

- Added detailed package-level comments to improve documentation coverage.
- Clarified parameter descriptions, return types, and functionality of exported methods across packages.
- Enhanced overall code readability and API documentation consistency.

internal/cmd/anthropic_login.go

@@ -12,6 +12,12 @@ import (
 )
 
 // DoClaudeLogin triggers the Claude OAuth flow through the shared authentication manager.
+// It initiates the OAuth authentication process for Anthropic Claude services and saves
+// the authentication tokens to the configured auth directory.
+//
+// Parameters:
+//   - cfg: The application configuration
+//   - options: Login options including browser behavior and prompts
 func DoClaudeLogin(cfg *config.Config, options *LoginOptions) {
 	if options == nil {
 		options = &LoginOptions{}

internal/cmd/auth_manager.go

@@ -4,6 +4,12 @@ import (
 	sdkAuth "github.com/router-for-me/CLIProxyAPI/v6/sdk/auth"
 )
 
+// newAuthManager creates a new authentication manager instance with all supported
+// authenticators and a file-based token store. It initializes authenticators for
+// Gemini, Codex, Claude, and Qwen providers.
+//
+// Returns:
+//   - *sdkAuth.Manager: A configured authentication manager instance
 func newAuthManager() *sdkAuth.Manager {
 	store := sdkAuth.NewFileTokenStore()
 	manager := sdkAuth.NewManager(store,

internal/cmd/login.go

@@ -1,3 +1,6 @@
+// Package cmd provides command-line interface functionality for the CLI Proxy API server.
+// It includes authentication flows for various AI service providers, service startup,
+// and other command-line operations.
 package cmd
 
 import (
@@ -10,6 +13,13 @@ import (
 )
 
 // DoLogin handles Google Gemini authentication using the shared authentication manager.
+// It initiates the OAuth flow for Google Gemini services and saves the authentication
+// tokens to the configured auth directory.
+//
+// Parameters:
+//   - cfg: The application configuration
+//   - projectID: Optional Google Cloud project ID for Gemini services
+//   - options: Login options including browser behavior and prompts
 func DoLogin(cfg *config.Config, projectID string, options *LoginOptions) {
 	if options == nil {
 		options = &LoginOptions{}

internal/cmd/openai_login.go

@@ -12,14 +12,23 @@ import (
 )
 
 // LoginOptions contains options for the login processes.
+// It provides configuration for authentication flows including browser behavior
+// and interactive prompting capabilities.
 type LoginOptions struct {
 	// NoBrowser indicates whether to skip opening the browser automatically.
 	NoBrowser bool
+
 	// Prompt allows the caller to provide interactive input when needed.
 	Prompt func(prompt string) (string, error)
 }
 
 // DoCodexLogin triggers the Codex OAuth flow through the shared authentication manager.
+// It initiates the OAuth authentication process for OpenAI Codex services and saves
+// the authentication tokens to the configured auth directory.
+//
+// Parameters:
+//   - cfg: The application configuration
+//   - options: Login options including browser behavior and prompts
 func DoCodexLogin(cfg *config.Config, options *LoginOptions) {
 	if options == nil {
 		options = &LoginOptions{}

internal/cmd/qwen_login.go

@@ -11,6 +11,12 @@ import (
 )
 
 // DoQwenLogin handles the Qwen device flow using the shared authentication manager.
+// It initiates the device-based authentication process for Qwen services and saves
+// the authentication tokens to the configured auth directory.
+//
+// Parameters:
+//   - cfg: The application configuration
+//   - options: Login options including browser behavior and prompts
 func DoQwenLogin(cfg *config.Config, options *LoginOptions) {
 	if options == nil {
 		options = &LoginOptions{}

internal/cmd/run.go

@@ -1,3 +1,6 @@
+// Package cmd provides command-line interface functionality for the CLI Proxy API server.
+// It includes authentication flows for various AI service providers, service startup,
+// and other command-line operations.
 package cmd
 
 import (
@@ -12,6 +15,12 @@ import (
 )
 
 // StartService builds and runs the proxy service using the exported SDK.
+// It creates a new proxy service instance, sets up signal handling for graceful shutdown,
+// and starts the service with the provided configuration.
+//
+// Parameters:
+//   - cfg: The application configuration
+//   - configPath: The path to the configuration file
 func StartService(cfg *config.Config, configPath string) {
 	service, err := cliproxy.NewBuilder().
 		WithConfig(cfg).