diff --git a/cmd/server/main.go b/cmd/server/main.go
index e6e9e686..6e40c4f0 100644
--- a/cmd/server/main.go
+++ b/cmd/server/main.go
@@ -12,9 +12,11 @@ import (
 	"strings"
 )
 
+// LogFormatter defines a custom log format for logrus.
 type LogFormatter struct {
 }
 
+// Format renders a single log entry.
 func (m *LogFormatter) Format(entry *log.Entry) ([]byte, error) {
 	var b *bytes.Buffer
 	if entry.Buffer != nil {
@@ -25,33 +27,42 @@ func (m *LogFormatter) Format(entry *log.Entry) ([]byte, error) {
 
 	timestamp := entry.Time.Format("2006-01-02 15:04:05")
 	var newLog string
+	// Customize the log format to include timestamp, level, caller file/line, and message.
 	newLog = fmt.Sprintf("[%s] [%s] [%s:%d] %s\n", timestamp, entry.Level, path.Base(entry.Caller.File), entry.Caller.Line, entry.Message)
 
 	b.WriteString(newLog)
 	return b.Bytes(), nil
 }
 
+// init initializes the logger configuration.
 func init() {
+	// Set logger output to standard output.
 	log.SetOutput(os.Stdout)
+	// Enable reporting the caller function's file and line number.
 	log.SetReportCaller(true)
+	// Set the custom log formatter.
 	log.SetFormatter(&LogFormatter{})
 }
 
+// main is the entry point of the application.
 func main() {
 	var login bool
 	var projectID string
 	var configPath string
 
+	// Define command-line flags.
 	flag.BoolVar(&login, "login", false, "Login Google Account")
 	flag.StringVar(&projectID, "project_id", "", "Project ID")
 	flag.StringVar(&configPath, "config", "", "Configure File Path")
 
+	// Parse the command-line flags.
 	flag.Parse()
 
 	var err error
 	var cfg *config.Config
 	var wd string
 
+	// Load configuration from the specified path or the default path.
 	if configPath != "" {
 		cfg, err = config.LoadConfig(configPath)
 	} else {
@@ -65,12 +76,14 @@ func main() {
 		log.Fatalf("failed to load config: %v", err)
 	}
 
+	// Set the log level based on the configuration.
 	if cfg.Debug {
 		log.SetLevel(log.DebugLevel)
 	} else {
 		log.SetLevel(log.InfoLevel)
 	}
 
+	// Expand the tilde (~) in the auth directory path to the user's home directory.
 	if strings.HasPrefix(cfg.AuthDir, "~") {
 		home, errUserHomeDir := os.UserHomeDir()
 		if errUserHomeDir != nil {
@@ -85,6 +98,7 @@ func main() {
 		}
 	}
 
+	// Either perform login or start the service based on the 'login' flag.
 	if login {
 		cmd.DoLogin(cfg, projectID)
 	} else {
diff --git a/config.yaml b/config.yaml
index ccc53dce..3f8b1885 100644
--- a/config.yaml
+++ b/config.yaml
@@ -1,6 +1,6 @@
 port: 8317
 auth_dir: "~/.cli-proxy-api"
-debug: false
+debug: true
 proxy-url: ""
 api_keys:
   - "12345"
diff --git a/internal/api/handlers.go b/internal/api/handlers.go
index f549934b..85bdfef9 100644
--- a/internal/api/handlers.go
+++ b/internal/api/handlers.go
@@ -2,14 +2,12 @@ package api
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
+	"github.com/luispater/CLIProxyAPI/internal/api/translator"
 	"github.com/luispater/CLIProxyAPI/internal/client"
 	log "github.com/sirupsen/logrus"
 	"github.com/tidwall/gjson"
-	"github.com/tidwall/sjson"
 	"net/http"
-	"strings"
 	"sync"
 	"time"
 
@@ -21,13 +19,15 @@ var (
 	lastUsedClientIndex = 0
 )
 
-// APIHandlers contains the handlers for API endpoints
+// APIHandlers contains the handlers for API endpoints.
+// It holds a pool of clients to interact with the backend service.
 type APIHandlers struct {
 	cliClients []*client.Client
 	debug      bool
 }
 
-// NewAPIHandlers creates a new API handlers instance
+// NewAPIHandlers creates a new API handlers instance.
+// It takes a slice of clients and a debug flag as input.
 func NewAPIHandlers(cliClients []*client.Client, debug bool) *APIHandlers {
 	return &APIHandlers{
 		cliClients: cliClients,
@@ -35,6 +35,8 @@ func NewAPIHandlers(cliClients []*client.Client, debug bool) *APIHandlers {
 	}
 }
 
+// Models handles the /v1/models endpoint.
+// It returns a hardcoded list of available AI models.
 func (h *APIHandlers) Models(c *gin.Context) {
 	c.JSON(http.StatusOK, gin.H{
 		"data": []map[string]any{
@@ -162,15 +164,23 @@ func (h *APIHandlers) Models(c *gin.Context) {
 	})
 }
 
-// ChatCompletions handles the /v1/chat/completions endpoint
+// ChatCompletions handles the /v1/chat/completions endpoint.
+// It determines whether the request is for a streaming or non-streaming response
+// and calls the appropriate handler.
 func (h *APIHandlers) ChatCompletions(c *gin.Context) {
 	rawJson, err := c.GetRawData()
-	// If data retrieval fails, return 400 error
+	// If data retrieval fails, return a 400 Bad Request error.
 	if err != nil {
-		c.JSON(http.StatusBadRequest, gin.H{"error": fmt.Sprintf("Invalid request: %v", err), "code": 400})
+		c.JSON(http.StatusBadRequest, ErrorResponse{
+			Error: ErrorDetail{
+				Message: fmt.Sprintf("Invalid request: %v", err),
+				Type:    "invalid_request_error",
+			},
+		})
 		return
 	}
 
+	// Check if the client requested a streaming response.
 	streamResult := gjson.GetBytes(rawJson, "stream")
 	if streamResult.Type == gjson.True {
 		h.handleStreamingResponse(c, rawJson)
@@ -179,184 +189,9 @@ func (h *APIHandlers) ChatCompletions(c *gin.Context) {
 	}
 }
 
-func (h *APIHandlers) prepareRequest(rawJson []byte) (string, []client.Content, []client.ToolDeclaration) {
-	// log.Debug(string(rawJson))
-	modelName := "gemini-2.5-pro"
-	modelResult := gjson.GetBytes(rawJson, "model")
-	if modelResult.Type == gjson.String {
-		modelName = modelResult.String()
-	}
-
-	contents := make([]client.Content, 0)
-	messagesResult := gjson.GetBytes(rawJson, "messages")
-	if messagesResult.IsArray() {
-		messagesResults := messagesResult.Array()
-		for i := 0; i < len(messagesResults); i++ {
-			messageResult := messagesResults[i]
-			roleResult := messageResult.Get("role")
-			contentResult := messageResult.Get("content")
-			if roleResult.Type == gjson.String {
-				if roleResult.String() == "system" {
-					if contentResult.Type == gjson.String {
-						contents = append(contents, client.Content{Role: "user", Parts: []client.Part{{Text: contentResult.String()}}})
-					} else if contentResult.IsObject() {
-						contentTypeResult := contentResult.Get("type")
-						if contentTypeResult.Type == gjson.String && contentTypeResult.String() == "text" {
-							contentTextResult := contentResult.Get("text")
-							if contentTextResult.Type == gjson.String {
-								contents = append(contents, client.Content{Role: "user", Parts: []client.Part{{Text: contentTextResult.String()}}})
-								contents = append(contents, client.Content{Role: "model", Parts: []client.Part{{Text: "Understood. I will follow these instructions and use my tools to assist you."}}})
-							}
-						}
-					}
-				} else if roleResult.String() == "user" {
-					if contentResult.Type == gjson.String {
-						contents = append(contents, client.Content{Role: "user", Parts: []client.Part{{Text: contentResult.String()}}})
-					} else if contentResult.IsObject() {
-						contentTypeResult := contentResult.Get("type")
-						if contentTypeResult.Type == gjson.String && contentTypeResult.String() == "text" {
-							contentTextResult := contentResult.Get("text")
-							if contentTextResult.Type == gjson.String {
-								contents = append(contents, client.Content{Role: "user", Parts: []client.Part{{Text: contentTextResult.String()}}})
-							}
-						}
-					} else if contentResult.IsArray() {
-						contentItemResults := contentResult.Array()
-						parts := make([]client.Part, 0)
-						for j := 0; j < len(contentItemResults); j++ {
-							contentItemResult := contentItemResults[j]
-							contentTypeResult := contentItemResult.Get("type")
-							if contentTypeResult.Type == gjson.String && contentTypeResult.String() == "text" {
-								contentTextResult := contentItemResult.Get("text")
-								if contentTextResult.Type == gjson.String {
-									parts = append(parts, client.Part{Text: contentTextResult.String()})
-								}
-							} else if contentTypeResult.Type == gjson.String && contentTypeResult.String() == "image_url" {
-								imageURLResult := contentItemResult.Get("image_url.url")
-								if imageURLResult.Type == gjson.String {
-									imageURL := imageURLResult.String()
-									if len(imageURL) > 5 {
-										imageURLs := strings.SplitN(imageURL[5:], ";", 2)
-										if len(imageURLs) == 2 {
-											if len(imageURLs[1]) > 7 {
-												parts = append(parts, client.Part{InlineData: &client.InlineData{
-													MimeType: imageURLs[0],
-													Data:     imageURLs[1][7:],
-												}})
-											}
-										}
-									}
-								}
-							} else if contentTypeResult.Type == gjson.String && contentTypeResult.String() == "file" {
-								filenameResult := contentItemResult.Get("file.filename")
-								fileDataResult := contentItemResult.Get("file.file_data")
-								if filenameResult.Type == gjson.String && fileDataResult.Type == gjson.String {
-									filename := filenameResult.String()
-									splitFilename := strings.Split(filename, ".")
-									ext := splitFilename[len(splitFilename)-1]
-
-									mimeType, ok := MimeTypes[ext]
-									if !ok {
-										log.Warnf("Unknown file name extension '%s' at index %d, skipping file", ext, j)
-										continue
-									}
-
-									parts = append(parts, client.Part{InlineData: &client.InlineData{
-										MimeType: mimeType,
-										Data:     fileDataResult.String(),
-									}})
-								}
-							}
-						}
-						contents = append(contents, client.Content{Role: "user", Parts: parts})
-					}
-				} else if roleResult.String() == "assistant" {
-					if contentResult.Type == gjson.String {
-						contents = append(contents, client.Content{Role: "model", Parts: []client.Part{{Text: contentResult.String()}}})
-					} else if contentResult.IsObject() {
-						contentTypeResult := contentResult.Get("type")
-						if contentTypeResult.Type == gjson.String && contentTypeResult.String() == "text" {
-							contentTextResult := contentResult.Get("text")
-							if contentTextResult.Type == gjson.String {
-								contents = append(contents, client.Content{Role: "user", Parts: []client.Part{{Text: contentTextResult.String()}}})
-							}
-						}
-					} else if !contentResult.Exists() || contentResult.Type == gjson.Null {
-						toolCallsResult := messageResult.Get("tool_calls")
-						if toolCallsResult.IsArray() {
-							tcsResult := toolCallsResult.Array()
-							for j := 0; j < len(tcsResult); j++ {
-								tcResult := tcsResult[j]
-								functionNameResult := tcResult.Get("function.name")
-								functionArguments := tcResult.Get("function.arguments")
-								if functionNameResult.Exists() && functionNameResult.Type == gjson.String && functionArguments.Exists() && functionArguments.Type == gjson.String {
-									var args map[string]any
-									err := json.Unmarshal([]byte(functionArguments.String()), &args)
-									if err == nil {
-										contents = append(contents, client.Content{
-											Role: "model", Parts: []client.Part{
-												{
-													FunctionCall: &client.FunctionCall{
-														Name: functionNameResult.String(),
-														Args: args,
-													},
-												},
-											},
-										})
-									}
-								}
-							}
-						}
-					}
-				} else if roleResult.String() == "tool" {
-					toolCallIDResult := messageResult.Get("tool_call_id")
-					if toolCallIDResult.Exists() && toolCallIDResult.Type == gjson.String {
-						if contentResult.Type == gjson.String {
-							functionResponse := client.FunctionResponse{Name: toolCallIDResult.String(), Response: map[string]interface{}{"result": contentResult.String()}}
-							contents = append(contents, client.Content{Role: "tool", Parts: []client.Part{{FunctionResponse: &functionResponse}}})
-						} else if contentResult.IsObject() {
-							contentTypeResult := contentResult.Get("type")
-							if contentTypeResult.Type == gjson.String && contentTypeResult.String() == "text" {
-								contentTextResult := contentResult.Get("text")
-								if contentTextResult.Type == gjson.String {
-									functionResponse := client.FunctionResponse{Name: toolCallIDResult.String(), Response: map[string]interface{}{"result": contentResult.String()}}
-									contents = append(contents, client.Content{Role: "tool", Parts: []client.Part{{FunctionResponse: &functionResponse}}})
-								}
-							}
-						}
-					}
-				}
-			}
-		}
-	}
-
-	var tools []client.ToolDeclaration
-	toolsResult := gjson.GetBytes(rawJson, "tools")
-	if toolsResult.IsArray() {
-		tools = make([]client.ToolDeclaration, 1)
-		tools[0].FunctionDeclarations = make([]any, 0)
-		toolsResults := toolsResult.Array()
-		for i := 0; i < len(toolsResults); i++ {
-			toolTypeResult := toolsResults[i].Get("type")
-			if toolTypeResult.Type != gjson.String || toolTypeResult.String() != "function" {
-				continue
-			}
-			functionTypeResult := toolsResults[i].Get("function")
-			if functionTypeResult.Exists() && functionTypeResult.IsObject() {
-				var functionDeclaration any
-				err := json.Unmarshal([]byte(functionTypeResult.Raw), &functionDeclaration)
-				if err == nil {
-					tools[0].FunctionDeclarations = append(tools[0].FunctionDeclarations, functionDeclaration)
-				}
-			}
-		}
-	} else {
-		tools = make([]client.ToolDeclaration, 0)
-	}
-	return modelName, contents, tools
-}
-
-// handleNonStreamingResponse handles non-streaming responses
+// handleNonStreamingResponse handles non-streaming chat completion responses.
+// It selects a client from the pool, sends the request, and aggregates the response
+// before sending it back to the client.
 func (h *APIHandlers) handleNonStreamingResponse(c *gin.Context, rawJson []byte) {
 	c.Header("Content-Type", "application/json")
 
@@ -372,7 +207,7 @@ func (h *APIHandlers) handleNonStreamingResponse(c *gin.Context, rawJson []byte)
 		return
 	}
 
-	modelName, contents, tools := h.prepareRequest(rawJson)
+	modelName, contents, tools := translator.PrepareRequest(rawJson)
 	cliCtx, cliCancel := context.WithCancel(context.Background())
 	var cliClient *client.Client
 	defer func() {
@@ -425,19 +260,13 @@ func (h *APIHandlers) handleNonStreamingResponse(c *gin.Context, rawJson []byte)
 				cliCancel()
 				return
 			} else {
-				jsonTemplate = h.convertCliToOpenAINonStream(jsonTemplate, chunk)
+				jsonTemplate = translator.ConvertCliToOpenAINonStream(jsonTemplate, chunk)
 			}
 		case err, okError := <-errChan:
 			if okError {
 				c.Status(err.StatusCode)
 				_, _ = fmt.Fprint(c.Writer, err.Error.Error())
 				flusher.Flush()
-				// c.JSON(http.StatusInternalServerError, ErrorResponse{
-				// 	Error: ErrorDetail{
-				// 		Message: err.Error(),
-				// 		Type:    "server_error",
-				// 	},
-				// })
 				cliCancel()
 				return
 			}
@@ -455,7 +284,7 @@ func (h *APIHandlers) handleStreamingResponse(c *gin.Context, rawJson []byte) {
 	c.Header("Connection", "keep-alive")
 	c.Header("Access-Control-Allow-Origin", "*")
 
-	// Handle streaming manually
+	// Get the http.Flusher interface to manually flush the response.
 	flusher, ok := c.Writer.(http.Flusher)
 	if !ok {
 		c.JSON(http.StatusInternalServerError, ErrorResponse{
@@ -466,28 +295,33 @@ func (h *APIHandlers) handleStreamingResponse(c *gin.Context, rawJson []byte) {
 		})
 		return
 	}
-	modelName, contents, tools := h.prepareRequest(rawJson)
+
+	// Prepare the request for the backend client.
+	modelName, contents, tools := translator.PrepareRequest(rawJson)
 	cliCtx, cliCancel := context.WithCancel(context.Background())
 	var cliClient *client.Client
 	defer func() {
+		// Ensure the client's mutex is unlocked on function exit.
 		if cliClient != nil {
 			cliClient.RequestMutex.Unlock()
 		}
 	}()
 
-	// Lock the mutex to update the last used page index
+	// Use a round-robin approach to select the next available client.
+	// This distributes the load among the available clients.
 	mutex.Lock()
 	startIndex := lastUsedClientIndex
 	currentIndex := (startIndex + 1) % len(h.cliClients)
 	lastUsedClientIndex = currentIndex
 	mutex.Unlock()
 
-	// Reorder the pages to start from the last used index
+	// Reorder the clients to start from the next client in the rotation.
 	reorderedPages := make([]*client.Client, len(h.cliClients))
 	for i := 0; i < len(h.cliClients); i++ {
 		reorderedPages[i] = h.cliClients[(startIndex+1+i)%len(h.cliClients)]
 	}
 
+	// Attempt to lock a client for the request.
 	locked := false
 	for i := 0; i < len(reorderedPages); i++ {
 		cliClient = reorderedPages[i]
@@ -496,235 +330,52 @@ func (h *APIHandlers) handleStreamingResponse(c *gin.Context, rawJson []byte) {
 			break
 		}
 	}
+	// If no client is available, block and wait for the first client.
 	if !locked {
 		cliClient = h.cliClients[0]
 		cliClient.RequestMutex.Lock()
 	}
-
 	log.Debugf("Request use account: %s, project id: %s", cliClient.GetEmail(), cliClient.GetProjectID())
+	// Send the message and receive response chunks and errors via channels.
 	respChan, errChan := cliClient.SendMessageStream(cliCtx, rawJson, modelName, contents, tools)
 	for {
 		select {
+		// Handle client disconnection.
 		case <-c.Request.Context().Done():
 			if c.Request.Context().Err().Error() == "context canceled" {
 				log.Debugf("Client disconnected: %v", c.Request.Context().Err())
-				cliCancel()
+				cliCancel() // Cancel the backend request.
 				return
 			}
+		// Process incoming response chunks.
 		case chunk, okStream := <-respChan:
 			if !okStream {
+				// Stream is closed, send the final [DONE] message.
 				_, _ = fmt.Fprintf(c.Writer, "data: [DONE]\n\n")
 				flusher.Flush()
 				cliCancel()
 				return
 			} else {
-				openAIFormat := h.convertCliToOpenAI(chunk)
+				// Convert the chunk to OpenAI format and send it to the client.
+				openAIFormat := translator.ConvertCliToOpenAI(chunk)
 				if openAIFormat != "" {
 					_, _ = fmt.Fprintf(c.Writer, "data: %s\n\n", openAIFormat)
 					flusher.Flush()
 				}
 			}
+		// Handle errors from the backend.
 		case err, okError := <-errChan:
 			if okError {
 				c.Status(err.StatusCode)
 				_, _ = fmt.Fprint(c.Writer, err.Error.Error())
 				flusher.Flush()
-				// c.JSON(http.StatusInternalServerError, ErrorResponse{
-				// 	Error: ErrorDetail{
-				// 		Message: err.Error(),
-				// 		Type:    "server_error",
-				// 	},
-				// })
 				cliCancel()
 				return
 			}
+		// Send a keep-alive signal to the client.
 		case <-time.After(500 * time.Millisecond):
 			_, _ = c.Writer.Write([]byte(": CLI-PROXY-API PROCESSING\n\n"))
 			flusher.Flush()
 		}
 	}
 }
-
-func (h *APIHandlers) convertCliToOpenAI(rawJson []byte) string {
-	// log.Debugf(string(rawJson))
-	template := `{"id":"","object":"chat.completion.chunk","created":12345,"model":"model","choices":[{"index":0,"delta":{"role":null,"content":null,"reasoning_content":null,"tool_calls":null},"finish_reason":null,"native_finish_reason":null}]}`
-
-	modelVersionResult := gjson.GetBytes(rawJson, "response.modelVersion")
-	if modelVersionResult.Exists() && modelVersionResult.Type == gjson.String {
-		template, _ = sjson.Set(template, "model", modelVersionResult.String())
-	}
-
-	createTimeResult := gjson.GetBytes(rawJson, "response.createTime")
-	if createTimeResult.Exists() && createTimeResult.Type == gjson.String {
-		t, err := time.Parse(time.RFC3339Nano, createTimeResult.String())
-		var unixTimestamp int64
-		if err == nil {
-			unixTimestamp = t.Unix()
-		} else {
-			unixTimestamp = time.Now().Unix()
-		}
-		template, _ = sjson.Set(template, "created", unixTimestamp)
-	}
-
-	responseIdResult := gjson.GetBytes(rawJson, "response.responseId")
-	if responseIdResult.Exists() && responseIdResult.Type == gjson.String {
-		template, _ = sjson.Set(template, "id", responseIdResult.String())
-	}
-
-	finishReasonResult := gjson.GetBytes(rawJson, "response.candidates.0.finishReason")
-	if finishReasonResult.Exists() && finishReasonResult.Type == gjson.String {
-		template, _ = sjson.Set(template, "choices.0.finish_reason", finishReasonResult.String())
-		template, _ = sjson.Set(template, "choices.0.native_finish_reason", finishReasonResult.String())
-	}
-
-	usageResult := gjson.GetBytes(rawJson, "response.usageMetadata")
-	candidatesTokenCountResult := usageResult.Get("candidatesTokenCount")
-	if candidatesTokenCountResult.Exists() && candidatesTokenCountResult.Type == gjson.Number {
-		template, _ = sjson.Set(template, "usage.completion_tokens", candidatesTokenCountResult.Int())
-	}
-	totalTokenCountResult := usageResult.Get("totalTokenCount")
-	if totalTokenCountResult.Exists() && totalTokenCountResult.Type == gjson.Number {
-		template, _ = sjson.Set(template, "usage.total_tokens", totalTokenCountResult.Int())
-	}
-	thoughtsTokenCountResult := usageResult.Get("thoughtsTokenCount")
-	promptTokenCountResult := usageResult.Get("promptTokenCount")
-	if promptTokenCountResult.Exists() && promptTokenCountResult.Type == gjson.Number {
-		if thoughtsTokenCountResult.Exists() && thoughtsTokenCountResult.Type == gjson.Number {
-			template, _ = sjson.Set(template, "usage.prompt_tokens", promptTokenCountResult.Int()+thoughtsTokenCountResult.Int())
-		} else {
-			template, _ = sjson.Set(template, "usage.prompt_tokens", promptTokenCountResult.Int())
-		}
-	}
-	if thoughtsTokenCountResult.Exists() && thoughtsTokenCountResult.Type == gjson.Number {
-		template, _ = sjson.Set(template, "usage.completion_tokens_details.reasoning_tokens", thoughtsTokenCountResult.Int())
-	}
-
-	partResult := gjson.GetBytes(rawJson, "response.candidates.0.content.parts.0")
-	partTextResult := partResult.Get("text")
-	functionCallResult := partResult.Get("functionCall")
-
-	if partTextResult.Exists() && partTextResult.Type == gjson.String {
-		partThoughtResult := partResult.Get("thought")
-		if partThoughtResult.Exists() && partThoughtResult.Type == gjson.True {
-			template, _ = sjson.Set(template, "choices.0.delta.reasoning_content", partTextResult.String())
-		} else {
-			template, _ = sjson.Set(template, "choices.0.delta.content", partTextResult.String())
-		}
-		template, _ = sjson.Set(template, "choices.0.delta.role", "assistant")
-	} else if functionCallResult.Exists() {
-		functionCallTemplate := `[{"id": "","type": "function","function": {"name": "","arguments": ""}}]`
-		fcNameResult := functionCallResult.Get("name")
-		if fcNameResult.Exists() && fcNameResult.Type == gjson.String {
-			functionCallTemplate, _ = sjson.Set(functionCallTemplate, "0.id", fcNameResult.String())
-			functionCallTemplate, _ = sjson.Set(functionCallTemplate, "0.function.name", fcNameResult.String())
-		}
-		fcArgsResult := functionCallResult.Get("args")
-		if fcArgsResult.Exists() && fcArgsResult.IsObject() {
-			functionCallTemplate, _ = sjson.Set(functionCallTemplate, "0.function.arguments", fcArgsResult.Raw)
-		}
-		template, _ = sjson.Set(template, "choices.0.delta.role", "assistant")
-		template, _ = sjson.SetRaw(template, "choices.0.delta.tool_calls", functionCallTemplate)
-	} else {
-		return ""
-	}
-
-	return template
-}
-
-func (h *APIHandlers) convertCliToOpenAINonStream(template string, rawJson []byte) string {
-	modelVersionResult := gjson.GetBytes(rawJson, "response.modelVersion")
-	if modelVersionResult.Exists() && modelVersionResult.Type == gjson.String {
-		template, _ = sjson.Set(template, "model", modelVersionResult.String())
-	}
-
-	createTimeResult := gjson.GetBytes(rawJson, "response.createTime")
-	if createTimeResult.Exists() && createTimeResult.Type == gjson.String {
-		t, err := time.Parse(time.RFC3339Nano, createTimeResult.String())
-		var unixTimestamp int64
-		if err == nil {
-			unixTimestamp = t.Unix()
-		} else {
-			unixTimestamp = time.Now().Unix()
-		}
-		template, _ = sjson.Set(template, "created", unixTimestamp)
-	}
-
-	responseIdResult := gjson.GetBytes(rawJson, "response.responseId")
-	if responseIdResult.Exists() && responseIdResult.Type == gjson.String {
-		template, _ = sjson.Set(template, "id", responseIdResult.String())
-	}
-
-	finishReasonResult := gjson.GetBytes(rawJson, "response.candidates.0.finishReason")
-	if finishReasonResult.Exists() && finishReasonResult.Type == gjson.String {
-		template, _ = sjson.Set(template, "choices.0.finish_reason", finishReasonResult.String())
-		template, _ = sjson.Set(template, "choices.0.native_finish_reason", finishReasonResult.String())
-	}
-
-	usageResult := gjson.GetBytes(rawJson, "response.usageMetadata")
-	candidatesTokenCountResult := usageResult.Get("candidatesTokenCount")
-	if candidatesTokenCountResult.Exists() && candidatesTokenCountResult.Type == gjson.Number {
-		template, _ = sjson.Set(template, "usage.completion_tokens", candidatesTokenCountResult.Int())
-	}
-	totalTokenCountResult := usageResult.Get("totalTokenCount")
-	if totalTokenCountResult.Exists() && totalTokenCountResult.Type == gjson.Number {
-		template, _ = sjson.Set(template, "usage.total_tokens", totalTokenCountResult.Int())
-	}
-	thoughtsTokenCountResult := usageResult.Get("thoughtsTokenCount")
-	promptTokenCountResult := usageResult.Get("promptTokenCount")
-	if promptTokenCountResult.Exists() && promptTokenCountResult.Type == gjson.Number {
-		if thoughtsTokenCountResult.Exists() && thoughtsTokenCountResult.Type == gjson.Number {
-			template, _ = sjson.Set(template, "usage.prompt_tokens", promptTokenCountResult.Int()+thoughtsTokenCountResult.Int())
-		} else {
-			template, _ = sjson.Set(template, "usage.prompt_tokens", promptTokenCountResult.Int())
-		}
-	}
-	if thoughtsTokenCountResult.Exists() && thoughtsTokenCountResult.Type == gjson.Number {
-		template, _ = sjson.Set(template, "usage.completion_tokens_details.reasoning_tokens", thoughtsTokenCountResult.Int())
-	}
-
-	partResult := gjson.GetBytes(rawJson, "response.candidates.0.content.parts.0")
-	partTextResult := partResult.Get("text")
-	functionCallResult := partResult.Get("functionCall")
-
-	if partTextResult.Exists() && partTextResult.Type == gjson.String {
-		partThoughtResult := partResult.Get("thought")
-		if partThoughtResult.Exists() && partThoughtResult.Type == gjson.True {
-			reasoningContentResult := gjson.Get(template, "choices.0.message.reasoning_content")
-			if reasoningContentResult.Type == gjson.String {
-				template, _ = sjson.Set(template, "choices.0.message.reasoning_content", reasoningContentResult.String()+partTextResult.String())
-			} else {
-				template, _ = sjson.Set(template, "choices.0.message.reasoning_content", partTextResult.String())
-			}
-		} else {
-			reasoningContentResult := gjson.Get(template, "choices.0.message.content")
-			if reasoningContentResult.Type == gjson.String {
-				template, _ = sjson.Set(template, "choices.0.message.content", reasoningContentResult.String()+partTextResult.String())
-			} else {
-				template, _ = sjson.Set(template, "choices.0.message.content", partTextResult.String())
-			}
-		}
-		template, _ = sjson.Set(template, "choices.0.message.role", "assistant")
-	} else if functionCallResult.Exists() {
-		toolCallsResult := gjson.Get(template, "choices.0.message.tool_calls")
-		if !toolCallsResult.Exists() || toolCallsResult.Type == gjson.Null {
-			template, _ = sjson.SetRaw(template, "choices.0.message.tool_calls", `[]`)
-		}
-
-		functionCallItemTemplate := `{"id": "","type": "function","function": {"name": "","arguments": ""}}`
-		fcNameResult := functionCallResult.Get("name")
-		if fcNameResult.Exists() && fcNameResult.Type == gjson.String {
-			functionCallItemTemplate, _ = sjson.Set(functionCallItemTemplate, "id", fcNameResult.String())
-			functionCallItemTemplate, _ = sjson.Set(functionCallItemTemplate, "function.name", fcNameResult.String())
-		}
-		fcArgsResult := functionCallResult.Get("args")
-		if fcArgsResult.Exists() && fcArgsResult.IsObject() {
-			functionCallItemTemplate, _ = sjson.Set(functionCallItemTemplate, "function.arguments", fcArgsResult.Raw)
-		}
-		template, _ = sjson.Set(template, "choices.0.message.role", "assistant")
-		template, _ = sjson.SetRaw(template, "choices.0.message.tool_calls.-1", functionCallItemTemplate)
-	} else {
-		return ""
-	}
-
-	return template
-}
diff --git a/internal/api/models.go b/internal/api/models.go
index 8cfbbea6..71f2bb5a 100644
--- a/internal/api/models.go
+++ b/internal/api/models.go
@@ -1,13 +1,18 @@
 package api
 
-// ErrorResponse represents an error response
+// ErrorResponse represents a standard error response format for the API.
+// It contains a single ErrorDetail field.
 type ErrorResponse struct {
 	Error ErrorDetail `json:"error"`
 }
 
-// ErrorDetail represents error details
+// ErrorDetail provides specific information about an error that occurred.
+// It includes a human-readable message, an error type, and an optional error code.
 type ErrorDetail struct {
+	// A human-readable message providing more details about the error.
 	Message string `json:"message"`
-	Type    string `json:"type"`
-	Code    string `json:"code,omitempty"`
+	// The type of error that occurred (e.g., "invalid_request_error").
+	Type string `json:"type"`
+	// A short code identifying the error, if applicable.
+	Code string `json:"code,omitempty"`
 }
diff --git a/internal/api/server.go b/internal/api/server.go
index 0f8e7ac2..8bfea165 100644
--- a/internal/api/server.go
+++ b/internal/api/server.go
@@ -11,7 +11,8 @@ import (
 	"strings"
 )
 
-// Server represents the API server
+// Server represents the main API server.
+// It encapsulates the Gin engine, HTTP server, handlers, and configuration.
 type Server struct {
 	engine   *gin.Engine
 	server   *http.Server
@@ -19,14 +20,18 @@ type Server struct {
 	cfg      *ServerConfig
 }
 
-// ServerConfig contains configuration for the API server
+// ServerConfig contains the configuration for the API server.
 type ServerConfig struct {
-	Port    string
-	Debug   bool
+	// Port is the port number the server will listen on.
+	Port string
+	// Debug enables or disables debug mode for the server and Gin.
+	Debug bool
+	// ApiKeys is a list of valid API keys for authentication.
 	ApiKeys []string
 }
 
-// NewServer creates a new API server instance
+// NewServer creates and initializes a new API server instance.
+// It sets up the Gin engine, middleware, routes, and handlers.
 func NewServer(config *ServerConfig, cliClients []*client.Client) *Server {
 	// Set gin mode
 	if !config.Debug {
@@ -63,7 +68,8 @@ func NewServer(config *ServerConfig, cliClients []*client.Client) *Server {
 	return s
 }
 
-// setupRoutes configures the API routes
+// setupRoutes configures the API routes for the server.
+// It defines the endpoints and associates them with their respective handlers.
 func (s *Server) setupRoutes() {
 	// OpenAI compatible API routes
 	v1 := s.engine.Group("/v1")
@@ -86,11 +92,12 @@ func (s *Server) setupRoutes() {
 	})
 }
 
-// Start starts the API server
+// Start begins listening for and serving HTTP requests.
+// It's a blocking call and will only return on an unrecoverable error.
 func (s *Server) Start() error {
 	log.Debugf("Starting API server on %s", s.server.Addr)
 
-	// Start the HTTP server
+	// Start the HTTP server.
 	if err := s.server.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
 		return fmt.Errorf("failed to start HTTP server: %v", err)
 	}
@@ -98,11 +105,12 @@ func (s *Server) Start() error {
 	return nil
 }
 
-// Stop gracefully stops the API server
+// Stop gracefully shuts down the API server without interrupting any
+// active connections.
 func (s *Server) Stop(ctx context.Context) error {
 	log.Debug("Stopping API server...")
 
-	// Shutdown the HTTP server
+	// Shutdown the HTTP server.
 	if err := s.server.Shutdown(ctx); err != nil {
 		return fmt.Errorf("failed to shutdown HTTP server: %v", err)
 	}
@@ -111,7 +119,8 @@ func (s *Server) Stop(ctx context.Context) error {
 	return nil
 }
 
-// corsMiddleware adds CORS headers
+// corsMiddleware returns a Gin middleware handler that adds CORS headers
+// to every response, allowing cross-origin requests.
 func corsMiddleware() gin.HandlerFunc {
 	return func(c *gin.Context) {
 		c.Header("Access-Control-Allow-Origin", "*")
@@ -127,7 +136,8 @@ func corsMiddleware() gin.HandlerFunc {
 	}
 }
 
-// AuthMiddleware authenticates requests using API keys
+// AuthMiddleware returns a Gin middleware handler that authenticates requests
+// using API keys. If no API keys are configured, it allows all requests.
 func AuthMiddleware(cfg *ServerConfig) gin.HandlerFunc {
 	return func(c *gin.Context) {
 		if len(cfg.ApiKeys) == 0 {
diff --git a/internal/api/mine-type.go b/internal/api/translator/mime-type.go
similarity index 99%
rename from internal/api/mine-type.go
rename to internal/api/translator/mime-type.go
index 98b62408..95938ff1 100644
--- a/internal/api/mine-type.go
+++ b/internal/api/translator/mime-type.go
@@ -1,5 +1,7 @@
-package api
+package translator
 
+// MimeTypes is a comprehensive map of file extensions to their corresponding MIME types.
+// This is used to identify the type of file being uploaded or processed.
 var MimeTypes = map[string]string{
 	"ez":          "application/andrew-inset",
 	"aw":          "application/applixware",
diff --git a/internal/api/translator/request.go b/internal/api/translator/request.go
new file mode 100644
index 00000000..69a9794e
--- /dev/null
+++ b/internal/api/translator/request.go
@@ -0,0 +1,163 @@
+package translator
+
+import (
+	"encoding/json"
+	"strings"
+
+	"github.com/luispater/CLIProxyAPI/internal/client"
+	log "github.com/sirupsen/logrus"
+	"github.com/tidwall/gjson"
+)
+
+// PrepareRequest translates a raw JSON request from an OpenAI-compatible format
+// to the internal format expected by the backend client. It parses messages,
+// roles, content types (text, image, file), and tool calls.
+func PrepareRequest(rawJson []byte) (string, []client.Content, []client.ToolDeclaration) {
+	// Extract the model name from the request, defaulting to "gemini-2.5-pro".
+	modelName := "gemini-2.5-pro"
+	modelResult := gjson.GetBytes(rawJson, "model")
+	if modelResult.Type == gjson.String {
+		modelName = modelResult.String()
+	}
+
+	// Process the array of messages.
+	contents := make([]client.Content, 0)
+	messagesResult := gjson.GetBytes(rawJson, "messages")
+	if messagesResult.IsArray() {
+		messagesResults := messagesResult.Array()
+		for i := 0; i < len(messagesResults); i++ {
+			messageResult := messagesResults[i]
+			roleResult := messageResult.Get("role")
+			contentResult := messageResult.Get("content")
+			if roleResult.Type != gjson.String {
+				continue
+			}
+
+			switch roleResult.String() {
+			// System messages are converted to a user message followed by a model's acknowledgment.
+			case "system":
+				if contentResult.Type == gjson.String {
+					contents = append(contents, client.Content{Role: "user", Parts: []client.Part{{Text: contentResult.String()}}})
+					contents = append(contents, client.Content{Role: "model", Parts: []client.Part{{Text: "Understood. I will follow these instructions and use my tools to assist you."}}})
+				} else if contentResult.IsObject() {
+					// Handle object-based system messages.
+					if contentResult.Get("type").String() == "text" {
+						contents = append(contents, client.Content{Role: "user", Parts: []client.Part{{Text: contentResult.Get("text").String()}}})
+						contents = append(contents, client.Content{Role: "model", Parts: []client.Part{{Text: "Understood. I will follow these instructions and use my tools to assist you."}}})
+					}
+				}
+			// User messages can contain simple text or a multi-part body.
+			case "user":
+				if contentResult.Type == gjson.String {
+					contents = append(contents, client.Content{Role: "user", Parts: []client.Part{{Text: contentResult.String()}}})
+				} else if contentResult.IsArray() {
+					// Handle multi-part user messages (text, images, files).
+					contentItemResults := contentResult.Array()
+					parts := make([]client.Part, 0)
+					for j := 0; j < len(contentItemResults); j++ {
+						contentItemResult := contentItemResults[j]
+						contentTypeResult := contentItemResult.Get("type")
+						switch contentTypeResult.String() {
+						case "text":
+							parts = append(parts, client.Part{Text: contentItemResult.Get("text").String()})
+						case "image_url":
+							// Parse data URI for images.
+							imageURL := contentItemResult.Get("image_url.url").String()
+							if len(imageURL) > 5 {
+								imageURLs := strings.SplitN(imageURL[5:], ";", 2)
+								if len(imageURLs) == 2 && len(imageURLs[1]) > 7 {
+									parts = append(parts, client.Part{InlineData: &client.InlineData{
+										MimeType: imageURLs[0],
+										Data:     imageURLs[1][7:],
+									}})
+								}
+							}
+						case "file":
+							// Handle file attachments by determining MIME type from extension.
+							filename := contentItemResult.Get("file.filename").String()
+							fileData := contentItemResult.Get("file.file_data").String()
+							ext := ""
+							if split := strings.Split(filename, "."); len(split) > 1 {
+								ext = split[len(split)-1]
+							}
+							if mimeType, ok := MimeTypes[ext]; ok {
+								parts = append(parts, client.Part{InlineData: &client.InlineData{
+									MimeType: mimeType,
+									Data:     fileData,
+								}})
+							} else {
+								log.Warnf("Unknown file name extension '%s' at index %d, skipping file", ext, j)
+							}
+						}
+					}
+					contents = append(contents, client.Content{Role: "user", Parts: parts})
+				}
+			// Assistant messages can contain text or tool calls.
+			case "assistant":
+				if contentResult.Type == gjson.String {
+					contents = append(contents, client.Content{Role: "model", Parts: []client.Part{{Text: contentResult.String()}}})
+				} else if !contentResult.Exists() || contentResult.Type == gjson.Null {
+					// Handle tool calls made by the assistant.
+					toolCallsResult := messageResult.Get("tool_calls")
+					if toolCallsResult.IsArray() {
+						tcsResult := toolCallsResult.Array()
+						for j := 0; j < len(tcsResult); j++ {
+							tcResult := tcsResult[j]
+							functionName := tcResult.Get("function.name").String()
+							functionArgs := tcResult.Get("function.arguments").String()
+							var args map[string]any
+							if err := json.Unmarshal([]byte(functionArgs), &args); err == nil {
+								contents = append(contents, client.Content{
+									Role: "model", Parts: []client.Part{{
+										FunctionCall: &client.FunctionCall{
+											Name: functionName,
+											Args: args,
+										},
+									}},
+								})
+							}
+						}
+					}
+				}
+			// Tool messages contain the output of a tool call.
+			case "tool":
+				toolCallID := messageResult.Get("tool_call_id").String()
+				if toolCallID != "" {
+					var responseData string
+					if contentResult.Type == gjson.String {
+						responseData = contentResult.String()
+					} else if contentResult.IsObject() && contentResult.Get("type").String() == "text" {
+						responseData = contentResult.Get("text").String()
+					}
+					functionResponse := client.FunctionResponse{Name: toolCallID, Response: map[string]interface{}{"result": responseData}}
+					contents = append(contents, client.Content{Role: "tool", Parts: []client.Part{{FunctionResponse: &functionResponse}}})
+				}
+			}
+		}
+	}
+
+	// Translate the tool declarations from the request.
+	var tools []client.ToolDeclaration
+	toolsResult := gjson.GetBytes(rawJson, "tools")
+	if toolsResult.IsArray() {
+		tools = make([]client.ToolDeclaration, 1)
+		tools[0].FunctionDeclarations = make([]any, 0)
+		toolsResults := toolsResult.Array()
+		for i := 0; i < len(toolsResults); i++ {
+			toolResult := toolsResults[i]
+			if toolResult.Get("type").String() == "function" {
+				functionTypeResult := toolResult.Get("function")
+				if functionTypeResult.Exists() && functionTypeResult.IsObject() {
+					var functionDeclaration any
+					if err := json.Unmarshal([]byte(functionTypeResult.Raw), &functionDeclaration); err == nil {
+						tools[0].FunctionDeclarations = append(tools[0].FunctionDeclarations, functionDeclaration)
+					}
+				}
+			}
+		}
+	} else {
+		tools = make([]client.ToolDeclaration, 0)
+	}
+
+	return modelName, contents, tools
+}
diff --git a/internal/api/translator/response.go b/internal/api/translator/response.go
new file mode 100644
index 00000000..885b5f30
--- /dev/null
+++ b/internal/api/translator/response.go
@@ -0,0 +1,169 @@
+package translator
+
+import (
+	"time"
+
+	"github.com/tidwall/gjson"
+	"github.com/tidwall/sjson"
+)
+
+// ConvertCliToOpenAI translates a single chunk of a streaming response from the
+// backend client format to the OpenAI Server-Sent Events (SSE) format.
+// It returns an empty string if the chunk contains no useful data.
+func ConvertCliToOpenAI(rawJson []byte) string {
+	// Initialize the OpenAI SSE template.
+	template := `{"id":"","object":"chat.completion.chunk","created":12345,"model":"model","choices":[{"index":0,"delta":{"role":null,"content":null,"reasoning_content":null,"tool_calls":null},"finish_reason":null,"native_finish_reason":null}]}`
+
+	// Extract and set the model version.
+	if modelVersionResult := gjson.GetBytes(rawJson, "response.modelVersion"); modelVersionResult.Exists() {
+		template, _ = sjson.Set(template, "model", modelVersionResult.String())
+	}
+
+	// Extract and set the creation timestamp.
+	if createTimeResult := gjson.GetBytes(rawJson, "response.createTime"); createTimeResult.Exists() {
+		t, err := time.Parse(time.RFC3339Nano, createTimeResult.String())
+		unixTimestamp := time.Now().Unix()
+		if err == nil {
+			unixTimestamp = t.Unix()
+		}
+		template, _ = sjson.Set(template, "created", unixTimestamp)
+	}
+
+	// Extract and set the response ID.
+	if responseIdResult := gjson.GetBytes(rawJson, "response.responseId"); responseIdResult.Exists() {
+		template, _ = sjson.Set(template, "id", responseIdResult.String())
+	}
+
+	// Extract and set the finish reason.
+	if finishReasonResult := gjson.GetBytes(rawJson, "response.candidates.0.finishReason"); finishReasonResult.Exists() {
+		template, _ = sjson.Set(template, "choices.0.finish_reason", finishReasonResult.String())
+		template, _ = sjson.Set(template, "choices.0.native_finish_reason", finishReasonResult.String())
+	}
+
+	// Extract and set usage metadata (token counts).
+	if usageResult := gjson.GetBytes(rawJson, "response.usageMetadata"); usageResult.Exists() {
+		if candidatesTokenCountResult := usageResult.Get("candidatesTokenCount"); candidatesTokenCountResult.Exists() {
+			template, _ = sjson.Set(template, "usage.completion_tokens", candidatesTokenCountResult.Int())
+		}
+		if totalTokenCountResult := usageResult.Get("totalTokenCount"); totalTokenCountResult.Exists() {
+			template, _ = sjson.Set(template, "usage.total_tokens", totalTokenCountResult.Int())
+		}
+		promptTokenCount := usageResult.Get("promptTokenCount").Int()
+		thoughtsTokenCount := usageResult.Get("thoughtsTokenCount").Int()
+		template, _ = sjson.Set(template, "usage.prompt_tokens", promptTokenCount+thoughtsTokenCount)
+		if thoughtsTokenCount > 0 {
+			template, _ = sjson.Set(template, "usage.completion_tokens_details.reasoning_tokens", thoughtsTokenCount)
+		}
+	}
+
+	// Process the main content part of the response.
+	partResult := gjson.GetBytes(rawJson, "response.candidates.0.content.parts.0")
+	partTextResult := partResult.Get("text")
+	functionCallResult := partResult.Get("functionCall")
+
+	if partTextResult.Exists() {
+		// Handle text content, distinguishing between regular content and reasoning/thoughts.
+		if partResult.Get("thought").Bool() {
+			template, _ = sjson.Set(template, "choices.0.delta.reasoning_content", partTextResult.String())
+		} else {
+			template, _ = sjson.Set(template, "choices.0.delta.content", partTextResult.String())
+		}
+		template, _ = sjson.Set(template, "choices.0.delta.role", "assistant")
+	} else if functionCallResult.Exists() {
+		// Handle function call content.
+		functionCallTemplate := `[{"id": "","type": "function","function": {"name": "","arguments": ""}}]`
+		fcName := functionCallResult.Get("name").String()
+		functionCallTemplate, _ = sjson.Set(functionCallTemplate, "0.id", fcName)
+		functionCallTemplate, _ = sjson.Set(functionCallTemplate, "0.function.name", fcName)
+		if fcArgsResult := functionCallResult.Get("args"); fcArgsResult.Exists() {
+			functionCallTemplate, _ = sjson.Set(functionCallTemplate, "0.function.arguments", fcArgsResult.Raw)
+		}
+		template, _ = sjson.Set(template, "choices.0.delta.role", "assistant")
+		template, _ = sjson.SetRaw(template, "choices.0.delta.tool_calls", functionCallTemplate)
+	} else {
+		// If no usable content is found, return an empty string.
+		return ""
+	}
+
+	return template
+}
+
+// ConvertCliToOpenAINonStream aggregates response chunks from the backend client
+// into a single, non-streaming OpenAI-compatible JSON response.
+func ConvertCliToOpenAINonStream(template string, rawJson []byte) string {
+	// Extract and set metadata fields that are typically set once per response.
+	if gjson.Get(template, "id").String() == "" {
+		if modelVersionResult := gjson.GetBytes(rawJson, "response.modelVersion"); modelVersionResult.Exists() {
+			template, _ = sjson.Set(template, "model", modelVersionResult.String())
+		}
+		if createTimeResult := gjson.GetBytes(rawJson, "response.createTime"); createTimeResult.Exists() {
+			t, err := time.Parse(time.RFC3339Nano, createTimeResult.String())
+			unixTimestamp := time.Now().Unix()
+			if err == nil {
+				unixTimestamp = t.Unix()
+			}
+			template, _ = sjson.Set(template, "created", unixTimestamp)
+		}
+		if responseIdResult := gjson.GetBytes(rawJson, "response.responseId"); responseIdResult.Exists() {
+			template, _ = sjson.Set(template, "id", responseIdResult.String())
+		}
+	}
+
+	// Extract and set the finish reason.
+	if finishReasonResult := gjson.GetBytes(rawJson, "response.candidates.0.finishReason"); finishReasonResult.Exists() {
+		template, _ = sjson.Set(template, "choices.0.finish_reason", finishReasonResult.String())
+		template, _ = sjson.Set(template, "choices.0.native_finish_reason", finishReasonResult.String())
+	}
+
+	// Extract and set usage metadata (token counts).
+	if usageResult := gjson.GetBytes(rawJson, "response.usageMetadata"); usageResult.Exists() {
+		if candidatesTokenCountResult := usageResult.Get("candidatesTokenCount"); candidatesTokenCountResult.Exists() {
+			template, _ = sjson.Set(template, "usage.completion_tokens", candidatesTokenCountResult.Int())
+		}
+		if totalTokenCountResult := usageResult.Get("totalTokenCount"); totalTokenCountResult.Exists() {
+			template, _ = sjson.Set(template, "usage.total_tokens", totalTokenCountResult.Int())
+		}
+		promptTokenCount := usageResult.Get("promptTokenCount").Int()
+		thoughtsTokenCount := usageResult.Get("thoughtsTokenCount").Int()
+		template, _ = sjson.Set(template, "usage.prompt_tokens", promptTokenCount+thoughtsTokenCount)
+		if thoughtsTokenCount > 0 {
+			template, _ = sjson.Set(template, "usage.completion_tokens_details.reasoning_tokens", thoughtsTokenCount)
+		}
+	}
+
+	// Process the main content part of the response.
+	partResult := gjson.GetBytes(rawJson, "response.candidates.0.content.parts.0")
+	partTextResult := partResult.Get("text")
+	functionCallResult := partResult.Get("functionCall")
+
+	if partTextResult.Exists() {
+		// Append text content, distinguishing between regular content and reasoning.
+		if partResult.Get("thought").Bool() {
+			currentContent := gjson.Get(template, "choices.0.message.reasoning_content").String()
+			template, _ = sjson.Set(template, "choices.0.message.reasoning_content", currentContent+partTextResult.String())
+		} else {
+			currentContent := gjson.Get(template, "choices.0.message.content").String()
+			template, _ = sjson.Set(template, "choices.0.message.content", currentContent+partTextResult.String())
+		}
+		template, _ = sjson.Set(template, "choices.0.message.role", "assistant")
+	} else if functionCallResult.Exists() {
+		// Append function call content to the tool_calls array.
+		if !gjson.Get(template, "choices.0.message.tool_calls").Exists() {
+			template, _ = sjson.SetRaw(template, "choices.0.message.tool_calls", `[]`)
+		}
+		functionCallItemTemplate := `{"id": "","type": "function","function": {"name": "","arguments": ""}}`
+		fcName := functionCallResult.Get("name").String()
+		functionCallItemTemplate, _ = sjson.Set(functionCallItemTemplate, "id", fcName)
+		functionCallItemTemplate, _ = sjson.Set(functionCallItemTemplate, "function.name", fcName)
+		if fcArgsResult := functionCallResult.Get("args"); fcArgsResult.Exists() {
+			functionCallItemTemplate, _ = sjson.Set(functionCallItemTemplate, "function.arguments", fcArgsResult.Raw)
+		}
+		template, _ = sjson.Set(template, "choices.0.message.role", "assistant")
+		template, _ = sjson.SetRaw(template, "choices.0.message.tool_calls.-1", functionCallItemTemplate)
+	} else {
+		// If no usable content is found, return an empty string.
+		return ""
+	}
+
+	return template
+}
diff --git a/internal/auth/auth.go b/internal/auth/auth.go
index f1be254f..208c90d2 100644
--- a/internal/auth/auth.go
+++ b/internal/auth/auth.go
@@ -5,17 +5,18 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"github.com/luispater/CLIProxyAPI/internal/config"
-	log "github.com/sirupsen/logrus"
-	"github.com/skratchdot/open-golang/open"
-	"github.com/tidwall/gjson"
-	"golang.org/x/net/proxy"
 	"io"
 	"net"
 	"net/http"
 	"net/url"
 	"time"
 
+	"github.com/luispater/CLIProxyAPI/internal/config"
+	log "github.com/sirupsen/logrus"
+	"github.com/skratchdot/open-golang/open"
+	"github.com/tidwall/gjson"
+	"golang.org/x/net/proxy"
+
 	"golang.org/x/oauth2"
 	"golang.org/x/oauth2/google"
 )
@@ -33,76 +34,78 @@ var (
 	}
 )
 
-// GetAuthenticatedClient configures and returns an HTTP client with OAuth2 tokens.
-// It handles the entire flow: loading, refreshing, and fetching new tokens.
+// GetAuthenticatedClient configures and returns an HTTP client ready for making authenticated API calls.
+// It manages the entire OAuth2 flow, including handling proxies, loading existing tokens,
+// initiating a new web-based OAuth flow if necessary, and refreshing tokens.
 func GetAuthenticatedClient(ctx context.Context, ts *TokenStorage, cfg *config.Config) (*http.Client, error) {
+	// Configure proxy settings for the HTTP client if a proxy URL is provided.
 	proxyURL, err := url.Parse(cfg.ProxyUrl)
 	if err == nil {
+		var transport *http.Transport
 		if proxyURL.Scheme == "socks5" {
+			// Handle SOCKS5 proxy.
 			username := proxyURL.User.Username()
 			password, _ := proxyURL.User.Password()
-			auth := &proxy.Auth{
-				User:     username,
-				Password: password,
-			}
+			auth := &proxy.Auth{User: username, Password: password}
 			dialer, errSOCKS5 := proxy.SOCKS5("tcp", proxyURL.Host, auth, proxy.Direct)
 			if errSOCKS5 != nil {
 				log.Fatalf("create SOCKS5 dialer failed: %v", errSOCKS5)
 			}
-
-			transport := &http.Transport{
-				DialContext: func(ctx context.Context, network, addr string) (c net.Conn, err error) {
+			transport = &http.Transport{
+				DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
 					return dialer.Dial(network, addr)
 				},
 			}
-			proxyClient := &http.Client{
-				Transport: transport,
-			}
-
-			ctx = context.WithValue(ctx, oauth2.HTTPClient, proxyClient)
 		} else if proxyURL.Scheme == "http" || proxyURL.Scheme == "https" {
-			transport := &http.Transport{
-				Proxy: http.ProxyURL(proxyURL),
-			}
-			proxyClient := &http.Client{
-				Transport: transport,
-			}
+			// Handle HTTP/HTTPS proxy.
+			transport = &http.Transport{Proxy: http.ProxyURL(proxyURL)}
+		}
+
+		if transport != nil {
+			proxyClient := &http.Client{Transport: transport}
 			ctx = context.WithValue(ctx, oauth2.HTTPClient, proxyClient)
 		}
 	}
 
+	// Configure the OAuth2 client.
 	conf := &oauth2.Config{
 		ClientID:     oauthClientID,
 		ClientSecret: oauthClientSecret,
-		RedirectURL:  "http://localhost:8085/oauth2callback", // Placeholder, will be updated
+		RedirectURL:  "http://localhost:8085/oauth2callback", // This will be used by the local server.
 		Scopes:       oauthScopes,
 		Endpoint:     google.Endpoint,
 	}
 
 	var token *oauth2.Token
 
+	// If no token is found in storage, initiate the web-based OAuth flow.
 	if ts.Token == nil {
 		log.Info("Could not load token from file, starting OAuth flow.")
 		token, err = getTokenFromWeb(ctx, conf)
 		if err != nil {
 			return nil, fmt.Errorf("failed to get token from web: %w", err)
 		}
-		newTs, errSaveTokenToFile := createTokenStorage(ctx, conf, token, ts.ProjectID)
-		if errSaveTokenToFile != nil {
-			log.Errorf("Warning: failed to save token to file: %v", err)
-			return nil, errSaveTokenToFile
+		// After getting a new token, create a new token storage object with user info.
+		newTs, errCreateTokenStorage := createTokenStorage(ctx, conf, token, ts.ProjectID)
+		if errCreateTokenStorage != nil {
+			log.Errorf("Warning: failed to create token storage: %v", errCreateTokenStorage)
+			return nil, errCreateTokenStorage
 		}
 		*ts = *newTs
 	}
+
+	// Unmarshal the stored token into an oauth2.Token object.
 	tsToken, _ := json.Marshal(ts.Token)
 	if err = json.Unmarshal(tsToken, &token); err != nil {
-		return nil, err
+		return nil, fmt.Errorf("failed to unmarshal token: %w", err)
 	}
 
+	// Return an HTTP client that automatically handles token refreshing.
 	return conf.Client(ctx, token), nil
 }
 
-// createTokenStorage creates a token storage.
+// createTokenStorage creates a new TokenStorage object. It fetches the user's email
+// using the provided token and populates the storage structure.
 func createTokenStorage(ctx context.Context, config *oauth2.Config, token *oauth2.Token, projectID string) (*TokenStorage, error) {
 	httpClient := config.Client(ctx, token)
 	req, err := http.NewRequestWithContext(ctx, "GET", "https://www.googleapis.com/oauth2/v1/userinfo?alt=json", nil)
@@ -117,7 +120,9 @@ func createTokenStorage(ctx context.Context, config *oauth2.Config, token *oauth
 		return nil, fmt.Errorf("failed to execute request: %w", err)
 	}
 	defer func() {
-		_ = resp.Body.Close()
+		if err = resp.Body.Close(); err != nil {
+			log.Printf("warn: failed to close response body: %v", err)
+		}
 	}()
 
 	bodyBytes, _ := io.ReadAll(resp.Body)
@@ -154,7 +159,10 @@ func createTokenStorage(ctx context.Context, config *oauth2.Config, token *oauth
 	return &ts, nil
 }
 
-// getTokenFromWeb starts a local server to handle the OAuth2 flow.
+// getTokenFromWeb initiates the web-based OAuth2 authorization flow.
+// It starts a local HTTP server to listen for the callback from Google's auth server,
+// opens the user's browser to the authorization URL, and exchanges the received
+// authorization code for an access token.
 func getTokenFromWeb(ctx context.Context, config *oauth2.Config) (*oauth2.Token, error) {
 	// Use a channel to pass the authorization code from the HTTP handler to the main function.
 	codeChan := make(chan string)
diff --git a/internal/auth/models.go b/internal/auth/models.go
index c90d47c5..33c03745 100644
--- a/internal/auth/models.go
+++ b/internal/auth/models.go
@@ -1,9 +1,17 @@
 package auth
 
+// TokenStorage defines the structure for storing OAuth2 token information,
+// along with associated user and project details. This data is typically
+// serialized to a JSON file for persistence.
 type TokenStorage struct {
-	Token     any    `json:"token"`
+	// Token holds the raw OAuth2 token data, including access and refresh tokens.
+	Token any `json:"token"`
+	// ProjectID is the Google Cloud Project ID associated with this token.
 	ProjectID string `json:"project_id"`
-	Email     string `json:"email"`
-	Auto      bool   `json:"auto"`
-	Checked   bool   `json:"checked"`
+	// Email is the email address of the authenticated user.
+	Email string `json:"email"`
+	// Auto indicates if the project ID was automatically selected.
+	Auto bool `json:"auto"`
+	// Checked indicates if the associated Cloud AI API has been verified as enabled.
+	Checked bool `json:"checked"`
 }
diff --git a/internal/client/client.go b/internal/client/client.go
index f721c3d7..07fb6d9c 100644
--- a/internal/client/client.go
+++ b/internal/client/client.go
@@ -6,12 +6,6 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
-	"github.com/luispater/CLIProxyAPI/internal/auth"
-	"github.com/luispater/CLIProxyAPI/internal/config"
-	log "github.com/sirupsen/logrus"
-	"github.com/tidwall/gjson"
-	"github.com/tidwall/sjson"
-	"golang.org/x/oauth2"
 	"io"
 	"net/http"
 	"os"
@@ -20,6 +14,13 @@ import (
 	"strings"
 	"sync"
 	"time"
+
+	"github.com/luispater/CLIProxyAPI/internal/auth"
+	"github.com/luispater/CLIProxyAPI/internal/config"
+	log "github.com/sirupsen/logrus"
+	"github.com/tidwall/gjson"
+	"github.com/tidwall/sjson"
+	"golang.org/x/oauth2"
 )
 
 const (
@@ -194,7 +195,9 @@ func (c *Client) makeAPIRequest(ctx context.Context, endpoint, method string, bo
 		return fmt.Errorf("failed to execute request: %w", err)
 	}
 	defer func() {
-		_ = resp.Body.Close()
+		if err = resp.Body.Close(); err != nil {
+			log.Printf("warn: failed to close response body: %v", err)
+		}
 	}()
 
 	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
@@ -253,7 +256,9 @@ func (c *Client) StreamAPIRequest(ctx context.Context, endpoint string, body int
 
 	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
 		defer func() {
-			_ = resp.Body.Close()
+			if err = resp.Body.Close(); err != nil {
+				log.Printf("warn: failed to close response body: %v", err)
+			}
 		}()
 		bodyBytes, _ := io.ReadAll(resp.Body)
 
@@ -355,6 +360,9 @@ func (c *Client) SendMessageStream(ctx context.Context, rawJson []byte, model st
 	return dataChan, errChan
 }
 
+// CheckCloudAPIIsEnabled sends a simple test request to the API to verify
+// that the Cloud AI API is enabled for the user's project. It provides
+// an activation URL if the API is disabled.
 func (c *Client) CheckCloudAPIIsEnabled() (bool, error) {
 	ctx, cancel := context.WithCancel(context.Background())
 	defer func() {
@@ -363,79 +371,78 @@ func (c *Client) CheckCloudAPIIsEnabled() (bool, error) {
 	}()
 	c.RequestMutex.Lock()
 
-	requestBody := `{"project":"%s","request":{"contents":[{"role":"user","parts":[{"text":"Be concise. What is the capital of France?"}]}],"generationConfig":{"thinkingConfig":{"include_thoughts":false,"thinkingBudget":0}}},"model":"gemini-2.5-flash"}`
-	requestBody = fmt.Sprintf(requestBody, c.tokenStorage.ProjectID)
-	// log.Debug(requestBody)
+	// A simple request to test the API endpoint.
+	requestBody := fmt.Sprintf(`{"project":"%s","request":{"contents":[{"role":"user","parts":[{"text":"Be concise. What is the capital of France?"}]}],"generationConfig":{"thinkingConfig":{"include_thoughts":false,"thinkingBudget":0}}},"model":"gemini-2.5-flash"}`, c.tokenStorage.ProjectID)
+
 	stream, err := c.StreamAPIRequest(ctx, "streamGenerateContent", []byte(requestBody))
 	if err != nil {
+		// If a 403 Forbidden error occurs, it likely means the API is not enabled.
 		if err.StatusCode == 403 {
 			errJson := err.Error.Error()
-			codeResult := gjson.Get(errJson, "error.code")
-			if codeResult.Exists() && codeResult.Type == gjson.Number {
-				if codeResult.Int() == 403 {
-					activationUrlResult := gjson.Get(errJson, "error.details.0.metadata.activationUrl")
-					if activationUrlResult.Exists() {
-						log.Warnf(
-							"\n\nPlease activate your account with this url:\n\n%s\n And execute this command again:\n%s --login --project_id %s",
-							activationUrlResult.String(),
-							os.Args[0],
-							c.tokenStorage.ProjectID,
-						)
-					}
+			// Check for a specific error code and extract the activation URL.
+			if gjson.Get(errJson, "error.code").Int() == 403 {
+				activationUrl := gjson.Get(errJson, "error.details.0.metadata.activationUrl").String()
+				if activationUrl != "" {
+					log.Warnf(
+						"\n\nPlease activate your account with this url:\n\n%s\n And execute this command again:\n%s --login --project_id %s",
+						activationUrl,
+						os.Args[0],
+						c.tokenStorage.ProjectID,
+					)
 				}
 			}
 			return false, nil
 		}
 		return false, err.Error
 	}
+	defer func() {
+		_ = stream.Close()
+	}()
 
+	// We only need to know if the request was successful, so we can drain the stream.
 	scanner := bufio.NewScanner(stream)
 	for scanner.Scan() {
-		line := scanner.Text()
-		if !strings.HasPrefix(line, "data: ") {
-			continue
-		}
+		// Do nothing, just consume the stream.
 	}
 
-	if scannerErr := scanner.Err(); scannerErr != nil {
-		_ = stream.Close()
-	} else {
-		_ = stream.Close()
-	}
-
-	return true, nil
+	return scanner.Err() == nil, scanner.Err()
 }
 
+// GetProjectList fetches a list of Google Cloud projects accessible by the user.
 func (c *Client) GetProjectList(ctx context.Context) (*GCPProject, error) {
 	token, err := c.httpClient.Transport.(*oauth2.Transport).Source.Token()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get token: %w", err)
+	}
+
 	req, err := http.NewRequestWithContext(ctx, "GET", "https://cloudresourcemanager.googleapis.com/v1/projects", nil)
 	if err != nil {
-		return nil, fmt.Errorf("could not get project list: %v", err)
+		return nil, fmt.Errorf("could not create project list request: %v", err)
 	}
-	req.Header.Set("Content-Type", "application/json")
 	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token.AccessToken))
 
 	resp, err := c.httpClient.Do(req)
 	if err != nil {
-		return nil, fmt.Errorf("failed to execute request: %w", err)
+		return nil, fmt.Errorf("failed to execute project list request: %w", err)
 	}
 	defer func() {
 		_ = resp.Body.Close()
 	}()
 
-	bodyBytes, _ := io.ReadAll(resp.Body)
 	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
-		return nil, fmt.Errorf("get user info request failed with status %d: %s", resp.StatusCode, string(bodyBytes))
+		bodyBytes, _ := io.ReadAll(resp.Body)
+		return nil, fmt.Errorf("project list request failed with status %d: %s", resp.StatusCode, string(bodyBytes))
 	}
 
 	var project GCPProject
-	err = json.Unmarshal(bodyBytes, &project)
-	if err != nil {
+	if err = json.NewDecoder(resp.Body).Decode(&project); err != nil {
 		return nil, fmt.Errorf("failed to unmarshal project list: %w", err)
 	}
 	return &project, nil
 }
 
+// SaveTokenToFile serializes the client's current token storage to a JSON file.
+// The filename is constructed from the user's email and project ID.
 func (c *Client) SaveTokenToFile() error {
 	if err := os.MkdirAll(c.cfg.AuthDir, 0700); err != nil {
 		return fmt.Errorf("failed to create directory: %v", err)
@@ -457,7 +464,8 @@ func (c *Client) SaveTokenToFile() error {
 	return nil
 }
 
-// getClientMetadata returns metadata about the client environment.
+// getClientMetadata returns a map of metadata about the client environment,
+// such as IDE type, platform, and plugin version.
 func getClientMetadata() map[string]string {
 	return map[string]string{
 		"ideType":       "IDE_UNSPECIFIED",
@@ -467,7 +475,8 @@ func getClientMetadata() map[string]string {
 	}
 }
 
-// getClientMetadataString returns the metadata as a comma-separated string.
+// getClientMetadataString returns the client metadata as a single,
+// comma-separated string, which is required for the 'Client-Metadata' header.
 func getClientMetadataString() string {
 	md := getClientMetadata()
 	parts := make([]string, 0, len(md))
@@ -477,11 +486,13 @@ func getClientMetadataString() string {
 	return strings.Join(parts, ",")
 }
 
+// getUserAgent constructs the User-Agent string for HTTP requests.
 func getUserAgent() string {
-	return fmt.Sprintf(fmt.Sprintf("GeminiCLI/%s (%s; %s)", pluginVersion, runtime.GOOS, runtime.GOARCH))
+	return fmt.Sprintf("GeminiCLI/%s (%s; %s)", pluginVersion, runtime.GOOS, runtime.GOARCH)
 }
 
-// getPlatform returns the OS and architecture in the format expected by the API.
+// getPlatform determines the operating system and architecture and formats
+// it into a string expected by the backend API.
 func getPlatform() string {
 	goOS := runtime.GOOS
 	arch := runtime.GOARCH
diff --git a/internal/client/models.go b/internal/client/models.go
index 23515000..a6aa9d44 100644
--- a/internal/client/models.go
+++ b/internal/client/models.go
@@ -2,17 +2,23 @@ package client
 
 import "time"
 
+// ErrorMessage encapsulates an error with an associated HTTP status code.
 type ErrorMessage struct {
 	StatusCode int
 	Error      error
 }
 
+// GCPProject represents the response structure for a Google Cloud project list request.
 type GCPProject struct {
 	Projects []GCPProjectProjects `json:"projects"`
 }
+
+// GCPProjectLabels defines the labels associated with a GCP project.
 type GCPProjectLabels struct {
 	GenerativeLanguage string `json:"generative-language"`
 }
+
+// GCPProjectProjects contains details about a single Google Cloud project.
 type GCPProjectProjects struct {
 	ProjectNumber  string           `json:"projectNumber"`
 	ProjectID      string           `json:"projectId"`
@@ -22,12 +28,14 @@ type GCPProjectProjects struct {
 	CreateTime     time.Time        `json:"createTime"`
 }
 
+// Content represents a single message in a conversation, with a role and parts.
 type Content struct {
 	Role  string `json:"role"`
 	Parts []Part `json:"parts"`
 }
 
-// Part represents a single part of a message's content.
+// Part represents a distinct piece of content within a message, which can be
+// text, inline data (like an image), a function call, or a function response.
 type Part struct {
 	Text             string            `json:"text,omitempty"`
 	InlineData       *InlineData       `json:"inlineData,omitempty"`
@@ -35,46 +43,48 @@ type Part struct {
 	FunctionResponse *FunctionResponse `json:"functionResponse,omitempty"`
 }
 
+// InlineData represents base64-encoded data with its MIME type.
 type InlineData struct {
 	MimeType string `json:"mime_type,omitempty"`
 	Data     string `json:"data,omitempty"`
 }
 
-// FunctionCall represents a tool call requested by the model.
+// FunctionCall represents a tool call requested by the model, including the
+// function name and its arguments.
 type FunctionCall struct {
 	Name string                 `json:"name"`
 	Args map[string]interface{} `json:"args"`
 }
 
-// FunctionResponse represents the result of a tool execution.
+// FunctionResponse represents the result of a tool execution, sent back to the model.
 type FunctionResponse struct {
 	Name     string                 `json:"name"`
 	Response map[string]interface{} `json:"response"`
 }
 
-// GenerateContentRequest is the request payload for the streamGenerateContent endpoint.
+// GenerateContentRequest is the top-level request structure for the streamGenerateContent endpoint.
 type GenerateContentRequest struct {
 	Contents         []Content         `json:"contents"`
 	Tools            []ToolDeclaration `json:"tools,omitempty"`
 	GenerationConfig `json:"generationConfig"`
 }
 
-// GenerationConfig defines model generation parameters.
+// GenerationConfig defines parameters that control the model's generation behavior.
 type GenerationConfig struct {
 	ThinkingConfig GenerationConfigThinkingConfig `json:"thinkingConfig,omitempty"`
 	Temperature    float64                        `json:"temperature,omitempty"`
 	TopP           float64                        `json:"topP,omitempty"`
 	TopK           float64                        `json:"topK,omitempty"`
-	// Temperature, TopP, TopK, etc. can be added here.
 }
 
+// GenerationConfigThinkingConfig specifies configuration for the model's "thinking" process.
 type GenerationConfigThinkingConfig struct {
+	// IncludeThoughts determines whether the model should output its reasoning process.
 	IncludeThoughts bool `json:"include_thoughts,omitempty"`
 }
 
-// ToolDeclaration is the structure for declaring tools to the API.
-// For now, we'll assume a simple structure. A more complete implementation
-// would mirror the OpenAPI schema definition.
+// ToolDeclaration defines the structure for declaring tools (like functions)
+// that the model can call.
 type ToolDeclaration struct {
 	FunctionDeclarations []interface{} `json:"functionDeclarations"`
 }
diff --git a/internal/cmd/login.go b/internal/cmd/login.go
index d71b85a9..3d6aa94a 100644
--- a/internal/cmd/login.go
+++ b/internal/cmd/login.go
@@ -9,6 +9,9 @@ import (
 	"os"
 )
 
+// DoLogin handles the entire user login and setup process.
+// It authenticates the user, sets up the user's project, checks API enablement,
+// and saves the token for future use.
 func DoLogin(cfg *config.Config, projectID string) {
 	var err error
 	var ts auth.TokenStorage
@@ -16,9 +19,8 @@ func DoLogin(cfg *config.Config, projectID string) {
 		ts.ProjectID = projectID
 	}
 
-	// 2. Initialize authenticated HTTP Client
+	// Initialize an authenticated HTTP client. This will trigger the OAuth flow if necessary.
 	clientCtx := context.Background()
-
 	log.Info("Initializing authentication...")
 	httpClient, errGetClient := auth.GetAuthenticatedClient(clientCtx, &ts, cfg)
 	if errGetClient != nil {
@@ -27,51 +29,57 @@ func DoLogin(cfg *config.Config, projectID string) {
 	}
 	log.Info("Authentication successful.")
 
-	// 3. Initialize CLI Client
+	// Initialize the API client.
 	cliClient := client.NewClient(httpClient, &ts, cfg)
+
+	// Perform the user setup process.
 	err = cliClient.SetupUser(clientCtx, ts.Email, projectID)
 	if err != nil {
+		// Handle the specific case where a project ID is required but not provided.
 		if err.Error() == "failed to start user onboarding, need define a project id" {
-			log.Error("failed to start user onboarding")
+			log.Error("Failed to start user onboarding: A project ID is required.")
+			// Fetch and display the user's available projects to help them choose one.
 			project, errGetProjectList := cliClient.GetProjectList(clientCtx)
 			if errGetProjectList != nil {
-				log.Fatalf("failed to complete user setup: %v", err)
+				log.Fatalf("Failed to get project list: %v", err)
 			} else {
-				log.Infof("Your account %s needs specify a project id.", ts.Email)
+				log.Infof("Your account %s needs to specify a project ID.", ts.Email)
 				log.Info("========================================================================")
-				for i := 0; i < len(project.Projects); i++ {
-					log.Infof("Project ID: %s", project.Projects[i].ProjectID)
-					log.Infof("Project Name: %s", project.Projects[i].Name)
-					log.Info("========================================================================")
+				for _, p := range project.Projects {
+					log.Infof("Project ID: %s", p.ProjectID)
+					log.Infof("Project Name: %s", p.Name)
+					log.Info("------------------------------------------------------------------------")
 				}
-				log.Infof("Please run this command to login again:\n\n%s --login --project_id <project_id>\n", os.Args[0])
+				log.Infof("Please run this command to login again with a specific project:\n\n%s --login --project_id <project_id>\n", os.Args[0])
 			}
 		} else {
-			// Log as a warning because in some cases, the CLI might still be usable
-			// or the user might want to retry setup later.
-			log.Fatalf("failed to complete user setup: %v", err)
+			log.Fatalf("Failed to complete user setup: %v", err)
 		}
-	} else {
-		auto := projectID == ""
-		cliClient.SetIsAuto(auto)
+		return // Exit after handling the error.
+	}
 
-		if !cliClient.IsChecked() && !cliClient.IsAuto() {
-			isChecked, checkErr := cliClient.CheckCloudAPIIsEnabled()
-			if checkErr != nil {
-				log.Fatalf("failed to check cloud api is enabled: %v", checkErr)
-				return
-			}
-			cliClient.SetIsChecked(isChecked)
-		}
+	// If setup is successful, proceed to check API status and save the token.
+	auto := projectID == ""
+	cliClient.SetIsAuto(auto)
 
-		if !cliClient.IsChecked() && !cliClient.IsAuto() {
+	// If the project was not automatically selected, check if the Cloud AI API is enabled.
+	if !cliClient.IsChecked() && !cliClient.IsAuto() {
+		isChecked, checkErr := cliClient.CheckCloudAPIIsEnabled()
+		if checkErr != nil {
+			log.Fatalf("Failed to check if Cloud AI API is enabled: %v", checkErr)
 			return
 		}
-
-		err = cliClient.SaveTokenToFile()
-		if err != nil {
-			log.Fatal(err)
+		cliClient.SetIsChecked(isChecked)
+		// If the check fails (returns false), the CheckCloudAPIIsEnabled function
+		// will have already printed instructions, so we can just exit.
+		if !isChecked {
 			return
 		}
 	}
+
+	// Save the successfully obtained and verified token to a file.
+	err = cliClient.SaveTokenToFile()
+	if err != nil {
+		log.Fatalf("Failed to save token to file: %v", err)
+	}
 }
diff --git a/internal/cmd/run.go b/internal/cmd/run.go
index 8bf291bf..5fa6ebb1 100644
--- a/internal/cmd/run.go
+++ b/internal/cmd/run.go
@@ -18,20 +18,25 @@ import (
 	"time"
 )
 
+// StartService initializes and starts the main API proxy service.
+// It loads all available authentication tokens, creates a pool of clients,
+// starts the API server, and handles graceful shutdown signals.
 func StartService(cfg *config.Config) {
-	// Create API server configuration
+	// Configure the API server based on the main application config.
 	apiConfig := &api.ServerConfig{
 		Port:    fmt.Sprintf("%d", cfg.Port),
 		Debug:   cfg.Debug,
 		ApiKeys: cfg.ApiKeys,
 	}
 
+	// Create a pool of API clients, one for each token file found.
 	cliClients := make([]*client.Client, 0)
 	err := filepath.Walk(cfg.AuthDir, func(path string, info fs.FileInfo, err error) error {
 		if err != nil {
 			return err
 		}
 
+		// Process only JSON files in the auth directory.
 		if !info.IsDir() && strings.HasSuffix(info.Name(), ".json") {
 			log.Debugf("Loading token from: %s", path)
 			f, errOpen := os.Open(path)
@@ -42,58 +47,62 @@ func StartService(cfg *config.Config) {
 				_ = f.Close()
 			}()
 
+			// Decode the token storage file.
 			var ts auth.TokenStorage
 			if err = json.NewDecoder(f).Decode(&ts); err == nil {
-				// 2. Initialize authenticated HTTP Client
+				// For each valid token, create an authenticated client.
 				clientCtx := context.Background()
-
-				log.Info("Initializing authentication...")
+				log.Info("Initializing authentication for token...")
 				httpClient, errGetClient := auth.GetAuthenticatedClient(clientCtx, &ts, cfg)
 				if errGetClient != nil {
-					log.Fatalf("failed to get authenticated client: %v", errGetClient)
+					// Log fatal will exit, but we return the error for completeness.
+					log.Fatalf("failed to get authenticated client for token %s: %v", path, errGetClient)
 					return errGetClient
 				}
 				log.Info("Authentication successful.")
 
-				// 3. Initialize CLI Client
+				// Add the new client to the pool.
 				cliClient := client.NewClient(httpClient, &ts, cfg)
 				cliClients = append(cliClients, cliClient)
 			}
 		}
 		return nil
 	})
+	if err != nil {
+		log.Fatalf("Error walking auth directory: %v", err)
+	}
 
-	// Create API server
+	// Create and start the API server with the pool of clients.
 	apiServer := api.NewServer(apiConfig, cliClients)
 	log.Infof("Starting API server on port %s", apiConfig.Port)
 	if err = apiServer.Start(); err != nil {
 		log.Fatalf("API server failed to start: %v", err)
-		return
 	}
 
-	// Set up graceful shutdown
+	// Set up a channel to listen for OS signals for graceful shutdown.
 	sigChan := make(chan os.Signal, 1)
 	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
 
+	// Main loop to wait for shutdown signal.
 	for {
 		select {
 		case <-sigChan:
 			log.Debugf("Received shutdown signal. Cleaning up...")
 
-			// Create shutdown context
+			// Create a context with a timeout for the shutdown process.
 			ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
-			_ = ctx // Mark ctx as used to avoid error, as apiServer.Stop(ctx) is commented out
+			_ = cancel
 
-			// Stop API server
+			// Stop the API server gracefully.
 			if err = apiServer.Stop(ctx); err != nil {
 				log.Debugf("Error stopping API server: %v", err)
 			}
-			cancel()
 
 			log.Debugf("Cleanup completed. Exiting...")
 			os.Exit(0)
 		case <-time.After(5 * time.Second):
-
+			// This case is currently empty and acts as a periodic check.
+			// It could be used for periodic tasks in the future.
 		}
 	}
 }
diff --git a/internal/config/config.go b/internal/config/config.go
index 01bc8bf0..38fb864d 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -6,33 +6,35 @@ import (
 	"os"
 )
 
-// Config represents the application's configuration
+// Config represents the application's configuration, loaded from a YAML file.
 type Config struct {
-	Port     int      `yaml:"port"`
-	AuthDir  string   `yaml:"auth_dir"`
-	Debug    bool     `yaml:"debug"`
-	ProxyUrl string   `yaml:"proxy-url"`
-	ApiKeys  []string `yaml:"api_keys"`
+	// Port is the network port on which the API server will listen.
+	Port int `yaml:"port"`
+	// AuthDir is the directory where authentication token files are stored.
+	AuthDir string `yaml:"auth_dir"`
+	// Debug enables or disables debug-level logging and other debug features.
+	Debug bool `yaml:"debug"`
+	// ProxyUrl is the URL of an optional proxy server to use for outbound requests.
+	ProxyUrl string `yaml:"proxy-url"`
+	// ApiKeys is a list of keys for authenticating clients to this proxy server.
+	ApiKeys []string `yaml:"api_keys"`
 }
 
-// / LoadConfig loads the configuration from the specified file
+// LoadConfig reads a YAML configuration file from the given path,
+// unmarshals it into a Config struct, and returns it.
 func LoadConfig(configFile string) (*Config, error) {
-	// Read the configuration file
+	// Read the entire configuration file into memory.
 	data, err := os.ReadFile(configFile)
-	// If reading the file fails
 	if err != nil {
-		// Return an error
 		return nil, fmt.Errorf("failed to read config file: %w", err)
 	}
 
-	// Parse the YAML data
+	// Unmarshal the YAML data into the Config struct.
 	var config Config
-	// If parsing the YAML data fails
 	if err = yaml.Unmarshal(data, &config); err != nil {
-		// Return an error
 		return nil, fmt.Errorf("failed to parse config file: %w", err)
 	}
 
-	// Return the configuration
+	// Return the populated configuration struct.
 	return &config, nil
 }