fix(providers): fix GitHub Copilot provider session lifecycle and response handling

- Store client as struct field to prevent premature garbage collection
- Remove defer client.Stop() from constructor which was killing the gRPC
  client immediately after NewGitHubCopilotProvider returned, causing all
  subsequent Chat() calls to silently fail
- Add proper error handling for CreateSession (was ignoring error with _)
- Replace session.Send() with session.SendAndWait(): Send() only returns a
  message UUID, not the response text; SendAndWait() blocks until the
  assistant is idle and returns the actual SessionEvent with content
- Add Close() method for proper client lifecycle management
- Add 15s connection timeout to fail fast if CLI is unreachable

pkg/providers/github_copilot_provider.go

@@ -2,56 +2,70 @@ package providers
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
+	"time"
+
+	json "encoding/json"
 
 	copilot "github.com/github/copilot-sdk/go"
 )
 
 type GitHubCopilotProvider struct {
 	uri         string
-	connectMode string // `stdio` or `grpc``
+	connectMode string // `stdio` or `grpc`
 
+	client  *copilot.Client
 	session *copilot.Session
 }
 
 func NewGitHubCopilotProvider(uri string, connectMode string, model string) (*GitHubCopilotProvider, error) {
+
 	var session *copilot.Session
+	var client *copilot.Client
 	if connectMode == "" {
 		connectMode = "grpc"
 	}
 	switch connectMode {
 
 	case "stdio":
-		// todo
+		//todo
 	case "grpc":
-		client := copilot.NewClient(&copilot.ClientOptions{
+		client = copilot.NewClient(&copilot.ClientOptions{
 			CLIUrl: uri,
 		})
-		if err := client.Start(context.Background()); err != nil {
-			return nil, fmt.Errorf(
-				"Can't connect to Github Copilot, https://github.com/github/copilot-sdk/blob/main/docs/getting-started.md#connecting-to-an-external-cli-server for details",
-			)
+		connectCtx, connectCancel := context.WithTimeout(context.Background(), 15*time.Second)
+		defer connectCancel()
+		if err := client.Start(connectCtx); err != nil {
+			return nil, fmt.Errorf("can't connect to Github Copilot: %w", err)
 		}
-		defer client.Stop()
-		session, _ = client.CreateSession(context.Background(), &copilot.SessionConfig{
+		var err error
+		session, err = client.CreateSession(connectCtx, &copilot.SessionConfig{
 			Model: model,
 			Hooks: &copilot.SessionHooks{},
 		})
+		if err != nil {
+			client.Stop()
+			return nil, fmt.Errorf("failed to create Copilot session: %w", err)
+		}
 
 	}
 
 	return &GitHubCopilotProvider{
 		uri:         uri,
 		connectMode: connectMode,
+		client:      client,
 		session:     session,
 	}, nil
 }
 
+func (p *GitHubCopilotProvider) Close() {
+	if p.client != nil {
+		p.client.Stop()
+	}
+}
+
 // Chat sends a chat request to GitHub Copilot
-func (p *GitHubCopilotProvider) Chat(
-	ctx context.Context, messages []Message, tools []ToolDefinition, model string, options map[string]any,
-) (*LLMResponse, error) {
+func (p *GitHubCopilotProvider) Chat(ctx context.Context, messages []Message, tools []ToolDefinition, model string, options map[string]interface{}) (*LLMResponse, error) {
 	type tempMessage struct {
 		Role    string `json:"role"`
 		Content string `json:"content"`
@@ -67,16 +81,25 @@ func (p *GitHubCopilotProvider) Chat(
 
 	fullcontent, _ := json.Marshal(out)
 
-	content, _ := p.session.Send(ctx, copilot.MessageOptions{
+	event, err := p.session.SendAndWait(ctx, copilot.MessageOptions{
 		Prompt: string(fullcontent),
 	})
+	if err != nil {
+		return nil, fmt.Errorf("copilot error: %w", err)
+	}
+
+	if event == nil || event.Data.Content == nil {
+		return nil, fmt.Errorf("empty response from Copilot")
+	}
 
 	return &LLMResponse{
 		FinishReason: "stop",
-		Content:      content,
+		Content:      *event.Data.Content,
 	}, nil
+
 }
 
 func (p *GitHubCopilotProvider) GetDefaultModel() string {
+
 	return "gpt-4.1"
 }