feat: enhance completion service with session management and language support

- Introduced session management using Redis for tracking active sessions.
- Added session claiming and releasing functionality in the completion manager.
- Enhanced HTTP and WebSocket completion endpoints to support multiple languages.
- Implemented request timeout and maximum body size configurations for API routes.
- Updated client-side code to handle session IDs and language parameters in completion requests.
- Improved error handling for unsupported languages and session conflicts.
- Added tests for the completion manager to ensure proper session handling and cleanup.

backend/internal/lsp/client.go

@@ -33,6 +33,8 @@ type Client struct {
 	nextID atomic.Int64
 
 	workspaceDir string
+	languageID   string
+	clientName   string
 
 	pendingMu sync.Mutex
 	pending   map[string]chan rpcResponse
@@ -74,19 +76,33 @@ type lspCompletionList struct {
 	Items        []lspCompletionItem `json:"items"`
 }
 
-func NewClient(parent context.Context, goplsPath, rootPath string) (*Client, error) {
-	if goplsPath == "" {
-		goplsPath = "gopls"
+type Config struct {
+	Command    string
+	Args       []string
+	RootPath   string
+	LanguageID string
+	ClientName string
+}
+
+func NewClient(parent context.Context, cfg Config) (*Client, error) {
+	if cfg.Command == "" {
+		cfg.Command = "gopls"
 	}
-	if rootPath == "" {
+	if cfg.RootPath == "" {
 		cwd, err := os.Getwd()
 		if err != nil {
 			return nil, fmt.Errorf("get working directory: %w", err)
 		}
-		rootPath = cwd
+		cfg.RootPath = cwd
+	}
+	if cfg.LanguageID == "" {
+		cfg.LanguageID = "go"
+	}
+	if cfg.ClientName == "" {
+		cfg.ClientName = "monica-lsp-gateway"
 	}
 
-	cmd := exec.Command(goplsPath)
+	cmd := exec.Command(cfg.Command, cfg.Args...)
 	stdin, err := cmd.StdinPipe()
 	if err != nil {
 		return nil, fmt.Errorf("create stdin pipe: %w", err)
@@ -98,13 +114,15 @@ func NewClient(parent context.Context, goplsPath, rootPath string) (*Client, err
 	cmd.Stderr = os.Stderr
 
 	if err := cmd.Start(); err != nil {
-		return nil, fmt.Errorf("start gopls: %w", err)
+		return nil, fmt.Errorf("start language server %q: %w", cfg.Command, err)
 	}
 
 	client := &Client{
 		cmd:          cmd,
 		stdin:        stdin,
-		workspaceDir: rootPath,
+		workspaceDir: cfg.RootPath,
+		languageID:   cfg.LanguageID,
+		clientName:   cfg.ClientName,
 		pending:      make(map[string]chan rpcResponse),
 		exitCh:       make(chan error, 1),
 	}
@@ -117,7 +135,7 @@ func NewClient(parent context.Context, goplsPath, rootPath string) (*Client, err
 	initCtx, cancel := context.WithTimeout(parent, 10*time.Second)
 	defer cancel()
 
-	if err := client.initialize(initCtx, rootPath); err != nil {
+	if err := client.initialize(initCtx, cfg.RootPath); err != nil {
 		_ = client.Close()
 		return nil, err
 	}
@@ -150,7 +168,7 @@ func (c *Client) initialize(ctx context.Context, rootPath string) error {
 			},
 		},
 		"clientInfo": map[string]string{
-			"name":    "monica-go-completion-backend",
+			"name":    c.clientName,
 			"version": "0.1.0",
 		},
 	}
@@ -174,7 +192,7 @@ func (c *Client) DidOpen(ctx context.Context, uri, text string, version int) err
 	params := map[string]any{
 		"textDocument": map[string]any{
 			"uri":        normalizedURI,
-			"languageId": "go",
+			"languageId": c.languageID,
 			"version":    version,
 			"text":       text,
 		},