Add -open flag to trigger initial opening of workspace files

Author: virtuald

README.md

@@ -129,6 +129,7 @@ This is an [MCP](https://modelcontextprotocol.io/introduction) server that runs
   <div>
     <p><strong>Install clangd</strong>: Download prebuilt binaries from the <a href="https://github.com/clangd/clangd/releases">official LLVM releases page</a> or install via your system's package manager (e.g., <code>apt install clangd</code>, <code>brew install clangd</code>).</p>
     <p><strong>Configure your MCP client</strong>: This will be different but similar for each client. For Claude Desktop, add the following to <code>~/Library/Application\\ Support/Claude/claude_desktop_config.json</code></p>
+    <p><strong>NOTE</strong>: clangd will not resolve symbols until the first file is opened. Use the `-open` argument to trigger indexing.</p>
 
 <pre>
 {
@@ -140,6 +141,8 @@ This is an [MCP](https://modelcontextprotocol.io/introduction) server that runs
         "/Users/you/dev/yourproject/",
         "--lsp",
         "/path/to/your/clangd_binary",
+        "--open",
+        "/Users/you/dev/yourproject/main.cpp",
         "--",
         "--compile-commands-dir=/path/to/yourproject/build_or_compile_commands_dir"
       ]

go.mod

@@ -3,6 +3,7 @@ module github.com/isaacphi/mcp-language-server
 go 1.24.0
 
 require (
+	github.com/bmatcuk/doublestar/v4 v4.8.1
 	github.com/davecgh/go-spew v1.1.1
 	github.com/fsnotify/fsnotify v1.9.0
 	github.com/mark3labs/mcp-go v0.25.0

go.sum

@@ -1,5 +1,7 @@
 github.com/BurntSushi/toml v1.4.1-0.20240526193622-a339e1f7089c h1:pxW6RcqyfI9/kWtOwnv/G+AzdKuy2ZrqINhenH4HyNs=
 github.com/BurntSushi/toml v1.4.1-0.20240526193622-a339e1f7089c/go.mod h1:ukJfTF/6rtPPRCnwkur4qwRxa8vTRFBF0uk2lLoLwho=
+github.com/bmatcuk/doublestar/v4 v4.8.1 h1:54Bopc5c2cAvhLRAzqOGCYHYyhcDHsFF4wWIR5wKP38=
+github.com/bmatcuk/doublestar/v4 v4.8.1/go.mod h1:xBQ8jztBU6kakFMg+8WGxn0c6z1fTSPVIjEY1Wr7jzc=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=

main.go

@@ -8,9 +8,11 @@ import (
 	"os/exec"
 	"os/signal"
 	"path/filepath"
+	"strings"
 	"syscall"
 	"time"
 
+	"github.com/bmatcuk/doublestar/v4"
 	"github.com/isaacphi/mcp-language-server/internal/logging"
 	"github.com/isaacphi/mcp-language-server/internal/lsp"
 	"github.com/isaacphi/mcp-language-server/internal/watcher"
@@ -23,6 +25,7 @@ var coreLogger = logging.NewLogger(logging.Core)
 type config struct {
 	workspaceDir string
 	lspCommand   string
+	openGlobs    StringArrayFlag
 	lspArgs      []string
 }
 
@@ -35,10 +38,25 @@ type mcpServer struct {
 	workspaceWatcher *watcher.WorkspaceWatcher
 }
 
+// StringArrayFlag is a custom flag type to handle an array of strings
+type StringArrayFlag []string
+
+// Set appends a new value to the custom flag value
+func (s *StringArrayFlag) Set(value string) error {
+	*s = append(*s, value)
+	return nil
+}
+
+// String returns the string representation of the custom flag value
+func (s *StringArrayFlag) String() string {
+	return strings.Join(*s, ",")
+}
+
 func parseConfig() (*config, error) {
 	cfg := &config{}
 	flag.StringVar(&cfg.workspaceDir, "workspace", "", "Path to workspace directory")
 	flag.StringVar(&cfg.lspCommand, "lsp", "", "LSP command to run (args should be passed after --)")
+	flag.Var(&cfg.openGlobs, "open", "Glob of files to open by default (can specify more than once)")
 	flag.Parse()
 
 	// Get remaining args after -- as LSP arguments
@@ -99,10 +117,41 @@ func (s *mcpServer) initializeLSP() error {
 
 	coreLogger.Debug("Server capabilities: %+v", initResult.Capabilities)
 
+	if len(s.config.openGlobs) > 0 {
+		s.openInitialFiles()
+	}
+
 	go s.workspaceWatcher.WatchWorkspace(s.ctx, s.config.workspaceDir)
 	return client.WaitForServerReady(s.ctx)
 }
 
+func (s *mcpServer) openInitialFiles() {
+
+	filepath.WalkDir(s.config.workspaceDir, func(path string, d os.DirEntry, err error) error {
+		if err != nil {
+			return err
+		}
+
+		if !d.IsDir() {
+			for _, pattern := range s.config.openGlobs {
+				match, err := doublestar.PathMatch(pattern, path)
+				if err != nil {
+					return err
+				}
+
+				if match {
+					if err := s.lspClient.OpenFile(s.ctx, path); err != nil {
+						coreLogger.Error("Failed to open file %s: %v", path, err)
+					}
+					break
+				}
+			}
+		}
+
+		return nil
+	})
+}
+
 func (s *mcpServer) start() error {
 	if err := s.initializeLSP(); err != nil {
 		return err