feat(mcp): add HTTP transport for network access

Add HTTP server transport as alternative to stdio:
- HTTPServer wraps MCP server with HTTP/JSON-RPC interface
- Health endpoint at /health for monitoring
- CORS support with configurable allowed origins
- Graceful shutdown with signal handling
- Streaming support via SSE and line-delimited JSON

Usage: pathfinder serve --http --address :8080

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: shivasurya

sast-engine/cmd/serve.go

@@ -1,8 +1,11 @@
 package cmd
 
 import (
+	"context"
 	"fmt"
 	"os"
+	"os/signal"
+	"syscall"
 	"time"
 
 	"github.com/shivasurya/code-pathfinder/sast-engine/graph"
@@ -16,25 +19,33 @@ import (
 var serveCmd = &cobra.Command{
 	Use:   "serve",
 	Short: "Start MCP server for AI coding assistants",
-	Long: `Builds code index and starts MCP server on stdio.
+	Long: `Builds code index and starts MCP server.
 
 Designed for integration with Claude Code, Codex CLI, and other AI assistants
 that support the Model Context Protocol (MCP).
 
 The server indexes the codebase once at startup, then responds to queries
-about symbols, call graphs, and code relationships.`,
+about symbols, call graphs, and code relationships.
+
+Transport modes:
+  - stdio (default): Standard input/output for direct integration
+  - http: HTTP server for network access`,
 	RunE: runServe,
 }
 
 func init() {
 	rootCmd.AddCommand(serveCmd)
 	serveCmd.Flags().StringP("project", "p", ".", "Project path to index")
 	serveCmd.Flags().String("python-version", "3.11", "Python version for stdlib resolution")
+	serveCmd.Flags().Bool("http", false, "Use HTTP transport instead of stdio")
+	serveCmd.Flags().String("address", ":8080", "HTTP server address (only with --http)")
 }
 
 func runServe(cmd *cobra.Command, _ []string) error {
 	projectPath, _ := cmd.Flags().GetString("project")
 	pythonVersion, _ := cmd.Flags().GetString("python-version")
+	useHTTP, _ := cmd.Flags().GetBool("http")
+	address, _ := cmd.Flags().GetString("address")
 
 	fmt.Fprintln(os.Stderr, "Building index...")
 	start := time.Now()
@@ -66,9 +77,45 @@ func runServe(cmd *cobra.Command, _ []string) error {
 	fmt.Fprintf(os.Stderr, "  Call edges: %d\n", len(callGraph.Edges))
 	fmt.Fprintf(os.Stderr, "  Modules: %d\n", len(moduleRegistry.Modules))
 
-	// 4. Create and run MCP server
+	// 4. Create MCP server
 	server := mcp.NewServer(projectPath, pythonVersion, callGraph, moduleRegistry, codeGraph, buildTime)
 
+	// 5. Start appropriate transport
+	if useHTTP {
+		return runHTTPServer(server, address)
+	}
+
 	fmt.Fprintln(os.Stderr, "Starting MCP server on stdio...")
 	return server.ServeStdio()
 }
+
+func runHTTPServer(mcpServer *mcp.Server, address string) error {
+	config := &mcp.HTTPConfig{
+		Address:         address,
+		ReadTimeout:     30 * time.Second,
+		WriteTimeout:    30 * time.Second,
+		ShutdownTimeout: 5 * time.Second,
+		AllowedOrigins:  []string{"*"},
+	}
+
+	httpServer := mcp.NewHTTPServer(mcpServer, config)
+
+	// Handle graceful shutdown.
+	sigChan := make(chan os.Signal, 1)
+	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
+
+	errChan := make(chan error, 1)
+	go func() {
+		errChan <- httpServer.Start()
+	}()
+
+	select {
+	case err := <-errChan:
+		return err
+	case sig := <-sigChan:
+		fmt.Fprintf(os.Stderr, "\nReceived %v, shutting down...\n", sig)
+		ctx, cancel := context.WithTimeout(context.Background(), config.ShutdownTimeout)
+		defer cancel()
+		return httpServer.Shutdown(ctx)
+	}
+}