feat: CLI self-update command, update check, and wfctl mcp subcommand (#203)

* Initial plan

* feat: add CLI self-update command, update check, and wfctl mcp command

Co-authored-by: intel352 <77607+intel352@users.noreply.github.com>

* fix: address review comments on self-update and MCP commands

Co-authored-by: intel352 <77607+intel352@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: intel352 <77607+intel352@users.noreply.github.com>

Author: Copilot

cmd/wfctl/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"fmt"
 	"os"
+	"time"
 )
 
 var version = "dev"
@@ -29,6 +30,8 @@ var commands = map[string]func([]string) error{
 	"generate": runGenerate,
 	"git":      runGit,
 	"registry": runRegistry,
+	"update":   runUpdate,
+	"mcp":      runMCP,
 }
 
 func usage() {
@@ -59,6 +62,8 @@ Commands:
   generate   Code generation (github-actions: generate CI/CD workflows from config)
   git        Git integration (connect: link to GitHub repo, push: commit and push)
   registry   Registry management (list, add, remove plugin registry sources)
+  update     Update wfctl to the latest version (use --check to only check)
+  mcp        Start the MCP server over stdio for AI assistant integration
 
 Run 'wfctl <command> -h' for command-specific help.
 `, version)
@@ -87,8 +92,25 @@ func main() {
 		os.Exit(1)
 	}
 
+	// Start the update check in the background before running the command so
+	// that it runs concurrently. For long-running commands (mcp, run) we skip
+	// it entirely. After the command finishes we wait briefly for the result.
+	var updateNoticeDone <-chan struct{}
+	if cmd != "mcp" && cmd != "run" {
+		updateNoticeDone = checkForUpdateNotice()
+	}
+
 	if err := fn(os.Args[2:]); err != nil {
 		fmt.Fprintf(os.Stderr, "error: %v\n", err) //nolint:gosec // G705: CLI error output
 		os.Exit(1)
 	}
+
+	// Wait briefly for the update notice after the command completes.
+	// A 1-second ceiling ensures we never meaningfully delay the shell prompt.
+	if updateNoticeDone != nil {
+		select {
+		case <-updateNoticeDone:
+		case <-time.After(time.Second):
+		}
+	}
 }

cmd/wfctl/mcp.go

@@ -0,0 +1,53 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+
+	workflowmcp "github.com/GoCodeAlone/workflow/mcp"
+)
+
+// runMCP starts the workflow MCP (Model Context Protocol) server over stdio.
+// This exposes workflow engine tools and resources to AI assistants.
+func runMCP(args []string) error {
+	fs := flag.NewFlagSet("mcp", flag.ContinueOnError)
+	pluginDir := fs.String("plugin-dir", "data/plugins", "Plugin data directory")
+	fs.Usage = func() {
+		fmt.Fprintf(fs.Output(), `Usage: wfctl mcp [options]
+
+Start the workflow MCP (Model Context Protocol) server over stdio.
+This exposes workflow engine tools and resources to AI assistants such as
+Claude Desktop, VS Code with GitHub Copilot, and Cursor.
+
+The server provides tools for listing module types, validating configs,
+generating schemas, and inspecting workflow YAML configurations.
+
+Options:
+`)
+		fs.PrintDefaults()
+		fmt.Fprintf(fs.Output(), `
+Example Claude Desktop configuration (~/.config/claude/claude_desktop_config.json):
+
+  {
+    "mcpServers": {
+      "workflow": {
+        "command": "wfctl",
+        "args": ["mcp", "-plugin-dir", "/path/to/data/plugins"]
+      }
+    }
+  }
+
+See docs/mcp.md for full setup instructions.
+`)
+	}
+	if err := fs.Parse(args); err != nil {
+		return err
+	}
+
+	// Propagate the CLI version so the MCP handshake and version output
+	// reflect the release version set at build time.
+	workflowmcp.Version = version
+
+	srv := workflowmcp.NewServer(*pluginDir)
+	return srv.ServeStdio()
+}

cmd/wfctl/mcp_test.go

@@ -0,0 +1,21 @@
+package main
+
+import (
+	"testing"
+)
+
+func TestRunMCP_Usage(t *testing.T) {
+	// Passing -h should return an error from flag parsing (ExitOnError calls os.Exit,
+	// but we use ContinueOnError in runMCP so it returns an error instead).
+	err := runMCP([]string{"-h"})
+	if err == nil {
+		t.Fatal("expected error from -h flag")
+	}
+}
+
+func TestRunMCP_UnknownFlag(t *testing.T) {
+	err := runMCP([]string{"--unknown-flag"})
+	if err == nil {
+		t.Fatal("expected error for unknown flag")
+	}
+}