feat: ftl-mcp added for Goose

.go-arch-lint.yml

@@ -43,6 +43,7 @@ components:
   ftl-proxy-pg-cmd: { in: cmd/ftl-proxy-pg/** }
   ftl-raft-tester-cmd: { in: cmd/raft-tester/** }
   ftl-sqlc-cmd: { in: cmd/ftl-sqlc/** }
+  ftl-mcp-cmd: { in: cmd/ftl-mcp/** }
 
   go2proto: { in: cmd/go2proto/** }
 

.goreleaser.yaml

@@ -18,6 +18,10 @@ builds:
     main: ./cmd/ftl-sqlc
     binary: ftl-sqlc
     <<: *settings
+  - id: ftl-mcp
+    main: ./cmd/ftl-mcp
+    binary: ftl-mcp
+    <<: *settings
   - id: ftl-language-go
     main: ./go-runtime/cmd/ftl-language-go
     binary: ftl-language-go

Justfile

@@ -164,7 +164,7 @@ build-without-frontend +tools: build-protos build-zips capture-hermit-versions
 
 # Build all backend binaries
 build-backend:
-  just build ftl ftl-controller ftl-runner ftl-sqlc ftl-admin ftl-cron ftl-http-ingress ftl-lease ftl-provisioner ftl-schema ftl-timeline
+  just build ftl ftl-controller ftl-runner ftl-sqlc ftl-admin ftl-cron ftl-http-ingress ftl-lease ftl-provisioner ftl-schema ftl-timeline ftl-mcp
 
 # Build all backend tests
 build-backend-tests:

cmd/ftl-mcp/main.go

@@ -0,0 +1,58 @@
+package main
+
+import (
+	"context"
+	"net/url"
+	"os"
+
+	"github.com/alecthomas/kong"
+	"github.com/mark3labs/mcp-go/mcp"
+	"github.com/mark3labs/mcp-go/server"
+
+	"github.com/block/ftl"
+	"github.com/block/ftl/backend/protos/xyz/block/ftl/buildengine/v1/buildenginepbconnect"
+	"github.com/block/ftl/backend/protos/xyz/block/ftl/v1/ftlv1connect"
+	"github.com/block/ftl/internal/log"
+	_ "github.com/block/ftl/internal/prodinit"
+	"github.com/block/ftl/internal/rpc"
+)
+
+var cli struct {
+	Version         kong.VersionFlag `help:"Show version."`
+	LogConfig       log.Config       `embed:"" prefix:"log-"`
+	AdminEndpoint   *url.URL         `help:"Admin endpoint." env:"FTL_ENDPOINT" default:"http://127.0.0.1:8892"`
+	UpdatesEndpoint *url.URL         `help:"Socket to bind to." default:"http://127.0.0.1:8900" env:"FTL_BUILD_UPDATES_ENDPOINT"`
+}
+
+func main() {
+	kctx := kong.Parse(&cli,
+		kong.Description(`FTL - Model Context Protocol Server`),
+		kong.UsageOnError(),
+		kong.Vars{"version": ftl.FormattedVersion},
+	)
+
+	buildEngineClient := rpc.Dial(buildenginepbconnect.NewBuildEngineServiceClient, cli.UpdatesEndpoint.String(), log.Error)
+	adminClient := rpc.Dial(ftlv1connect.NewAdminServiceClient, cli.AdminEndpoint.String(), log.Error)
+
+	s := server.NewMCPServer(
+		"FTL",
+		ftl.Version,
+		server.WithResourceCapabilities(true, true),
+		server.WithLogging(),
+	)
+
+	s.AddTool(mcp.NewTool(
+		"Status",
+		mcp.WithDescription("Get the current status of each FTL module and the current schema"),
+	), func(ctx context.Context, request mcp.CallToolRequest) (*mcp.CallToolResult, error) {
+		return statusTool(ctx, buildEngineClient, adminClient)
+	})
+
+	// Start the server
+	err := server.ServeStdio(s)
+	kctx.FatalIfErrorf(err, "failed to start mcp")
+}
+
+func contextFromServerContext(ctx context.Context) context.Context {
+	return log.ContextWithLogger(ctx, log.Configure(os.Stderr, cli.LogConfig).Scope("mcp"))
+}

cmd/ftl-mcp/status.go

@@ -0,0 +1,129 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"github.com/mark3labs/mcp-go/mcp"
+
+	"github.com/block/ftl/backend/protos/xyz/block/ftl/buildengine/v1/buildenginepbconnect"
+	"github.com/block/ftl/backend/protos/xyz/block/ftl/v1/ftlv1connect"
+	"github.com/block/ftl/common/reflect"
+	"github.com/block/ftl/common/schema"
+	"github.com/block/ftl/common/slices"
+	devstate "github.com/block/ftl/internal/devstate"
+)
+
+type statusOutput struct {
+	Modules []devstate.ModuleState
+	Schema  string
+}
+
+func statusTool(ctx context.Context, buildEngineClient buildenginepbconnect.BuildEngineServiceClient, adminClient ftlv1connect.AdminServiceClient) (*mcp.CallToolResult, error) {
+	ctx = contextFromServerContext(ctx)
+	result, err := devstate.WaitForDevState(ctx, buildEngineClient, adminClient)
+	if err != nil {
+		return nil, fmt.Errorf("could not get status: %w", err)
+	}
+
+	sch := reflect.DeepCopy(result.Schema)
+	for _, module := range sch.Modules {
+		moduleState, ok := slices.Find(result.Modules, func(m devstate.ModuleState) bool {
+			return m.Name == module.Name
+		})
+		if !ok {
+			continue
+		}
+		for _, decl := range module.Decls {
+			switch decl := decl.(type) {
+			case *schema.Topic:
+				c, err := commentForPath(decl.Pos, moduleState.Path)
+				if err != nil {
+					return nil, err
+				}
+				decl.Comments = append(decl.Comments, c)
+			case *schema.Verb:
+				c, err := commentForPath(decl.Pos, moduleState.Path)
+				if err != nil {
+					return nil, err
+				}
+				decl.Comments = append(decl.Comments, c)
+			case *schema.Config:
+				c, err := commentForPath(decl.Pos, moduleState.Path)
+				if err != nil {
+					return nil, err
+				}
+				decl.Comments = append(decl.Comments, c)
+			case *schema.Secret:
+				c, err := commentForPath(decl.Pos, moduleState.Path)
+				if err != nil {
+					return nil, err
+				}
+				decl.Comments = append(decl.Comments, c)
+			case *schema.Database:
+				c, err := commentForPath(decl.Pos, moduleState.Path)
+				if err != nil {
+					return nil, err
+				}
+				decl.Comments = append(decl.Comments, c)
+			case *schema.Data:
+				c, err := commentForPath(decl.Pos, moduleState.Path)
+				if err != nil {
+					return nil, err
+				}
+				decl.Comments = append(decl.Comments, c)
+			case *schema.Enum:
+				c, err := commentForPath(decl.Pos, moduleState.Path)
+				if err != nil {
+					return nil, err
+				}
+				decl.Comments = append(decl.Comments, c)
+			case *schema.TypeAlias:
+				c, err := commentForPath(decl.Pos, moduleState.Path)
+				if err != nil {
+					return nil, err
+				}
+				decl.Comments = append(decl.Comments, c)
+			}
+		}
+	}
+
+	output := statusOutput{
+		Modules: result.Modules,
+		Schema:  sch.String(),
+	}
+	data, err := json.Marshal(output)
+	if err != nil {
+		return nil, fmt.Errorf("could not marshal status: %w", err)
+	}
+	return mcp.NewToolResultText(string(data)), nil
+}
+
+func commentForPath(pos schema.Position, modulePath string) (string, error) {
+	if pos.Filename == "" {
+		return "", nil
+	}
+	// each position has a prefix of "ftl/modulename". We want to replace that with the module file path
+	parts := strings.SplitN(pos.Filename, string(filepath.Separator), 3)
+	if len(parts) > 2 {
+		parts = parts[1:]
+		parts[0] = modulePath
+	} else {
+		return "", fmt.Errorf("unexpected path format: %s", pos.Filename)
+	}
+	components := []string{
+		filepath.Join(parts...),
+	}
+
+	if pos.Line != 0 {
+		components = append(components, strconv.Itoa(pos.Line))
+		if pos.Column != 0 {
+			components = append(components, strconv.Itoa(pos.Column))
+		}
+	}
+	return "Code at " + strings.Join(components, ":"), nil
+}