MCP: Streamline validation for node.js templates (#3985)

## Changes

Validation for 'overfit' for the tRPC template. I generalized it to
follow node.js standards that all node.js templates can implement.

Before: 
* Build
  * npm run build
* Typecheck
  * cd client && npx tsc --noEmit
* Test
  * npm test

After:
* Build
  * npm run build –if-present
* Typecheck
  * npm run typecheck –if-present
* Test
  * npm run test –if-present



## Why
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might be missing.
For example, were there any decisions behind the change that are not
reflected in the code itself? -->

## Tests
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<!-- If your PR needs to be included in the release notes for next
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add a separate entry in NEXT_CHANGELOG.md as part of your PR. -->

Author: fjakobs

experimental/apps-mcp/lib/providers/io/validate.go

@@ -43,13 +43,13 @@ func (p *Provider) Validate(ctx context.Context, args *ValidateArgs) (*ValidateR
 		valConfig := p.config.Validation
 		if valConfig.Command != "" {
 			log.Infof(ctx, "using custom validation command: command=%s", valConfig.Command)
-			validation = NewValidationCmd(valConfig.Command, "")
+			validation = NewValidationCmd(valConfig.Command)
 		}
 	}
 
 	if validation == nil {
-		log.Info(ctx, "using default tRPC validation strategy")
-		validation = NewValidationTRPC()
+		log.Info(ctx, "using default Node.js validation strategy")
+		validation = NewValidationNodeJs()
 	}
 
 	result, err := validation.Validate(ctx, workDir)

experimental/apps-mcp/lib/providers/io/validation.go

@@ -57,80 +57,72 @@ func (vr *ValidateResult) String() string {
 // Validation defines the interface for project validation strategies.
 type Validation interface {
 	Validate(ctx context.Context, workDir string) (*ValidateResult, error)
-	DockerImage() string
 }
 
-// ValidationTRPC implements validation for tRPC-based projects using build, type check, and tests.
-type ValidationTRPC struct{}
+// ValidationNodeJs implements validation for Node.js-based projects using build, type check, and tests.
+type ValidationNodeJs struct{}
 
-func NewValidationTRPC() Validation {
-	return &ValidationTRPC{}
+func NewValidationNodeJs() Validation {
+	return &ValidationNodeJs{}
 }
 
-func (v *ValidationTRPC) DockerImage() string {
-	return "node:20-alpine3.22"
+type validationStep struct {
+	name        string
+	command     string
+	errorPrefix string
+	displayName string
 }
 
-func (v *ValidationTRPC) Validate(ctx context.Context, workDir string) (*ValidateResult, error) {
-	log.Info(ctx, "starting tRPC validation (build + type check + tests)")
+func (v *ValidationNodeJs) Validate(ctx context.Context, workDir string) (*ValidateResult, error) {
+	log.Info(ctx, "Starting Node.js validation: build + typecheck + tests")
 	startTime := time.Now()
 	var progressLog []string
 
-	progressLog = append(progressLog, "🔄 Starting validation: build + type check + tests")
-
-	log.Info(ctx, "step 1/3: running build...")
-	progressLog = append(progressLog, "⏳ Step 1/3: Running build...")
-	buildStart := time.Now()
-	if err := v.runBuild(ctx, workDir); err != nil {
-		buildDuration := time.Since(buildStart)
-		log.Errorf(ctx, "build failed (duration: %.1fs)", buildDuration.Seconds())
-		progressLog = append(progressLog, fmt.Sprintf("❌ Build failed (%.1fs)", buildDuration.Seconds()))
-		return &ValidateResult{
-			Success:     false,
-			Message:     "Build failed",
-			Details:     err,
-			ProgressLog: progressLog,
-		}, nil
-	}
-	buildDuration := time.Since(buildStart)
-	log.Infof(ctx, "✓ build passed: duration=%.1fs", buildDuration.Seconds())
-	progressLog = append(progressLog, fmt.Sprintf("✅ Build passed (%.1fs)", buildDuration.Seconds()))
-
-	log.Info(ctx, "step 2/3: running type check...")
-	progressLog = append(progressLog, "⏳ Step 2/3: Running type check...")
-	typeCheckStart := time.Now()
-	if err := v.runClientTypeCheck(ctx, workDir); err != nil {
-		typeCheckDuration := time.Since(typeCheckStart)
-		log.Errorf(ctx, "type check failed (duration: %.1fs)", typeCheckDuration.Seconds())
-		progressLog = append(progressLog, fmt.Sprintf("❌ Type check failed (%.1fs)", typeCheckDuration.Seconds()))
-		return &ValidateResult{
-			Success:     false,
-			Message:     "Type check failed",
-			Details:     err,
-			ProgressLog: progressLog,
-		}, nil
+	progressLog = append(progressLog, "🔄 Starting Node.js validation: build + typecheck + tests")
+
+	steps := []validationStep{
+		{
+			name:        "build",
+			command:     "npm run build --if-present",
+			errorPrefix: "Failed to run npm build",
+			displayName: "Build",
+		},
+		{
+			name:        "typecheck",
+			command:     "npm run typecheck --if-present",
+			errorPrefix: "Failed to run client typecheck",
+			displayName: "Type check",
+		},
+		{
+			name:        "tests",
+			command:     "npm run test --if-present",
+			errorPrefix: "Failed to run tests",
+			displayName: "Tests",
+		},
 	}
-	typeCheckDuration := time.Since(typeCheckStart)
-	log.Infof(ctx, "✓ type check passed: duration=%.1fs", typeCheckDuration.Seconds())
-	progressLog = append(progressLog, fmt.Sprintf("✅ Type check passed (%.1fs)", typeCheckDuration.Seconds()))
-
-	log.Info(ctx, "step 3/3: running tests...")
-	progressLog = append(progressLog, "⏳ Step 3/3: Running tests...")
-	testStart := time.Now()
-	if err := v.runTests(ctx, workDir); err != nil {
-		testDuration := time.Since(testStart)
-		log.Errorf(ctx, "tests failed (duration: %.1fs)", testDuration.Seconds())
-		progressLog = append(progressLog, fmt.Sprintf("❌ Tests failed (%.1fs)", testDuration.Seconds()))
-		return &ValidateResult{
-			Success:     false,
-			Message:     "Tests failed",
-			Details:     err,
-			ProgressLog: progressLog,
-		}, nil
+
+	for i, step := range steps {
+		stepNum := fmt.Sprintf("%d/%d", i+1, len(steps))
+		log.Infof(ctx, "step %s: running %s...", stepNum, step.name)
+		progressLog = append(progressLog, fmt.Sprintf("⏳ Step %s: Running %s...", stepNum, step.displayName))
+
+		stepStart := time.Now()
+		err := runCommand(ctx, workDir, step.command)
+		if err != nil {
+			stepDuration := time.Since(stepStart)
+			log.Errorf(ctx, "%s failed (duration: %.1fs)", step.name, stepDuration.Seconds())
+			progressLog = append(progressLog, fmt.Sprintf("❌ %s failed (%.1fs)", step.displayName, stepDuration.Seconds()))
+			return &ValidateResult{
+				Success:     false,
+				Message:     step.errorPrefix,
+				Details:     err,
+				ProgressLog: progressLog,
+			}, nil
+		}
+		stepDuration := time.Since(stepStart)
+		log.Infof(ctx, "✓ %s passed: duration=%.1fs", step.name, stepDuration.Seconds())
+		progressLog = append(progressLog, fmt.Sprintf("✅ %s passed (%.1fs)", step.displayName, stepDuration.Seconds()))
 	}
-	testDuration := time.Since(testStart)
-	log.Infof(ctx, "✓ tests passed: duration=%.1fs", testDuration.Seconds())
-	progressLog = append(progressLog, fmt.Sprintf("✅ Tests passed (%.1fs)", testDuration.Seconds()))
 
 	totalDuration := time.Since(startTime)
 	log.Infof(ctx, "✓ all validation checks passed: total_duration=%.1fs, steps=%s",
@@ -139,27 +131,15 @@ func (v *ValidationTRPC) Validate(ctx context.Context, workDir string) (*Validat
 
 	return &ValidateResult{
 		Success:     true,
-		Message:     "All validation checks passed (build + type check + tests)",
+		Message:     "All validation checks passed",
 		ProgressLog: progressLog,
 	}, nil
 }
 
-func (v *ValidationTRPC) runBuild(ctx context.Context, workDir string) *ValidationDetail {
-	return runCommand(ctx, workDir, "npm run build")
-}
-
-func (v *ValidationTRPC) runClientTypeCheck(ctx context.Context, workDir string) *ValidationDetail {
-	return runCommand(ctx, workDir, "cd client && npx tsc --noEmit")
-}
-
-func (v *ValidationTRPC) runTests(ctx context.Context, workDir string) *ValidationDetail {
-	return runCommand(ctx, workDir, "npm test")
-}
-
 // runCommand executes a shell command in the specified directory
-func runCommand(ctx context.Context, dir, command string) *ValidationDetail {
+func runCommand(ctx context.Context, workDir, command string) *ValidationDetail {
 	cmd := exec.CommandContext(ctx, "sh", "-c", command)
-	cmd.Dir = dir
+	cmd.Dir = workDir
 
 	var stdout, stderr bytes.Buffer
 	cmd.Stdout = &stdout
@@ -192,40 +172,36 @@ func runCommand(ctx context.Context, dir, command string) *ValidationDetail {
 
 // ValidationCmd implements validation using a custom command specified by the user.
 type ValidationCmd struct {
-	Command   string
-	DockerImg string
+	Command string
 }
 
-func NewValidationCmd(command, dockerImage string) Validation {
-	if dockerImage == "" {
-		dockerImage = "node:20-alpine3.22"
-	}
+func NewValidationCmd(command string) Validation {
 	return &ValidationCmd{
-		Command:   command,
-		DockerImg: dockerImage,
+		Command: command,
 	}
 }
 
-func (v *ValidationCmd) DockerImage() string {
-	return v.DockerImg
-}
-
 func (v *ValidationCmd) Validate(ctx context.Context, workDir string) (*ValidateResult, error) {
 	log.Infof(ctx, "starting custom validation: command=%s", v.Command)
 	startTime := time.Now()
 	var progressLog []string
 
 	progressLog = append(progressLog, "🔄 Starting custom validation: "+v.Command)
 
-	detail := runCommand(ctx, workDir, v.Command)
-	if detail != nil {
+	fullCommand := v.Command
+	err := runCommand(ctx, workDir, fullCommand)
+	if err != nil {
 		duration := time.Since(startTime)
-		log.Errorf(ctx, "custom validation failed (duration: %.1fs, exit_code: %d)", duration.Seconds(), detail.ExitCode)
-		progressLog = append(progressLog, fmt.Sprintf("❌ Validation failed (%.1fs) - exit code: %d", duration.Seconds(), detail.ExitCode))
+		log.Errorf(ctx, "custom validation command failed (duration: %.1fs, error: %v)", duration.Seconds(), err)
+		progressLog = append(progressLog, fmt.Sprintf("❌ Command failed (%.1fs): %v", duration.Seconds(), err))
 		return &ValidateResult{
-			Success:     false,
-			Message:     "Custom validation command failed",
-			Details:     detail,
+			Success: false,
+			Message: "Custom validation command failed",
+			Details: &ValidationDetail{
+				ExitCode: -1,
+				Stdout:   "",
+				Stderr:   fmt.Sprintf("Failed to run validation command: %v", err),
+			},
 			ProgressLog: progressLog,
 		}, nil
 	}

experimental/apps-mcp/lib/templates/trpc/client/package.json

@@ -5,8 +5,9 @@
   "type": "module",
   "scripts": {
     "dev": "vite --host",
-    "build": "tsc -b && vite build -l info",
+    "build": "tsc -p tsconfig.json -b && vite build -l info",
     "lint": "eslint .",
+    "check": "tsc --noEmit",
     "preview": "vite preview"
   },
   "dependencies": {

experimental/apps-mcp/lib/templates/trpc/package.json

@@ -3,7 +3,8 @@
   "private": true,
   "scripts": {
     "install:all": "cd server && npm install && cd ../client && npm install",
-    "build": "npm run install:all && cd server && npm run check && cd .. && cd client && npm run build && cd .. && rm -rf server/public && mv client/dist server/public",
+    "build": "npm run install:all && cd server && cd ../client && npm run build && cd .. && rm -rf server/public && mv client/dist server/public",
+    "typecheck": "cd server && npm run check && cd ../client && npm run check",
     "start": "cd server && npm start",
     "test": "cd server && npm test",
     "clean": "rm -rf server/public server/node_modules server/dist client/node_modules"