fix: make code_file required for transformations

Reverts the implicit dist/index.js default — users must explicitly
declare where their transformation code lives.

Author: Swahjak

pkg/deploy/deploy.go

@@ -358,16 +358,14 @@ func buildConnectionRequest(conn *manifest.ConnectionConfig, sourceID, destinati
 }
 
 // resolveCode reads the code file for a transformation.
-// If CodeFile is empty, defaults to "dist/index.js" (standard esbuild output).
 func resolveCode(tr *manifest.TransformationConfig, codeRoot string) (string, error) {
-	codeFile := tr.CodeFile
-	if codeFile == "" {
-		codeFile = "dist/index.js"
+	if tr.CodeFile == "" {
+		return "", fmt.Errorf("code_file is required")
 	}
 
-	path := codeFile
+	path := tr.CodeFile
 	if codeRoot != "" {
-		path = codeRoot + "/" + codeFile
+		path = codeRoot + "/" + tr.CodeFile
 	}
 
 	// For now we pass the code_file path as the code value. In the real deploy

pkg/deploy/deploy_test.go

@@ -3,6 +3,7 @@ package deploy
 import (
 	"context"
 	"fmt"
+	"strings"
 	"testing"
 
 	"github.com/toppynl/hookdeck-deploy-cli/pkg/manifest"
@@ -131,6 +132,22 @@ func TestDeploy_DryRun_ConnectionWithRules(t *testing.T) {
 	}
 }
 
+func TestDeploy_MissingCodeFile(t *testing.T) {
+	m := &manifest.Manifest{
+		Transformation: &manifest.TransformationConfig{
+			Name: "no-code-file",
+		},
+	}
+
+	_, err := Deploy(context.Background(), &mockClient{}, m, Options{})
+	if err == nil {
+		t.Fatal("expected error when code_file is missing, got nil")
+	}
+	if !strings.Contains(err.Error(), "code_file is required") {
+		t.Errorf("expected error to contain %q, got %q", "code_file is required", err.Error())
+	}
+}
+
 // --- mock client tests (live mode with mock) ---
 
 type mockClient struct {

schemas/hookdeck-transformation.schema.json

@@ -43,7 +43,7 @@
 					}
 				}
 			},
-			"required": ["name"],
+			"required": ["name", "code_file"],
 			"additionalProperties": false
 		},
 		"env": {