feat(build): honor configured main package path

cmd/build/cmd_project.go

@@ -115,6 +115,7 @@ func runProjectBuild(ctx context.Context, buildType string, ciMode bool, targets
 	// Create build config for the builder
 	cfg := &build.Config{
 		FS:         filesystem,
+		Project:    buildConfig.Project,
 		ProjectDir: projectDir,
 		OutputDir:  outputDir,
 		Name:       binaryName,

pkg/build/build.go

@@ -71,6 +71,8 @@ type Artifact struct {
 type Config struct {
 	// FS is the medium used for file operations.
 	FS io.Medium
+	// Project holds build-time project metadata.
+	Project Project
 	// ProjectDir is the root directory of the project.
 	ProjectDir string
 	// OutputDir is where build artifacts are placed.

pkg/build/builders/go.go

@@ -108,8 +108,12 @@ func (b *GoBuilder) buildTarget(ctx context.Context, cfg *build.Config, target b
 	// Add output path
 	args = append(args, "-o", outputPath)
 
-	// Add the project directory as the build target (current directory)
-	args = append(args, ".")
+	// Build the configured main package path, defaulting to the project root.
+	mainPackage := cfg.Project.Main
+	if mainPackage == "" {
+		mainPackage = "."
+	}
+	args = append(args, mainPackage)
 
 	// Set up environment.
 	env := append([]string{}, cfg.Env...)

pkg/build/builders/go_test.go

@@ -382,6 +382,42 @@ func TestGo_GoBuilderBuild_Good(t *testing.T) {
 		assert.Contains(t, args, ".")
 	})
 
+	t.Run("builds the configured main package path", func(t *testing.T) {
+		projectDir := setupGoTestProject(t)
+		err := ax.MkdirAll(ax.Join(projectDir, "cmd", "myapp"), 0755)
+		require.NoError(t, err)
+		err = ax.WriteFile(ax.Join(projectDir, "cmd", "myapp", "main.go"), []byte("package main\n\nfunc main() {}\n"), 0644)
+		require.NoError(t, err)
+
+		outputDir := t.TempDir()
+		logPath := ax.Join(t.TempDir(), "go-build-args.log")
+		t.Setenv("GO_BUILD_LOG_FILE", logPath)
+
+		builder := NewGoBuilder()
+		cfg := &build.Config{
+			FS:         io.Local,
+			ProjectDir: projectDir,
+			OutputDir:  outputDir,
+			Name:       "mainpackage",
+		}
+		cfg.Project.Main = "./cmd/myapp"
+		targets := []build.Target{
+			{OS: runtime.GOOS, Arch: runtime.GOARCH},
+		}
+
+		artifacts, err := builder.Build(context.Background(), cfg, targets)
+		require.NoError(t, err)
+		require.Len(t, artifacts, 1)
+
+		content, err := ax.ReadFile(logPath)
+		require.NoError(t, err)
+
+		args := strings.Split(strings.TrimSpace(string(content)), "\n")
+		require.NotEmpty(t, args)
+		assert.Contains(t, args, "./cmd/myapp")
+		assert.NotContains(t, args, ".")
+	})
+
 	t.Run("creates output directory if missing", func(t *testing.T) {
 		projectDir := setupGoTestProject(t)
 		outputDir := ax.Join(t.TempDir(), "nested", "output")