Make public options opaque

engine.go

@@ -52,7 +52,15 @@ type Config struct {
 }
 
 // Option customizes engine construction.
-type Option func(*engineOptions) error
+type Option interface {
+	apply(*engineOptions) error
+}
+
+type optionFunc func(*engineOptions) error
+
+func (f optionFunc) apply(options *engineOptions) error {
+	return f(options)
+}
 
 type engineOptions struct {
 	llmClient       llm.Client
@@ -68,17 +76,17 @@ type engineOptions struct {
 
 // WithLLMClient injects a custom LLM client for execution.
 func WithLLMClient(client LLMClient) Option {
-	return func(options *engineOptions) error {
+	return optionFunc(func(options *engineOptions) error {
 		if client == nil {
 			return ErrInvalidConfig
 		}
 		options.llmClient = publicLLMClientAdapter{client: client}
 		return nil
-	}
+	})
 }
 
 func WithPromptFS(fsys fs.FS, root string) Option {
-	return func(options *engineOptions) error {
+	return optionFunc(func(options *engineOptions) error {
 		if fsys == nil {
 			return ErrInvalidConfig
 		}
@@ -88,11 +96,11 @@ func WithPromptFS(fsys fs.FS, root string) Option {
 		options.promptDefs = promptdef.NewFSRepository(fsys, root)
 		options.promptSource = true
 		return nil
-	}
+	})
 }
 
 func WithPromptFile(path string) Option {
-	return func(options *engineOptions) error {
+	return optionFunc(func(options *engineOptions) error {
 		fsys, root, err := fileSource(path)
 		if err != nil {
 			return err
@@ -100,11 +108,11 @@ func WithPromptFile(path string) Option {
 		options.promptDefs = promptdef.NewFSRepository(fsys, root)
 		options.promptSource = true
 		return nil
-	}
+	})
 }
 
 func WithProfileFS(fsys fs.FS, root string) Option {
-	return func(options *engineOptions) error {
+	return optionFunc(func(options *engineOptions) error {
 		if fsys == nil {
 			return ErrInvalidConfig
 		}
@@ -114,11 +122,11 @@ func WithProfileFS(fsys fs.FS, root string) Option {
 		options.profiles = profile.NewFSRepository(fsys, root)
 		options.profileSource = true
 		return nil
-	}
+	})
 }
 
 func WithProfileFile(path string) Option {
-	return func(options *engineOptions) error {
+	return optionFunc(func(options *engineOptions) error {
 		fsys, root, err := fileSource(path)
 		if err != nil {
 			return err
@@ -126,13 +134,13 @@ func WithProfileFile(path string) Option {
 		options.profiles = profile.NewFSRepository(fsys, root)
 		options.profileSource = true
 		return nil
-	}
+	})
 }
 
 // WithProfiles configures in-memory profiles that take precedence over
 // configured profile files and built-in profiles.
 func WithProfiles(profiles ...Profile) Option {
-	return func(options *engineOptions) error {
+	return optionFunc(func(options *engineOptions) error {
 		repo, err := newMemoryProfileRepository(profiles)
 		if err != nil {
 			return err
@@ -140,11 +148,11 @@ func WithProfiles(profiles ...Profile) Option {
 		options.memoryProfiles = repo
 		options.memorySource = true
 		return nil
-	}
+	})
 }
 
 func WithSchemaFS(fsys fs.FS, root string) Option {
-	return func(options *engineOptions) error {
+	return optionFunc(func(options *engineOptions) error {
 		if fsys == nil {
 			return ErrInvalidConfig
 		}
@@ -154,11 +162,11 @@ func WithSchemaFS(fsys fs.FS, root string) Option {
 		options.validator = validate.NewFSValidator(fsys, root)
 		options.validatorSource = true
 		return nil
-	}
+	})
 }
 
 func WithSchemaFile(path string) Option {
-	return func(options *engineOptions) error {
+	return optionFunc(func(options *engineOptions) error {
 		fsys, root, err := fileSource(path)
 		if err != nil {
 			return err
@@ -166,7 +174,7 @@ func WithSchemaFile(path string) Option {
 		options.validator = validate.NewFSValidator(fsys, root)
 		options.validatorSource = true
 		return nil
-	}
+	})
 }
 
 // NewEngine constructs an Engine using the same default internal components as
@@ -177,7 +185,7 @@ func NewEngine(cfg Config, opts ...Option) (*Engine, error) {
 		if opt == nil {
 			continue
 		}
-		if err := opt(&options); err != nil {
+		if err := opt.apply(&options); err != nil {
 			return nil, fmt.Errorf("%w: %v", ErrInvalidConfig, err)
 		}
 	}