Add custom backend configuration

internal/adapter/cli/run.go

@@ -47,6 +47,7 @@ type runConfig struct {
 	maxTokens     int
 	topP          float64
 	schemaDir     string
+	backends      []appconfig.BackendSettings
 	timeout       time.Duration
 
 	defaultRenderFormat renderformat.PreparedRunOutputFormat
@@ -76,6 +77,7 @@ type serveConfig struct {
 	maxRequestBytes  int64
 	maxArtifactBytes int64
 	maxResponseBytes int64
+	backends         []appconfig.BackendSettings
 }
 
 type commonCommandSettings struct {
@@ -88,6 +90,7 @@ type commonCommandSettings struct {
 	maxArtifactBytes    int64
 	maxResponseBytes    int64
 	defaultRenderFormat renderformat.PreparedRunOutputFormat
+	backends            []appconfig.BackendSettings
 }
 
 type listFlag []string
@@ -134,7 +137,7 @@ func runCommand(args []string, stdout, stderr io.Writer) int {
 		return ExitRuntimeError
 	}
 
-	engine, err := newEngine(cfg)
+	engine, err := newEngine(cfg.engineSettings())
 	if err != nil {
 		fmt.Fprintf(stderr, "engine error: %v\n", err)
 		return ExitRuntimeError
@@ -168,7 +171,7 @@ func renderCommand(args []string, stdout, stderr io.Writer) int {
 		return ExitRuntimeError
 	}
 
-	engine, err := newEngine(&cfg.runConfig)
+	engine, err := newEngine(cfg.runConfig.engineSettings())
 	if err != nil {
 		fmt.Fprintf(stderr, "engine error: %v\n", err)
 		return ExitRuntimeError
@@ -206,11 +209,7 @@ func serveCommand(args []string, stderr io.Writer) int {
 		return ExitRuntimeError
 	}
 
-	engine, err := newEngine(&runConfig{
-		promptDir:  cfg.promptDir,
-		profileDir: cfg.profileDir,
-		schemaDir:  cfg.schemaDir,
-	}, promptkit.WithArtifactReader(artifactReader))
+	engine, err := newEngine(cfg.engineSettings(), promptkit.WithArtifactReader(artifactReader))
 	if err != nil {
 		fmt.Fprintf(stderr, "engine error: %v\n", err)
 		return ExitRuntimeError
@@ -330,6 +329,7 @@ func parseServeArgs(args []string) (*serveConfig, error) {
 	cfg.maxRequestBytes = settings.maxRequestBytes
 	cfg.maxArtifactBytes = settings.maxArtifactBytes
 	cfg.maxResponseBytes = settings.maxResponseBytes
+	cfg.backends = settings.backends
 
 	if err := validateRequiredLibraryDirs(cfg.promptDir); err != nil {
 		return nil, err
@@ -384,6 +384,7 @@ func finalizeExecutionRequestConfig(fs *flag.FlagSet, cfg *runConfig) error {
 	cfg.profileDir = settings.profileDir
 	cfg.schemaDir = settings.schemaDir
 	cfg.defaultRenderFormat = settings.defaultRenderFormat
+	cfg.backends = settings.backends
 
 	if err := validateRequiredLibraryDirs(cfg.promptDir); err != nil {
 		return err
@@ -527,6 +528,7 @@ func resolveCommonSettings(fs *flag.FlagSet, configPath string, overrides appcon
 		maxArtifactBytes:    settings.MaxArtifactBytes,
 		maxResponseBytes:    settings.MaxResponseBytes,
 		defaultRenderFormat: settings.DefaultRenderFormat,
+		backends:            settings.Backends,
 	}, nil
 }
 
@@ -537,12 +539,43 @@ func validateRequiredLibraryDirs(promptDir string) error {
 	return nil
 }
 
-func newEngine(cfg *runConfig, options ...promptkit.Option) (*promptkit.Engine, error) {
-	return promptkit.NewEngine(promptkit.Config{
-		PromptDir:  cfg.promptDir,
-		ProfileDir: cfg.profileDir,
-		SchemaDir:  cfg.schemaDir,
-	}, options...)
+type engineSettings struct {
+	promptDir  string
+	profileDir string
+	schemaDir  string
+	backends   []appconfig.BackendSettings
+}
+
+func (c runConfig) engineSettings() engineSettings {
+	return engineSettings{promptDir: c.promptDir, profileDir: c.profileDir, schemaDir: c.schemaDir, backends: c.backends}
+}
+
+func (c serveConfig) engineSettings() engineSettings {
+	return engineSettings{promptDir: c.promptDir, profileDir: c.profileDir, schemaDir: c.schemaDir, backends: c.backends}
+}
+
+func newEngine(settings engineSettings, options ...promptkit.Option) (*promptkit.Engine, error) {
+	engineOptions := make([]promptkit.Option, 0, len(settings.backends)+len(options))
+	for _, configured := range settings.backends {
+		engineOptions = append(engineOptions, promptkit.WithBackend(promptkit.Backend{
+			ID:               configured.ID,
+			Endpoint:         configured.Endpoint,
+			APIKeyEnv:        configured.APIKeyEnv,
+			ExtraParams:      configured.ExtraParams,
+			ConcurrencyLimit: configured.ConcurrencyLimit,
+			QueueCapacity:    configured.QueueCapacity,
+		}))
+	}
+	engineOptions = append(engineOptions, options...)
+	engine, err := promptkit.NewEngine(promptkit.Config{
+		PromptDir:  settings.promptDir,
+		ProfileDir: settings.profileDir,
+		SchemaDir:  settings.schemaDir,
+	}, engineOptions...)
+	if err != nil {
+		return nil, fmt.Errorf("engine initialization from application configuration: %w", err)
+	}
+	return engine, nil
 }
 
 func buildRunRequestFromConfig(cfg *runConfig) (promptkit.RunRequest, error) {