Refactored, added comprehensive testing.

config/validate.go

@@ -0,0 +1,17 @@
+package config
+
+import (
+	"fmt"
+)
+
+func validateConfig(cfg ConfigData) error {
+	if cfg.APIKey == "" {
+		return fmt.Errorf("API key required: use --key, --key-file, AICLI_API_KEY, AICLI_API_KEY_FILE, or key_file in config")
+	}
+
+	if cfg.Protocol != ProtocolOpenAI && cfg.Protocol != ProtocolOllama {
+		return fmt.Errorf("invalid protocol: must be openai or ollama")
+	}
+
+	return nil
+}