many fixes

ChatBot/Services/FileSystemPromptProvider.cs

@@ -0,0 +1,58 @@
+using System.Text;
+using ChatBot.Models.Configuration;
+using ChatBot.Services.Interfaces;
+using Microsoft.Extensions.Options;
+
+namespace ChatBot.Services
+{
+    /// <summary>
+    /// System prompt provider that loads prompt from file
+    /// </summary>
+    public class FileSystemPromptProvider : ISystemPromptProvider
+    {
+        private readonly string _filePath;
+        private readonly ILogger<FileSystemPromptProvider> _logger;
+        private readonly Lazy<string> _cachedPrompt;
+
+        public FileSystemPromptProvider(
+            IOptions<OllamaSettings> settings,
+            ILogger<FileSystemPromptProvider> logger
+        )
+        {
+            _filePath = settings.Value.SystemPromptFilePath;
+            _logger = logger;
+            _cachedPrompt = new Lazy<string>(LoadPrompt);
+        }
+
+        public string GetSystemPrompt() => _cachedPrompt.Value;
+
+        private string LoadPrompt()
+        {
+            if (!File.Exists(_filePath))
+            {
+                var error = $"System prompt file not found: {_filePath}";
+                _logger.LogError(error);
+                throw new FileNotFoundException(error);
+            }
+
+            try
+            {
+                var prompt = File.ReadAllText(_filePath, Encoding.UTF8);
+                _logger.LogInformation(
+                    "System prompt loaded from {FilePath} ({Length} characters)",
+                    _filePath,
+                    prompt.Length
+                );
+                return prompt;
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "Failed to read system prompt file: {FilePath}", _filePath);
+                throw new InvalidOperationException(
+                    $"Failed to read system prompt file '{_filePath}': {ex.Message}",
+                    ex
+                );
+            }
+        }
+    }
+}