refactor: apply Single Responsibility Principle to Program.cs and ReplLoop.cs

extracted responsibilities from Program.cs (208→46 lines) and ReplLoop.cs (274→174 lines) into focused service classes: HeaderRenderer, SessionManager, ApplicationStartup, ResponseStreamer, SpinnerService, UsageDisplayer, and ContextCompactionService. Each class now has a single, well-defined responsibility, improving testability and maintainability.

ApplicationStartup.cs

@@ -0,0 +1,176 @@
+using System.ClientModel;
+using AnchorCli.Commands;
+using AnchorCli.OpenRouter;
+using AnchorCli.Providers;
+using AnchorCli.Tools;
+using Microsoft.Extensions.AI;
+using OpenAI;
+using Spectre.Console;
+
+namespace AnchorCli;
+
+/// <summary>
+/// Encapsulates application startup logic, including configuration loading,
+/// API client creation, and component initialization.
+/// </summary>
+internal sealed class ApplicationStartup
+{
+    private readonly string[] _args;
+    private AnchorConfig? _config;
+    private ITokenExtractor? _tokenExtractor;
+    private ModelInfo? _modelInfo;
+    private IChatClient? _chatClient;
+    private TokenTracker? _tokenTracker;
+
+    public ApplicationStartup(string[] args)
+    {
+        _args = args;
+    }
+
+    public AnchorConfig Config => _config ?? throw new InvalidOperationException("Run InitializeAsync first");
+    public string ApiKey => _config?.ApiKey ?? throw new InvalidOperationException("API key not loaded");
+    public string Model => _config?.Model ?? throw new InvalidOperationException("Model not loaded");
+    public string Endpoint => _config?.Endpoint ?? "https://openrouter.ai/api/v1";
+    public string ProviderName => _tokenExtractor?.ProviderName ?? "Unknown";
+    public ITokenExtractor TokenExtractor => _tokenExtractor ?? throw new InvalidOperationException("Token extractor not initialized");
+    public ModelInfo? ModelInfo => _modelInfo;
+    public IChatClient ChatClient => _chatClient ?? throw new InvalidOperationException("Chat client not initialized");
+    public TokenTracker TokenTracker => _tokenTracker ?? throw new InvalidOperationException("Token tracker not initialized");
+
+    /// <summary>
+    /// Runs the setup TUI if the "setup" subcommand was passed. Returns true if setup was run.
+    /// </summary>
+    public bool HandleSetupSubcommand()
+    {
+        if (_args.Length > 0 && _args[0].Equals("setup", StringComparison.OrdinalIgnoreCase))
+        {
+            SetupTui.Run();
+            return true;
+        }
+        return false;
+    }
+
+    /// <summary>
+    /// Initializes the application by loading configuration and creating the chat client.
+    /// </summary>
+    public async Task InitializeAsync()
+    {
+        // Load configuration
+        _config = AnchorConfig.Load();
+
+        if (string.IsNullOrWhiteSpace(_config.ApiKey))
+        {
+            AnsiConsole.MarkupLine("[red]No API key configured. Run [bold]anchor setup[/] first.[/]");
+            throw new InvalidOperationException("API key not configured");
+        }
+
+        // Create token extractor
+        _tokenExtractor = ProviderFactory.CreateTokenExtractorForEndpoint(Endpoint);
+
+        // Fetch model pricing (only for OpenRouter)
+        if (ProviderFactory.IsOpenRouter(Endpoint))
+        {
+            await AnsiConsole.Status()
+                .Spinner(Spinner.Known.BouncingBar)
+                .SpinnerStyle(Style.Parse("cornflowerblue"))
+                .StartAsync("Fetching model pricing...", async ctx =>
+                {
+                    try
+                    {
+                        var pricingProvider = new OpenRouterProvider();
+                        _modelInfo = await pricingProvider.GetModelInfoAsync(Model);
+                    }
+                    catch
+                    {
+                        // Pricing is best-effort
+                    }
+                });
+        }
+
+        // Create chat client
+        var httpClient = new HttpClient();
+        OpenRouterHeaders.ApplyTo(httpClient);
+
+        var openAiClient = new OpenAIClient(
+            new ApiKeyCredential(ApiKey),
+            new OpenAIClientOptions
+            {
+                Endpoint = new Uri(Endpoint),
+                Transport = new System.ClientModel.Primitives.HttpClientPipelineTransport(httpClient)
+            });
+
+        _chatClient = openAiClient.GetChatClient(Model).AsIChatClient();
+
+        // Initialize token tracker
+        _tokenTracker = new TokenTracker(new ChatSession(_chatClient))
+        {
+            Provider = _tokenExtractor.ProviderName
+        };
+
+        if (_modelInfo?.Pricing != null)
+        {
+            _tokenTracker.InputPrice = PricingProvider.ParsePrice(_modelInfo.Pricing.Prompt);
+            _tokenTracker.OutputPrice = PricingProvider.ParsePrice(_modelInfo.Pricing.Completion);
+            _tokenTracker.RequestPrice = PricingProvider.ParsePrice(_modelInfo.Pricing.Request);
+        }
+
+        if (_modelInfo != null)
+        {
+            _tokenTracker.ContextLength = _modelInfo.ContextLength;
+        }
+    }
+
+    /// <summary>
+    /// Creates a new ChatSession with the initialized chat client.
+    /// </summary>
+    public ChatSession CreateSession()
+    {
+        return new ChatSession(ChatClient);
+    }
+
+    /// <summary>
+    /// Configures tool logging to use Spectre.Console.
+    /// </summary>
+    public void ConfigureToolLogging()
+    {
+        object consoleLock = new();
+
+        void ToolLog(string message)
+        {
+            lock (consoleLock)
+            {
+                Console.Write("\r" + new string(' ', 40) + "\r");
+                AnsiConsole.MarkupLine($"[dim grey]{Markup.Escape(message)}[/]");
+            }
+        }
+
+        CommandTool.Log =
+        DirTools.Log =
+        FileTools.Log =
+        EditTools.Log = ToolLog;
+    }
+
+    /// <summary>
+    /// Creates and populates a CommandRegistry with all available commands.
+    /// </summary>
+    public CommandRegistry CreateCommandRegistry(ChatSession session)
+    {
+        var registry = new CommandRegistry();
+        registry.Register(new ExitCommand());
+        registry.Register(new HelpCommand(registry));
+        registry.Register(new ClearCommand());
+        registry.Register(new StatusCommand(Model, Endpoint));
+        registry.Register(new CompactCommand(session.Compactor, session.History));
+        registry.Register(new SetupCommand());
+        registry.Register(new ResetCommand(session, TokenTracker));
+        return registry;
+    }
+
+    /// <summary>
+    /// Creates a HeaderRenderer with the current configuration.
+    /// </summary>
+    public HeaderRenderer CreateHeaderRenderer()
+    {
+        return new HeaderRenderer(Model, Endpoint, ProviderName, _modelInfo, _tokenTracker);
+    }
+}

ContextCompactionService.cs

@@ -0,0 +1,61 @@
+using Microsoft.Extensions.AI;
+using Spectre.Console;
+using AnchorCli.OpenRouter;
+
+namespace AnchorCli;
+
+/// <summary>
+/// Handles context compaction when the conversation approaches token limits.
+/// </summary>
+internal sealed class ContextCompactionService
+{
+    private readonly ContextCompactor _compactor;
+    private readonly List<ChatMessage> _history;
+    private readonly TokenTracker _tokenTracker;
+
+    public ContextCompactionService(
+        ContextCompactor compactor,
+        List<ChatMessage> history,
+        TokenTracker tokenTracker)
+    {
+        _compactor = compactor;
+        _history = history;
+        _tokenTracker = tokenTracker;
+    }
+
+    /// <summary>
+    /// Checks if compaction is needed and performs it if so.
+    /// Returns true if compaction was performed.
+    /// </summary>
+    public async Task<bool> TryCompactAsync()
+    {
+        if (!_tokenTracker.ShouldCompact())
+        {
+            return false;
+        }
+
+        var pct = _tokenTracker.ContextUsagePercent;
+        AnsiConsole.MarkupLine(
+            $"[yellow]⚠ Context at {pct:F0}% — compacting conversation history...[/]");
+
+        bool compacted = await AnsiConsole.Status()
+            .Spinner(Spinner.Known.BouncingBar)
+            .SpinnerStyle(Style.Parse("yellow"))
+            .StartAsync("Compacting context...", async ctx =>
+                await _compactor.TryCompactAsync(_history, default));
+
+        if (compacted)
+        {
+            AnsiConsole.MarkupLine(
+                $"[green]✓ Context compacted ({_history.Count} messages remaining)[/]");
+        }
+        else
+        {
+            AnsiConsole.MarkupLine(
+                "[dim grey]  (compaction skipped — not enough history to compress)[/]");
+        }
+
+        AnsiConsole.WriteLine();
+        return compacted;
+    }
+}

HeaderRenderer.cs

@@ -0,0 +1,110 @@
+using System.Reflection;
+using Spectre.Console;
+using AnchorCli.OpenRouter;
+
+namespace AnchorCli;
+
+/// <summary>
+/// Renders the application header, including ASCII art logo and configuration info table.
+/// </summary>
+internal sealed class HeaderRenderer
+{
+    private readonly string _model;
+    private readonly string _endpoint;
+    private readonly string _providerName;
+    private readonly ModelInfo? _modelInfo;
+    private readonly TokenTracker? _tokenTracker;
+
+    public HeaderRenderer(
+        string model,
+        string endpoint,
+        string providerName,
+        ModelInfo? modelInfo = null,
+        TokenTracker? tokenTracker = null)
+    {
+        _model = model;
+        _endpoint = endpoint;
+        _providerName = providerName;
+        _modelInfo = modelInfo;
+        _tokenTracker = tokenTracker;
+    }
+
+    /// <summary>
+    /// Renders the full header including logo, subtitle, and info table.
+    /// </summary>
+    public void Render()
+    {
+        RenderLogo();
+        RenderSubtitle();
+        RenderInfoTable();
+    }
+
+    /// <summary>
+    /// Renders the ASCII art logo.
+    /// </summary>
+    public void RenderLogo()
+    {
+        var fontStream = Assembly.GetExecutingAssembly().GetManifestResourceStream("AnchorCli.Assets.3d.flf");
+        if (fontStream != null)
+        {
+            var font = FigletFont.Load(fontStream);
+            AnsiConsole.Write(
+                new FigletText(font, "anchor")
+                    .Color(Color.CornflowerBlue));
+        }
+        else
+        {
+            AnsiConsole.Write(
+                new FigletText("anchor")
+                    .Color(Color.CornflowerBlue));
+        }
+    }
+
+    /// <summary>
+    /// Renders the subtitle rule.
+    /// </summary>
+    public void RenderSubtitle()
+    {
+        AnsiConsole.Write(
+            new Rule("[dim]AI-powered coding assistant[/]")
+                .RuleStyle(Style.Parse("cornflowerblue dim"))
+                .LeftJustified());
+        AnsiConsole.WriteLine();
+    }
+
+    /// <summary>
+    /// Renders the configuration info table.
+    /// </summary>
+    public void RenderInfoTable()
+    {
+        var version = Assembly.GetExecutingAssembly().GetName().Version?.ToString() ?? "unknown";
+
+        var table = new Table()
+            .Border(TableBorder.Rounded)
+            .BorderColor(Color.Grey)
+            .AddColumn(new TableColumn("[dim]Setting[/]").NoWrap())
+            .AddColumn(new TableColumn("[dim]Value[/]"));
+
+        table.AddRow("[grey]Model[/]", $"[cyan]{Markup.Escape(_modelInfo?.Name ?? _model)}[/]");
+        table.AddRow("[grey]Provider[/]", $"[blue]{_providerName}[/]");
+        table.AddRow("[grey]Endpoint[/]", $"[dim]{_endpoint}[/]");
+        table.AddRow("[grey]Version[/]", $"[magenta]{version}[/]");
+
+        if (_modelInfo?.Pricing != null && _tokenTracker != null)
+        {
+            var inM = _tokenTracker.InputPrice * 1_000_000m;
+            var outM = _tokenTracker.OutputPrice * 1_000_000m;
+            table.AddRow("[grey]Pricing[/]",
+                $"[yellow]${inM:F2}[/][dim]/M in[/]  [yellow]${outM:F2}[/][dim]/M out[/]");
+        }
+
+        if (_modelInfo != null)
+        {
+            table.AddRow("[grey]Context[/]",
+                $"[dim]{_modelInfo.ContextLength:N0} tokens[/]");
+        }
+
+        AnsiConsole.Write(table);
+        AnsiConsole.WriteLine();
+    }
+}

OpenRouter/TokenTracker.cs

@@ -5,13 +5,23 @@ namespace AnchorCli.OpenRouter;
 /// </summary>
 internal sealed class TokenTracker
 {
-    private readonly ChatSession _session;
+    private ChatSession _session;
     
     public TokenTracker(ChatSession session)
     {
         _session = session;
     }
 
+    /// <summary>
+    /// Gets or sets the session. Allows setting the session after construction
+    /// to support dependency injection patterns.
+    /// </summary>
+    public ChatSession Session
+    {
+        get => _session;
+        set => _session = value;
+    }
+    
     public string Provider { get; set; } = "Unknown";
     public long SessionInputTokens => _session.SessionInputTokens;
     public long SessionOutputTokens => _session.SessionOutputTokens;

Program.cs

@@ -1,208 +1,45 @@
-using System.ClientModel;
-using System.Reflection;
-using AnchorCli.Providers;
-using Microsoft.Extensions.AI;
-using OpenAI;
 using AnchorCli;
-using AnchorCli.Tools;
 using AnchorCli.Commands;
-using AnchorCli.OpenRouter;
 using Spectre.Console;
 
 Console.InputEncoding = System.Text.Encoding.UTF8;
 Console.OutputEncoding = System.Text.Encoding.UTF8;
 
-// ── Setup subcommand ─────────────────────────────────────────────────────
+// ── Application entry point ───────────────────────────────────────────────
-if (args.Length > 0 && args[0].Equals("setup", StringComparison.OrdinalIgnoreCase))
+var startup = new ApplicationStartup(args);
+
+// Handle setup subcommand
+if (startup.HandleSetupSubcommand())
 {
-    SetupTui.Run();
     return;
 }
 
-// ── Config ──────────────────────────────────────────────────────────────
+// Initialize application (load config, create clients, fetch pricing)
-var cfg = AnchorConfig.Load();
+await startup.InitializeAsync();
-string apiKey = cfg.ApiKey;
-string model = cfg.Model;
-string provider = cfg.Provider ?? "openrouter";
-string endpoint = cfg.Endpoint ?? "https://openrouter.ai/api/v1";
 
-if (string.IsNullOrWhiteSpace(apiKey))
+// Render header
-{
+var headerRenderer = startup.CreateHeaderRenderer();
-    AnsiConsole.MarkupLine("[red]No API key configured. Run [bold]anchor setup[/] first.[/]");
+headerRenderer.Render();
-    return;
-}
 
-// ── Create token extractor for this provider ───────────────────────────
+// Configure tool logging
-var tokenExtractor = ProviderFactory.CreateTokenExtractorForEndpoint(endpoint);
+startup.ConfigureToolLogging();
-
-// ── Fetch model pricing (only for supported providers) ─────────────────
-ModelInfo? modelInfo = null;
-TokenTracker? tokenTracker = null;
-if (ProviderFactory.IsOpenRouter(endpoint))
-{
-    await AnsiConsole.Status()
-        .Spinner(Spinner.Known.BouncingBar)
-        .SpinnerStyle(Style.Parse("cornflowerblue"))
-        .StartAsync("Fetching model pricing...", async ctx =>
-        {
-            try
-            {
-                var pricingProvider = new OpenRouterProvider();
-                modelInfo = await pricingProvider.GetModelInfoAsync(model);
-            }
-            catch { /* pricing is best-effort */ }
-        });
-}
-
-
-// ── Pretty header ───────────────────────────────────────────────────────
-var fontStream = Assembly.GetExecutingAssembly().GetManifestResourceStream("AnchorCli.Assets.3d.flf");
-if (fontStream != null)
-{
-    var font = FigletFont.Load(fontStream);
-    AnsiConsole.Write(
-        new FigletText(font, "anchor")
-            .Color(Color.CornflowerBlue));
-}
-else
-{
-    AnsiConsole.Write(
-        new FigletText("anchor")
-            .Color(Color.CornflowerBlue));
-}
-
-
-var version = Assembly.GetExecutingAssembly().GetName().Version?.ToString() ?? "unknown";
-
-// ── Pretty header ───────────────────────────────────────────────────────
-
-AnsiConsole.Write(
-    new Rule("[dim]AI-powered coding assistant[/]")
-        .RuleStyle(Style.Parse("cornflowerblue dim"))
-        .LeftJustified());
-
-AnsiConsole.WriteLine();
-
-var infoTable = new Table()
-    .Border(TableBorder.Rounded)
-    .BorderColor(Color.Grey)
-    .AddColumn(new TableColumn("[dim]Setting[/]").NoWrap())
-    .AddColumn(new TableColumn("[dim]Value[/]"));
-
-infoTable.AddRow("[grey]Model[/]", $"[cyan]{Markup.Escape(modelInfo?.Name ?? model)}[/]");
-infoTable.AddRow("[grey]Provider[/]", $"[blue]{tokenExtractor.ProviderName}[/]");
-infoTable.AddRow("[grey]Endpoint[/]", $"[dim]{endpoint}[/]");
-infoTable.AddRow("[grey]Version[/]", $"[magenta]{version}[/]");
-
-if (modelInfo?.Pricing != null && tokenTracker != null)
-
-{
-    var inM = tokenTracker.InputPrice * 1_000_000m;
-    var outM = tokenTracker.OutputPrice * 1_000_000m;
-    infoTable.AddRow("[grey]Pricing[/]",
-        $"[yellow]${inM:F2}[/][dim]/M in[/]  [yellow]${outM:F2}[/][dim]/M out[/]");
-}
-if (modelInfo != null)
-{
-    infoTable.AddRow("[grey]Context[/]",
-        $"[dim]{modelInfo.ContextLength:N0} tokens[/]");
-}
-
-AnsiConsole.Write(infoTable);
-AnsiConsole.WriteLine();
-
-// ── Build the chat client with tool-calling support ─────────────────────
-var httpClient = new HttpClient();
-OpenRouterHeaders.ApplyTo(httpClient);
-
-var openAiClient = new OpenAIClient(new ApiKeyCredential(apiKey), new OpenAIClientOptions
-{
-    Endpoint = new Uri(endpoint),
-    Transport = new System.ClientModel.Primitives.HttpClientPipelineTransport(httpClient)
-});
-
-IChatClient innerClient = openAiClient.GetChatClient(model).AsIChatClient();
-
-// ── Tool call logging via Spectre ───────────────────────────────────────
-object consoleLock = new();
-
-void ToolLog(string message)
-{
-    lock (consoleLock)
-    {
-        Console.Write("\r" + new string(' ', 40) + "\r");
-        AnsiConsole.MarkupLine($"[dim grey]{Markup.Escape(message)}[/]");
-    }
-}
-
-CommandTool.Log =
-DirTools.Log =
-FileTools.Log =
-EditTools.Log = ToolLog;
-
-// ── Instantiate Core Components ──────────────────────────────────────────
-
-var session = new ChatSession(innerClient);
-tokenTracker = new TokenTracker(session) { Provider = tokenExtractor.ProviderName };
-if (modelInfo != null)
-{
-    if (modelInfo.Pricing != null)
-    {
-        tokenTracker.InputPrice = PricingProvider.ParsePrice(modelInfo.Pricing.Prompt);
-        tokenTracker.OutputPrice = PricingProvider.ParsePrice(modelInfo.Pricing.Completion);
-        tokenTracker.RequestPrice = PricingProvider.ParsePrice(modelInfo.Pricing.Request);
-    }
-    tokenTracker.ContextLength = modelInfo.ContextLength;
-}
-
-var commandRegistry = new CommandRegistry();
-commandRegistry.Register(new ExitCommand());
-commandRegistry.Register(new HelpCommand(commandRegistry));
-commandRegistry.Register(new ClearCommand());
-commandRegistry.Register(new StatusCommand(model, endpoint));
-commandRegistry.Register(new CompactCommand(session.Compactor, session.History));
-commandRegistry.Register(new SetupCommand());
-commandRegistry.Register(new ResetCommand(session, tokenTracker));
 
+// Create core components
+var session = startup.CreateSession();
+startup.TokenTracker.Session = session;
 
+var commandRegistry = startup.CreateCommandRegistry(session);
 var commandDispatcher = new CommandDispatcher(commandRegistry);
 
-// ── Run Repl ────────────────────────────────────────────────────────────
+// Create session manager
+var sessionManager = new SessionManager(session);
 
 // Auto-load session if it exists
-const string sessionPath = ".anchor/session.json";
+await sessionManager.TryLoadAsync();
-if (File.Exists(sessionPath))
-{
-    try
-    {
-        await session.LoadAsync(sessionPath, default);
-        AnsiConsole.MarkupLine($"[dim grey]Auto-loaded previous session.[/]");
 
-        // Print the last message if there is one
+// Run REPL loop
-        if (session.History.Count > 1)
+var repl = new ReplLoop(session, startup.TokenTracker, commandDispatcher, sessionManager);
-        {
-            var lastMessage = session.History[^1];
-            var preview = lastMessage.Text.Length > 280
-                ? lastMessage.Text[..277] + "..."
-                : lastMessage.Text;
-            AnsiConsole.MarkupLine($"[dim grey]  Last message: {Markup.Escape(preview)}[/]");
-        }
-    }
-    catch { /* Ignore load errors on startup */ }
-}
-
-var repl = new ReplLoop(session, tokenTracker, commandDispatcher);
 await repl.RunAsync();
 
 // Auto-save session on clean exit
-try
+await sessionManager.TrySaveAsync();
-{
-    var directory = Path.GetDirectoryName(sessionPath);
-    if (!string.IsNullOrEmpty(directory) && !Directory.Exists(directory))
-    {
-        Directory.CreateDirectory(directory);
-    }
-    await session.SaveAsync(sessionPath, default);
-}
-catch { /* Ignore save errors on exit */ }
-

ReplLoop.cs

@@ -1,23 +1,38 @@
-using Microsoft.Extensions.AI;
+using System.Text;
-using OpenAI;
 using Spectre.Console;
-using AnchorCli.OpenRouter;
 using AnchorCli.Commands;
 using AnchorCli.Tools;
+using AnchorCli.OpenRouter;
 
 namespace AnchorCli;
 
+/// <summary>
+/// Manages the interactive REPL (Read-Eval-Print Loop) for user interaction.
+/// Orchestrates input handling, command dispatching, and response display.
+/// </summary>
 internal sealed class ReplLoop
 {
     private readonly ChatSession _session;
     private readonly TokenTracker _tokenTracker;
     private readonly CommandDispatcher _commandDispatcher;
+    private readonly SessionManager _sessionManager;
+    private readonly ResponseStreamer _streamer;
+    private readonly UsageDisplayer _usageDisplayer;
+    private readonly ContextCompactionService _compactionService;
 
-    public ReplLoop(ChatSession session, TokenTracker tokenTracker, CommandDispatcher commandDispatcher)
+    public ReplLoop(
+        ChatSession session,
+        TokenTracker tokenTracker,
+        CommandDispatcher commandDispatcher,
+        SessionManager sessionManager)
     {
         _session = session;
         _tokenTracker = tokenTracker;
         _commandDispatcher = commandDispatcher;
+        _sessionManager = sessionManager;
+        _streamer = new ResponseStreamer(session);
+        _usageDisplayer = new UsageDisplayer(tokenTracker);
+        _compactionService = new ContextCompactionService(session.Compactor, session.History, tokenTracker);
     }
 
     public async Task RunAsync()
@@ -29,7 +44,7 @@ internal sealed class ReplLoop
 
         Console.CancelKeyPress += (_, e) =>
         {
-            e.Cancel = true; // Prevent process termination
+            e.Cancel = true;
             responseCts?.Cancel();
         };
 
@@ -42,215 +57,23 @@ internal sealed class ReplLoop
 
             if (await _commandDispatcher.TryExecuteAsync(input, default)) continue;
 
-            _session.History.Add(new ChatMessage(ChatRole.User, input));
+            _session.History.Add(new Microsoft.Extensions.AI.ChatMessage(Microsoft.Extensions.AI.ChatRole.User, input));
-            int turnStartIndex = _session.History.Count;
-
             AnsiConsole.WriteLine();
 
+            responseCts?.Dispose();
             responseCts = new CancellationTokenSource();
-            string fullResponse = "";
 
             try
             {
-                await using var stream = _session
+                await ProcessTurnAsync(responseCts.Token);
-                    .GetStreamingResponseAsync(responseCts.Token)
-                    .GetAsyncEnumerator(responseCts.Token);
-
-                string? firstChunk = null;
-                int respIn = 0, respOut = 0;
-
-                void CaptureUsage(ChatResponseUpdate update)
-                {
-                    if (update.RawRepresentation is OpenAI.Chat.StreamingChatCompletionUpdate raw
-                        && raw.Usage != null)
-                    {
-                        respIn = raw.Usage.InputTokenCount;   // last call = actual context size
-                        respOut += raw.Usage.OutputTokenCount; // additive — each round generates new output
-                    }
-                }
-
-                object consoleLock = new();
-                using var spinnerCts = CancellationTokenSource.CreateLinkedTokenSource(responseCts.Token);
-                bool showSpinner = true;
-
-                CommandTool.PauseSpinner = () =>
-                {
-                    lock (consoleLock)
-                    {
-                        showSpinner = false;
-                        Console.Write("\r" + new string(' ', 40) + "\r");
-                    }
-                };
-                CommandTool.ResumeSpinner = () =>
-                {
-                    lock (consoleLock)
-                    {
-                        showSpinner = true;
-                    }
-                };
-                FileTools.OnFileRead = _ =>
-                {
-                    int n = ContextCompactor.CompactStaleToolResults(_session.History);
-                    if (n > 0)
-                        AnsiConsole.MarkupLine(
-                            $"[dim grey]  ♻ Compacted {n} stale tool result(s)[/]");
-                };
-
-                var spinnerTask = Task.Run(async () =>
-                {
-                    var frames = Spinner.Known.BouncingBar.Frames;
-                    var interval = Spinner.Known.BouncingBar.Interval;
-                    int i = 0;
-
-                    Console.Write("\x1b[?25l");
-                    try
-                    {
-                        while (!spinnerCts.Token.IsCancellationRequested)
-                        {
-                            lock (consoleLock)
-                            {
-                                if (showSpinner && !spinnerCts.Token.IsCancellationRequested)
-                                {
-                                    var frame = frames[i % frames.Count];
-                                    Console.Write($"\r\x1b[38;5;69m{frame}\x1b[0m Thinking...");
-                                    i++;
-                                }
-                            }
-                            try { await Task.Delay(interval, spinnerCts.Token); } catch { }
-                        }
-                    }
-                    finally
-                    {
-                        lock (consoleLock)
-                        {
-                            if (showSpinner)
-                                Console.Write("\r" + new string(' ', 40) + "\r");
-                            Console.Write("\x1b[?25h");
-                        }
-                    }
-                });
-
-                try
-                {
-                    while (await stream.MoveNextAsync())
-                    {
-                        responseCts.Token.ThrowIfCancellationRequested();
-                        CaptureUsage(stream.Current);
-                        if (!string.IsNullOrEmpty(stream.Current.Text))
-                        {
-                            firstChunk = stream.Current.Text;
-                            fullResponse = firstChunk;
-                            break;
-                        }
-                    }
-                }
-                finally
-                {
-                    spinnerCts.Cancel();
-                    await Task.WhenAny(spinnerTask);
-                    CommandTool.PauseSpinner = null;
-                    CommandTool.ResumeSpinner = null;
-                    FileTools.OnFileRead = null;
-                }
-
-                if (firstChunk != null)
-                {
-                    AnsiConsole.Markup(Markup.Escape(firstChunk));
-                }
-
-                while (await stream.MoveNextAsync())
-                {
-                    responseCts.Token.ThrowIfCancellationRequested();
-                    CaptureUsage(stream.Current);
-                    var text = stream.Current.Text;
-                    if (!string.IsNullOrEmpty(text))
-                    {
-                        AnsiConsole.Markup(Markup.Escape(text));
-                    }
-                    fullResponse += text;
-                }
-
-                if (respIn > 0 || respOut > 0)
-                {
-                    _tokenTracker.AddUsage(respIn, respOut);
-                    var cost = _tokenTracker.CalculateCost(respIn, respOut);
-                    var ctxPct = _tokenTracker.ContextUsagePercent;
-                    AnsiConsole.WriteLine();
-                    AnsiConsole.MarkupLine(
-                        $"[dim grey]  {TokenTracker.FormatTokens(respIn)}↑ {TokenTracker.FormatTokens(respOut)}↓" +
-                        $"  {TokenTracker.FormatCost(cost)}" +
-                        (ctxPct >= 0 ? $"  ctx:{ctxPct:F0}%" : "") +
-                        $"  │  session: {TokenTracker.FormatCost(_tokenTracker.SessionCost)}[/]");
-                }
-                else
-                {
-                    AnsiConsole.WriteLine();
-                }
-
-                AnsiConsole.Write(new Rule().RuleStyle(Style.Parse("grey dim")));
-
-                _session.History.Add(new ChatMessage(ChatRole.Assistant, fullResponse));
-
-                if (_tokenTracker.ShouldCompact())
-                {
-                    var pct = _tokenTracker.ContextUsagePercent;
-                    AnsiConsole.MarkupLine(
-                        $"[yellow]⚠ Context at {pct:F0}% — compacting conversation history...[/]");
-
-                    bool compacted = await AnsiConsole.Status()
-                        .Spinner(Spinner.Known.BouncingBar)
-                        .SpinnerStyle(Style.Parse("yellow"))
-                        .StartAsync("Compacting context...", async ctx =>
-                            await _session.Compactor.TryCompactAsync(_session.History, default));
-
-                    if (compacted)
-                    {
-                        AnsiConsole.MarkupLine(
-                            $"[green]✓ Context compacted ({_session.History.Count} messages remaining)[/]");
-                    }
-                    else
-                    {
-                        AnsiConsole.MarkupLine(
-                            "[dim grey]  (compaction skipped — not enough history to compress)[/]");
-                    }
-                    AnsiConsole.WriteLine();
-                }
-
-                // Save session after each LLM turn completes
-                try
-                {
-                    const string sessionPath = ".anchor/session.json";
-                    var directory = Path.GetDirectoryName(sessionPath);
-                    if (!string.IsNullOrEmpty(directory) && !Directory.Exists(directory))
-                    {
-                        Directory.CreateDirectory(directory);
-                    }
-                    await _session.SaveAsync(sessionPath, default);
             }
             catch (OperationCanceledException)
             {
-                    AnsiConsole.WriteLine();
+                HandleCancellation();
-                    AnsiConsole.MarkupLine("[dim grey]  ✗ Cancelled[/]");
-                    AnsiConsole.Write(new Rule().RuleStyle(Style.Parse("grey dim")));
-                    AnsiConsole.WriteLine();
-
-                    if (!string.IsNullOrEmpty(fullResponse))
-                    {
-                        _session.History.Add(new ChatMessage(ChatRole.Assistant, fullResponse));
-                    }
-                    _session.History.Add(new ChatMessage(ChatRole.User,
-                        "[Response cancelled by user. Acknowledge briefly and wait for the next instruction. Do not repeat what was already said.]"));
             }
             catch (Exception ex)
             {
-                    AnsiConsole.WriteLine();
+                DisplayError(ex);
-                    AnsiConsole.Write(
-                        new Panel($"[red]{Markup.Escape(ex.Message)}[/]")
-                            .Header("[bold red] Error [/]")
-                            .BorderColor(Color.Red)
-                            .RoundedBorder()
-                            .Padding(1, 0));
-                    AnsiConsole.WriteLine();
             }
             finally
             {
@@ -258,7 +81,84 @@ internal sealed class ReplLoop
                 responseCts = null;
             }
         }
-            catch (Exception ex)
+    }
+
+    private async Task ProcessTurnAsync(CancellationToken cancellationToken)
+    {
+        using var spinner = new SpinnerService();
+        spinner.Start(cancellationToken);
+
+        // Configure tool callbacks for spinner control and stale result compaction
+        var originalPause = CommandTool.PauseSpinner;
+        var originalResume = CommandTool.ResumeSpinner;
+        var originalOnFileRead = FileTools.OnFileRead;
+
+        CommandTool.PauseSpinner = spinner.Pause;
+        CommandTool.ResumeSpinner = spinner.Resume;
+        FileTools.OnFileRead = _ =>
+        {
+            int n = ContextCompactor.CompactStaleToolResults(_session.History);
+            if (n > 0)
+                AnsiConsole.MarkupLine($"[dim grey]  ♻ Compacted {n} stale tool result(s)[/]");
+        };
+
+        var responseBuilder = new StringBuilder();
+        bool firstChunkDisplayed = false;
+
+        try
+        {
+            await foreach (var chunk in _streamer.StreamAsync(cancellationToken))
+            {
+                // Stop spinner before displaying first chunk
+                if (!firstChunkDisplayed)
+                {
+                    await spinner.StopAsync();
+                    firstChunkDisplayed = true;
+                }
+
+                AnsiConsole.Markup(Markup.Escape(chunk));
+                responseBuilder.Append(chunk);
+            }
+        }
+        finally
+        {
+            if (!firstChunkDisplayed)
+            {
+                await spinner.StopAsync();
+            }
+            CommandTool.PauseSpinner = originalPause;
+            CommandTool.ResumeSpinner = originalResume;
+            FileTools.OnFileRead = originalOnFileRead;
+        }
+
+        var fullResponse = responseBuilder.ToString();
+
+        // Display usage statistics
+        _usageDisplayer.Display(_streamer.LastInputTokens, _streamer.LastOutputTokens);
+        _usageDisplayer.DisplaySeparator();
+
+        // Add response to history
+        _session.History.Add(new Microsoft.Extensions.AI.ChatMessage(Microsoft.Extensions.AI.ChatRole.Assistant, fullResponse));
+
+        // Check for context compaction
+        await _compactionService.TryCompactAsync();
+
+        // Save session after turn completes
+        await _sessionManager.SaveAfterTurnAsync();
+    }
+
+    private void HandleCancellation()
+    {
+        AnsiConsole.WriteLine();
+        AnsiConsole.MarkupLine("[dim grey]  ✗ Cancelled[/]");
+        AnsiConsole.Write(new Rule().RuleStyle(Style.Parse("grey dim")));
+        AnsiConsole.WriteLine();
+
+        _session.History.Add(new Microsoft.Extensions.AI.ChatMessage(Microsoft.Extensions.AI.ChatRole.User,
+            "[Response cancelled by user. Acknowledge briefly and wait for the next instruction. Do not repeat what was already said.]"));
+    }
+
+    private void DisplayError(Exception ex)
     {
         AnsiConsole.WriteLine();
         AnsiConsole.Write(
@@ -270,5 +170,3 @@ internal sealed class ReplLoop
         AnsiConsole.WriteLine();
     }
 }
-    }
-}

ResponseStreamer.cs

@@ -0,0 +1,60 @@
+using Microsoft.Extensions.AI;
+using OpenAI;
+
+namespace AnchorCli;
+
+/// <summary>
+/// Handles streaming responses from the chat client, including token usage capture.
+/// </summary>
+internal sealed class ResponseStreamer
+{
+    private readonly ChatSession _session;
+
+    public ResponseStreamer(ChatSession session)
+    {
+        _session = session;
+    }
+
+    /// <summary>
+    /// Streams a response from the session and captures token usage.
+    /// Returns an async enumerable that yields text chunks as they arrive.
+    /// </summary>
+    public async IAsyncEnumerable<string> StreamAsync(
+        [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken)
+    {
+        await using var stream = _session
+            .GetStreamingResponseAsync(cancellationToken)
+            .GetAsyncEnumerator(cancellationToken);
+
+        int respIn = 0, respOut = 0;
+
+        void CaptureUsage(ChatResponseUpdate update)
+        {
+            if (update.RawRepresentation is OpenAI.Chat.StreamingChatCompletionUpdate raw
+                && raw.Usage != null)
+            {
+                respIn = raw.Usage.InputTokenCount;
+                respOut += raw.Usage.OutputTokenCount;
+            }
+        }
+
+        // Stream all chunks
+        while (await stream.MoveNextAsync())
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+            CaptureUsage(stream.Current);
+            var text = stream.Current.Text;
+            if (!string.IsNullOrEmpty(text))
+            {
+                yield return text;
+            }
+        }
+
+        // Store final usage stats
+        LastInputTokens = respIn;
+        LastOutputTokens = respOut;
+    }
+
+    public int LastInputTokens { get; private set; }
+    public int LastOutputTokens { get; private set; }
+}

SessionManager.cs

@@ -0,0 +1,83 @@
+using Spectre.Console;
+
+namespace AnchorCli;
+
+/// <summary>
+/// Manages session persistence, including auto-load on startup and auto-save on exit.
+/// </summary>
+internal sealed class SessionManager
+{
+    private readonly ChatSession _session;
+    private readonly string _sessionPath;
+
+    public SessionManager(ChatSession session, string sessionPath = ".anchor/session.json")
+    {
+        _session = session;
+        _sessionPath = sessionPath;
+    }
+
+    /// <summary>
+    /// Attempts to load a session from disk. Returns true if successful.
+    /// </summary>
+    public async Task<bool> TryLoadAsync(CancellationToken cancellationToken = default)
+    {
+        if (!File.Exists(_sessionPath))
+        {
+            return false;
+        }
+
+        try
+        {
+            await _session.LoadAsync(_sessionPath, cancellationToken);
+            AnsiConsole.MarkupLine($"[dim grey]Auto-loaded previous session.[/]");
+
+            // Print the last message if there is one
+            if (_session.History.Count > 1)
+            {
+                var lastMessage = _session.History[^1];
+                var preview = lastMessage.Text.Length > 280
+                    ? lastMessage.Text[..277] + "..."
+                    : lastMessage.Text;
+                AnsiConsole.MarkupLine($"[dim grey]  Last message: {Markup.Escape(preview)}[/]");
+            }
+
+            return true;
+        }
+        catch
+        {
+            // Ignore load errors
+            return false;
+        }
+    }
+
+    /// <summary>
+    /// Attempts to save the session to disk. Returns true if successful.
+    /// </summary>
+    public async Task<bool> TrySaveAsync(CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            var directory = Path.GetDirectoryName(_sessionPath);
+            if (!string.IsNullOrEmpty(directory) && !Directory.Exists(directory))
+            {
+                Directory.CreateDirectory(directory);
+            }
+
+            await _session.SaveAsync(_sessionPath, cancellationToken);
+            return true;
+        }
+        catch
+        {
+            // Ignore save errors
+            return false;
+        }
+    }
+
+    /// <summary>
+    /// Saves the session after an LLM turn completes.
+    /// </summary>
+    public async Task SaveAfterTurnAsync(CancellationToken cancellationToken = default)
+    {
+        await TrySaveAsync(cancellationToken);
+    }
+}

SpinnerService.cs

@@ -0,0 +1,100 @@
+using Spectre.Console;
+
+namespace AnchorCli;
+
+/// <summary>
+/// Manages the "thinking" spinner animation during AI response generation.
+/// </summary>
+internal sealed class SpinnerService : IDisposable
+{
+    private readonly object _consoleLock = new();
+    private CancellationTokenSource? _spinnerCts;
+    private Task? _spinnerTask;
+    private bool _showSpinner = true;
+    private bool _disposed;
+
+    /// <summary>
+    /// Starts the spinner animation.
+    /// </summary>
+    public void Start(CancellationToken cancellationToken)
+    {
+        _spinnerCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
+        _showSpinner = true;
+
+        _spinnerTask = Task.Run(async () =>
+        {
+            var frames = Spinner.Known.BouncingBar.Frames;
+            var interval = Spinner.Known.BouncingBar.Interval;
+            int i = 0;
+
+            Console.Write("\x1b[?25l");
+            try
+            {
+                while (!_spinnerCts.Token.IsCancellationRequested)
+                {
+                    lock (_consoleLock)
+                    {
+                        if (_showSpinner && !_spinnerCts.Token.IsCancellationRequested)
+                        {
+                            var frame = frames[i % frames.Count];
+                            Console.Write($"\r\x1b[38;5;69m{frame}\x1b[0m Thinking...");
+                            i++;
+                        }
+                    }
+                    try { await Task.Delay(interval, _spinnerCts.Token); } catch { }
+                }
+            }
+            finally
+            {
+                lock (_consoleLock)
+                {
+                    if (_showSpinner)
+                        Console.Write("\r" + new string(' ', 40) + "\r");
+                    Console.Write("\x1b[?25h");
+                }
+            }
+        });
+    }
+
+    /// <summary>
+    /// Stops the spinner animation and waits for it to complete.
+    /// </summary>
+    public async Task StopAsync()
+    {
+        _spinnerCts?.Cancel();
+        if (_spinnerTask != null)
+        {
+            await Task.WhenAny(_spinnerTask);
+        }
+    }
+
+    /// <summary>
+    /// Pauses the spinner (e.g., during tool execution).
+    /// </summary>
+    public void Pause()
+    {
+        lock (_consoleLock)
+        {
+            _showSpinner = false;
+            Console.Write("\r" + new string(' ', 40) + "\r");
+        }
+    }
+
+    /// <summary>
+    /// Resumes the spinner after being paused.
+    /// </summary>
+    public void Resume()
+    {
+        lock (_consoleLock)
+        {
+            _showSpinner = true;
+        }
+    }
+
+    public void Dispose()
+    {
+        if (_disposed) return;
+        _spinnerCts?.Dispose();
+        _disposed = true;
+    }
+}

UsageDisplayer.cs

@@ -0,0 +1,48 @@
+using Spectre.Console;
+
+namespace AnchorCli.OpenRouter;
+
+/// <summary>
+/// Displays token usage and cost information to the console.
+/// </summary>
+internal sealed class UsageDisplayer
+{
+    private readonly TokenTracker _tokenTracker;
+
+    public UsageDisplayer(TokenTracker tokenTracker)
+    {
+        _tokenTracker = tokenTracker;
+    }
+
+    /// <summary>
+    /// Displays the usage statistics for a single response.
+    /// </summary>
+    public void Display(int inputTokens, int outputTokens)
+    {
+        if (inputTokens > 0 || outputTokens > 0)
+        {
+            _tokenTracker.AddUsage(inputTokens, outputTokens);
+            var cost = _tokenTracker.CalculateCost(inputTokens, outputTokens);
+            var ctxPct = _tokenTracker.ContextUsagePercent;
+
+            AnsiConsole.WriteLine();
+            AnsiConsole.MarkupLine(
+                $"[dim grey]  {TokenTracker.FormatTokens(inputTokens)}↑ {TokenTracker.FormatTokens(outputTokens)}↓" +
+                $"  {TokenTracker.FormatCost(cost)}" +
+                (ctxPct >= 0 ? $"  ctx:{ctxPct:F0}%" : "") +
+                $"  │  session: {TokenTracker.FormatCost(_tokenTracker.SessionCost)}[/]");
+        }
+        else
+        {
+            AnsiConsole.WriteLine();
+        }
+    }
+
+    /// <summary>
+    /// Displays a rule separator.
+    /// </summary>
+    public void DisplaySeparator()
+    {
+        AnsiConsole.Write(new Rule().RuleStyle(Style.Parse("grey dim")));
+    }
+}