2 files changed, 92 insertions, 0 deletions
diff --git a/src/Agent.App/Logging/JsonLinesRuntimeObserver.cs b/src/Agent.App/Logging/JsonLinesRuntimeObserver.cs
new file mode 100644
index 0000000..b7cbd26
--- /dev/null
+++ b/src/Agent.App/Logging/JsonLinesRuntimeObserver.cs
@@ -0,0 +1,37 @@
+using System.Text.Json;
+using Agent.Core.Ollama;
+using Agent.Core.Runtime;
+using Agent.Core.Tools;
+
+namespace Agent.App.Logging;
+
+public sealed class JsonLinesRuntimeObserver(string logDirectory) : IAgentRuntimeObserver
+{
+    private readonly object _sync = new();
+    private readonly string _path = Path.Combine(logDirectory, "llm.jsonl");
+
+    public void LlmRequest(Guid taskId, int iteration, IReadOnlyList<OllamaMessage> messages) => Write(new
+    {
+        timestamp = DateTimeOffset.UtcNow, task_id = taskId, event_name = "llm.request", iteration,
+        messages = messages.Select(static message => new { message.Role, message.Content, image_count = message.Images?.Count ?? 0, message.ToolName })
+    });
+
+    public void LlmResponse(Guid taskId, int iteration, OllamaResult result) => Write(new
+    {
+        timestamp = DateTimeOffset.UtcNow, task_id = taskId, event_name = "llm.response", iteration,
+        result.Content, input_tokens = result.InputTokens, output_tokens = result.OutputTokens,
+        tool_calls = result.ToolCalls?.Select(static call => call.Function.Name).ToArray() ?? []
+    });
+
+    public void ToolResult(Guid taskId, string toolName, ToolExecutionResult result) => Write(new
+    {
+        timestamp = DateTimeOffset.UtcNow, task_id = taskId, event_name = "llm.tool_result", tool_name = toolName,
+        result.Success, result.ExternalEffect, result.Output, result.FailureFingerprint
+    });
+
+    private void Write(object value)
+    {
+        string line = JsonSerializer.Serialize(value);
+        lock (_sync) File.AppendAllText(_path, line + Environment.NewLine);
+    }
+}
diff --git a/src/Agent.App/Logging/RollingFileLog.cs b/src/Agent.App/Logging/RollingFileLog.cs
new file mode 100644
index 0000000..801768d
--- /dev/null
+++ b/src/Agent.App/Logging/RollingFileLog.cs
@@ -0,0 +1,55 @@
+using System.Globalization;
+
+namespace Agent.App.Logging;
+
+public sealed class RollingFileLog : IDisposable
+{
+    private readonly object _sync = new();
+    private readonly string _path;
+    private readonly long _maxBytes;
+    private readonly int _retainedFiles;
+    private StreamWriter _writer;
+
+    public RollingFileLog(string directory, long maxBytes, int retainedFiles)
+    {
+        Directory.CreateDirectory(directory);
+        _path = Path.Combine(directory, "application.log");
+        _maxBytes = maxBytes;
+        _retainedFiles = retainedFiles;
+        _writer = Open();
+    }
+
+    public void Information(string message) => Write("INF", message);
+    public void Error(string message) => Write("ERR", message);
+
+    private void Write(string level, string message)
+    {
+        lock (_sync)
+        {
+            if (_writer.BaseStream.Length >= _maxBytes) Rotate();
+            string line = string.Create(CultureInfo.InvariantCulture, $"{DateTimeOffset.UtcNow:O} [{level}] {message}");
+            Console.Error.WriteLine(line);
+            _writer.WriteLine(line);
+            _writer.Flush();
+        }
+    }
+
+    private StreamWriter Open() => new(new FileStream(_path, FileMode.Append, FileAccess.Write, FileShare.Read), new System.Text.UTF8Encoding(false));
+
+    private void Rotate()
+    {
+        _writer.Dispose();
+        for (int index = _retainedFiles - 1; index >= 1; index--)
+        {
+            string source = $"{_path}.{index}";
+            if (File.Exists(source)) File.Move(source, $"{_path}.{index + 1}", true);
+        }
+        if (File.Exists(_path)) File.Move(_path, $"{_path}.1", true);
+        _writer = Open();
+    }
+
+    public void Dispose()
+    {
+        lock (_sync) _writer.Dispose();
+    }
+}