diff --git a/DevProxy.Plugins/Inspection/OpenAITelemetryPlugin.cs b/DevProxy.Plugins/Inspection/OpenAITelemetryPlugin.cs
index 126db908..7ff4a0b1 100644
--- a/DevProxy.Plugins/Inspection/OpenAITelemetryPlugin.cs
+++ b/DevProxy.Plugins/Inspection/OpenAITelemetryPlugin.cs
@@ -11,12 +11,12 @@
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Logging.Abstractions;
 using OpenTelemetry;
 using OpenTelemetry.Exporter;
 using OpenTelemetry.Metrics;
 using OpenTelemetry.Resources;
 using OpenTelemetry.Trace;
-using System.Collections.Concurrent;
 using System.Diagnostics;
 using System.Diagnostics.Metrics;
 using System.Text.Json;
@@ -67,7 +67,6 @@ public sealed class OpenAITelemetryPlugin(
     private LanguageModelPricesLoader? _loader;
     private MeterProvider? _meterProvider;
     private TracerProvider? _tracerProvider;
-    private readonly ConcurrentDictionary<string, List<OpenAITelemetryPluginReportModelUsageInformation>> _modelUsage = [];
 
     public override string Name => nameof(OpenAITelemetryPlugin);
 
@@ -196,17 +195,18 @@ public override Task AfterRecordingStopAsync(RecordingArgs e, CancellationToken
     {
         Logger.LogTrace("{Method} called", nameof(AfterRecordingStopAsync));
 
+        ArgumentNullException.ThrowIfNull(e);
+
         var report = new OpenAITelemetryPluginReport
         {
             Application = Configuration.Application,
             Environment = Configuration.Environment,
             Currency = Configuration.Currency,
             IncludeCosts = Configuration.IncludeCosts,
-            ModelUsage = _modelUsage.ToDictionary()
+            ModelUsage = GetOpenAIModelUsage(e.RequestLogs)
         };
 
         StoreReport(report, e);
-        _modelUsage.Clear();
 
         Logger.LogTrace("Left {Name}", nameof(AfterRecordingStopAsync));
         return Task.CompletedTask;
@@ -849,16 +849,6 @@ private void RecordUsageMetrics(Activity activity, OpenAIRequest request, OpenAI
             .SetTag(SemanticConvention.GEN_AI_USAGE_OUTPUT_TOKENS, usage.CompletionTokens)
             .SetTag(SemanticConvention.GEN_AI_USAGE_TOTAL_TOKENS, usage.TotalTokens);
 
-        var reportModelUsageInformation = new OpenAITelemetryPluginReportModelUsageInformation
-        {
-            Model = response.Model,
-            PromptTokens = usage.PromptTokens,
-            CompletionTokens = usage.CompletionTokens,
-            CachedTokens = usage.PromptTokensDetails?.CachedTokens ?? 0L
-        };
-        var usagePerModel = _modelUsage.GetOrAdd(response.Model, model => []);
-        usagePerModel.Add(reportModelUsageInformation);
-
         if (!Configuration.IncludeCosts || Configuration.Prices is null)
         {
             Logger.LogDebug("Cost tracking is disabled or prices data is not available");
@@ -895,7 +885,6 @@ private void RecordUsageMetrics(Activity activity, OpenAIRequest request, OpenAI
                 new(SemanticConvention.GEN_AI_REQUEST_MODEL, request.Model),
                 new(SemanticConvention.GEN_AI_RESPONSE_MODEL, response.Model)
             ]);
-            reportModelUsageInformation.Cost = totalCost;
         }
         else
         {
@@ -905,6 +894,100 @@ private void RecordUsageMetrics(Activity activity, OpenAIRequest request, OpenAI
         Logger.LogTrace("RecordUsageMetrics() finished");
     }
 
+    private Dictionary<string, List<OpenAITelemetryPluginReportModelUsageInformation>> GetOpenAIModelUsage(IEnumerable<RequestLog> requestLogs)
+    {
+        var modelUsage = new Dictionary<string, List<OpenAITelemetryPluginReportModelUsageInformation>>();
+        var openAIRequestLogs = requestLogs.Where(r =>
+            r is not null &&
+            r.Context is not null &&
+            r.Context.Session is not null &&
+            r.MessageType == MessageType.InterceptedResponse &&
+            string.Equals("POST", r.Context.Session.HttpClient.Request.Method, StringComparison.OrdinalIgnoreCase) &&
+            r.Context.Session.HttpClient.Response.StatusCode >= 200 &&
+            r.Context.Session.HttpClient.Response.StatusCode < 300 &&
+            r.Context.Session.HttpClient.Response.HasBody &&
+            !string.IsNullOrEmpty(r.Context.Session.HttpClient.Response.BodyString) &&
+            ProxyUtils.MatchesUrlToWatch(UrlsToWatch, r.Context.Session.HttpClient.Request.RequestUri.AbsoluteUri) &&
+            OpenAIRequest.TryGetOpenAIRequest(r.Context.Session.HttpClient.Request.BodyString, NullLogger.Instance, out var openAiRequest) &&
+            openAiRequest is not null
+        );
+
+        foreach (var requestLog in openAIRequestLogs)
+        {
+            try
+            {
+                var response = JsonSerializer.Deserialize<OpenAIResponse>(requestLog.Context!.Session.HttpClient.Response.BodyString, ProxyUtils.JsonSerializerOptions);
+                if (response is null)
+                {
+                    continue;
+                }
+
+                var reportModelUsageInfo = GetReportModelUsageInfo(response);
+                if (modelUsage.TryGetValue(response.Model, out var usagePerModel))
+                {
+                    usagePerModel.AddRange(reportModelUsageInfo);
+                }
+                else
+                {
+                    modelUsage.Add(response.Model, reportModelUsageInfo);
+                }
+            }
+            catch (JsonException ex)
+            {
+                Logger.LogError(ex, "Failed to deserialize OpenAI response");
+            }
+        }
+
+        return modelUsage;
+    }
+
+    private List<OpenAITelemetryPluginReportModelUsageInformation> GetReportModelUsageInfo(OpenAIResponse response)
+    {
+        Logger.LogTrace("GetReportModelUsageInfo() called");
+        var usagePerModel = new List<OpenAITelemetryPluginReportModelUsageInformation>();
+        var usage = response.Usage;
+        if (usage is null)
+        {
+            return usagePerModel;
+        }
+
+        var reportModelUsageInformation = new OpenAITelemetryPluginReportModelUsageInformation
+        {
+            Model = response.Model,
+            PromptTokens = usage.PromptTokens,
+            CompletionTokens = usage.CompletionTokens,
+            CachedTokens = usage.PromptTokensDetails?.CachedTokens ?? 0L
+        };
+        usagePerModel.Add(reportModelUsageInformation);
+
+        if (!Configuration.IncludeCosts || Configuration.Prices is null)
+        {
+            Logger.LogDebug("Cost tracking is disabled or prices data is not available");
+            return usagePerModel;
+        }
+
+        if (string.IsNullOrEmpty(response.Model))
+        {
+            Logger.LogDebug("Response model is empty or null");
+            return usagePerModel;
+        }
+
+        var (inputCost, outputCost) = Configuration.Prices.CalculateCost(response.Model, usage.PromptTokens, usage.CompletionTokens);
+
+        if (inputCost > 0)
+        {
+            var totalCost = inputCost + outputCost;
+            reportModelUsageInformation.Cost = totalCost;
+        }
+        else
+        {
+            Logger.LogDebug("Input cost is zero, skipping cost metrics recording");
+        }
+
+        Logger.LogTrace("GetReportModelUsageInfo() finished");
+        return usagePerModel;
+    }
+
     private static string GetOperationName(OpenAIRequest request)
     {
         if (request == null)
diff --git a/DevProxy/Proxy/ProxyStateController.cs b/DevProxy/Proxy/ProxyStateController.cs
index 1f418abe..93e6d6fb 100644
--- a/DevProxy/Proxy/ProxyStateController.cs
+++ b/DevProxy/Proxy/ProxyStateController.cs
@@ -69,7 +69,7 @@ public async Task StopRecordingAsync(CancellationToken cancellationToken)
 
     public async Task MockRequestAsync(CancellationToken cancellationToken)
     {
-        var eventArgs = new EventArgs();
+        var eventArgs = EventArgs.Empty;
 
         foreach (var plugin in _plugins.Where(p => p.Enabled))
         {