diff --git a/IMPLEMENTATION.md b/IMPLEMENTATION.md
index 04534f6..ddd093f 100644
--- a/IMPLEMENTATION.md
+++ b/IMPLEMENTATION.md
@@ -210,7 +210,7 @@ Each type lives in `src/FrameProcessor/Domain/`. Tests in `tests/FrameProcessor.
 
 ## Phase 9 — Observability
 
-### [ ] 9.1 Serilog wiring
+### [x] 9.1 Serilog wiring
 - `UseSerilog` with console + rolling file sinks (`logs/frame-processor-.log`, daily).
 - Structured fields: `FrameName`, `MacAddress`, `InputSource` (file/url), `InputBytes`, `OutputBytes`, `ElapsedMs`, `MqttPublished`.
 - Log one info line per upload at completion.
diff --git a/src/FrameProcessor/Controllers/FramesController.cs b/src/FrameProcessor/Controllers/FramesController.cs
index bfb2fd2..7fca916 100644
--- a/src/FrameProcessor/Controllers/FramesController.cs
+++ b/src/FrameProcessor/Controllers/FramesController.cs
@@ -1,3 +1,4 @@
+using System.Diagnostics;
 using FrameProcessor.Concurrency;
 using FrameProcessor.Configuration;
 using FrameProcessor.Domain;
@@ -19,6 +20,7 @@ public sealed class FramesController : ControllerBase
     private readonly MqttPublisher _mqtt;
     private readonly IImageUrlFetcher _urlFetcher;
     private readonly FrameLockProvider _locks;
+    private readonly ILogger<FramesController> _logger;
 
     public FramesController(
         FramesRegistry frames,
@@ -26,7 +28,8 @@ public sealed class FramesController : ControllerBase
         ImageStore store,
         MqttPublisher mqtt,
         IImageUrlFetcher urlFetcher,
-        FrameLockProvider locks)
+        FrameLockProvider locks,
+        ILogger<FramesController> logger)
     {
         _frames = frames;
         _pipeline = pipeline;
@@ -34,11 +37,14 @@ public sealed class FramesController : ControllerBase
         _mqtt = mqtt;
         _urlFetcher = urlFetcher;
         _locks = locks;
+        _logger = logger;
     }
 
     [HttpPost("{name}/image")]
     public async Task<IActionResult> UploadImage(string name, CancellationToken cancellationToken)
     {
+        var stopwatch = Stopwatch.StartNew();
+
         if (!FrameName.TryParse(name, out var frameName) || !_frames.TryGetByName(frameName, out var frame))
         {
             return NotFound();
@@ -58,7 +64,8 @@ public sealed class FramesController : ControllerBase
                 pngBytes = _pipeline.Process(stream, frame);
             }
 
-            return await FinishUploadAsync(frame, pngBytes, cancellationToken).ConfigureAwait(false);
+            return await FinishUploadAsync(frame, pngBytes, "file", file.Length, stopwatch, cancellationToken)
+                .ConfigureAwait(false);
         }
     }
 
@@ -68,6 +75,8 @@ public sealed class FramesController : ControllerBase
         [FromBody] ImageUrlRequest? body,
         CancellationToken cancellationToken)
     {
+        var stopwatch = Stopwatch.StartNew();
+
         if (!FrameName.TryParse(name, out var frameName) || !_frames.TryGetByName(frameName, out var frame))
         {
             return NotFound();
@@ -93,20 +102,42 @@ public sealed class FramesController : ControllerBase
             }
 
             byte[] pngBytes;
+            long inputBytes;
             await using (source)
             {
+                inputBytes = source.CanSeek ? source.Length : 0;
                 pngBytes = _pipeline.Process(source, frame);
             }
 
-            return await FinishUploadAsync(frame, pngBytes, cancellationToken).ConfigureAwait(false);
+            return await FinishUploadAsync(frame, pngBytes, "url", inputBytes, stopwatch, cancellationToken)
+                .ConfigureAwait(false);
         }
     }
 
-    private async Task<IActionResult> FinishUploadAsync(Frame frame, byte[] pngBytes, CancellationToken cancellationToken)
+    private async Task<IActionResult> FinishUploadAsync(
+        Frame frame,
+        byte[] pngBytes,
+        string inputSource,
+        long inputBytes,
+        Stopwatch stopwatch,
+        CancellationToken cancellationToken)
     {
         await _store.WriteAsync(frame.Mac, pngBytes, cancellationToken).ConfigureAwait(false);
 
         var publishResult = await _mqtt.PublishAsync(frame.Mac, cancellationToken).ConfigureAwait(false);
+        var mqttPublished = publishResult == PublishResult.Success;
+
+        stopwatch.Stop();
+
+        _logger.LogInformation(
+            "Processed upload for {FrameName} ({MacAddress}) source={InputSource} in={InputBytes} out={OutputBytes} elapsed={ElapsedMs}ms mqtt={MqttPublished}",
+            frame.Name.Value,
+            frame.Mac.ToString(),
+            inputSource,
+            inputBytes,
+            pngBytes.LongLength,
+            stopwatch.ElapsedMilliseconds,
+            mqttPublished);
 
         return Ok(new
         {
@@ -114,7 +145,7 @@ public sealed class FramesController : ControllerBase
             mac = frame.Mac.ToString(),
             url = $"/i/{frame.Mac}.png",
             processedAt = DateTimeOffset.UtcNow,
-            mqttPublished = publishResult == PublishResult.Success,
+            mqttPublished,
         });
     }
 
diff --git a/src/FrameProcessor/Program.cs b/src/FrameProcessor/Program.cs
index e6a81f5..d4fffbb 100644
--- a/src/FrameProcessor/Program.cs
+++ b/src/FrameProcessor/Program.cs
@@ -6,11 +6,21 @@ using FrameProcessor.Mqtt;
 using FrameProcessor.Storage;
 using FrameProcessor.UrlFetch;
 using Microsoft.Extensions.Options;
+using Serilog;
 
 var builder = WebApplication.CreateBuilder(args);
 
 builder.Configuration.AddJsonFile("frames.json", optional: false, reloadOnChange: true);
 
+builder.Host.UseSerilog((context, services, configuration) => configuration
+    .ReadFrom.Configuration(context.Configuration)
+    .ReadFrom.Services(services)
+    .Enrich.FromLogContext()
+    .WriteTo.Console()
+    .WriteTo.File(
+        path: "logs/frame-processor-.log",
+        rollingInterval: RollingInterval.Day));
+
 builder.Services.AddControllers();
 
 builder.Services.AddOptions<MqttOptions>()