[AZ-359] Refactor C07: collapse RegionService catch ladder via RegionFailureClassifier

Replace 9 nearly-identical catch blocks in
RegionService.ProcessRegionAsync with a single catch (Exception ex)
that delegates to RegionFailureClassifier.Classify, returning a
typed (category, errorMessage) pair. Preserves all original error
messages stored in region summary files; failure-path call into
HandleProcessingFailureAsync is unchanged.

Net source delta: -38 lines in RegionService, +71 lines in new
RegionFailureClassifier (pure static), +10 unit tests covering
each category, precedence, status-code propagation, null guard.

Tests: 68 unit (was 58) + 5 smoke + 3 stub-contract integration
tests pass.

Co-authored-by: Cursor <cursoragent@cursor.com>

SatelliteProvider.Services.RegionProcessing/RegionFailureClassifier.cs

@@ -0,0 +1,70 @@
+using SatelliteProvider.Common.Exceptions;
+
+namespace SatelliteProvider.Services.RegionProcessing;
+
+internal enum RegionFailureCategory
+{
+    Timeout,
+    ExternalCancellation,
+    TaskCanceledOther,
+    OperationCanceledOther,
+    RateLimit,
+    Network,
+    Unexpected,
+}
+
+internal sealed record RegionFailureClassification(RegionFailureCategory Category, string ErrorMessage);
+
+internal static class RegionFailureClassifier
+{
+    public const string TimeoutMessage =
+        "Processing timed out after 5 minutes. Unable to download tiles within the time limit.";
+
+    public const string ExternalCancellationMessage =
+        "Processing was cancelled externally (likely application shutdown).";
+
+    public static RegionFailureClassification Classify(
+        Exception ex,
+        CancellationTokenSource timeoutCts,
+        CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(ex);
+        ArgumentNullException.ThrowIfNull(timeoutCts);
+
+        return ex switch
+        {
+            TaskCanceledException when timeoutCts.IsCancellationRequested
+                => new RegionFailureClassification(RegionFailureCategory.Timeout, TimeoutMessage),
+
+            TaskCanceledException when cancellationToken.IsCancellationRequested
+                => new RegionFailureClassification(RegionFailureCategory.ExternalCancellation, ExternalCancellationMessage),
+
+            TaskCanceledException
+                => new RegionFailureClassification(
+                    RegionFailureCategory.TaskCanceledOther,
+                    $"Request cancelled or timed out: {ex.Message}. This may indicate HttpClient timeout or network issues."),
+
+            OperationCanceledException when timeoutCts.IsCancellationRequested
+                => new RegionFailureClassification(RegionFailureCategory.Timeout, TimeoutMessage),
+
+            OperationCanceledException
+                => new RegionFailureClassification(
+                    RegionFailureCategory.OperationCanceledOther,
+                    $"Operation cancelled: {ex.Message}"),
+
+            RateLimitException
+                => new RegionFailureClassification(
+                    RegionFailureCategory.RateLimit,
+                    $"Rate limit exceeded: {ex.Message}. Google Maps API rate limit was reached and retries were exhausted."),
+
+            HttpRequestException httpEx
+                => new RegionFailureClassification(
+                    RegionFailureCategory.Network,
+                    $"Network error (HTTP {httpEx.StatusCode}): {httpEx.Message}. Failed to download tiles from Google Maps."),
+
+            _ => new RegionFailureClassification(
+                RegionFailureCategory.Unexpected,
+                $"Unexpected error ({ex.GetType().Name}): {ex.Message}"),
+        };
+    }
+}

SatelliteProvider.Services.RegionProcessing/RegionService.cs

@@ -145,54 +145,16 @@ public class RegionService : IRegionService
             region.UpdatedAt = DateTime.UtcNow;
             await _regionRepository.UpdateAsync(region);
         }
-        catch (TaskCanceledException ex) when (timeoutCts.IsCancellationRequested)
-        {
-            errorMessage = "Processing timed out after 5 minutes. Unable to download tiles within the time limit.";
-            _logger.LogError(ex, "Region {RegionId} processing timed out after 5 minutes", id);
-            await HandleProcessingFailureAsync(id, region, startTime, tiles, tilesDownloaded, tilesReused, errorMessage);
-        }
-        catch (TaskCanceledException ex) when (cancellationToken.IsCancellationRequested)
-        {
-            errorMessage = "Processing was cancelled externally (likely application shutdown).";
-            _logger.LogError(ex, "Region {RegionId} processing was cancelled externally", id);
-            await HandleProcessingFailureAsync(id, region, startTime, tiles, tilesDownloaded, tilesReused, errorMessage);
-        }
-        catch (TaskCanceledException ex)
-        {
-            errorMessage = $"Request cancelled or timed out: {ex.Message}. This may indicate HttpClient timeout or network issues.";
-            _logger.LogError(ex, "Region {RegionId} processing was cancelled (TaskCanceledException)", id);
-            await HandleProcessingFailureAsync(id, region, startTime, tiles, tilesDownloaded, tilesReused, errorMessage);
-        }
-        catch (OperationCanceledException ex) when (timeoutCts.IsCancellationRequested)
-        {
-            errorMessage = "Processing timed out after 5 minutes. Unable to download tiles within the time limit.";
-            _logger.LogError(ex, "Region {RegionId} processing timed out after 5 minutes", id);
-            await HandleProcessingFailureAsync(id, region, startTime, tiles, tilesDownloaded, tilesReused, errorMessage);
-        }
-        catch (OperationCanceledException ex)
-        {
-            errorMessage = $"Operation cancelled: {ex.Message}";
-            _logger.LogError(ex, "Region {RegionId} processing was cancelled", id);
-            await HandleProcessingFailureAsync(id, region, startTime, tiles, tilesDownloaded, tilesReused, errorMessage);
-        }
-        catch (RateLimitException ex)
-        {
-            errorMessage = $"Rate limit exceeded: {ex.Message}. Google Maps API rate limit was reached and retries were exhausted.";
-            _logger.LogError(ex, "Rate limit exceeded for region {RegionId}. Google is throttling requests. Consider reducing request rate.", id);
-            await HandleProcessingFailureAsync(id, region, startTime, tiles, tilesDownloaded, tilesReused, errorMessage);
-        }
-        catch (HttpRequestException ex)
-        {
-            errorMessage = $"Network error (HTTP {ex.StatusCode}): {ex.Message}. Failed to download tiles from Google Maps.";
-            _logger.LogError(ex, "Network error processing region {RegionId}. StatusCode: {StatusCode}, Message: {Message}", 
-                id, ex.StatusCode, ex.Message);
-            await HandleProcessingFailureAsync(id, region, startTime, tiles, tilesDownloaded, tilesReused, errorMessage);
-        }
         catch (Exception ex)
         {
-            errorMessage = $"Unexpected error ({ex.GetType().Name}): {ex.Message}";
-            _logger.LogError(ex, "Failed to process region {RegionId}. Type: {ExceptionType}, Message: {Message}", 
-                id, ex.GetType().Name, ex.Message);
+            var classification = RegionFailureClassifier.Classify(ex, timeoutCts, cancellationToken);
+            errorMessage = classification.ErrorMessage;
+            _logger.LogError(
+                ex,
+                "Region {RegionId} processing failed (category={Category}): {ErrorMessage}",
+                id,
+                classification.Category,
+                classification.ErrorMessage);
             await HandleProcessingFailureAsync(id, region, startTime, tiles, tilesDownloaded, tilesReused, errorMessage);
         }
     }

SatelliteProvider.Services.RegionProcessing/SatelliteProvider.Services.RegionProcessing.csproj

@@ -19,4 +19,8 @@
       <ProjectReference Include="..\SatelliteProvider.DataAccess\SatelliteProvider.DataAccess.csproj" />
     </ItemGroup>
 
+    <ItemGroup>
+      <InternalsVisibleTo Include="SatelliteProvider.Tests" />
+    </ItemGroup>
+
 </Project>