Fix blob URL handling for large messages with special characters in instanceId

src/DurableTask.AzureStorage/MessageManager.cs

@@ -255,7 +255,9 @@ private async Task<string> DownloadAndDecompressAsBytesAsync(Blob blob, Cancella
 
         public string GetBlobUrl(string blobName)
         {
-            return Uri.UnescapeDataString(this.blobContainer.GetBlobReference(blobName).Uri.AbsoluteUri);
+            string baseUri = this.blobContainer.GetBlobContainerUri().ToString();
+
+            return $"{baseUri}/{EscapeBlobNamePreservingSlashes(blobName)}";
         }
 
         public MessageFormatFlags GetMessageFormatFlags(MessageData messageData)
@@ -304,6 +306,12 @@ public async Task<int> DeleteLargeMessageBlobs(string sanitizedInstanceId, Cance
 
             return storageOperationCount;
         }
+
+        /// Escapes a blob name for safe inclusion in a URI while preserving path structure.
+        static string EscapeBlobNamePreservingSlashes(string blobName)
+        {
+            return string.Join("/", blobName.Split('/').Select(Uri.EscapeDataString));
+        }
     }
 
 #if NETSTANDARD2_0

src/DurableTask.AzureStorage/Storage/BlobContainer.cs

@@ -108,6 +108,11 @@ public Task RenewLeaseAsync(string leaseId, CancellationToken cancellationToken
                 .DecorateFailure();
         }
 
+        public Uri GetBlobContainerUri()
+        {
+            return this.blobContainerClient.Uri;
+        }
+
         static bool IsHnsFolder(BlobItem item)
         {
             // Check the optional "hdi_isfolder" value in the metadata to determine whether

test/DurableTask.AzureStorage.Tests/AzureStorageScenarioTests.cs

@@ -1600,6 +1600,35 @@ await ValidateLargeMessageBlobUrlAsync(
             }
         }
 
+        /// <summary>
+        /// End-to-end test that validates large (>60KB) messages stored in blob storage can be retrieved successfully,
+        /// when the instance ID includes special characters like '|' that can affect blob URL encoding.
+        /// </summary>
+        [TestMethod]
+        public async Task LargeMessage_WithEscapedInstanceId_CanBeStoredAndFetchedSuccessfully()
+        {
+            // Genereates a random large message.
+            const int largeMessageSize = 60 * 1024;
+
+            using (TestOrchestrationHost host = TestHelpers.GetTestOrchestrationHost(enableExtendedSessions: false))
+            {
+                await host.StartAsync();
+
+                string message = this.GenerateMediumRandomStringPayload(largeMessageSize, utf8ByteSize: 1, utf16ByteSize: 2).ToString();
+
+                // Use an instanceId that contains special characters which must be escaped in URIs
+                string id = "test|123:with white spcae";
+                var client = await host.StartOrchestrationAsync(typeof(Orchestrations.Echo), input:message, instanceId: id);
+                var status = await client.WaitForCompletionAsync(TimeSpan.FromMinutes(2));
+
+                Assert.AreEqual(OrchestrationStatus.Completed, status?.OrchestrationStatus);
+
+                // Verify that the output matches the original message (the blob was successfully downloaded and not returned as a URL) 
+                StringAssert.Contains(status.Output.ToString(), message);
+                await host.StopAsync();
+            }
+        }
+
         [TestMethod]
         public async Task TagsAreAvailableInOrchestrationState()
         {

test/DurableTask.AzureStorage.Tests/MessageManagerTests.cs

@@ -13,12 +13,12 @@
 #nullable enable
 namespace DurableTask.AzureStorage.Tests
 {
-    using System;
-    using System.Collections.Generic;
     using DurableTask.AzureStorage.Storage;
     using DurableTask.Core.History;
     using Microsoft.VisualStudio.TestTools.UnitTesting;
     using Newtonsoft.Json;
+    using System;
+    using System.Collections.Generic;
 
     [TestClass]
     public class MessageManagerTests
@@ -70,10 +70,10 @@ public void DeserializesCustomTypes()
         }
 
         [DataTestMethod]
-        [DataRow("blob.bin")]
-        [DataRow("@#$%!")]
-        [DataRow("foo/bar/[email protected]")]
-        public void GetBlobUrlUnescaped(string blob)
+        [DataRow("blob.bin", "blob.bin")]
+        [DataRow("@#$%!", "%40%23%24%25%21")]
+        [DataRow("foo/bar/[email protected]", "foo/bar/b%40z.tar.gz")]
+        public void GetBlobUrlEscaped(string blob, string blobUrl)
         {
             var settings = new AzureStorageOrchestrationServiceSettings
             {
@@ -82,7 +82,8 @@ public void GetBlobUrlUnescaped(string blob)
 
             const string container = "@entity12345";
             var manager = new MessageManager(settings, new AzureStorageClient(settings), container);
-            var expected = $"http://127.0.0.1:10000/devstoreaccount1/{container}/{blob}";
+
+            var expected = $"http://127.0.0.1:10000/devstoreaccount1/{container}/{blobUrl}";
             Assert.AreEqual(expected, manager.GetBlobUrl(blob));
         }