diff --git a/src/ScadaLink.StoreAndForward/StoreAndForwardStorage.cs b/src/ScadaLink.StoreAndForward/StoreAndForwardStorage.cs
index 7b92655..f7564fa 100644
--- a/src/ScadaLink.StoreAndForward/StoreAndForwardStorage.cs
+++ b/src/ScadaLink.StoreAndForward/StoreAndForwardStorage.cs
@@ -497,10 +497,31 @@ public class StoreAndForwardStorage
                 // Audit Log #23 (ExecutionId Task 4): rows persisted before the
                 // additive migration have no execution_id / source_script value;
                 // IsDBNull guards keep those reading back as null (back-compat).
-                ExecutionId = reader.IsDBNull(12) ? null : Guid.Parse(reader.GetString(12)),
+                // Guid.TryParse (not Parse) guards the retry sweep: a corrupt
+                // non-null execution_id is treated as "no execution id" rather
+                // than throwing FormatException and aborting the whole sweep.
+                ExecutionId = ParseExecutionId(reader, 12),
                 SourceScript = reader.IsDBNull(13) ? null : reader.GetString(13)
             });
         }
         return results;
     }
+
+    /// <summary>
+    /// Audit Log #23 (ExecutionId Task 4): defensively reads the
+    /// <c>execution_id</c> column. A <c>null</c> value (legacy pre-migration
+    /// rows) and a malformed non-null value both yield <c>null</c> — a corrupt
+    /// id must not throw and abort the retry sweep, which reads many rows.
+    /// </summary>
+    private static Guid? ParseExecutionId(System.Data.Common.DbDataReader reader, int ordinal)
+    {
+        if (reader.IsDBNull(ordinal))
+        {
+            return null;
+        }
+
+        return Guid.TryParse(reader.GetString(ordinal), out var executionId)
+            ? executionId
+            : null;
+    }
 }
diff --git a/tests/ScadaLink.ExternalSystemGateway.Tests/DatabaseGatewayTests.cs b/tests/ScadaLink.ExternalSystemGateway.Tests/DatabaseGatewayTests.cs
index 3e8e796..36fbd9c 100644
--- a/tests/ScadaLink.ExternalSystemGateway.Tests/DatabaseGatewayTests.cs
+++ b/tests/ScadaLink.ExternalSystemGateway.Tests/DatabaseGatewayTests.cs
@@ -101,15 +101,27 @@ public class DatabaseGatewayTests
 
         var gateway = new DatabaseGateway(_repository, NullLogger<DatabaseGateway>.Instance, storeAndForward: sf);
 
+        // Audit Log #23 (ExecutionId Task 4): a known execution id / source
+        // script so the gateway -> EnqueueAsync hop can be asserted below.
+        var executionId = Guid.NewGuid();
+        const string sourceScript = "ScriptActor:WriteAudit";
+
         await gateway.CachedWriteAsync("testDb", "INSERT INTO t VALUES (@v)",
-            new Dictionary<string, object?> { ["v"] = 1 });
+            new Dictionary<string, object?> { ["v"] = 1 },
+            executionId: executionId, sourceScript: sourceScript);
 
         var depth = await storage.GetBufferDepthByCategoryAsync();
         Assert.Equal(1, depth[ScadaLink.Commons.Types.Enums.StoreAndForwardCategory.CachedDbWrite]);
 
-        var (maxRetries, retryIntervalMs) = ReadBufferedRetrySettings(connStr);
-        Assert.Equal(5, maxRetries);
-        Assert.Equal((long)TimeSpan.FromSeconds(12).TotalMilliseconds, retryIntervalMs);
+        var buffered = ReadBufferedRetrySettings(connStr);
+        Assert.Equal(5, buffered.MaxRetries);
+        Assert.Equal((long)TimeSpan.FromSeconds(12).TotalMilliseconds, buffered.RetryIntervalMs);
+
+        // ExecutionId Task 4: the gateway must forward executionId / sourceScript
+        // into EnqueueAsync, and the S&F layer must persist them on the
+        // sf_messages row so the retry loop can stamp the right provenance.
+        Assert.Equal(executionId, buffered.ExecutionId);
+        Assert.Equal(sourceScript, buffered.SourceScript);
     }
 
     [Fact]
@@ -148,21 +160,27 @@ public class DatabaseGatewayTests
 
         await gateway.CachedWriteAsync("testDb", "INSERT INTO t VALUES (1)");
 
-        var (maxRetries, _) = ReadBufferedRetrySettings(connStr);
+        var (maxRetries, _, _, _) = ReadBufferedRetrySettings(connStr);
         // Must be the bounded S&F default, never 0 — a stored 0 would mean retry-forever.
         Assert.Equal(99, maxRetries);
         Assert.NotEqual(0, maxRetries);
     }
 
-    private static (int MaxRetries, long RetryIntervalMs) ReadBufferedRetrySettings(string connStr)
+    private static (int MaxRetries, long RetryIntervalMs, Guid? ExecutionId, string? SourceScript)
+        ReadBufferedRetrySettings(string connStr)
     {
         using var conn = new Microsoft.Data.Sqlite.SqliteConnection(connStr);
         conn.Open();
         using var cmd = conn.CreateCommand();
-        cmd.CommandText = "SELECT max_retries, retry_interval_ms FROM sf_messages";
+        cmd.CommandText =
+            "SELECT max_retries, retry_interval_ms, execution_id, source_script FROM sf_messages";
         using var reader = cmd.ExecuteReader();
         Assert.True(reader.Read(), "expected exactly one buffered message");
-        var result = (reader.GetInt32(0), reader.GetInt64(1));
+        var result = (
+            reader.GetInt32(0),
+            reader.GetInt64(1),
+            reader.IsDBNull(2) ? (Guid?)null : Guid.Parse(reader.GetString(2)),
+            reader.IsDBNull(3) ? null : reader.GetString(3));
         Assert.False(reader.Read(), "expected exactly one buffered message");
         return result;
     }
diff --git a/tests/ScadaLink.ExternalSystemGateway.Tests/ExternalSystemClientTests.cs b/tests/ScadaLink.ExternalSystemGateway.Tests/ExternalSystemClientTests.cs
index 43def9b..3898456 100644
--- a/tests/ScadaLink.ExternalSystemGateway.Tests/ExternalSystemClientTests.cs
+++ b/tests/ScadaLink.ExternalSystemGateway.Tests/ExternalSystemClientTests.cs
@@ -371,26 +371,45 @@ public class ExternalSystemClientTests
             _httpClientFactory, _repository, NullLogger<ExternalSystemClient>.Instance,
             storeAndForward: sf);
 
-        var result = await client.CachedCallAsync("TestAPI", "postData");
+        // Audit Log #23 (ExecutionId Task 4): a known execution id / source
+        // script so the gateway -> EnqueueAsync hop can be asserted below.
+        var executionId = Guid.NewGuid();
+        const string sourceScript = "ScriptActor:CheckPressure";
+
+        var result = await client.CachedCallAsync(
+            "TestAPI", "postData",
+            executionId: executionId, sourceScript: sourceScript);
         Assert.True(result.WasBuffered);
 
         var depth = await storage.GetBufferDepthByCategoryAsync();
         Assert.Equal(1, depth[ScadaLink.Commons.Types.Enums.StoreAndForwardCategory.ExternalSystem]);
 
-        var (maxRetries, retryIntervalMs) = ReadBufferedRetrySettings(connStr);
-        Assert.Equal(7, maxRetries);
-        Assert.Equal((long)TimeSpan.FromSeconds(42).TotalMilliseconds, retryIntervalMs);
+        var buffered = ReadBufferedRetrySettings(connStr);
+        Assert.Equal(7, buffered.MaxRetries);
+        Assert.Equal((long)TimeSpan.FromSeconds(42).TotalMilliseconds, buffered.RetryIntervalMs);
+
+        // ExecutionId Task 4: the gateway must forward executionId / sourceScript
+        // into EnqueueAsync, and the S&F layer must persist them on the
+        // sf_messages row so the retry loop can stamp the right provenance.
+        Assert.Equal(executionId, buffered.ExecutionId);
+        Assert.Equal(sourceScript, buffered.SourceScript);
     }
 
-    private static (int MaxRetries, long RetryIntervalMs) ReadBufferedRetrySettings(string connStr)
+    private static (int MaxRetries, long RetryIntervalMs, Guid? ExecutionId, string? SourceScript)
+        ReadBufferedRetrySettings(string connStr)
     {
         using var conn = new SqliteConnection(connStr);
         conn.Open();
         using var cmd = conn.CreateCommand();
-        cmd.CommandText = "SELECT max_retries, retry_interval_ms FROM sf_messages";
+        cmd.CommandText =
+            "SELECT max_retries, retry_interval_ms, execution_id, source_script FROM sf_messages";
         using var reader = cmd.ExecuteReader();
         Assert.True(reader.Read(), "expected exactly one buffered message");
-        var result = (reader.GetInt32(0), reader.GetInt64(1));
+        var result = (
+            reader.GetInt32(0),
+            reader.GetInt64(1),
+            reader.IsDBNull(2) ? (Guid?)null : Guid.Parse(reader.GetString(2)),
+            reader.IsDBNull(3) ? null : reader.GetString(3));
         Assert.False(reader.Read(), "expected exactly one buffered message");
         return result;
     }
@@ -436,7 +455,7 @@ public class ExternalSystemClientTests
 
         await client.CachedCallAsync("TestAPI", "postData");
 
-        var (maxRetries, _) = ReadBufferedRetrySettings(connStr);
+        var (maxRetries, _, _, _) = ReadBufferedRetrySettings(connStr);
         // Must be the bounded S&F default, never 0 — a stored 0 would mean retry-forever.
         Assert.Equal(99, maxRetries);
         Assert.NotEqual(0, maxRetries);
diff --git a/tests/ScadaLink.SiteRuntime.Tests/Scripts/DatabaseCachedWriteEmissionTests.cs b/tests/ScadaLink.SiteRuntime.Tests/Scripts/DatabaseCachedWriteEmissionTests.cs
index d4a9b2f..405b38e 100644
--- a/tests/ScadaLink.SiteRuntime.Tests/Scripts/DatabaseCachedWriteEmissionTests.cs
+++ b/tests/ScadaLink.SiteRuntime.Tests/Scripts/DatabaseCachedWriteEmissionTests.cs
@@ -155,6 +155,46 @@ public class DatabaseCachedWriteEmissionTests
             Times.Once);
     }
 
+    /// <summary>
+    /// Audit Log #23 (ExecutionId Task 4): the helper → gateway hop of the
+    /// threading chain. The cached-write helper must forward the runtime
+    /// context's <c>ExecutionId</c> and <c>SourceScript</c> verbatim into
+    /// <see cref="IDatabaseGateway.CachedWriteAsync"/> — so the buffered retry
+    /// loop later stamps the right provenance onto its audit rows. This
+    /// asserts the exact id/script (not <c>It.IsAny</c>), so a regression that
+    /// dropped the threading would fail here.
+    /// </summary>
+    [Fact]
+    public async Task CachedWrite_ThreadsExecutionIdAndSourceScript_IntoGateway()
+    {
+        var gateway = new Mock<IDatabaseGateway>();
+        gateway
+            .Setup(g => g.CachedWriteAsync(
+                "myDb", "INSERT INTO t VALUES (1)",
+                It.IsAny<IReadOnlyDictionary<string, object?>?>(),
+                InstanceName,
+                It.IsAny<CancellationToken>(),
+                It.IsAny<TrackedOperationId?>(),
+                It.IsAny<Guid?>(), It.IsAny<string?>()))
+            .Returns(Task.CompletedTask);
+        var forwarder = new CapturingForwarder();
+
+        var helper = CreateHelper(gateway.Object, forwarder);
+        await helper.CachedWrite("myDb", "INSERT INTO t VALUES (1)");
+
+        // The known TestExecutionId and SourceScript must reach the gateway
+        // unchanged — these are what the S&F retry loop persists and replays.
+        gateway.Verify(g => g.CachedWriteAsync(
+            "myDb", "INSERT INTO t VALUES (1)",
+            It.IsAny<IReadOnlyDictionary<string, object?>?>(),
+            InstanceName,
+            It.IsAny<CancellationToken>(),
+            It.IsAny<TrackedOperationId?>(),
+            It.Is<Guid?>(id => id == TestExecutionId),
+            It.Is<string?>(s => s == SourceScript)),
+            Times.Once);
+    }
+
     [Fact]
     public async Task CachedWrite_ForwarderThrows_StillReturnsTrackedOperationId()
     {
diff --git a/tests/ScadaLink.SiteRuntime.Tests/Scripts/ExternalSystemCachedCallEmissionTests.cs b/tests/ScadaLink.SiteRuntime.Tests/Scripts/ExternalSystemCachedCallEmissionTests.cs
index 8f7dde9..ce392cb 100644
--- a/tests/ScadaLink.SiteRuntime.Tests/Scripts/ExternalSystemCachedCallEmissionTests.cs
+++ b/tests/ScadaLink.SiteRuntime.Tests/Scripts/ExternalSystemCachedCallEmissionTests.cs
@@ -188,6 +188,46 @@ public class ExternalSystemCachedCallEmissionTests
             Times.Once);
     }
 
+    /// <summary>
+    /// Audit Log #23 (ExecutionId Task 4): the helper → gateway hop of the
+    /// threading chain. The cached-call helper must forward the runtime
+    /// context's <c>ExecutionId</c> and <c>SourceScript</c> verbatim into
+    /// <see cref="IExternalSystemClient.CachedCallAsync"/> — so the buffered
+    /// retry loop later stamps the right provenance onto its audit rows.
+    /// This asserts the exact id/script (not <c>It.IsAny</c>), so a regression
+    /// that dropped the threading would fail here.
+    /// </summary>
+    [Fact]
+    public async Task CachedCall_ThreadsExecutionIdAndSourceScript_IntoClient()
+    {
+        var client = new Mock<IExternalSystemClient>();
+        client
+            .Setup(c => c.CachedCallAsync(
+                "ERP", "GetOrder",
+                It.IsAny<IReadOnlyDictionary<string, object?>?>(),
+                InstanceName,
+                It.IsAny<CancellationToken>(),
+                It.IsAny<TrackedOperationId?>(),
+                It.IsAny<Guid?>(), It.IsAny<string?>()))
+            .ReturnsAsync(new ExternalCallResult(true, null, null, WasBuffered: true));
+        var forwarder = new CapturingForwarder();
+
+        var helper = CreateHelper(client.Object, forwarder);
+        await helper.CachedCall("ERP", "GetOrder");
+
+        // The known TestExecutionId and SourceScript must reach the client
+        // unchanged — these are what the S&F retry loop persists and replays.
+        client.Verify(c => c.CachedCallAsync(
+            "ERP", "GetOrder",
+            It.IsAny<IReadOnlyDictionary<string, object?>?>(),
+            InstanceName,
+            It.IsAny<CancellationToken>(),
+            It.IsAny<TrackedOperationId?>(),
+            It.Is<Guid?>(id => id == TestExecutionId),
+            It.Is<string?>(s => s == SourceScript)),
+            Times.Once);
+    }
+
     [Fact]
     public async Task CachedCall_ForwarderThrows_StillReturnsTrackedOperationId_OriginalCallProceeds()
     {
diff --git a/tests/ScadaLink.StoreAndForward.Tests/StoreAndForwardStorageTests.cs b/tests/ScadaLink.StoreAndForward.Tests/StoreAndForwardStorageTests.cs
index be5820e..6fed58e 100644
--- a/tests/ScadaLink.StoreAndForward.Tests/StoreAndForwardStorageTests.cs
+++ b/tests/ScadaLink.StoreAndForward.Tests/StoreAndForwardStorageTests.cs
@@ -396,6 +396,46 @@ public class StoreAndForwardStorageTests : IAsyncLifetime, IDisposable
         Assert.Null(retrieved.SourceScript);
     }
 
+    [Fact]
+    public async Task MalformedExecutionId_ReadsBackAsNull_DoesNotAbortRetrySweep()
+    {
+        // Defensive read path: a corrupt (non-null, non-GUID) execution_id must
+        // be treated as "no execution id" rather than throwing FormatException
+        // — a single bad row must not abort the whole GetMessagesForRetryAsync
+        // sweep, which reads many rows. Persist two due rows, then corrupt the
+        // execution_id of one directly in the DB.
+        var goodId = Guid.NewGuid();
+        var good = CreateMessage("good1", StoreAndForwardCategory.ExternalSystem);
+        good.ExecutionId = goodId;
+        good.LastAttemptAt = null; // due immediately
+        await _storage.EnqueueAsync(good);
+
+        var bad = CreateMessage("bad1", StoreAndForwardCategory.ExternalSystem);
+        bad.ExecutionId = Guid.NewGuid();
+        bad.LastAttemptAt = null; // due immediately
+        await _storage.EnqueueAsync(bad);
+
+        await using (var conn = new SqliteConnection($"Data Source={_dbName};Mode=Memory;Cache=Shared"))
+        {
+            await conn.OpenAsync();
+            await using var corrupt = conn.CreateCommand();
+            corrupt.CommandText =
+                "UPDATE sf_messages SET execution_id = 'not-a-guid' WHERE id = 'bad1';";
+            await corrupt.ExecuteNonQueryAsync();
+        }
+
+        // The sweep must not throw; the corrupt row reads back with a null
+        // ExecutionId, the well-formed row keeps its value.
+        var due = await _storage.GetMessagesForRetryAsync();
+        Assert.Null(Assert.Single(due, m => m.Id == "bad1").ExecutionId);
+        Assert.Equal(goodId, Assert.Single(due, m => m.Id == "good1").ExecutionId);
+
+        // The single-row read path is equally defensive.
+        var retrieved = await _storage.GetMessageByIdAsync("bad1");
+        Assert.NotNull(retrieved);
+        Assert.Null(retrieved!.ExecutionId);
+    }
+
     [Fact]
     public async Task InitializeAsync_IsIdempotent_WhenColumnsAlreadyExist()
     {