diff --git a/src/ZB.MOM.WW.ScadaBridge.Commons/Messages/Artifacts/ExternalSystemArtifact.cs b/src/ZB.MOM.WW.ScadaBridge.Commons/Messages/Artifacts/ExternalSystemArtifact.cs
index f93e6ebb..6e689145 100644
--- a/src/ZB.MOM.WW.ScadaBridge.Commons/Messages/Artifacts/ExternalSystemArtifact.cs
+++ b/src/ZB.MOM.WW.ScadaBridge.Commons/Messages/Artifacts/ExternalSystemArtifact.cs
@@ -5,4 +5,5 @@ public record ExternalSystemArtifact(
     string EndpointUrl,
     string AuthType,
     string? AuthConfiguration,
-    string? MethodDefinitionsJson);
+    string? MethodDefinitionsJson,
+    int TimeoutSeconds = 0);
diff --git a/src/ZB.MOM.WW.ScadaBridge.DeploymentManager/ArtifactDeploymentService.cs b/src/ZB.MOM.WW.ScadaBridge.DeploymentManager/ArtifactDeploymentService.cs
index 8d3d310c..41f06bf8 100644
--- a/src/ZB.MOM.WW.ScadaBridge.DeploymentManager/ArtifactDeploymentService.cs
+++ b/src/ZB.MOM.WW.ScadaBridge.DeploymentManager/ArtifactDeploymentService.cs
@@ -192,7 +192,7 @@ public class ArtifactDeploymentService
                 }))
                 : null;
             externalSystemArtifacts.Add(new ExternalSystemArtifact(
-                es.Name, es.EndpointUrl, es.AuthType, es.AuthConfiguration, methodsJson));
+                es.Name, es.EndpointUrl, es.AuthType, es.AuthConfiguration, methodsJson, es.TimeoutSeconds));
         }
 
         // Map database connections
diff --git a/src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Actors/DeploymentManagerActor.cs b/src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Actors/DeploymentManagerActor.cs
index f4953b55..fbbcf723 100644
--- a/src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Actors/DeploymentManagerActor.cs
+++ b/src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Actors/DeploymentManagerActor.cs
@@ -1885,7 +1885,7 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
                     foreach (var es in command.ExternalSystems)
                     {
                         await _storage.StoreExternalSystemAsync(es.Name, es.EndpointUrl,
-                            es.AuthType, es.AuthConfiguration, es.MethodDefinitionsJson);
+                            es.AuthType, es.AuthConfiguration, es.MethodDefinitionsJson, es.TimeoutSeconds);
                     }
                 }
 
diff --git a/src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Actors/SiteReplicationActor.cs b/src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Actors/SiteReplicationActor.cs
index fe8a3a64..f7d9d375 100644
--- a/src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Actors/SiteReplicationActor.cs
+++ b/src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Actors/SiteReplicationActor.cs
@@ -349,7 +349,7 @@ public class SiteReplicationActor : ReceiveActor
 
                 if (command.ExternalSystems != null)
                     foreach (var es in command.ExternalSystems)
-                        await _storage.StoreExternalSystemAsync(es.Name, es.EndpointUrl, es.AuthType, es.AuthConfiguration, es.MethodDefinitionsJson);
+                        await _storage.StoreExternalSystemAsync(es.Name, es.EndpointUrl, es.AuthType, es.AuthConfiguration, es.MethodDefinitionsJson, es.TimeoutSeconds);
 
                 if (command.DatabaseConnections != null)
                     foreach (var db in command.DatabaseConnections)
diff --git a/src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Persistence/SiteStorageService.cs b/src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Persistence/SiteStorageService.cs
index a4c86003..60800328 100644
--- a/src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Persistence/SiteStorageService.cs
+++ b/src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Persistence/SiteStorageService.cs
@@ -174,6 +174,10 @@ public class SiteStorageService
         // Native-alarm display metadata (UA4) — restored on rehydration so a persisted condition
         // renders fully (type/category/message/values) before the first source snapshot arrives.
         await TryAddColumnAsync(connection, "native_alarm_state", "metadata_json", "TEXT");
+
+        // Per-external-system call timeout (ExternalSystemGateway Timeout) — carried through the
+        // artifact pipeline so site-side calls honor it; 0 = use the site default.
+        await TryAddColumnAsync(connection, "external_systems", "timeout_seconds", "INTEGER NOT NULL DEFAULT 0");
     }
 
     private async Task TryAddColumnAsync(SqliteConnection connection, string table, string column, string type)
@@ -716,22 +720,25 @@ public class SiteStorageService
     /// <param name="authType">The authentication type (e.g., 'ApiKey', 'BasicAuth').</param>
     /// <param name="authConfig">Authentication configuration JSON, if applicable.</param>
     /// <param name="methodDefs">JSON representation of available method definitions, if any.</param>
+    /// <param name="timeoutSeconds">Per-system call timeout in seconds (0 = use the site default).</param>
     /// <returns>A task that completes when the external system definition has been stored or updated.</returns>
     public async Task StoreExternalSystemAsync(
-        string name, string endpointUrl, string authType, string? authConfig, string? methodDefs)
+        string name, string endpointUrl, string authType, string? authConfig, string? methodDefs,
+        int timeoutSeconds = 0)
     {
         await using var connection = new SqliteConnection(_connectionString);
         await connection.OpenAsync();
 
         await using var command = connection.CreateCommand();
         command.CommandText = @"
-            INSERT INTO external_systems (name, endpoint_url, auth_type, auth_configuration, method_definitions, updated_at)
-            VALUES (@name, @url, @authType, @authConfig, @methodDefs, @updatedAt)
+            INSERT INTO external_systems (name, endpoint_url, auth_type, auth_configuration, method_definitions, timeout_seconds, updated_at)
+            VALUES (@name, @url, @authType, @authConfig, @methodDefs, @timeoutSeconds, @updatedAt)
             ON CONFLICT(name) DO UPDATE SET
                 endpoint_url = excluded.endpoint_url,
                 auth_type = excluded.auth_type,
                 auth_configuration = excluded.auth_configuration,
                 method_definitions = excluded.method_definitions,
+                timeout_seconds = excluded.timeout_seconds,
                 updated_at = excluded.updated_at";
 
         command.Parameters.AddWithValue("@name", name);
@@ -739,6 +746,7 @@ public class SiteStorageService
         command.Parameters.AddWithValue("@authType", authType);
         command.Parameters.AddWithValue("@authConfig", (object?)authConfig ?? DBNull.Value);
         command.Parameters.AddWithValue("@methodDefs", (object?)methodDefs ?? DBNull.Value);
+        command.Parameters.AddWithValue("@timeoutSeconds", timeoutSeconds);
         command.Parameters.AddWithValue("@updatedAt", DateTimeOffset.UtcNow.ToString("O"));
 
         await command.ExecuteNonQueryAsync();
diff --git a/src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Repositories/SiteExternalSystemRepository.cs b/src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Repositories/SiteExternalSystemRepository.cs
index 8b378390..efb8a48e 100644
--- a/src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Repositories/SiteExternalSystemRepository.cs
+++ b/src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Repositories/SiteExternalSystemRepository.cs
@@ -36,7 +36,7 @@ public class SiteExternalSystemRepository : IExternalSystemRepository
 
         await using var command = connection.CreateCommand();
         command.CommandText = @"
-            SELECT name, endpoint_url, auth_type, auth_configuration
+            SELECT name, endpoint_url, auth_type, auth_configuration, timeout_seconds
             FROM external_systems";
 
         var results = new List<ExternalSystemDefinition>();
@@ -68,7 +68,7 @@ public class SiteExternalSystemRepository : IExternalSystemRepository
 
         await using var command = connection.CreateCommand();
         command.CommandText = @"
-            SELECT name, endpoint_url, auth_type, auth_configuration
+            SELECT name, endpoint_url, auth_type, auth_configuration, timeout_seconds
             FROM external_systems
             WHERE name = @name";
         command.Parameters.AddWithValue("@name", name);
@@ -263,7 +263,8 @@ public class SiteExternalSystemRepository : IExternalSystemRepository
             authType: reader.GetString(2))
         {
             Id = GenerateSyntheticId(name),
-            AuthConfiguration = reader.IsDBNull(3) ? null : reader.GetString(3)
+            AuthConfiguration = reader.IsDBNull(3) ? null : reader.GetString(3),
+            TimeoutSeconds = reader.IsDBNull(4) ? 0 : reader.GetInt32(4)
         };
     }
 
diff --git a/tests/ZB.MOM.WW.ScadaBridge.SiteRuntime.Tests/Repositories/SiteRepositoryTests.cs b/tests/ZB.MOM.WW.ScadaBridge.SiteRuntime.Tests/Repositories/SiteRepositoryTests.cs
index c1a3e88e..14b1f08b 100644
--- a/tests/ZB.MOM.WW.ScadaBridge.SiteRuntime.Tests/Repositories/SiteRepositoryTests.cs
+++ b/tests/ZB.MOM.WW.ScadaBridge.SiteRuntime.Tests/Repositories/SiteRepositoryTests.cs
@@ -54,6 +54,26 @@ public class SiteRepositoryTests : IDisposable
         Assert.Equal("https://api.example.com", all[0].EndpointUrl);
     }
 
+    /// <summary>
+    /// ExternalSystemGateway (Timeout): the per-system <c>TimeoutSeconds</c> stored via
+    /// <see cref="SiteStorageService.StoreExternalSystemAsync"/> must round-trip through the
+    /// site SQLite store and back out via the repository, so site-side calls honor it.
+    /// </summary>
+    [Fact]
+    public async Task SiteStorage_ExternalSystem_TimeoutSeconds_RoundTrips()
+    {
+        var storage = NewStorage();
+        await storage.InitializeAsync();
+        await storage.StoreExternalSystemAsync(
+            "WeatherApi", "https://api.example.com", "ApiKey", "{\"key\":\"x\"}", null, 7);
+
+        var repo = new SiteExternalSystemRepository(storage);
+        var found = await repo.GetExternalSystemByNameAsync("WeatherApi");
+
+        Assert.NotNull(found);
+        Assert.Equal(7, found!.TimeoutSeconds);
+    }
+
     /// <summary>
     /// SiteRuntime-007: the synthetic ID for an external system must be identical when
     /// the storage service and repository are re-created (simulating a process restart).