feat(otopcua): set Modbus/S7/Galaxy re-discovery policy to Once + Once-branch test (follow-up B)

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy/GalaxyDriver.cs

@@ -584,6 +584,15 @@ public sealed class GalaxyDriver
 
     // ===== ITagDiscovery (PR 4.1) =====
 
+    /// <summary>
+    ///     Run-once: <see cref="DiscoverAsync"/> fetches the full Galaxy hierarchy inline and
+    ///     streams the complete node set within a single awaited call — there is no FOCAS-style
+    ///     background cache that fills in after connect. Galaxy is a heavy network driver, so the
+    ///     bounded post-connect retry loop is deliberately avoided; re-discovery on Galaxy
+    ///     redeploy is handled separately via <see cref="IRediscoverable"/> + the deploy-event watcher.
+    /// </summary>
+    public DiscoveryRediscoverPolicy RediscoverPolicy => DiscoveryRediscoverPolicy.Once;
+
     /// <inheritdoc />
     public async Task DiscoverAsync(IAddressSpaceBuilder builder, CancellationToken cancellationToken)
     {

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Modbus/ModbusDriver.cs

@@ -261,6 +261,13 @@ public sealed class ModbusDriver
 
     // ---- ITagDiscovery ----
 
+    /// <summary>
+    ///     Run-once: <see cref="DiscoverAsync"/> emits the complete node set synchronously from
+    ///     the configured tag table in a single pass — nothing fills in asynchronously after
+    ///     connect, so a single discovery pass is sufficient.
+    /// </summary>
+    public DiscoveryRediscoverPolicy RediscoverPolicy => DiscoveryRediscoverPolicy.Once;
+
     /// <summary>Discovers tags and builds the OPC UA address space.</summary>
     /// <param name="builder">Address space builder.</param>
     /// <param name="cancellationToken">Cancellation token.</param>

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.S7/S7Driver.cs

@@ -1133,6 +1133,13 @@ public sealed class S7Driver
 
     // ---- ITagDiscovery ----
 
+    /// <summary>
+    ///     Run-once: <see cref="DiscoverAsync"/> emits the complete node set synchronously from
+    ///     the configured tag table in a single pass — nothing fills in asynchronously after
+    ///     connect, so a single discovery pass is sufficient.
+    /// </summary>
+    public DiscoveryRediscoverPolicy RediscoverPolicy => DiscoveryRediscoverPolicy.Once;
+
     /// <summary>Discovers tags and builds the OPC UA address space.</summary>
     /// <param name="builder">Address space builder.</param>
     /// <param name="cancellationToken">Cancellation token.</param>

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Tests/AbLegacyDriverTests.cs

@@ -18,6 +18,17 @@ public sealed class AbLegacyDriverTests
         drv.DriverInstanceId.ShouldBe("drv-1");
     }
 
+    /// <summary>
+    ///     Verifies AbLegacy opts into run-once post-connect re-discovery — it discovers its
+    ///     complete node set synchronously from config, with no FOCAS-style background cache fill.
+    /// </summary>
+    [Fact]
+    public void RediscoverPolicy_is_Once()
+    {
+        var drv = new AbLegacyDriver(new AbLegacyDriverOptions(), "drv-1");
+        drv.RediscoverPolicy.ShouldBe(DiscoveryRediscoverPolicy.Once);
+    }
+
     /// <summary>Verifies that InitializeAsync with devices assigns family profiles.</summary>
     [Fact]
     public async Task InitializeAsync_with_devices_assigns_family_profiles()