fix(dcl): remove unused poll-based WriteBatchAndWaitAsync from IDataConnection and both adapters (review 2026-10-21 02/U3)

docs/requirements/Component-DataConnectionLayer.md

@@ -31,11 +31,12 @@ IDataConnection : IAsyncDisposable
 ├── ReadBatch(tagPaths) → values
 ├── Write(tagPath, value) → void
 ├── WriteBatch(values) → void
-├── WriteBatchAndWait(values, flagPath, flagValue, responsePath, responseValue, timeout) → bool
 ├── Status → ConnectionHealth
 └── Disconnected → event Action?
 ```
 
+There is deliberately no write-and-wait handshake on the adapter interface: the script-facing `Attributes.WriteBatchAndWaitAsync` composes a `WriteTagBatchRequest` (batch + trigger write) with the Instance Actor's event-driven attribute waiter, so the handshake can never fall back to a polling read loop that bypasses the waiter (the adapters' former poll-based `WriteBatchAndWaitAsync` was unused and was removed — review 2026-10-21).
+
 The `Disconnected` event is raised by an adapter when it detects an unexpected connection loss (server offline, network failure, keep-alive timeout). The `DataConnectionActor` subscribes to this event to trigger the reconnection state machine. Additional protocols can be added by implementing this interface.
 
 ### Batch Capability Seam

src/ZB.MOM.WW.ScadaBridge.Commons/Interfaces/Protocol/IDataConnection.cs

@@ -56,16 +56,6 @@ public interface IDataConnection : IAsyncDisposable
     /// <param name="cancellationToken">Cancellation token.</param>
     /// <returns>A dictionary of tag paths to their write results.</returns>
     Task<IReadOnlyDictionary<string, WriteResult>> WriteBatchAsync(IDictionary<string, object?> values, CancellationToken cancellationToken = default);
-    /// <summary>Writes a batch of values, then writes a flag and waits for a specific response value within the timeout.</summary>
-    /// <param name="values">Tag values to write before the flag.</param>
-    /// <param name="flagPath">Tag path of the trigger flag.</param>
-    /// <param name="flagValue">Value to write to the flag tag.</param>
-    /// <param name="responsePath">Tag path to monitor for the expected response value.</param>
-    /// <param name="responseValue">The response value that indicates completion.</param>
-    /// <param name="timeout">Maximum time to wait for the response.</param>
-    /// <param name="cancellationToken">Cancellation token.</param>
-    /// <returns><c>true</c> if the response value was observed within the timeout; otherwise <c>false</c>.</returns>
-    Task<bool> WriteBatchAndWaitAsync(IDictionary<string, object?> values, string flagPath, object? flagValue, string responsePath, object? responseValue, TimeSpan timeout, CancellationToken cancellationToken = default);
     /// <summary>Current connection health status.</summary>
     ConnectionHealth Status { get; }
 

src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Actors/DataConnectionActor.cs

@@ -1972,8 +1972,9 @@ public class DataConnectionActor : UntypedActor, IWithTimers
     /// the timeout, or an adapter exception is translated into a failed
     /// <see cref="WriteTagBatchResponse"/> returned synchronously to the caller — never a
     /// dropped reply. NOTE: this deliberately composes the batch + trigger primitives and
-    /// uses the EXISTING event-driven WaitForAttribute waiter for the wait half; it does
+    /// uses the EXISTING event-driven WaitForAttribute waiter for the wait half (the
-    /// NOT call the adapter's poll-based <c>WriteBatchAndWaitAsync</c>.
+    /// adapters' former poll-based <c>WriteBatchAndWaitAsync</c> was removed — review
+    /// 2026-10-21 02/U3 — so no polling handshake can bypass that waiter).
     /// </summary>
     private void HandleWriteBatch(WriteTagBatchRequest request)
     {

src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/MxGatewayDataConnection.cs

@@ -420,35 +420,6 @@ public class MxGatewayDataConnection
         return results.ToDictionary(w => w.TagPath, w => new WriteResult(w.Success, w.Error));
     }
 
-    /// <inheritdoc />
-    public async Task<bool> WriteBatchAndWaitAsync(
-        IDictionary<string, object?> values, string flagPath, object? flagValue,
-        string responsePath, object? responseValue, TimeSpan timeout, CancellationToken cancellationToken = default)
-    {
-        await WriteBatchAsync(values, cancellationToken);
-        await WriteAsync(flagPath, flagValue, cancellationToken);
-
-        using var timeoutCts = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
-        timeoutCts.CancelAfter(timeout);
-        try
-        {
-            while (!timeoutCts.IsCancellationRequested)
-            {
-                var r = await ReadAsync(responsePath, timeoutCts.Token);
-                // r.Value is a TagValue wrapper; compare its underlying scalar. String
-                // projection tolerates numeric type differences across the gRPC boundary.
-                if (r.Success && string.Equals(r.Value?.Value?.ToString(), responseValue?.ToString(), StringComparison.Ordinal))
-                    return true;
-                await Task.Delay(TimeSpan.FromMilliseconds(200), timeoutCts.Token);
-            }
-        }
-        catch (OperationCanceledException) when (!cancellationToken.IsCancellationRequested)
-        {
-            // Timeout elapsed (the linked CTS, not the caller's token) — fall through to false.
-        }
-        return false;
-    }
-
     /// <inheritdoc />
     public async Task<BrowseChildrenResult> BrowseChildrenAsync(
         string? parentNodeId,

src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Adapters/OpcUaDataConnection.cs

@@ -416,34 +416,6 @@ public class OpcUaDataConnection
         return _client.SearchAddressSpaceAsync(query, maxDepth, maxResults, cancellationToken);
     }
 
-    /// <inheritdoc />
-    public async Task<bool> WriteBatchAndWaitAsync(
-        IDictionary<string, object?> values, string flagPath, object? flagValue,
-        string responsePath, object? responseValue, TimeSpan timeout,
-        CancellationToken cancellationToken = default)
-    {
-        // Write all values including the flag
-        var allValues = new Dictionary<string, object?>(values) { [flagPath] = flagValue };
-        var writeResults = await WriteBatchAsync(allValues, cancellationToken);
-
-        if (writeResults.Values.Any(r => !r.Success))
-            return false;
-
-        // Poll for response value within timeout
-        var deadline = DateTimeOffset.UtcNow + timeout;
-        while (DateTimeOffset.UtcNow < deadline)
-        {
-            cancellationToken.ThrowIfCancellationRequested();
-            var readResult = await ReadAsync(responsePath, cancellationToken);
-            if (readResult.Success && readResult.Value != null && Equals(readResult.Value.Value, responseValue))
-                return true;
-
-            await Task.Delay(100, cancellationToken);
-        }
-
-        return false;
-    }
-
     private void StopHeartbeatMonitor()
     {
         _staleMonitor?.Dispose();

tests/ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Tests/Actors/FakeBatchDataConnection.cs

@@ -163,13 +163,6 @@ public sealed class FakeBatchDataConnection
         => Task.FromResult<IReadOnlyDictionary<string, WriteResult>>(
             values.ToDictionary(kv => kv.Key, _ => new WriteResult(true, null)));
 
-    // Fake behaviour: Reports that the handshake matched without writing anything.
-    /// <inheritdoc />
-    public Task<bool> WriteBatchAndWaitAsync(
-        IDictionary<string, object?> values, string flagPath, object? flagValue, string responsePath,
-        object? responseValue, TimeSpan timeout, CancellationToken cancellationToken = default)
-        => Task.FromResult(true);
-
     // Fake behaviour: Captures the alarm callback and returns a generated subscription id.
     /// <inheritdoc />
     public Task<string> SubscribeAlarmsAsync(

tests/ZB.MOM.WW.ScadaBridge.DataConnectionLayer.Tests/Adapters/MxGatewayDataConnectionTests.cs

@@ -186,59 +186,6 @@ public class MxGatewayDataConnectionTests
         Assert.Equal("rejected", r.ErrorMessage);
     }
 
-    // ── WriteBatchAndWait ──
-
-    /// <summary>Verifies that a batch write and wait returns true when the response value matches.</summary>
-    /// <returns>A task that represents the asynchronous operation.</returns>
-    [Fact]
-    public async Task WriteBatchAndWait_returns_true_when_response_matches()
-    {
-        var writeCalls = new List<string>();
-        var fake = new FakeMxGatewayClient
-        {
-            WriteHandler = writes =>
-            {
-                writeCalls.AddRange(writes.Select(w => w.TagPath));
-                return writes.Select(w => new MxWriteOutcome(w.TagPath, true, null)).ToList();
-            },
-            // Response path already reads the expected value.
-            ReadHandler = tags => tags.Select(t =>
-                new MxReadOutcome(t, true, "DONE", QualityCode.Good, DateTimeOffset.UtcNow, null)).ToList()
-        };
-        var adapter = NewAdapter(fake);
-        await adapter.ConnectAsync(Details());
-
-        var ok = await adapter.WriteBatchAndWaitAsync(
-            new Dictionary<string, object?> { ["V"] = 1 }, "Flag", 1, "Resp", "DONE",
-            TimeSpan.FromSeconds(5));
-
-        Assert.True(ok);
-        // Values written before the flag, and the flag itself.
-        Assert.Contains("V", writeCalls);
-        Assert.Contains("Flag", writeCalls);
-    }
-
-    /// <summary>Verifies that a batch write and wait returns false on timeout.</summary>
-    /// <returns>A task that represents the asynchronous operation.</returns>
-    [Fact]
-    public async Task WriteBatchAndWait_returns_false_on_timeout()
-    {
-        var fake = new FakeMxGatewayClient
-        {
-            WriteHandler = writes => writes.Select(w => new MxWriteOutcome(w.TagPath, true, null)).ToList(),
-            ReadHandler = tags => tags.Select(t =>
-                new MxReadOutcome(t, true, "NEVER", QualityCode.Good, DateTimeOffset.UtcNow, null)).ToList()
-        };
-        var adapter = NewAdapter(fake);
-        await adapter.ConnectAsync(Details());
-
-        var ok = await adapter.WriteBatchAndWaitAsync(
-            new Dictionary<string, object?> { ["V"] = 1 }, "Flag", 1, "Resp", "DONE",
-            TimeSpan.FromMilliseconds(300));
-
-        Assert.False(ok);
-    }
-
     // ── browse ──
 
     /// <summary>Verifies that browsing children maps the children and the truncated flag.</summary>

tests/ZB.MOM.WW.ScadaBridge.LoadHarness/SimulatedDataConnection.cs

@@ -152,14 +152,6 @@ public sealed class SimulatedDataConnection : IDataConnection, IBatchSubscribabl
         return Task.FromResult<IReadOnlyDictionary<string, WriteResult>>(results);
     }
 
-    // Accepts the batch and reports that the awaited response matched immediately.
-    /// <inheritdoc />
-    public Task<bool> WriteBatchAndWaitAsync(
-        IDictionary<string, object?> values, string flagPath, object? flagValue,
-        string responsePath, object? responseValue, TimeSpan timeout,
-        CancellationToken cancellationToken = default)
-        => Task.FromResult(true);
-
     /// <summary>Releases the connection; the simulated connection holds no resources.</summary>
     /// <returns>A task that represents the asynchronous operation.</returns>
     public ValueTask DisposeAsync() => ValueTask.CompletedTask;