e2e: port batch subcommand to all five client CLIs

scripts/run-client-e2e-tests.ps1 expects each language CLI to expose a
`batch` subcommand that reads command lines from stdin, runs each
through the normal subcommand dispatch, writes the JSON result, then
a sentinel line `__MXGW_BATCH_EOR__`. The implementation lived on a
divergent branch (commit 6126099) that was never merged into main —
this commit ports the same protocol to HEAD's renamed CLIs so the
existing matrix script runs end-to-end.

The protocol:
  - one line of stdin = one full CLI invocation
  - successful output → stdout, then __MXGW_BATCH_EOR__
  - failure → {"error":"...","type":"error"} JSON on stdout, then
    __MXGW_BATCH_EOR__ (errors do NOT exit the loop)
  - empty line or EOF terminates the loop

Per-CLI additions:

  .NET: RunBatchAsync + per-line StringWriter capture, JSON error
    envelope when forceJsonErrors is true. Two new tests in
    MxGatewayClientCliTests covering the success and error paths.

  Go:   runBatch with bufio.Scanner, runs each line through the
    existing runWithIO switch with a buffered stdout writer. One new
    test pinning the EOR sentinel.

  Rust: new `Batch` variant on the clap Command enum, run_batch
    re-parses each line via Cli::try_parse_from. Two new tests in the
    inline mod tests block.

  Python: new `batch` click command in commands.py that uses
    CliRunner to dispatch each line; synthesises {"error",..."type"}
    JSON from click error messages when the captured output isn't
    already JSON-shaped. Three new tests in test_cli.py.

  Java: BatchCommand inner @Command with BufferedReader stdin loop,
    fresh commandLine() per dispatch with captured stdout/stderr
    PrintWriters; non-zero exit codes and uncaught exceptions both
    surface as JSON-error blocks. Two new tests.

Also fixes scripts/run-client-e2e-tests.ps1 line 705: the Python
invocation was still passing the old module name `mxgateway_cli` to
`python -m`; the client SDK rename in 397d3c5 moved it to
`zb_mom_ww_mxgateway_cli`. Without the fix the Python leg fails
with "No module named mxgateway_cli" before reaching open-session.

Verification: full matrix at the redeployed gateway (localhost:5120,
running ZB.MOM.WW.MxGateway.Server.exe / ZB.MOM.WW.MxGateway.Worker.exe)
with -SkipBulk -SkipReadWriteBulk -SkipParity -SkipAuth (those phases
exercise bulk read/write CLI subcommands that also live on the
divergent branch — porting those is a follow-up). All five clients
report `closed=true, addedItems=120, eventCount=5` and overall
`success=true`. Per-language unit tests pass:
  - dotnet: 59/59
  - go:     all packages clean
  - rust:   cargo test --workspace clean
  - python: 42/42
  - java:   gradle build SUCCESSFUL

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

clients/dotnet/ZB.MOM.WW.MxGateway.Client.Cli/MxGatewayClientCli.cs

@@ -16,6 +16,8 @@ public static class MxGatewayClientCli
 
     private static readonly JsonSerializerOptions JsonOptions = new(JsonSerializerDefaults.Web);
 
+    private const string BatchEndOfRecord = "__MXGW_BATCH_EOR__";
+
     /// <summary>Runs the CLI synchronously with the given arguments, writing output and errors.</summary>
     /// <param name="args">Command-line arguments (command name followed by options).</param>
     /// <param name="standardOutput">TextWriter for command output.</param>
@@ -25,7 +27,7 @@ public static class MxGatewayClientCli
         TextWriter standardOutput,
         TextWriter standardError)
     {
-        return RunAsync(args, standardOutput, standardError)
+        return RunAsync(args, standardOutput, standardError, clientFactory: null, standardInput: null)
             .GetAwaiter()
             .GetResult();
     }
@@ -35,11 +37,13 @@ public static class MxGatewayClientCli
     /// <param name="standardOutput">TextWriter for command output.</param>
     /// <param name="standardError">TextWriter for error messages.</param>
     /// <param name="clientFactory">Optional factory to create the gateway client; defaults to MxGatewayClient.Create.</param>
+    /// <param name="standardInput">Optional TextReader for batch-mode stdin; defaults to <see cref="Console.In"/>.</param>
     public static Task<int> RunAsync(
         string[] args,
         TextWriter standardOutput,
         TextWriter standardError,
-        Func<MxGatewayClientOptions, IMxGatewayCliClient>? clientFactory = null)
+        Func<MxGatewayClientOptions, IMxGatewayCliClient>? clientFactory = null,
+        TextReader? standardInput = null)
     {
         ArgumentNullException.ThrowIfNull(args);
         ArgumentNullException.ThrowIfNull(standardOutput);
@@ -49,14 +53,17 @@ public static class MxGatewayClientCli
             args,
             standardOutput,
             standardError,
-            clientFactory ?? CreateDefaultClient);
+            clientFactory ?? CreateDefaultClient,
+            standardInput ?? Console.In);
     }
 
     private static async Task<int> RunCoreAsync(
         string[] args,
         TextWriter standardOutput,
         TextWriter standardError,
-        Func<MxGatewayClientOptions, IMxGatewayCliClient> clientFactory)
+        Func<MxGatewayClientOptions, IMxGatewayCliClient> clientFactory,
+        TextReader standardInput,
+        bool forceJsonErrors = false)
     {
         if (args.Length is 0 || IsHelp(args[0]))
         {
@@ -65,6 +72,12 @@ public static class MxGatewayClientCli
         }
 
         string command = args[0].ToLowerInvariant();
+
+        if (command is "batch")
+        {
+            return await RunBatchAsync(standardOutput, clientFactory, standardInput).ConfigureAwait(false);
+        }
+
         CliArguments arguments = new(args.Skip(1));
 
         try
@@ -125,7 +138,7 @@ public static class MxGatewayClientCli
             string? apiKey = arguments.GetOptional("api-key");
             string message = MxGatewayCliSecretRedactor.Redact(exception.Message, apiKey);
 
-            if (arguments.HasFlag("json"))
+            if (forceJsonErrors || arguments.HasFlag("json"))
             {
                 standardError.WriteLine(JsonSerializer.Serialize(
                     new { error = message, type = exception.GetType().Name },
@@ -140,6 +153,82 @@ public static class MxGatewayClientCli
         }
     }
 
+    /// <summary>
+    ///     Runs the CLI in batch mode: reads one command line at a time from
+    ///     <paramref name="standardInput"/>, dispatches it through the normal
+    ///     routing, writes all output to <paramref name="standardOutput"/>, and
+    ///     then appends <see cref="BatchEndOfRecord"/> as a sentinel so the
+    ///     caller can delimit command results. Continues on failure; errors are
+    ///     written as JSON to <paramref name="standardOutput"/> (not stderr) so
+    ///     that the harness sees them inside the same delimited block. Exits 0
+    ///     on EOF or empty line.
+    /// </summary>
+    private static async Task<int> RunBatchAsync(
+        TextWriter standardOutput,
+        Func<MxGatewayClientOptions, IMxGatewayCliClient> clientFactory,
+        TextReader standardInput)
+    {
+        while (true)
+        {
+            string? line = await standardInput.ReadLineAsync().ConfigureAwait(false);
+
+            // EOF or empty line signals clean exit.
+            if (line is null || line.Length is 0)
+            {
+                return 0;
+            }
+
+            // Split on runs of ASCII whitespace — no quoting support by design.
+            string[] lineArgs = line.Split((char[]?)null, StringSplitOptions.RemoveEmptyEntries);
+
+            // Per-command output is buffered so we can redirect errors to stdout.
+            using StringWriter commandOutput = new();
+
+            // Errors in batch mode go to stdout (same delimited block), formatted as JSON.
+            // We use a capturing error writer and re-emit through commandOutput after the
+            // command returns, so the EOR sentinel always follows the complete result.
+            using StringWriter commandError = new();
+
+            try
+            {
+                await RunCoreAsync(
+                        lineArgs,
+                        commandOutput,
+                        commandError,
+                        clientFactory,
+                        standardInput,
+                        forceJsonErrors: true)
+                    .ConfigureAwait(false);
+            }
+            catch (Exception exception) when (exception is not OperationCanceledException)
+            {
+                // Unexpected exception that escaped RunCoreAsync (shouldn't happen, but be safe).
+                commandError.WriteLine(JsonSerializer.Serialize(
+                    new { error = exception.Message, type = exception.GetType().Name },
+                    JsonOptions));
+            }
+
+            // Write any buffered normal output first.
+            string commandOutputText = commandOutput.ToString();
+            if (commandOutputText.Length > 0)
+            {
+                standardOutput.Write(commandOutputText);
+            }
+
+            // Then any error output — in batch mode it belongs on stdout so the harness
+            // sees it inside the delimited record.
+            string commandErrorText = commandError.ToString();
+            if (commandErrorText.Length > 0)
+            {
+                standardOutput.Write(commandErrorText);
+            }
+
+            // Write the end-of-record sentinel and flush so the harness can unblock.
+            standardOutput.WriteLine(BatchEndOfRecord);
+            await standardOutput.FlushAsync().ConfigureAwait(false);
+        }
+    }
+
     private static IMxGatewayCliClient CreateDefaultClient(MxGatewayClientOptions options)
     {
         return new MxGatewayCliClientAdapter(MxGatewayClient.Create(options));
@@ -1032,6 +1121,7 @@ public static class MxGatewayClientCli
 
     private static void WriteUsage(TextWriter writer)
     {
+        writer.WriteLine("mxgw-dotnet batch  (reads commands from stdin; writes output + __MXGW_BATCH_EOR__ after each)");
         writer.WriteLine("mxgw-dotnet version [--json]");
         writer.WriteLine("mxgw-dotnet ping --session-id <id> [--json]");
         writer.WriteLine("mxgw-dotnet open-session [--client-name <name>] [--json]");

clients/dotnet/ZB.MOM.WW.MxGateway.Client.Tests/MxGatewayClientCliTests.cs

@@ -368,6 +368,66 @@ public sealed class MxGatewayClientCliTests
         Assert.Contains("\"objectCount\": 99", text);
     }
 
+    /// <summary>Verifies that batch mode dispatches a single version command and emits the EOR sentinel.</summary>
+    [Fact]
+    public async Task RunAsync_Batch_DispatchesVersionAndWritesEndOfRecord()
+    {
+        using var output = new StringWriter();
+        using var error = new StringWriter();
+        using var input = new StringReader("version --json\n");
+
+        int exitCode = await MxGatewayClientCli.RunAsync(
+            ["batch"],
+            output,
+            error,
+            clientFactory: null,
+            standardInput: input);
+
+        Assert.Equal(0, exitCode);
+        string text = output.ToString();
+        Assert.Contains("\"gatewayProtocolVersion\":3", text);
+        Assert.Contains("__MXGW_BATCH_EOR__", text);
+        // The EOR marker must come after the JSON output.
+        int jsonIndex = text.IndexOf("\"gatewayProtocolVersion\"", StringComparison.Ordinal);
+        int eorIndex = text.IndexOf("__MXGW_BATCH_EOR__", StringComparison.Ordinal);
+        Assert.True(jsonIndex >= 0 && eorIndex > jsonIndex);
+        Assert.Equal(string.Empty, error.ToString());
+    }
+
+    /// <summary>Verifies that batch mode routes per-command errors to stdout as JSON between EOR markers.</summary>
+    [Fact]
+    public async Task RunAsync_Batch_WritesErrorsToStdoutAsJson()
+    {
+        using var output = new StringWriter();
+        using var error = new StringWriter();
+        // Unknown command should produce an error on the captured error stream,
+        // which batch mode re-emits to stdout inside the same delimited block.
+        using var input = new StringReader("nope-not-a-command\nversion\n");
+
+        int exitCode = await MxGatewayClientCli.RunAsync(
+            ["batch"],
+            output,
+            error,
+            clientFactory: null,
+            standardInput: input);
+
+        Assert.Equal(0, exitCode);
+        string text = output.ToString();
+        // Two records → two EOR markers.
+        int firstEor = text.IndexOf("__MXGW_BATCH_EOR__", StringComparison.Ordinal);
+        int secondEor = text.IndexOf(
+            "__MXGW_BATCH_EOR__",
+            firstEor + 1,
+            StringComparison.Ordinal);
+        Assert.True(firstEor > 0);
+        Assert.True(secondEor > firstEor);
+        // The unknown-command error message must be on stdout (not on stderr).
+        Assert.Contains("nope-not-a-command", text);
+        Assert.DoesNotContain("nope-not-a-command", error.ToString());
+        // The follow-up `version` line should still succeed.
+        Assert.Contains("gateway-protocol=", text);
+    }
+
     /// <summary>Fake CLI client for testing.</summary>
     private sealed class FakeCliClient : IMxGatewayCliClient
     {

clients/go/cmd/mxgw-go/main.go

@@ -6,6 +6,7 @@
 package main
 
 import (
+	"bufio"
 	"context"
 	"encoding/json"
 	"errors"
@@ -103,6 +104,8 @@ func runWithIO(ctx context.Context, args []string, stdout, stderr io.Writer) err
 		return runGalaxyDiscover(ctx, args[1:], stdout, stderr)
 	case "galaxy-watch":
 		return runGalaxyWatch(ctx, args[1:], stdout, stderr)
+	case "batch":
+		return runBatch(ctx, os.Stdin, stdout, stderr)
 	default:
 		writeUsage(stderr)
 		return fmt.Errorf("unknown command %q", args[0])
@@ -666,7 +669,43 @@ type protojsonMessage interface {
 }
 
 func writeUsage(writer io.Writer) {
-	fmt.Fprintln(writer, "usage: mxgw-go <version|open-session|close-session|register|add-item|advise|subscribe-bulk|unsubscribe-bulk|write|stream-events|smoke|galaxy-test-connection|galaxy-last-deploy|galaxy-discover|galaxy-watch>")
+	fmt.Fprintln(writer, "usage: mxgw-go <version|open-session|close-session|register|add-item|advise|subscribe-bulk|unsubscribe-bulk|write|stream-events|smoke|galaxy-test-connection|galaxy-last-deploy|galaxy-discover|galaxy-watch|batch>")
+}
+
+// batchEOR is the end-of-result sentinel emitted to stdout after every command
+// in batch mode, regardless of success or failure.
+const batchEOR = "__MXGW_BATCH_EOR__"
+
+// runBatch reads one command line at a time from in, dispatches each via the
+// normal runWithIO routing, and writes a batchEOR sentinel to stdout after
+// every result. Errors are serialised as JSON to stdout (not stderr) so the
+// harness can parse them without interleaving stderr. The loop never terminates
+// on command error; only stdin EOF (or an empty line) ends the session.
+func runBatch(ctx context.Context, in io.Reader, stdout, stderr io.Writer) error {
+	bw := bufio.NewWriter(stdout)
+	scanner := bufio.NewScanner(in)
+	for scanner.Scan() {
+		line := scanner.Text()
+		if line == "" {
+			break
+		}
+		args := strings.Fields(line)
+		if len(args) == 0 {
+			continue
+		}
+		if err := runWithIO(ctx, args, bw, stderr); err != nil {
+			// Write error as JSON to stdout (bw) so the harness sees it in the
+			// same stream as normal output, framed by the EOR sentinel.
+			errPayload := map[string]string{
+				"error": err.Error(),
+				"type":  "error",
+			}
+			_ = writeJSON(bw, errPayload)
+		}
+		_, _ = fmt.Fprintln(bw, batchEOR)
+		_ = bw.Flush()
+	}
+	return scanner.Err()
 }
 
 func dialGalaxyForCommand(ctx context.Context, common *commonOptions) (*mxgateway.GalaxyClient, commonOptions, error) {

clients/go/cmd/mxgw-go/main_test.go

@@ -47,6 +47,34 @@ func TestCommonOptionsRedactsAPIKey(t *testing.T) {
 	}
 }
 
+func TestRunBatchEmitsEORAfterVersion(t *testing.T) {
+	var stdout bytes.Buffer
+	var stderr bytes.Buffer
+
+	in := strings.NewReader("version --json\n")
+	if err := runBatch(t.Context(), in, &stdout, &stderr); err != nil {
+		t.Fatalf("runBatch() error = %v; stderr = %s", err, stderr.String())
+	}
+
+	out := stdout.String()
+	if !strings.Contains(out, "\n"+batchEOR+"\n") && !strings.HasSuffix(out, batchEOR+"\n") {
+		t.Fatalf("expected EOR marker %q in stdout; got: %q", batchEOR, out)
+	}
+
+	idx := strings.Index(out, batchEOR)
+	if idx <= 0 {
+		t.Fatalf("EOR marker not found or appeared before any output: %q", out)
+	}
+	payload := out[:idx]
+	var output versionOutput
+	if err := json.Unmarshal([]byte(payload), &output); err != nil {
+		t.Fatalf("parse JSON block before EOR: %v (payload=%q)", err, payload)
+	}
+	if output.GatewayProtocolVersion == 0 || output.WorkerProtocolVersion == 0 {
+		t.Fatalf("protocol versions were not populated: %+v", output)
+	}
+}
+
 func TestParseValueBuildsTypedValue(t *testing.T) {
 	value, err := parseValue("int32", "123")
 	if err != nil {

clients/java/zb-mom-ww-mxgateway-cli/src/main/java/com/zb/mom/ww/mxgateway/cli/MxGatewayCli.java

@@ -14,7 +14,11 @@ import galaxy_repository.v1.GalaxyRepositoryOuterClass.GalaxyAttribute;
 import galaxy_repository.v1.GalaxyRepositoryOuterClass.GalaxyObject;
 import com.google.protobuf.Message;
 import com.google.protobuf.util.JsonFormat;
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
 import java.io.PrintWriter;
+import java.io.StringWriter;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Path;
 import java.time.Duration;
 import java.time.Instant;
@@ -116,9 +120,90 @@ public final class MxGatewayCli implements Callable<Integer> {
         commandLine.addSubcommand("galaxy-deploy-time", new GalaxyDeployTimeCommand());
         commandLine.addSubcommand("galaxy-discover", new GalaxyDiscoverCommand());
         commandLine.addSubcommand("galaxy-watch", new GalaxyWatchCommand());
+        commandLine.addSubcommand("batch", new BatchCommand(clientFactory));
         return commandLine;
     }
 
+    /** Sentinel written to stdout after every command result in batch mode. */
+    static final String BATCH_EOR = "__MXGW_BATCH_EOR__";
+
+    /**
+     * Reads one CLI invocation per stdin line, executes each via a fresh
+     * {@link CommandLine}, and writes {@value #BATCH_EOR} to stdout after
+     * every result. Errors are written as JSON to stdout so the harness
+     * sees them in the same stream, delimited by the same sentinel. The
+     * loop never terminates on command failure; only stdin EOF (or an
+     * empty line) ends the session.
+     */
+    @Command(name = "batch", description = "Reads CLI invocations from stdin and executes them sequentially.")
+    static final class BatchCommand implements Callable<Integer> {
+        private final MxGatewayCliClientFactory clientFactory;
+
+        @Spec
+        private CommandSpec spec;
+
+        BatchCommand(MxGatewayCliClientFactory clientFactory) {
+            this.clientFactory = clientFactory;
+        }
+
+        @Override
+        public Integer call() {
+            PrintWriter out = spec.commandLine().getOut();
+            try (BufferedReader reader = new BufferedReader(
+                    new InputStreamReader(System.in, StandardCharsets.UTF_8))) {
+                String line;
+                while ((line = reader.readLine()) != null) {
+                    if (line.isEmpty()) {
+                        break;
+                    }
+                    String[] args = line.trim().split("\\s+");
+                    if (args.length == 0 || (args.length == 1 && args[0].isEmpty())) {
+                        continue;
+                    }
+                    StringWriter cmdOut = new StringWriter();
+                    StringWriter cmdErr = new StringWriter();
+                    PrintWriter cmdOutWriter = new PrintWriter(cmdOut, true);
+                    PrintWriter cmdErrWriter = new PrintWriter(cmdErr, true);
+                    try {
+                        CommandLine cmd = commandLine(clientFactory);
+                        cmd.setOut(cmdOutWriter);
+                        cmd.setErr(cmdErrWriter);
+                        int exitCode = cmd.execute(args);
+                        cmdOutWriter.flush();
+                        cmdErrWriter.flush();
+                        String cmdOutput = cmdOut.toString();
+                        if (!cmdOutput.isEmpty()) {
+                            out.print(cmdOutput);
+                        }
+                        if (exitCode != 0) {
+                            // Non-zero exit: emit the stderr content (if any) as a JSON
+                            // error object to stdout so the harness can parse it in the
+                            // same delimited stream.
+                            String errText = cmdErr.toString().trim();
+                            if (errText.isEmpty()) {
+                                errText = "command exited with code " + exitCode;
+                            }
+                            Map<String, Object> errorPayload = new LinkedHashMap<>();
+                            errorPayload.put("error", errText);
+                            errorPayload.put("type", "error");
+                            out.println(jsonObject(errorPayload));
+                        }
+                    } catch (Exception ex) {
+                        Map<String, Object> errorPayload = new LinkedHashMap<>();
+                        errorPayload.put("error", ex.getMessage() != null ? ex.getMessage() : ex.getClass().getName());
+                        errorPayload.put("type", "error");
+                        out.println(jsonObject(errorPayload));
+                    }
+                    out.println(BATCH_EOR);
+                    out.flush();
+                }
+            } catch (java.io.IOException ex) {
+                // Stdin closed unexpectedly — treat as EOF and exit normally.
+            }
+            return 0;
+        }
+    }
+
     abstract static class GalaxyCommand implements Callable<Integer> {
         @Mixin
         CommonOptions common = new CommonOptions();

clients/java/zb-mom-ww-mxgateway-cli/src/test/java/com/zb/mom/ww/mxgateway/cli/MxGatewayCliTests.java

@@ -4,8 +4,11 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import java.io.ByteArrayInputStream;
+import java.io.InputStream;
 import java.io.PrintWriter;
 import java.io.StringWriter;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.List;
 import mxaccess_gateway.v1.MxaccessGateway.AddItemReply;
@@ -141,6 +144,47 @@ final class MxGatewayCliTests {
         assertTrue(run.output().contains("\"wasSuccessful\":true"));
     }
 
+    @Test
+    void batchCommandExecutesVersionAndEmitsEorMarker() {
+        CliRun run = executeBatch(new FakeClientFactory(), "version --json\n");
+
+        assertEquals(0, run.exitCode());
+        String out = run.output();
+        assertTrue(out.contains("\"clientVersion\""), out);
+        assertTrue(out.contains(MxGatewayCli.BATCH_EOR), out);
+    }
+
+    @Test
+    void batchCommandEmitsEorAfterFailedCommandAndContinues() {
+        // An unknown subcommand causes a picocli parse error (non-zero exit).
+        // The loop must still emit BATCH_EOR for the failure and continue
+        // processing the subsequent valid command.
+        CliRun run = executeBatch(new FakeClientFactory(), "no-such-subcommand\nversion --json\n");
+
+        assertEquals(0, run.exitCode());
+        String out = run.output();
+        long eorCount = out.lines()
+                .filter(l -> l.equals(MxGatewayCli.BATCH_EOR))
+                .count();
+        assertEquals(2, eorCount, "expected exactly 2 EOR sentinels, got: " + eorCount + "\nOutput:\n" + out);
+        assertTrue(out.contains("\"clientVersion\""), out);
+    }
+
+    /**
+     * Runs the CLI with {@code batch} as the subcommand, using the provided
+     * string as standard input content. Temporarily replaces {@link System#in}
+     * for the duration of the call.
+     */
+    private static CliRun executeBatch(MxGatewayCli.MxGatewayCliClientFactory factory, String stdinContent) {
+        InputStream originalIn = System.in;
+        try {
+            System.setIn(new ByteArrayInputStream(stdinContent.getBytes(StandardCharsets.UTF_8)));
+            return execute(factory, "batch");
+        } finally {
+            System.setIn(originalIn);
+        }
+    }
+
     private static CliRun execute(MxGatewayCli.MxGatewayCliClientFactory factory, String... args) {
         StringWriter output = new StringWriter();
         StringWriter errors = new StringWriter();

clients/python/src/zb_mom_ww_mxgateway_cli/commands.py

@@ -5,11 +5,13 @@ from __future__ import annotations
 import asyncio
 import json
 import os
+import sys
 from collections.abc import Awaitable, Callable
 from datetime import datetime, timezone
 from typing import Any
 
 import click
+from click.testing import CliRunner
 from google.protobuf.json_format import MessageToDict
 
 from zb_mom_ww_mxgateway import __version__
@@ -22,6 +24,8 @@ from zb_mom_ww_mxgateway.values import MxValueInput
 
 MAX_AGGREGATE_EVENTS = 10_000
 
+_BATCH_EOR = "__MXGW_BATCH_EOR__"
+
 
 @click.group()
 def main() -> None:
@@ -41,6 +45,80 @@ def version(output_json: bool) -> None:
     _emit(payload, output_json=output_json, text=f"mxgw-py {__version__}")
 
 
+@main.command()
+def batch() -> None:
+    """Read commands from stdin and execute each, writing output + __MXGW_BATCH_EOR__ after each.
+
+    Each non-empty line of stdin is a complete argument string (no quoting support — the
+    harness never passes whitespace-containing arguments). Lines are split on runs of ASCII
+    whitespace and dispatched through the normal CLI parser. On EOF or an empty line, exit 0.
+
+    Errors do NOT terminate the loop. Each command's output (including any error JSON) is
+    written to stdout followed by a line containing exactly ``__MXGW_BATCH_EOR__``, then
+    stdout is flushed. Error output is formatted as ``{"error": "...", "type": "..."}``.
+    """
+
+    runner = CliRunner()
+
+    for raw_line in sys.stdin:
+        line = raw_line.rstrip("\n").rstrip("\r")
+        if not line:
+            # Empty line signals clean exit (matches the spec and .NET behaviour).
+            break
+
+        args = line.split()
+
+        try:
+            result = runner.invoke(main, args, catch_exceptions=True)
+        except Exception as exc:  # noqa: BLE001 — be safe; never let batch loop die
+            _batch_write_error(exc.__class__.__name__, str(exc))
+            _batch_flush_eor()
+            continue
+
+        if result.exit_code == 0:
+            # Normal success — write captured output as-is.
+            sys.stdout.write(result.output)
+        else:
+            # Something went wrong.  If the command already emitted a JSON object
+            # (e.g. the output starts with '{'), trust that and relay it verbatim.
+            # Otherwise synthesise the standard {"error": ..., "type": ...} shape.
+            output = result.output or ""
+            exc = result.exception
+
+            if output.lstrip().startswith("{"):
+                # Already JSON — relay verbatim (may or may not end with newline).
+                sys.stdout.write(output)
+                if not output.endswith("\n"):
+                    sys.stdout.write("\n")
+            elif exc is not None and not isinstance(exc, SystemExit):
+                _batch_write_error(type(exc).__name__, str(exc))
+            else:
+                # Click's default error format is "Error: <message>\n"; extract the
+                # message so the harness gets clean JSON.
+                msg = output.strip()
+                if msg.startswith("Error: "):
+                    msg = msg[len("Error: "):]
+                exc_type = (
+                    type(exc).__name__
+                    if exc is not None and not isinstance(exc, SystemExit)
+                    else "CliError"
+                )
+                _batch_write_error(exc_type, msg)
+
+        _batch_flush_eor()
+
+
+def _batch_write_error(exc_type: str, message: str) -> None:
+    """Write a JSON error record to stdout in the standard batch error shape."""
+    sys.stdout.write(json.dumps({"error": message, "type": exc_type}) + "\n")
+
+
+def _batch_flush_eor() -> None:
+    """Write the end-of-record sentinel and flush stdout."""
+    sys.stdout.write(_BATCH_EOR + "\n")
+    sys.stdout.flush()
+
+
 def gateway_options(command: Callable[..., Any]) -> Callable[..., Any]:
     """Apply the shared gateway connection options to a Click command."""
     command = click.option("--endpoint", default="localhost:5000", show_default=True)(command)

clients/python/tests/test_cli.py

@@ -7,6 +7,8 @@ from click.testing import CliRunner
 from zb_mom_ww_mxgateway import __version__
 from zb_mom_ww_mxgateway_cli.commands import main
 
+_BATCH_EOR = "__MXGW_BATCH_EOR__"
+
 
 def test_version_json_is_deterministic() -> None:
     runner = CliRunner()
@@ -66,3 +68,59 @@ def test_cli_error_output_redacts_api_key() -> None:
 
     assert result.exit_code != 0
     assert "mxgw_test_secret" not in result.output
+
+
+def test_batch_runs_version_command_and_writes_eor() -> None:
+    runner = CliRunner()
+
+    result = runner.invoke(main, ["batch"], input="version --json\n")
+
+    assert result.exit_code == 0
+    blocks = [block for block in result.output.split(_BATCH_EOR + "\n") if block]
+    assert len(blocks) == 1
+    payload = json.loads(blocks[0].strip())
+    assert payload == {
+        "client": "mxgw-py",
+        "package": "mxaccess-gateway-client",
+        "version": __version__,
+    }
+
+
+def test_batch_terminates_on_empty_line() -> None:
+    runner = CliRunner()
+
+    result = runner.invoke(
+        main,
+        ["batch"],
+        input="version --json\n\nversion --json\n",
+    )
+
+    assert result.exit_code == 0
+    # Only the first command runs; the empty line breaks the loop before the second.
+    assert result.output.count(_BATCH_EOR) == 1
+
+
+def test_batch_continues_after_error_line() -> None:
+    runner = CliRunner()
+
+    # First line is invalid (unknown subcommand), second is a valid version call.
+    result = runner.invoke(
+        main,
+        ["batch"],
+        input="not-a-real-command\nversion --json\n",
+    )
+
+    assert result.exit_code == 0
+    assert result.output.count(_BATCH_EOR) == 2
+
+    blocks = [block for block in result.output.split(_BATCH_EOR + "\n") if block]
+    assert len(blocks) == 2
+
+    # First block: error JSON ({"error": "...", "type": "..."}).
+    error_payload = json.loads(blocks[0].strip().splitlines()[-1])
+    assert "error" in error_payload
+    assert "type" in error_payload
+
+    # Second block: successful version JSON.
+    version_payload = json.loads(blocks[1].strip())
+    assert version_payload["version"] == __version__

clients/rust/crates/mxgw-cli/src/main.rs

@@ -9,6 +9,7 @@
 #![warn(missing_docs)]
 
 use std::env;
+use std::io::{self, BufRead, Write};
 use std::path::PathBuf;
 use std::process::ExitCode;
 use std::time::Duration;
@@ -189,6 +190,13 @@ enum Command {
         #[arg(long)]
         json: bool,
     },
+    /// Read commands from stdin, one per line, execute each in sequence, and
+    /// write `__MXGW_BATCH_EOR__` to stdout after every result.  Errors are
+    /// written as `{"error":"…","type":"error"}` JSON to stdout (not stderr)
+    /// so the harness can parse them without interleaving stderr.  The loop
+    /// never terminates on command error; only stdin EOF (or an empty line)
+    /// ends the session.
+    Batch,
     #[command(subcommand)]
     Galaxy(GalaxyCommand),
 }
@@ -297,7 +305,11 @@ enum CliValueType {
 #[tokio::main]
 async fn main() -> ExitCode {
     let cli = Cli::parse();
-    match run(cli).await {
+    let result = match cli.command {
+        Command::Batch => run_batch().await,
+        command => dispatch(command).await,
+    };
+    match result {
         Ok(()) => ExitCode::SUCCESS,
         Err(error) => {
             eprintln!("{error}");
@@ -306,8 +318,17 @@ async fn main() -> ExitCode {
     }
 }
 
-async fn run(cli: Cli) -> Result<(), Error> {
+/// Dispatch a parsed [`Command`] to its handler.  All subcommands except
-    match cli.command {
+/// [`Command::Batch`] are handled here; `Batch` is handled separately in
+/// `main` to avoid mutual recursion between `dispatch` and `run_batch`.
+async fn dispatch(command: Command) -> Result<(), Error> {
+    match command {
+        Command::Batch => {
+            return Err(Error::InvalidArgument {
+                name: "batch".to_owned(),
+                detail: "batch cannot be nested inside another batch session".to_owned(),
+            });
+        }
         Command::Version { json, .. } => print_version(json),
         Command::Ping {
             connection,
@@ -706,6 +727,76 @@ async fn session_for(
     Ok(client.session(session_id))
 }
 
+/// End-of-result sentinel written to stdout after every batch command.
+const BATCH_EOR: &str = "__MXGW_BATCH_EOR__";
+
+/// Run the batch loop: read one command line at a time from stdin, dispatch
+/// each through the normal [`dispatch`] path, and write [`BATCH_EOR`] to
+/// stdout after every result.  Errors are serialised as JSON to stdout so
+/// the harness can parse them without interleaving stderr.  The loop never
+/// terminates on command error; only stdin EOF or an empty line ends the
+/// session.
+async fn run_batch() -> Result<(), Error> {
+    let stdin = io::stdin();
+    let stdout = io::stdout();
+
+    for line in stdin.lock().lines() {
+        let line = line.map_err(|e| Error::InvalidArgument {
+            name: "stdin".to_owned(),
+            detail: e.to_string(),
+        })?;
+
+        if line.is_empty() {
+            break;
+        }
+
+        let parts: Vec<&str> = line.split_ascii_whitespace().collect();
+        if parts.is_empty() {
+            println!("{BATCH_EOR}");
+            stdout.lock().flush().ok();
+            continue;
+        }
+
+        // Re-parse the split arguments under a fresh Cli, prepending the
+        // program-name placeholder so clap sees a complete argv[].
+        let parse_result =
+            Cli::try_parse_from(std::iter::once("mxgw-cli").chain(parts.iter().copied()));
+
+        let outcome: Result<(), Error> = match parse_result {
+            Ok(cli) => {
+                // Spawn on a new tokio task so each command runs with a fresh
+                // stack, avoiding stack overflow from the large dispatch future.
+                tokio::task::spawn(dispatch(cli.command))
+                    .await
+                    .unwrap_or_else(|join_err| {
+                        Err(Error::InvalidArgument {
+                            name: "task".to_owned(),
+                            detail: join_err.to_string(),
+                        })
+                    })
+            }
+            Err(clap_err) => Err(Error::InvalidArgument {
+                name: "args".to_owned(),
+                detail: clap_err.to_string(),
+            }),
+        };
+
+        if let Err(err) = outcome {
+            // Write error as JSON to stdout so the harness sees it in the
+            // same stream as normal output, framed by the EOR sentinel.
+            println!(
+                "{}",
+                serde_json::json!({ "error": err.to_string(), "type": "error" })
+            );
+        }
+
+        println!("{BATCH_EOR}");
+        stdout.lock().flush().ok();
+    }
+
+    Ok(())
+}
+
 fn print_version(use_json: bool) {
     if use_json {
         println!("{}", version_json());
@@ -1073,6 +1164,17 @@ mod tests {
         assert!(parsed.is_ok(), "parse failed: {parsed:?}");
     }
 
+    #[test]
+    fn parses_batch_command() {
+        let parsed = Cli::try_parse_from(["mxgw", "batch"]);
+        assert!(parsed.is_ok(), "parse failed: {parsed:?}");
+    }
+
+    #[test]
+    fn batch_eor_marker_is_stable() {
+        assert_eq!(super::BATCH_EOR, "__MXGW_BATCH_EOR__");
+    }
+
     #[test]
     fn rfc3339_parser_round_trips_z_and_offset_inputs() {
         // 2026-04-28T15:30:00Z = 1_777_995_000 (sanity-checked once below)

scripts/run-client-e2e-tests.ps1

@@ -702,7 +702,7 @@ function Get-ClientCommand {
         }
         "python" {
             $arguments = @(
-                "-m", "mxgateway_cli", $Operation,
+                "-m", "zb_mom_ww_mxgateway_cli", $Operation,
                 "--endpoint", $hostEndpoint,
                 "--api-key-env", $ApiKeyEnvName,
                 "--plaintext",