fix(ablegacy): wire the authored probeTimeoutSeconds into Test Connect

Dead config field (user decision: wire them all): the AdminUI form authors
probeTimeoutSeconds ("Admin UI probe timeout", default 5) but AbLegacyDriverProbe
never read it, so Test Connect always ran on the caller's budget. It now
tightens that budget (never raises it), the same rule as the Galaxy probe; a
non-positive value keeps the caller's budget.

Refs #738
Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/AbLegacyDriverProbe.cs

@@ -55,6 +55,10 @@ public sealed class AbLegacyDriverProbe : IDriverProbe
         catch (Exception ex) { return new(false, $"Config JSON is invalid: {ex.Message}", null); }
         if (opts is null) return new(false, "Config JSON deserialized to null.", null);
 
+        // The authored "Admin UI probe timeout" (probeTimeoutSeconds) tightens the caller's budget. It was parsed by
+        // nothing before: Test Connect always ran on the caller's budget alone.
+        timeout = EffectiveTimeout(timeout, opts.ProbeTimeoutSeconds);
+
         var (parsed, firstDevice) = ExtractTarget(opts);
         if (parsed is null || string.IsNullOrWhiteSpace(parsed.Gateway) || parsed.Port <= 0)
             return new(false, "Config has no host/port to probe.", null);
@@ -169,6 +173,22 @@ public sealed class AbLegacyDriverProbe : IDriverProbe
     /// <returns>Whether the status proves the controller answered.</returns>
     internal static bool IsReachableStatus(AbStatus s) => s is AbStatus.Ok or AbStatus.NotFound;
 
+    /// <summary>
+    ///     The deadline the probe runs under: the caller's budget, tightened by the config's
+    ///     <see cref="AbLegacyDriverOptions.ProbeTimeoutSeconds"/> when that is positive and shorter (same rule as the
+    ///     Galaxy probe). A non-positive caller budget is floored to 1 s first.
+    /// </summary>
+    /// <param name="callerTimeout">The budget the host handed the probe.</param>
+    /// <param name="configuredSeconds">The config's <c>probeTimeoutSeconds</c>; ignored when not positive.</param>
+    /// <returns>The effective probe deadline.</returns>
+    internal static TimeSpan EffectiveTimeout(TimeSpan callerTimeout, int configuredSeconds)
+    {
+        var caller = callerTimeout > TimeSpan.Zero ? callerTimeout : TimeSpan.FromSeconds(1);
+        if (configuredSeconds <= 0) return caller;
+        var configured = TimeSpan.FromSeconds(configuredSeconds);
+        return configured < caller ? configured : caller;
+    }
+
     private static (AbLegacyHostAddress? parsed, AbLegacyDeviceOptions? device) ExtractTarget(AbLegacyDriverOptions opts)
     {
         // Parse the first device's ab:// host address to extract the gateway IP + EIP port.

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

@@ -192,6 +192,40 @@ public sealed class AbLegacyDriverProbeTests
         LibplctagLegacyName.Translate(status!).ShouldBe("S2:0");
     }
 
+    private sealed class StallingTag(AbLegacyTagCreateParams p) : FakeAbLegacyTag(p)
+    {
+        public override Task InitializeAsync(CancellationToken ct) => Task.Delay(Timeout.Infinite, ct);
+    }
+
+    /// <summary>
+    ///     The authored <c>probeTimeoutSeconds</c> ("Admin UI probe timeout") was parsed by nothing — Test Connect ran
+    ///     on the caller's budget alone. It now tightens that budget (never raises it); absent or non-positive keeps
+    ///     the caller's budget (the positive control).
+    /// </summary>
+    [Theory]
+    [InlineData(",\"probeTimeoutSeconds\":1", "1s")]
+    [InlineData(",\"probeTimeoutSeconds\":30", "2s")]
+    [InlineData("", "2s")]
+    [InlineData(",\"probeTimeoutSeconds\":0", "2s")]
+    public async Task Configured_probe_timeout_tightens_the_caller_budget(string key, string expectedBudget)
+    {
+        var listener = new TcpListener(IPAddress.Loopback, 0);
+        listener.Start();
+        try
+        {
+            var port = ((IPEndPoint)listener.LocalEndpoint).Port;
+            var factory = new FakeAbLegacyTagFactory { Customise = p => new StallingTag(p) };
+            var json = $"{{\"devices\":[{{\"hostAddress\":\"ab://127.0.0.1:{port}/1,0\"}}]{key}}}";
+
+            var result = await new AbLegacyDriverProbe(factory)
+                .ProbeAsync(json, TimeSpan.FromSeconds(2), TestContext.Current.CancellationToken);
+
+            result.Ok.ShouldBeFalse();
+            result.Message.ShouldBe($"Probe timed out after {expectedBudget}.");
+        }
+        finally { listener.Stop(); }
+    }
+
     [Fact]
     public async Task Unparseable_probe_address_is_a_clean_failure_not_an_exception()
     {