feat(settings): edit the OPC UA address in the settings window

AGENTS.md

@@ -32,8 +32,8 @@ the tracked file (`docs/architecture/overview.md`).
 
 The settings window (`SemiPlot.UI/Settings`) is the viewer's only writer of the section folders. It
 edits only keys that already exist, each in the file that owns it, and only the keys the operator
-changed; it creates no file, and it edits no key of `opc/` yet. The startup-failure window offers it only
-when both sections it edits, `app/` and `connection/`, read and carry every key it edits. The
+changed; it creates no file. The startup-failure window offers it only when all three sections it edits,
+`app/`, `connection/` and `opc/`, read and carry every key it edits. The
 production loaders validate a staged copy before any file is replaced, and every change takes effect at the
 next start except the theme, which every running process applies live
 (`docs/architecture/overview.md#the-live-theme`).

SemiPlot/SemiPlot.Tests.Unit/UI/Localization/ResourcesTests.cs

@@ -79,6 +79,7 @@ public void CompositeFormats_KeepTheirPlaceholder()
 	{
 		Resources.StatusLayerFormat.Should().Contain("{0}");
 		Resources.SettingsFieldRequired.Should().Contain("{0}");
+		Resources.SettingsKeyAbsent.Should().Contain("{0}").And.Contain("{1}");
 		Resources.ExportMessageStartUnreadable.Should().Contain("{0}");
 		Resources.ExportMessageEndUnreadable.Should().Contain("{0}");
 		Resources.ExportPensHeader.Should().Contain("{0}").And.Contain("{1}");

SemiPlot/SemiPlot.Tests.Unit/UI/Settings/SettingsSaveSandbox.cs

@@ -5,6 +5,7 @@
 using Microsoft.Extensions.Logging.Abstractions;
 
 using SemiPlot.Core.Configuration;
+using SemiPlot.DataSource.OpcUa.Configuration;
 using SemiPlot.DataSource.Postgres.Configuration;
 using SemiPlot.UI.Settings;
 using SemiPlot.UI.Startup;
@@ -25,6 +26,7 @@ public SettingsSaveSandbox()
 		ConfigDirectory = _temporary.Path;
 		AppDirectory = Path.Combine(ConfigDirectory, StartupSequence.SettingsDirectoryName);
 		ConnectionDirectory = Path.Combine(ConfigDirectory, StartupProbe.ConnectionDirectoryName);
+		OpcDirectory = Path.Combine(ConfigDirectory, StartupProbe.OpcDirectoryName);
 		ShippedConfiguration.CopyTo(ConfigDirectory, "secret");
 	}
 
@@ -34,6 +36,8 @@ public SettingsSaveSandbox()
 
 	public string ConnectionDirectory { get; }
 
+	public string OpcDirectory { get; }
+
 	public string ConnectionFile => Path.Combine(ConnectionDirectory, ConnectionFileName);
 
 	public void Dispose()
@@ -61,7 +65,13 @@ public static TError SingleError<TError>(Result result)
 
 	public string DirectoryOf(ConfigurationSectionName section)
 	{
-		return section == ConfigurationSectionName.App ? AppDirectory : ConnectionDirectory;
+		return section switch
+		{
+			ConfigurationSectionName.App => AppDirectory,
+			ConfigurationSectionName.Connection => ConnectionDirectory,
+			ConfigurationSectionName.Opc => OpcDirectory,
+			_ => throw new ArgumentOutOfRangeException(nameof(section), section, null)
+		};
 	}
 
 	public Result Save(IReadOnlyDictionary<ConfigurationSectionName, IReadOnlyDictionary<string, string>> edits)
@@ -78,6 +88,15 @@ public PostgresConnectionSettings LoadConnection()
 		return loaded.Value;
 	}
 
+	public OpcUaConnectionSettings LoadOpc()
+	{
+		var loaded = OpcUaConnectionLoader.Load(OpcDirectory);
+
+		loaded.IsSuccess.Should().BeTrue(Describe(loaded));
+
+		return loaded.Value;
+	}
+
 	public Dictionary<string, byte[]> Snapshot()
 	{
 		return Directory.GetFiles(ConfigDirectory, "*", SearchOption.AllDirectories)

SemiPlot/SemiPlot.Tests.Unit/UI/Settings/SettingsSaveTests.cs

@@ -7,6 +7,7 @@
 
 using SemiPlot.Core.Configuration;
 using SemiPlot.Core.Data.Errors;
+using SemiPlot.DataSource.OpcUa.Configuration;
 using SemiPlot.DataSource.Postgres.Configuration;
 using SemiPlot.UI.Messages;
 using SemiPlot.UI.Settings;
@@ -38,6 +39,8 @@ public void Dispose()
 	[InlineData(ConfigurationSectionName.Connection, "port", "70000", ConnectionFileProblem.OutOfRange)]
 	[InlineData(ConfigurationSectionName.Connection, "host", "scada-01", ConnectionFileProblem.HostNotIPv4)]
 	[InlineData(ConfigurationSectionName.Connection, "password", "", ConnectionFileProblem.MissingField)]
+	[InlineData(ConfigurationSectionName.Opc, "port", "70000", ConnectionFileProblem.OutOfRange)]
+	[InlineData(ConfigurationSectionName.Opc, "host", "scada-01", ConnectionFileProblem.HostNotIPv4)]
 	public void AnInvalidValueIsRefusedAndNoFileChanges(
 		ConfigurationSectionName section,
 		string key,
@@ -58,6 +61,7 @@ public void AnInvalidValueIsRefusedAndNoFileChanges(
 		problem.Should().Be(expectedProblem);
 		(error as AppSettingsError)?.Key.Should().Be(key);
 		(error as ConnectionFileError)?.Fields.Should().Equal(key);
+		(error as ConnectionFileError)?.Section.Should().Be(section);
 		_sandbox.ShouldMatch(before);
 	}
 
@@ -253,6 +257,7 @@ public void AnUnmodifiedShippedCopyWithOnlyThePasswordFilledPromotes()
 	[Theory]
 	[InlineData(ConfigurationSectionName.App, "locale", "de")]
 	[InlineData(ConfigurationSectionName.Connection, "port", "70000")]
+	[InlineData(ConfigurationSectionName.Opc, "port", "70000")]
 	public void ARefusedSaveNamesTheOperatorsFolderAndNeverTheStagingOne(
 		ConfigurationSectionName section,
 		string key,
@@ -271,8 +276,53 @@ public void ARefusedSaveNamesTheOperatorsFolderAndNeverTheStagingOne(
 		};
 		path.Should().Be(realDirectory);
 		(error as ConnectionFileError)?.Fields.Should().Equal(key);
+		(error as ConnectionFileError)?.Section.Should().Be(section);
 		var detail = ArchiveFailureMapper.Map(error).Detail;
 		detail.Should().Contain(realDirectory).And.NotContain(SettingsSave.StagingPrefix);
 	}
 
+	[Fact]
+	public void AnOpcEditReachesTheOpcFileAndLeavesTheOtherSectionsByteIdentical()
+	{
+		var before = _sandbox.Snapshot();
+
+		var result = _sandbox.Save(Edit(ConfigurationSectionName.Opc, ("port", "55875")));
+
+		result.IsSuccess.Should().BeTrue(Describe(result));
+		var opc = _sandbox.LoadOpc();
+		opc.Host.Should().Be("127.0.0.1");
+		opc.Port.Should().Be(55875);
+		var after = _sandbox.Snapshot();
+		after.Keys.Should().BeEquivalentTo(before.Keys, "the save creates no file");
+		var otherSections = before.Keys
+			.Where(file => Path.GetDirectoryName(file)
+				is StartupSequence.SettingsDirectoryName or StartupProbe.ConnectionDirectoryName)
+			.ToList();
+		otherSections.Should().HaveCount(2, "the shipped set carries one app file and one connection file");
+
+		foreach (var file in otherSections)
+		{
+			after[file].Should().Equal(before[file], file);
+		}
+
+		_sandbox.StagingDirectories().Should().BeEmpty();
+	}
+
+	[Fact]
+	public void TheCertificateStoreUnderTheOpcSectionSurvivesASaveUntouched()
+	{
+		var certificates = Path.Combine(
+			_sandbox.OpcDirectory, OpcUaConnectionLoader.CertificateStoreDirectoryName, "own", "certs");
+		Directory.CreateDirectory(certificates);
+		var certificate = Path.Combine(certificates, "semiplot.der");
+		byte[] content = [0x30, 0x82, 0x01, 0x0a];
+		File.WriteAllBytes(certificate, content);
+
+		var result = _sandbox.Save(Edit(ConfigurationSectionName.Opc, ("port", "55875")));
+
+		result.IsSuccess.Should().BeTrue(Describe(result));
+		_sandbox.LoadOpc().Port.Should().Be(55875);
+		File.ReadAllBytes(certificate).Should().Equal(content);
+		_sandbox.StagingDirectories().Should().BeEmpty();
+	}
 }

SemiPlot/SemiPlot.Tests.Unit/UI/Settings/SettingsViewModelStand.cs

@@ -13,12 +13,9 @@ public static SettingsViewModel Build(
 		MessagePanelViewModel messagePanel,
 		Action? restartApplication = null)
 	{
-		var (app, connection) = SettingsSave.ReadOwned(configDirectory);
-
 		return new SettingsViewModel(
 			configDirectory,
-			app,
-			connection,
+			SettingsSave.ReadOwned(configDirectory),
 			messagePanel,
 			NullLogger<SettingsViewModel>.Instance,
 			restartApplication ?? (() => { }));