Phase 0 WP-0.2–0.9: Implement Commons (types, entities, interfaces, messages, protocol, tests)

- WP-0.2: Namespace/folder skeleton (26 directories)
- WP-0.3: Shared data types (6 enums, RetryPolicy, Result<T>)
- WP-0.4: 24 domain entity POCOs across 10 domain areas
- WP-0.5: 7 repository interfaces with full CRUD signatures
- WP-0.6: IAuditService cross-cutting interface
- WP-0.7: 26 message contract records across 8 concern areas
- WP-0.8: IDataConnection protocol abstraction with batch ops
- WP-0.9: 8 architectural constraint enforcement tests
All 40 tests pass, zero warnings.

src/ScadaLink.Commons/Types/Enums/AlarmState.cs

@@ -0,0 +1,7 @@
+namespace ScadaLink.Commons.Types.Enums;
+
+public enum AlarmState
+{
+    Active,
+    Normal
+}

src/ScadaLink.Commons/Types/Enums/AlarmTriggerType.cs

@@ -0,0 +1,8 @@
+namespace ScadaLink.Commons.Types.Enums;
+
+public enum AlarmTriggerType
+{
+    ValueMatch,
+    RangeViolation,
+    RateOfChange
+}

src/ScadaLink.Commons/Types/Enums/ConnectionHealth.cs

@@ -0,0 +1,9 @@
+namespace ScadaLink.Commons.Types.Enums;
+
+public enum ConnectionHealth
+{
+    Connected,
+    Disconnected,
+    Connecting,
+    Error
+}

src/ScadaLink.Commons/Types/Enums/DataType.cs

@@ -0,0 +1,12 @@
+namespace ScadaLink.Commons.Types.Enums;
+
+public enum DataType
+{
+    Boolean,
+    Int32,
+    Float,
+    Double,
+    String,
+    DateTime,
+    Binary
+}

src/ScadaLink.Commons/Types/Enums/DeploymentStatus.cs

@@ -0,0 +1,9 @@
+namespace ScadaLink.Commons.Types.Enums;
+
+public enum DeploymentStatus
+{
+    Pending,
+    InProgress,
+    Success,
+    Failed
+}

src/ScadaLink.Commons/Types/Enums/InstanceState.cs

@@ -0,0 +1,7 @@
+namespace ScadaLink.Commons.Types.Enums;
+
+public enum InstanceState
+{
+    Enabled,
+    Disabled
+}

src/ScadaLink.Commons/Types/Result.cs

@@ -0,0 +1,40 @@
+namespace ScadaLink.Commons.Types;
+
+public sealed class Result<T>
+{
+    private readonly T? _value;
+    private readonly string? _error;
+
+    private Result(T value)
+    {
+        _value = value;
+        _error = null;
+        IsSuccess = true;
+    }
+
+    private Result(string error)
+    {
+        _value = default;
+        _error = error;
+        IsSuccess = false;
+    }
+
+    public bool IsSuccess { get; }
+
+    public bool IsFailure => !IsSuccess;
+
+    public T Value => IsSuccess
+        ? _value!
+        : throw new InvalidOperationException("Cannot access Value on a failed Result. Error: " + _error);
+
+    public string Error => IsFailure
+        ? _error!
+        : throw new InvalidOperationException("Cannot access Error on a successful Result.");
+
+    public static Result<T> Success(T value) => new(value);
+
+    public static Result<T> Failure(string error) => new(error);
+
+    public TResult Match<TResult>(Func<T, TResult> onSuccess, Func<string, TResult> onFailure) =>
+        IsSuccess ? onSuccess(_value!) : onFailure(_error!);
+}

src/ScadaLink.Commons/Types/RetryPolicy.cs

@@ -0,0 +1,3 @@
+namespace ScadaLink.Commons.Types;
+
+public record RetryPolicy(int MaxRetries, TimeSpan Delay);