chore: initial project import

backend/shared/Monitor.Protocol/Raw/StreamBuilder.cs

@@ -0,0 +1,58 @@
+namespace Monitor.Protocol;
+
+/// <summary>按 <see cref="StreamSpec"/> 逐行构造一个 <see cref="RawStream"/>（用于测试、模拟器和离线工具，不用于节点热路径）。</summary>
+public sealed class StreamBuilder
+{
+    private readonly StreamSpec _spec;
+    private readonly List<long>[] _values;
+    private readonly List<bool>[] _valid;
+
+    public StreamBuilder(StreamSpec spec)
+    {
+        _spec = spec;
+        _values = new List<long>[spec.Columns.Count];
+        _valid = new List<bool>[spec.Columns.Count];
+        for (int i = 0; i < _values.Length; i++)
+        {
+            _values[i] = [];
+            _valid[i] = [];
+        }
+    }
+
+    public int Count { get; private set; }
+
+    /// <summary>添加一行；<c>null</c> 表示缺失值（只允许用于可空列）。</summary>
+    public StreamBuilder Add(params long?[] row)
+    {
+        if (row.Length != _values.Length)
+        {
+            throw new ArgumentException($"stream {_spec.Name} expects {_values.Length} values, got {row.Length}", nameof(row));
+        }
+
+        for (int i = 0; i < row.Length; i++)
+        {
+            if (row[i] is null && !_spec.Columns[i].Nullable)
+            {
+                throw new ArgumentException($"column {_spec.Columns[i].Name} is not nullable", nameof(row));
+            }
+
+            _values[i].Add(row[i] ?? 0);
+            _valid[i].Add(row[i] is not null);
+        }
+
+        Count++;
+        return this;
+    }
+
+    public RawStream Build()
+    {
+        var columns = new List<RawColumn>(_values.Length);
+        for (int i = 0; i < _values.Length; i++)
+        {
+            ColumnSpec spec = _spec.Columns[i];
+            columns.Add(new RawColumn(spec.Name, spec.Type, spec.Enc, spec.Nullable, spec.Role, [.. _values[i]], spec.Nullable ? [.. _valid[i]] : null));
+        }
+
+        return new RawStream(_spec.Name, Count, columns);
+    }
+}