sprints and audit work

src/Policy/__Libraries/StellaOps.Policy.Determinization/Models/SignalGap.cs

@@ -0,0 +1,57 @@
+using System.Text.Json.Serialization;
+
+namespace StellaOps.Policy.Determinization.Models;
+
+/// <summary>
+/// Describes a missing signal that contributes to uncertainty.
+/// </summary>
+public sealed record SignalGap
+{
+    /// <summary>
+    /// Signal name (e.g., "epss", "vex", "reachability").
+    /// </summary>
+    [JsonPropertyName("signal")]
+    public required string Signal { get; init; }
+
+    /// <summary>
+    /// Reason the signal is missing.
+    /// </summary>
+    [JsonPropertyName("reason")]
+    public required SignalGapReason Reason { get; init; }
+
+    /// <summary>
+    /// Prior assumption used in absence of signal.
+    /// </summary>
+    [JsonPropertyName("prior")]
+    public double? Prior { get; init; }
+
+    /// <summary>
+    /// Weight this signal contributes to total uncertainty.
+    /// </summary>
+    [JsonPropertyName("weight")]
+    public double Weight { get; init; }
+
+    /// <summary>
+    /// Human-readable description.
+    /// </summary>
+    [JsonPropertyName("description")]
+    public string? Description { get; init; }
+}
+
+/// <summary>
+/// Reason a signal is missing.
+/// </summary>
+public enum SignalGapReason
+{
+    /// <summary>Signal not yet queried.</summary>
+    NotQueried,
+
+    /// <summary>Signal legitimately does not exist (e.g., EPSS not published yet).</summary>
+    NotAvailable,
+
+    /// <summary>Signal query failed due to external error.</summary>
+    QueryFailed,
+
+    /// <summary>Signal not applicable for this artifact type.</summary>
+    NotApplicable
+}