Refactor code structure for improved readability and maintainability; optimize performance in key functions.

src/Policy/__Libraries/StellaOps.Policy.Exceptions/Models/RecheckPolicy.cs

@@ -0,0 +1,157 @@
+using System.Collections.Immutable;
+using System.Linq;
+
+namespace StellaOps.Policy.Exceptions.Models;
+
+/// <summary>
+/// Policy defining conditions that trigger exception re-evaluation.
+/// When any condition is met, the exception may be invalidated or flagged.
+/// </summary>
+public sealed record RecheckPolicy
+{
+    /// <summary>
+    /// Unique identifier for this policy configuration.
+    /// </summary>
+    public required string PolicyId { get; init; }
+
+    /// <summary>
+    /// Human-readable name for this policy.
+    /// </summary>
+    public required string Name { get; init; }
+
+    /// <summary>
+    /// Conditions that trigger recheck.
+    /// </summary>
+    public required ImmutableArray<RecheckCondition> Conditions { get; init; }
+
+    /// <summary>
+    /// Default action when any condition is triggered.
+    /// </summary>
+    public required RecheckAction DefaultAction { get; init; }
+
+    /// <summary>
+    /// Whether this policy is active.
+    /// </summary>
+    public bool IsActive { get; init; } = true;
+
+    /// <summary>
+    /// When this policy was created.
+    /// </summary>
+    public required DateTimeOffset CreatedAt { get; init; }
+}
+
+/// <summary>
+/// A single condition that triggers exception re-evaluation.
+/// </summary>
+public sealed record RecheckCondition
+{
+    /// <summary>
+    /// Type of condition to check.
+    /// </summary>
+    public required RecheckConditionType Type { get; init; }
+
+    /// <summary>
+    /// Threshold value (interpretation depends on Type).
+    /// </summary>
+    public decimal? Threshold { get; init; }
+
+    /// <summary>
+    /// Environment scopes where this condition applies.
+    /// </summary>
+    public ImmutableArray<string> EnvironmentScope { get; init; } = [];
+
+    /// <summary>
+    /// Action to take when this specific condition is triggered.
+    /// If null, uses policy's DefaultAction.
+    /// </summary>
+    public RecheckAction? Action { get; init; }
+
+    /// <summary>
+    /// Human-readable description of this condition.
+    /// </summary>
+    public string? Description { get; init; }
+}
+
+/// <summary>
+/// Types of recheck conditions.
+/// </summary>
+public enum RecheckConditionType
+{
+    /// <summary>Reachability graph changes (new paths discovered).</summary>
+    ReachGraphChange,
+
+    /// <summary>EPSS score exceeds threshold.</summary>
+    EPSSAbove,
+
+    /// <summary>CVSS score exceeds threshold.</summary>
+    CVSSAbove,
+
+    /// <summary>Unknown budget exceeds threshold.</summary>
+    UnknownsAbove,
+
+    /// <summary>New CVE added to same package.</summary>
+    NewCVEInPackage,
+
+    /// <summary>KEV (Known Exploited Vulnerability) flag set.</summary>
+    KEVFlagged,
+
+    /// <summary>Exception nearing expiry (days before).</summary>
+    ExpiryWithin,
+
+    /// <summary>VEX status changes (e.g., from NotAffected to Affected).</summary>
+    VEXStatusChange,
+
+    /// <summary>Package version changes.</summary>
+    PackageVersionChange
+}
+
+/// <summary>
+/// Action to take when a recheck condition is triggered.
+/// </summary>
+public enum RecheckAction
+{
+    /// <summary>Log warning but allow exception to remain active.</summary>
+    Warn,
+
+    /// <summary>Require manual re-approval of exception.</summary>
+    RequireReapproval,
+
+    /// <summary>Automatically revoke the exception.</summary>
+    Revoke,
+
+    /// <summary>Block build/deployment pipeline.</summary>
+    Block
+}
+
+/// <summary>
+/// Result of evaluating recheck conditions against an exception.
+/// </summary>
+public sealed record RecheckEvaluationResult
+{
+    /// <summary>Whether any conditions were triggered.</summary>
+    public required bool IsTriggered { get; init; }
+
+    /// <summary>List of triggered conditions with details.</summary>
+    public required ImmutableArray<TriggeredCondition> TriggeredConditions { get; init; }
+
+    /// <summary>Recommended action based on triggered conditions.</summary>
+    public required RecheckAction? RecommendedAction { get; init; }
+
+    /// <summary>When this evaluation was performed.</summary>
+    public required DateTimeOffset EvaluatedAt { get; init; }
+
+    /// <summary>Human-readable summary.</summary>
+    public string Summary => IsTriggered
+        ? $"{TriggeredConditions.Length} condition(s) triggered: {string.Join(", ", TriggeredConditions.Select(t => t.Type))}"
+        : "No conditions triggered";
+}
+
+/// <summary>
+/// Details of a triggered recheck condition.
+/// </summary>
+public sealed record TriggeredCondition(
+    RecheckConditionType Type,
+    string Description,
+    decimal? CurrentValue,
+    decimal? ThresholdValue,
+    RecheckAction Action);