Add PII redaction POC for secure LLM prompting.

Implements detect-redact-sanitize pipeline with regex, domain rules, and ONNX NER before the LLM boundary, plus NUnit tests and Xenovex push documentation.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/PiiRedaction.Core.Tests/Integration/RealNerPipelineTests.cs

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+using FluentAssertions;
+
+using PiiRedaction.Core.Abstractions;
+
+using PiiRedaction.Core.Models;
+
+using PiiRedaction.Core.Tests.TestSupport;
+
+using PiiRedaction.Tests.Shared;
+
+
+
+namespace PiiRedaction.Core.Tests.Integration;
+
+
+
+/// <summary>
+
+/// End-to-end pipeline proof using the real ONNX NER model (no fakes).
+
+/// </summary>
+
+[TestFixture]
+
+[Category("RealModel")]
+
+public sealed class RealNerPipelineTests : RealNerModelFixture
+
+{
+
+    private IPromptSanitizer _sanitizer = null!;
+
+
+
+    [OneTimeSetUp]
+
+    public void OneTimeSetUpPipeline()
+
+    {
+
+        _sanitizer = ProductionPipelineFactory.CreateWithRealModel(Runner);
+
+    }
+
+
+
+    [Test]
+
+    public void Sanitize_FullFinancialWithCustomer_RedactsAllPiiTypes()
+
+    {
+
+        const string prompt =
+
+            "Customer Ravi Kumar with email ravi.kumar@gmail.com and phone 9876543210 has LoanNumber LN-456789 and PAN ABCDE1234F. Please summarize this customer issue.";
+
+
+
+        var result = _sanitizer.Sanitize(new SanitizationRequest(prompt));
+
+
+
+        result.SanitizedPrompt.Should().Be(
+
+            "Customer <PERSON_1> with email <EMAIL_1> and phone <PHONE_1> has LoanNumber <LOAN_NUMBER_1> and PAN <PAN_1>. Please summarize this customer issue.");
+
+
+
+        result.SanitizedPrompt.Should().NotContainAny("Ravi Kumar", "ravi.kumar@gmail.com", "9876543210", "LN-456789", "ABCDE1234F");
+
+        result.DetectedEntities.Should().Contain(entity =>
+
+            entity.Type == PiiEntityType.Person && entity.Source == PiiDetectionSource.Ner);
+
+    }
+
+
+
+    [Test]
+
+    public void Sanitize_TwoCustomersInOnePrompt_RedactsBothPeople()
+
+    {
+
+        const string prompt = "Customer Ravi Kumar and Customer Priya Nair disputed the same charge.";
+
+
+
+        var result = _sanitizer.Sanitize(new SanitizationRequest(prompt));
+
+
+
+        result.SanitizedPrompt.Should().Contain("<PERSON_1>");
+
+        result.SanitizedPrompt.Should().Contain("<PERSON_2>");
+
+        result.SanitizedPrompt.Should().NotContainAny("Ravi Kumar", "Priya Nair");
+
+        result.DetectedEntities.Count(entity => entity.Type == PiiEntityType.Person).Should().BeGreaterThanOrEqualTo(2);
+
+    }
+
+
+
+    [Test]
+
+    public void Sanitize_NoPiiCleanTicket_PassesThroughUnchanged()
+
+    {
+
+        const string prompt = "What is the status of ticket TKT-99887 and when will the API maintenance end?";
+
+
+
+        var result = _sanitizer.Sanitize(new SanitizationRequest(prompt));
+
+
+
+        result.SanitizedPrompt.Should().Be(prompt);
+
+        result.DetectedEntities.Should().BeEmpty();
+
+    }
+
+}
+
+