fixes: MRN generation race condition and Sepsis bundle creation race condition (TOCTOU)

VigilCareClinicalAPI/Configuration/PatientOptions.cs

@@ -0,0 +1,7 @@
+public class PatientOptions
+{
+    public const string Section = "Patient";
+
+    public string MrnPrefix { get; set; } = "MRN";
+    public int MrnDigits { get; set; } = 6;
+}

VigilCareClinicalAPI/Migrations/20260621082241_AddMrnSequence.cs

@@ -0,0 +1,36 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace VigilCareClinicalAPI.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddMrnSequence : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.Sql(@"
+                DO $$
+                DECLARE
+                    next_val bigint;
+                BEGIN
+                    SELECT COALESCE(MAX(
+                        CASE WHEN mrn ~ '^MRN-[0-9]+$'
+                             THEN CAST(SUBSTRING(mrn FROM 5) AS bigint)
+                             ELSE 0
+                        END
+                    ), 0) + 1 INTO next_val FROM patients;
+
+                    EXECUTE format('CREATE SEQUENCE mrn_seq START WITH %s INCREMENT BY 1', next_val);
+                END $$;
+            ");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.Sql("DROP SEQUENCE IF EXISTS mrn_seq;");
+        }
+    }
+}

VigilCareClinicalAPI/Migrations/20260621083035_AddSepsisBundleUniqueInProgressIndex.cs

@@ -0,0 +1,26 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace VigilCareClinicalAPI.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddSepsisBundleUniqueInProgressIndex : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.Sql(@"
+                CREATE UNIQUE INDEX ix_sepsis_bundles_encounter_in_progress
+                ON sepsis_bundles (encounter_id)
+                WHERE compliance_status = 'IN_PROGRESS';
+            ");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.Sql("DROP INDEX IF EXISTS ix_sepsis_bundles_encounter_in_progress;");
+        }
+    }
+}

VigilCareClinicalAPI/Program.cs

@@ -119,6 +119,9 @@ try
     builder.Services.Configure<FhirOptions>(
         builder.Configuration.GetSection(FhirOptions.Section));
 
+    builder.Services.Configure<PatientOptions>(
+        builder.Configuration.GetSection(PatientOptions.Section));
+
     builder.Services.AddCors(options =>
     {
         options.AddPolicy("Dashboard", policy =>

VigilCareClinicalAPI/Services/PatientService.cs

@@ -1,29 +1,32 @@
 using System.Text.Json;
 using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Options;
 
 public class PatientService : IPatientService
 {
     private readonly AppDbContext _db;
     private readonly IExternalIdentifierService _identifiers;
     private readonly IAuditService _audit;
+    private readonly PatientOptions _options;
 
     public PatientService(
         AppDbContext db,
         IExternalIdentifierService identifiers,
-        IAuditService audit)
+        IAuditService audit,
+        IOptions<PatientOptions> options)
     {
         _db = db;
         _identifiers = identifiers;
         _audit = audit;
+        _options = options.Value;
     }
 
     public async Task<Patient> RegisterAsync(RegisterPatientRequest req)
     {
-        var mrn = await GenerateMrnAsync();
         var patient = new Patient
         {
             Id = Guid.NewGuid(),
-            Mrn = mrn,
+            Mrn = await GenerateMrnAsync(),
             FirstName = req.FirstName,
             LastName = req.LastName,
             DateOfBirth = req.DateOfBirth,
@@ -35,7 +38,18 @@ public class PatientService : IPatientService
             CreatedAt = DateTimeOffset.UtcNow
         };
         _db.Patients.Add(patient);
-        await _db.SaveChangesAsync();
+
+        try
+        {
+            await _db.SaveChangesAsync();
+        }
+        catch (DbUpdateException ex) when (IsMrnUniqueViolation(ex))
+        {
+            _db.Entry(patient).State = EntityState.Detached;
+            patient.Mrn = await GenerateMrnAsync();
+            _db.Patients.Add(patient);
+            await _db.SaveChangesAsync();
+        }
 
         await _audit.WriteAsync(
             AuditAction.PatientRegistered,
@@ -46,6 +60,13 @@ public class PatientService : IPatientService
         return patient;
     }
 
+    private static bool IsMrnUniqueViolation(DbUpdateException ex)
+    {
+        return ex.InnerException is Npgsql.PostgresException pg
+            && pg.SqlState == "23505"
+            && pg.ConstraintName?.Contains("mrn") == true;
+    }
+
     public async Task<PagedResult<Patient>> ListAsync(
         string? q, int page, int pageSize)
     {
@@ -196,7 +217,9 @@ public class PatientService : IPatientService
 
     private async Task<string> GenerateMrnAsync()
     {
-        var count = await _db.Patients.CountAsync();
-        return $"MRN-{(count + 1):D6}";
+        var seq = await _db.Database
+            .SqlQueryRaw<long>("SELECT nextval('mrn_seq') AS \"Value\"")
+            .SingleAsync();
+        return $"{_options.MrnPrefix}-{seq.ToString($"D{_options.MrnDigits}")}";
     }
 }

VigilCareClinicalAPI/Services/SepsisBundleService.cs

@@ -82,7 +82,18 @@ public class SepsisBundleService : ISepsisBundleService
             CreatedAt = DateTimeOffset.UtcNow
         });
 
-        await _db.SaveChangesAsync(ct);
+        try
+        {
+            await _db.SaveChangesAsync(ct);
+        }
+        catch (DbUpdateException ex)
+            when (ex.InnerException is Npgsql.PostgresException { SqlState: "23505" } pg
+                  && pg.ConstraintName == "ix_sepsis_bundles_encounter_in_progress")
+        {
+            _db.ChangeTracker.Clear();
+            return null;
+        }
+
         return bundle;
     }