feat(notify): dual-write audit events to Timeline unified sink

Sprint SPRINT_20260408_005 DEPRECATE-001 (Notify, third service).

Same pattern as Authority + Policy dual-write: NotifyAuditRepository
now fans out to Timeline via the optional IAuditEventEmitter.
Fire-and-forget; local write stays authoritative.

Remaining DEPRECATE-001 services: Scheduler (ISchedulerAuditService),
JobEngine/ReleaseOrchestrator (PostgresAuditRepository.AppendAsync),
Attestor (audit log inserts).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/Notify/__Libraries/StellaOps.Notify.Persistence/Postgres/Repositories/NotifyAuditRepository.cs

@@ -1,5 +1,6 @@
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.Logging;
+using StellaOps.Audit.Emission;
 using StellaOps.Notify.Persistence.EfCore.Context;
 using StellaOps.Notify.Persistence.Postgres.Models;
 
@@ -10,11 +11,13 @@ public sealed class NotifyAuditRepository : INotifyAuditRepository
     private const int CommandTimeoutSeconds = 30;
     private readonly NotifyDataSource _dataSource;
     private readonly ILogger<NotifyAuditRepository> _logger;
+    private readonly IAuditEventEmitter? _timelineEmitter;
 
-    public NotifyAuditRepository(NotifyDataSource dataSource, ILogger<NotifyAuditRepository> logger)
+    public NotifyAuditRepository(NotifyDataSource dataSource, ILogger<NotifyAuditRepository> logger, IAuditEventEmitter? timelineEmitter = null)
     {
         _dataSource = dataSource;
         _logger = logger;
+        _timelineEmitter = timelineEmitter;
     }
 
     public async Task<long> CreateAsync(NotifyAuditEntity audit, CancellationToken cancellationToken = default)
@@ -23,9 +26,60 @@ public sealed class NotifyAuditRepository : INotifyAuditRepository
         await using var dbContext = NotifyDbContextFactory.Create(connection, CommandTimeoutSeconds, GetSchemaName());
         dbContext.Audit.Add(audit);
         await dbContext.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
+
+        // DEPRECATE-001: dual-write to Timeline. Fire-and-forget; local write remains authoritative.
+        if (_timelineEmitter is not null)
+        {
+            try
+            {
+                await _timelineEmitter.EmitAsync(MapToTimelinePayload(audit), cancellationToken).ConfigureAwait(false);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogWarning(ex, "Failed to emit notify audit event to Timeline (local write succeeded, id={AuditId})", audit.Id);
+            }
+        }
+
         return audit.Id;
     }
 
+    private static AuditEventPayload MapToTimelinePayload(NotifyAuditEntity audit)
+    {
+        var details = new Dictionary<string, object?>(StringComparer.Ordinal)
+        {
+            ["localAuditId"] = audit.Id
+        };
+        if (!string.IsNullOrWhiteSpace(audit.Details))
+        {
+            details["details"] = audit.Details;
+        }
+
+        return new AuditEventPayload
+        {
+            Id = $"notify-{audit.Id}",
+            Timestamp = audit.CreatedAt,
+            Module = "notify",
+            Action = audit.Action ?? "unknown",
+            Severity = "info",
+            Actor = new AuditActorPayload
+            {
+                Id = audit.UserId?.ToString() ?? "notify-system",
+                Name = audit.UserId?.ToString() ?? "notify-system",
+                Type = audit.UserId.HasValue ? "user" : "system"
+            },
+            Resource = new AuditResourcePayload
+            {
+                Type = audit.ResourceType ?? "notify_resource",
+                Id = audit.ResourceId ?? audit.Id.ToString(System.Globalization.CultureInfo.InvariantCulture)
+            },
+            Description = audit.Action ?? "notify audit event",
+            Details = details,
+            CorrelationId = audit.CorrelationId,
+            TenantId = audit.TenantId,
+            Tags = new[] { "notify", audit.Action ?? "unknown" }
+        };
+    }
+
     public async Task<IReadOnlyList<NotifyAuditEntity>> ListAsync(string tenantId, int limit = 100, int offset = 0, CancellationToken cancellationToken = default)
     {
         await using var connection = await _dataSource.OpenConnectionAsync(tenantId, "reader", cancellationToken).ConfigureAwait(false);

src/Notify/__Libraries/StellaOps.Notify.Persistence/StellaOps.Notify.Persistence.csproj

@@ -23,6 +23,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <ProjectReference Include="..\..\..\__Libraries\StellaOps.Audit.Emission\StellaOps.Audit.Emission.csproj" />
     <ProjectReference Include="..\StellaOps.Notify.Models\StellaOps.Notify.Models.csproj" />
     <ProjectReference Include="..\..\..\__Libraries\StellaOps.Infrastructure.Postgres\StellaOps.Infrastructure.Postgres.csproj" />
     <ProjectReference Include="..\..\..\__Libraries\StellaOps.Infrastructure.EfCore\StellaOps.Infrastructure.EfCore.csproj" />