audit work, fixed StellaOps.sln warnings/errors, fixed tests, sprints work, new advisories

src/Timeline/AGENTS.md

@@ -0,0 +1,66 @@
+# Timeline Module - AGENTS.md
+
+## Module Overview
+
+The Timeline module provides a unified event timeline service for querying, replaying, and exporting HLC-ordered events across all StellaOps services.
+
+## Roles Expected
+
+- **Backend Engineer**: Implement API endpoints, query services, and replay orchestration
+- **QA Engineer**: Create integration tests with Testcontainers PostgreSQL
+
+## Key Documentation
+
+Before working on this module, read:
+
+1. [CLAUDE.md](../../CLAUDE.md) - Code quality rules (especially 8.2 TimeProvider, 8.18 DateTimeOffset, 8.19 HLC)
+2. [docs/modules/eventing/event-envelope-schema.md](../../docs/modules/eventing/event-envelope-schema.md)
+3. [docs/modules/scheduler/hlc-ordering.md](../../docs/modules/scheduler/hlc-ordering.md)
+
+## Working Agreements
+
+### Directory Ownership
+
+- **WebService**: `src/Timeline/StellaOps.Timeline.WebService/`
+- **Core Library**: `src/Timeline/__Libraries/StellaOps.Timeline.Core/`
+- **Tests**: `src/Timeline/__Tests/`
+
+### Dependencies
+
+- Depends on: `StellaOps.Eventing`, `StellaOps.HybridLogicalClock`, `StellaOps.Replay.Core`
+- Consumed by: UI Console (Timeline view), CLI (replay commands)
+
+### API Conventions
+
+1. All endpoints under `/api/v1/timeline`
+2. HLC timestamps returned as sortable strings
+3. Pagination via `limit`, `offset`, and `nextCursor`
+4. Export produces NDJSON by default
+
+### Testing Requirements
+
+1. Unit tests with `[Trait("Category", "Unit")]`
+2. Integration tests with `[Trait("Category", "Integration")]`
+3. Use `FakeTimeProvider` for deterministic tests
+4. Use Testcontainers for PostgreSQL integration tests
+
+## Module-Specific Rules
+
+### HLC Ordering
+
+- All queries return events ordered by HLC timestamp (ascending)
+- Critical path analysis uses wall-clock duration but references HLC for linking
+- Replay must preserve HLC ordering
+
+### Export Format
+
+```ndjson
+{"event_id":"abc123","t_hlc":"1704585600000:0:node1","correlation_id":"scan-1","kind":"ENQUEUE",...}
+{"event_id":"def456","t_hlc":"1704585600001:0:node1","correlation_id":"scan-1","kind":"EXECUTE",...}
+```
+
+### Replay Contract
+
+- Replay is read-only (dry-run mode)
+- Verify mode compares replayed state to stored state
+- Replay operations are idempotent

src/Timeline/StellaOps.Timeline.WebService/AGENTS.md

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+# Timeline WebService Module Charter
+
+## Mission
+- Provide timeline API endpoints and service orchestration.
+
+## Responsibilities
+- Implement HTTP endpoints and request validation.
+- Orchestrate persistence and timeline workflows.
+- Enforce deterministic ordering in responses.
+
+## Required Reading
+- docs/README.md
+- docs/07_HIGH_LEVEL_ARCHITECTURE.md
+- docs/modules/platform/architecture-overview.md
+- docs/modules/timeline-indexer/architecture.md
+- docs/modules/timeline-indexer/README.md
+
+## Working Agreement
+- Deterministic ordering and invariant formatting.
+- Use TimeProvider and IGuidGenerator where timestamps or IDs are created.
+- Propagate CancellationToken for async operations.
+
+## Testing Strategy
+- API tests for validation and error handling.
+- Determinism checks for response ordering.

src/Timeline/StellaOps.Timeline.WebService/Authorization/TimelineAuthorizationMiddleware.cs

@@ -0,0 +1,157 @@
+// Copyright (c) StellaOps. Licensed under the AGPL-3.0-or-later.
+
+using System.Security.Claims;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Extensions.Logging;
+
+namespace StellaOps.Timeline.WebService.Authorization;
+
+/// <summary>
+/// Middleware for authorizing timeline access based on tenant/correlation ownership.
+/// </summary>
+public sealed class TimelineAuthorizationMiddleware
+{
+    private readonly RequestDelegate _next;
+    private readonly ILogger<TimelineAuthorizationMiddleware> _logger;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="TimelineAuthorizationMiddleware"/> class.
+    /// </summary>
+    public TimelineAuthorizationMiddleware(
+        RequestDelegate next,
+        ILogger<TimelineAuthorizationMiddleware> logger)
+    {
+        _next = next ?? throw new ArgumentNullException(nameof(next));
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+    }
+
+    /// <summary>
+    /// Invokes the middleware.
+    /// </summary>
+    public async Task InvokeAsync(
+        HttpContext context,
+        ITimelineAuthorizationService authorizationService)
+    {
+        // Skip authorization for health endpoints
+        if (context.Request.Path.StartsWithSegments("/health"))
+        {
+            await _next(context);
+            return;
+        }
+
+        // Extract correlation ID from route if present
+        var correlationId = ExtractCorrelationId(context);
+
+        if (!string.IsNullOrEmpty(correlationId))
+        {
+            var user = context.User;
+            var tenantId = user.FindFirstValue("tenant_id");
+
+            if (string.IsNullOrEmpty(tenantId))
+            {
+                _logger.LogWarning("No tenant_id claim found for timeline access");
+                context.Response.StatusCode = StatusCodes.Status401Unauthorized;
+                await context.Response.WriteAsync("Unauthorized: Missing tenant claim");
+                return;
+            }
+
+            var hasAccess = await authorizationService.HasAccessToCorrelationAsync(
+                tenantId,
+                correlationId,
+                context.RequestAborted);
+
+            if (!hasAccess)
+            {
+                _logger.LogWarning(
+                    "Tenant {TenantId} denied access to correlation {CorrelationId}",
+                    tenantId,
+                    correlationId);
+                context.Response.StatusCode = StatusCodes.Status403Forbidden;
+                await context.Response.WriteAsync("Forbidden: No access to this correlation");
+                return;
+            }
+
+            // Log audit trail
+            _logger.LogInformation(
+                "Tenant {TenantId} accessed correlation {CorrelationId} via {Method} {Path}",
+                tenantId,
+                correlationId,
+                context.Request.Method,
+                context.Request.Path);
+        }
+
+        await _next(context);
+    }
+
+    private static string? ExtractCorrelationId(HttpContext context)
+    {
+        // Try to get from route values
+        if (context.Request.RouteValues.TryGetValue("correlationId", out var routeValue))
+        {
+            return routeValue?.ToString();
+        }
+
+        return null;
+    }
+}
+
+/// <summary>
+/// Service for authorizing timeline access.
+/// </summary>
+public interface ITimelineAuthorizationService
+{
+    /// <summary>
+    /// Checks if a tenant has access to a correlation ID.
+    /// </summary>
+    Task<bool> HasAccessToCorrelationAsync(
+        string tenantId,
+        string correlationId,
+        CancellationToken cancellationToken = default);
+}
+
+/// <summary>
+/// Default implementation that allows all access.
+/// Production should integrate with Authority service.
+/// </summary>
+public sealed class DefaultTimelineAuthorizationService : ITimelineAuthorizationService
+{
+    private readonly ILogger<DefaultTimelineAuthorizationService> _logger;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="DefaultTimelineAuthorizationService"/> class.
+    /// </summary>
+    public DefaultTimelineAuthorizationService(ILogger<DefaultTimelineAuthorizationService> logger)
+    {
+        _logger = logger;
+    }
+
+    /// <inheritdoc/>
+    public Task<bool> HasAccessToCorrelationAsync(
+        string tenantId,
+        string correlationId,
+        CancellationToken cancellationToken = default)
+    {
+        // Default: allow all access
+        // Production: check correlation -> tenant mapping in database or Authority
+        _logger.LogDebug(
+            "Authorization check: tenant={TenantId}, correlation={CorrelationId} -> allowed (default)",
+            tenantId,
+            correlationId);
+
+        return Task.FromResult(true);
+    }
+}
+
+/// <summary>
+/// Extension methods for timeline authorization.
+/// </summary>
+public static class TimelineAuthorizationExtensions
+{
+    /// <summary>
+    /// Adds timeline authorization middleware to the pipeline.
+    /// </summary>
+    public static IApplicationBuilder UseTimelineAuthorization(this IApplicationBuilder app)
+    {
+        return app.UseMiddleware<TimelineAuthorizationMiddleware>();
+    }
+}

src/Timeline/StellaOps.Timeline.WebService/Endpoints/ExportEndpoints.cs

@@ -0,0 +1,153 @@
+// Copyright (c) StellaOps. Licensed under the AGPL-3.0-or-later.
+
+using Microsoft.AspNetCore.Http.HttpResults;
+using StellaOps.Timeline.Core;
+
+namespace StellaOps.Timeline.WebService.Endpoints;
+
+/// <summary>
+/// Export endpoints for timeline bundles.
+/// </summary>
+public static class ExportEndpoints
+{
+    /// <summary>
+    /// Maps export endpoints.
+    /// </summary>
+    public static void MapExportEndpoints(this IEndpointRouteBuilder app)
+    {
+        var group = app.MapGroup("/api/v1/timeline")
+            .WithTags("Export")
+            .WithOpenApi();
+
+        group.MapPost("/{correlationId}/export", ExportTimelineAsync)
+            .WithName("ExportTimeline")
+            .WithDescription("Export timeline events as NDJSON bundle with optional DSSE signing");
+
+        group.MapGet("/export/{exportId}", GetExportStatusAsync)
+            .WithName("GetExportStatus")
+            .WithDescription("Get the status of an export operation");
+
+        group.MapGet("/export/{exportId}/download", DownloadExportAsync)
+            .WithName("DownloadExport")
+            .WithDescription("Download the completed export bundle");
+    }
+
+    private static async Task<Results<Accepted<ExportInitiatedResponse>, BadRequest<string>>> ExportTimelineAsync(
+        string correlationId,
+        ExportRequest request,
+        ITimelineQueryService queryService,
+        CancellationToken cancellationToken)
+    {
+        if (string.IsNullOrWhiteSpace(correlationId))
+        {
+            return TypedResults.BadRequest("Correlation ID is required");
+        }
+
+        // Validate the correlation exists
+        var result = await queryService.GetByCorrelationIdAsync(correlationId, new TimelineQueryOptions { Limit = 1 }, cancellationToken);
+        if (result.Events.Count == 0)
+        {
+            return TypedResults.BadRequest($"No events found for correlation ID: {correlationId}");
+        }
+
+        // TODO: Queue export job
+        var exportId = Guid.NewGuid().ToString("N")[..16];
+
+        return TypedResults.Accepted(
+            $"/api/v1/timeline/export/{exportId}",
+            new ExportInitiatedResponse
+            {
+                ExportId = exportId,
+                CorrelationId = correlationId,
+                Format = request.Format,
+                SignBundle = request.SignBundle,
+                Status = "INITIATED",
+                EstimatedEventCount = result.TotalCount
+            });
+    }
+
+    private static async Task<Results<Ok<ExportStatusResponse>, NotFound>> GetExportStatusAsync(
+        string exportId,
+        CancellationToken cancellationToken)
+    {
+        // TODO: Integrate with export state store
+        await Task.CompletedTask;
+
+        return TypedResults.Ok(new ExportStatusResponse
+        {
+            ExportId = exportId,
+            Status = "COMPLETED",
+            Format = "ndjson",
+            EventCount = 100,
+            FileSizeBytes = 45678,
+            CreatedAt = DateTimeOffset.UtcNow.AddMinutes(-1),
+            CompletedAt = DateTimeOffset.UtcNow.AddSeconds(-30)
+        });
+    }
+
+    private static async Task<Results<FileStreamHttpResult, NotFound>> DownloadExportAsync(
+        string exportId,
+        CancellationToken cancellationToken)
+    {
+        // TODO: Integrate with export storage
+        await Task.CompletedTask;
+
+        // Return stub for now - real implementation would stream from storage
+        var stubContent = """
+            {"event_id":"abc123","correlation_id":"scan-1","kind":"ENQUEUE"}
+            {"event_id":"def456","correlation_id":"scan-1","kind":"EXECUTE"}
+            """;
+        var stream = new MemoryStream(System.Text.Encoding.UTF8.GetBytes(stubContent));
+
+        return TypedResults.File(
+            stream,
+            contentType: "application/x-ndjson",
+            fileDownloadName: $"timeline-{exportId}.ndjson");
+    }
+}
+
+// DTOs
+public sealed record ExportRequest
+{
+    /// <summary>
+    /// Export format: "ndjson" or "json".
+    /// </summary>
+    public string Format { get; init; } = "ndjson";
+
+    /// <summary>
+    /// Whether to DSSE-sign the bundle.
+    /// </summary>
+    public bool SignBundle { get; init; } = false;
+
+    /// <summary>
+    /// Optional HLC range start.
+    /// </summary>
+    public string? FromHlc { get; init; }
+
+    /// <summary>
+    /// Optional HLC range end.
+    /// </summary>
+    public string? ToHlc { get; init; }
+}
+
+public sealed record ExportInitiatedResponse
+{
+    public required string ExportId { get; init; }
+    public required string CorrelationId { get; init; }
+    public required string Format { get; init; }
+    public bool SignBundle { get; init; }
+    public required string Status { get; init; }
+    public long EstimatedEventCount { get; init; }
+}
+
+public sealed record ExportStatusResponse
+{
+    public required string ExportId { get; init; }
+    public required string Status { get; init; }
+    public required string Format { get; init; }
+    public long EventCount { get; init; }
+    public long FileSizeBytes { get; init; }
+    public DateTimeOffset CreatedAt { get; init; }
+    public DateTimeOffset? CompletedAt { get; init; }
+    public string? Error { get; init; }
+}

src/Timeline/StellaOps.Timeline.WebService/Endpoints/HealthEndpoints.cs

@@ -0,0 +1,62 @@
+// Copyright (c) StellaOps. Licensed under the AGPL-3.0-or-later.
+
+using Microsoft.Extensions.Diagnostics.HealthChecks;
+using StellaOps.Eventing.Storage;
+
+namespace StellaOps.Timeline.WebService.Endpoints;
+
+/// <summary>
+/// Health check endpoints.
+/// </summary>
+public static class HealthEndpoints
+{
+    /// <summary>
+    /// Maps health check endpoints.
+    /// </summary>
+    public static void MapHealthEndpoints(this IEndpointRouteBuilder app)
+    {
+        app.MapHealthChecks("/health");
+        app.MapHealthChecks("/health/ready", new Microsoft.AspNetCore.Diagnostics.HealthChecks.HealthCheckOptions
+        {
+            Predicate = check => check.Tags.Contains("ready")
+        });
+        app.MapHealthChecks("/health/live", new Microsoft.AspNetCore.Diagnostics.HealthChecks.HealthCheckOptions
+        {
+            Predicate = check => check.Tags.Contains("live")
+        });
+    }
+}
+
+/// <summary>
+/// Health check for timeline service.
+/// </summary>
+public sealed class TimelineHealthCheck : IHealthCheck
+{
+    private readonly ITimelineEventStore _eventStore;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="TimelineHealthCheck"/> class.
+    /// </summary>
+    public TimelineHealthCheck(ITimelineEventStore eventStore)
+    {
+        _eventStore = eventStore;
+    }
+
+    /// <inheritdoc/>
+    public async Task<HealthCheckResult> CheckHealthAsync(
+        HealthCheckContext context,
+        CancellationToken cancellationToken = default)
+    {
+        try
+        {
+            // Simple check - try to count events for a nonexistent correlation
+            // This validates database connectivity
+            await _eventStore.CountByCorrelationIdAsync("__health_check__", cancellationToken);
+            return HealthCheckResult.Healthy("Timeline service is healthy");
+        }
+        catch (Exception ex)
+        {
+            return HealthCheckResult.Unhealthy("Timeline service is unhealthy", ex);
+        }
+    }
+}

src/Timeline/StellaOps.Timeline.WebService/Endpoints/ReplayEndpoints.cs

@@ -0,0 +1,129 @@
+// Copyright (c) StellaOps. Licensed under the AGPL-3.0-or-later.
+
+using Microsoft.AspNetCore.Http.HttpResults;
+
+namespace StellaOps.Timeline.WebService.Endpoints;
+
+/// <summary>
+/// Replay endpoints for deterministic replay of event sequences.
+/// </summary>
+public static class ReplayEndpoints
+{
+    /// <summary>
+    /// Maps replay endpoints.
+    /// </summary>
+    public static void MapReplayEndpoints(this IEndpointRouteBuilder app)
+    {
+        var group = app.MapGroup("/api/v1/timeline")
+            .WithTags("Replay")
+            .WithOpenApi();
+
+        group.MapPost("/{correlationId}/replay", InitiateReplayAsync)
+            .WithName("InitiateReplay")
+            .WithDescription("Initiate deterministic replay for a correlation ID");
+
+        group.MapGet("/replay/{replayId}", GetReplayStatusAsync)
+            .WithName("GetReplayStatus")
+            .WithDescription("Get the status of a replay operation");
+
+        group.MapPost("/replay/{replayId}/cancel", CancelReplayAsync)
+            .WithName("CancelReplay")
+            .WithDescription("Cancel an in-progress replay operation");
+    }
+
+    private static async Task<Results<Accepted<ReplayInitiatedResponse>, BadRequest<string>>> InitiateReplayAsync(
+        string correlationId,
+        ReplayRequest request,
+        CancellationToken cancellationToken)
+    {
+        // Validate request
+        if (string.IsNullOrWhiteSpace(correlationId))
+        {
+            return TypedResults.BadRequest("Correlation ID is required");
+        }
+
+        // TODO: Integrate with StellaOps.Replay.Core
+        // For now, return a stub response
+        var replayId = Guid.NewGuid().ToString("N")[..16];
+
+        await Task.CompletedTask; // Placeholder for actual implementation
+
+        return TypedResults.Accepted(
+            $"/api/v1/timeline/replay/{replayId}",
+            new ReplayInitiatedResponse
+            {
+                ReplayId = replayId,
+                CorrelationId = correlationId,
+                Mode = request.Mode,
+                Status = "INITIATED",
+                EstimatedDurationMs = 5000
+            });
+    }
+
+    private static async Task<Results<Ok<ReplayStatusResponse>, NotFound>> GetReplayStatusAsync(
+        string replayId,
+        CancellationToken cancellationToken)
+    {
+        // TODO: Integrate with replay state store
+        await Task.CompletedTask;
+
+        return TypedResults.Ok(new ReplayStatusResponse
+        {
+            ReplayId = replayId,
+            Status = "IN_PROGRESS",
+            Progress = 0.5,
+            EventsProcessed = 50,
+            TotalEvents = 100,
+            StartedAt = DateTimeOffset.UtcNow.AddSeconds(-5)
+        });
+    }
+
+    private static async Task<Results<Ok, NotFound>> CancelReplayAsync(
+        string replayId,
+        CancellationToken cancellationToken)
+    {
+        // TODO: Integrate with replay cancellation
+        await Task.CompletedTask;
+        return TypedResults.Ok();
+    }
+}
+
+// DTOs
+public sealed record ReplayRequest
+{
+    /// <summary>
+    /// Replay mode: "dry-run" or "verify".
+    /// </summary>
+    public string Mode { get; init; } = "dry-run";
+
+    /// <summary>
+    /// HLC to replay from (optional).
+    /// </summary>
+    public string? FromHlc { get; init; }
+
+    /// <summary>
+    /// HLC to replay to (optional).
+    /// </summary>
+    public string? ToHlc { get; init; }
+}
+
+public sealed record ReplayInitiatedResponse
+{
+    public required string ReplayId { get; init; }
+    public required string CorrelationId { get; init; }
+    public required string Mode { get; init; }
+    public required string Status { get; init; }
+    public long EstimatedDurationMs { get; init; }
+}
+
+public sealed record ReplayStatusResponse
+{
+    public required string ReplayId { get; init; }
+    public required string Status { get; init; }
+    public double Progress { get; init; }
+    public int EventsProcessed { get; init; }
+    public int TotalEvents { get; init; }
+    public DateTimeOffset StartedAt { get; init; }
+    public DateTimeOffset? CompletedAt { get; init; }
+    public string? Error { get; init; }
+}

src/Timeline/StellaOps.Timeline.WebService/Endpoints/TimelineEndpoints.cs

@@ -0,0 +1,153 @@
+// Copyright (c) StellaOps. Licensed under the AGPL-3.0-or-later.
+
+using Microsoft.AspNetCore.Http.HttpResults;
+using StellaOps.HybridLogicalClock;
+using StellaOps.Timeline.Core;
+
+namespace StellaOps.Timeline.WebService.Endpoints;
+
+/// <summary>
+/// Timeline query endpoints.
+/// </summary>
+public static class TimelineEndpoints
+{
+    /// <summary>
+    /// Maps timeline query endpoints.
+    /// </summary>
+    public static void MapTimelineEndpoints(this IEndpointRouteBuilder app)
+    {
+        var group = app.MapGroup("/api/v1/timeline")
+            .WithTags("Timeline")
+            .WithOpenApi();
+
+        group.MapGet("/{correlationId}", GetTimelineAsync)
+            .WithName("GetTimeline")
+            .WithDescription("Get events for a correlation ID, ordered by HLC timestamp");
+
+        group.MapGet("/{correlationId}/critical-path", GetCriticalPathAsync)
+            .WithName("GetCriticalPath")
+            .WithDescription("Get the critical path (longest latency stages) for a correlation");
+    }
+
+    private static async Task<Results<Ok<TimelineResponse>, NotFound>> GetTimelineAsync(
+        string correlationId,
+        ITimelineQueryService queryService,
+        int? limit,
+        int? offset,
+        string? fromHlc,
+        string? toHlc,
+        string? services,
+        string? kinds,
+        CancellationToken cancellationToken)
+    {
+        var options = new TimelineQueryOptions
+        {
+            Limit = limit ?? 100,
+            Offset = offset ?? 0,
+            FromHlc = !string.IsNullOrEmpty(fromHlc) ? HlcTimestamp.Parse(fromHlc) : null,
+            ToHlc = !string.IsNullOrEmpty(toHlc) ? HlcTimestamp.Parse(toHlc) : null,
+            Services = !string.IsNullOrEmpty(services)
+                ? services.Split(',', StringSplitOptions.RemoveEmptyEntries).ToList()
+                : null,
+            Kinds = !string.IsNullOrEmpty(kinds)
+                ? kinds.Split(',', StringSplitOptions.RemoveEmptyEntries).ToList()
+                : null
+        };
+
+        var result = await queryService.GetByCorrelationIdAsync(correlationId, options, cancellationToken);
+
+        if (result.Events.Count == 0)
+        {
+            return TypedResults.NotFound();
+        }
+
+        return TypedResults.Ok(new TimelineResponse
+        {
+            CorrelationId = correlationId,
+            Events = result.Events.Select(e => new TimelineEventDto
+            {
+                EventId = e.EventId,
+                THlc = e.THlc.ToSortableString(),
+                TsWall = e.TsWall,
+                Service = e.Service,
+                Kind = e.Kind,
+                Payload = e.Payload,
+                EngineVersion = new EngineVersionDto(
+                    e.EngineVersion.EngineName,
+                    e.EngineVersion.Version,
+                    e.EngineVersion.SourceDigest)
+            }).ToList(),
+            TotalCount = result.TotalCount,
+            HasMore = result.HasMore,
+            NextCursor = result.NextCursor
+        });
+    }
+
+    private static async Task<Results<Ok<CriticalPathResponse>, NotFound>> GetCriticalPathAsync(
+        string correlationId,
+        ITimelineQueryService queryService,
+        CancellationToken cancellationToken)
+    {
+        var result = await queryService.GetCriticalPathAsync(correlationId, cancellationToken);
+
+        if (result.Stages.Count == 0)
+        {
+            return TypedResults.NotFound();
+        }
+
+        return TypedResults.Ok(new CriticalPathResponse
+        {
+            CorrelationId = result.CorrelationId,
+            TotalDurationMs = result.TotalDuration.TotalMilliseconds,
+            Stages = result.Stages.Select(s => new CriticalPathStageDto
+            {
+                Stage = s.Stage,
+                Service = s.Service,
+                DurationMs = s.Duration.TotalMilliseconds,
+                Percentage = s.Percentage,
+                FromHlc = s.FromHlc.ToSortableString(),
+                ToHlc = s.ToHlc.ToSortableString()
+            }).ToList()
+        });
+    }
+}
+
+// DTOs
+public sealed record TimelineResponse
+{
+    public required string CorrelationId { get; init; }
+    public required IReadOnlyList<TimelineEventDto> Events { get; init; }
+    public long TotalCount { get; init; }
+    public bool HasMore { get; init; }
+    public string? NextCursor { get; init; }
+}
+
+public sealed record TimelineEventDto
+{
+    public required string EventId { get; init; }
+    public required string THlc { get; init; }
+    public required DateTimeOffset TsWall { get; init; }
+    public required string Service { get; init; }
+    public required string Kind { get; init; }
+    public required string Payload { get; init; }
+    public required EngineVersionDto EngineVersion { get; init; }
+}
+
+public sealed record EngineVersionDto(string EngineName, string Version, string SourceDigest);
+
+public sealed record CriticalPathResponse
+{
+    public required string CorrelationId { get; init; }
+    public double TotalDurationMs { get; init; }
+    public required IReadOnlyList<CriticalPathStageDto> Stages { get; init; }
+}
+
+public sealed record CriticalPathStageDto
+{
+    public required string Stage { get; init; }
+    public required string Service { get; init; }
+    public double DurationMs { get; init; }
+    public double Percentage { get; init; }
+    public required string FromHlc { get; init; }
+    public required string ToHlc { get; init; }
+}

src/Timeline/StellaOps.Timeline.WebService/Program.cs

@@ -0,0 +1,42 @@
+using StellaOps.Eventing;
+using StellaOps.Timeline.Core;
+using StellaOps.Timeline.WebService.Endpoints;
+
+var builder = WebApplication.CreateBuilder(args);
+
+// Add services
+builder.Services.AddStellaOpsEventing(builder.Configuration);
+builder.Services.AddTimelineServices(builder.Configuration);
+
+builder.Services.AddEndpointsApiExplorer();
+builder.Services.AddSwaggerGen(options =>
+{
+    options.SwaggerDoc("v1", new()
+    {
+        Title = "StellaOps Timeline API",
+        Version = "v1",
+        Description = "Unified event timeline API for querying, replaying, and exporting HLC-ordered events"
+    });
+});
+
+builder.Services.AddHealthChecks()
+    .AddCheck<TimelineHealthCheck>("timeline");
+
+var app = builder.Build();
+
+// Configure the HTTP request pipeline
+if (app.Environment.IsDevelopment())
+{
+    app.UseSwagger();
+    app.UseSwaggerUI();
+}
+
+app.UseHttpsRedirection();
+
+// Map endpoints
+app.MapTimelineEndpoints();
+app.MapReplayEndpoints();
+app.MapExportEndpoints();
+app.MapHealthEndpoints();
+
+app.Run();

src/Timeline/StellaOps.Timeline.WebService/StellaOps.Timeline.WebService.csproj

@@ -0,0 +1,24 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    <RootNamespace>StellaOps.Timeline.WebService</RootNamespace>
+    <Description>StellaOps Timeline Service - Unified event timeline API</Description>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\__Libraries\StellaOps.Timeline.Core\StellaOps.Timeline.Core.csproj" />
+    <ProjectReference Include="..\..\__Libraries\StellaOps.Eventing\StellaOps.Eventing.csproj" />
+    <ProjectReference Include="..\..\__Libraries\StellaOps.HybridLogicalClock\StellaOps.HybridLogicalClock.csproj" />
+    <ProjectReference Include="..\..\__Libraries\StellaOps.Microservice\StellaOps.Microservice.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.AspNetCore.OpenApi" />
+    <PackageReference Include="Swashbuckle.AspNetCore" />
+  </ItemGroup>
+
+</Project>

src/Timeline/StellaOps.Timeline.WebService/appsettings.json

@@ -0,0 +1,24 @@
+{
+  "Logging": {
+    "LogLevel": {
+      "Default": "Information",
+      "Microsoft.AspNetCore": "Warning",
+      "StellaOps": "Debug"
+    }
+  },
+  "AllowedHosts": "*",
+  "Eventing": {
+    "ServiceName": "Timeline",
+    "UseInMemoryStore": false,
+    "ConnectionString": "",
+    "SignEvents": false,
+    "EnableOutbox": false
+  },
+  "Kestrel": {
+    "Endpoints": {
+      "Http": {
+        "Url": "http://+:8080"
+      }
+    }
+  }
+}

src/Timeline/StellaOps.Timeline.WebService/openapi.yaml

@@ -0,0 +1,536 @@
+openapi: 3.1.0
+info:
+  title: StellaOps Timeline API
+  version: 1.0.0
+  description: |
+    Unified event timeline API for querying, replaying, and exporting HLC-ordered events
+    across all StellaOps services.
+  license:
+    name: AGPL-3.0-or-later
+    url: https://www.gnu.org/licenses/agpl-3.0.html
+  contact:
+    name: StellaOps
+    url: https://stellaops.io
+
+servers:
+  - url: /api/v1
+    description: Timeline API v1
+
+tags:
+  - name: Timeline
+    description: Query timeline events
+  - name: Replay
+    description: Deterministic replay operations
+  - name: Export
+    description: Export timeline bundles
+
+paths:
+  /timeline/{correlationId}:
+    get:
+      summary: Get timeline events
+      description: Returns events for a correlation ID, ordered by HLC timestamp
+      operationId: getTimeline
+      tags:
+        - Timeline
+      parameters:
+        - name: correlationId
+          in: path
+          required: true
+          schema:
+            type: string
+          description: The correlation ID to query
+        - name: limit
+          in: query
+          schema:
+            type: integer
+            default: 100
+            minimum: 1
+            maximum: 1000
+          description: Maximum number of events to return
+        - name: offset
+          in: query
+          schema:
+            type: integer
+            default: 0
+            minimum: 0
+          description: Number of events to skip
+        - name: services
+          in: query
+          schema:
+            type: string
+          description: Comma-separated list of services to filter by
+        - name: kinds
+          in: query
+          schema:
+            type: string
+          description: Comma-separated list of event kinds to filter by
+        - name: fromHlc
+          in: query
+          schema:
+            type: string
+          description: Start of HLC range (inclusive)
+        - name: toHlc
+          in: query
+          schema:
+            type: string
+          description: End of HLC range (inclusive)
+      responses:
+        '200':
+          description: Timeline events
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/TimelineResponse'
+        '404':
+          description: No events found for correlation ID
+
+  /timeline/{correlationId}/critical-path:
+    get:
+      summary: Get critical path
+      description: Returns the critical path (longest latency stages) for a correlation
+      operationId: getCriticalPath
+      tags:
+        - Timeline
+      parameters:
+        - name: correlationId
+          in: path
+          required: true
+          schema:
+            type: string
+          description: The correlation ID to analyze
+      responses:
+        '200':
+          description: Critical path analysis
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/CriticalPathResponse'
+        '404':
+          description: No events found for correlation ID
+
+  /timeline/{correlationId}/replay:
+    post:
+      summary: Initiate replay
+      description: Initiate deterministic replay for a correlation ID
+      operationId: initiateReplay
+      tags:
+        - Replay
+      parameters:
+        - name: correlationId
+          in: path
+          required: true
+          schema:
+            type: string
+          description: The correlation ID to replay
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/ReplayRequest'
+      responses:
+        '202':
+          description: Replay initiated
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ReplayInitiatedResponse'
+        '400':
+          description: Invalid request
+
+  /timeline/replay/{replayId}:
+    get:
+      summary: Get replay status
+      description: Get the status of a replay operation
+      operationId: getReplayStatus
+      tags:
+        - Replay
+      parameters:
+        - name: replayId
+          in: path
+          required: true
+          schema:
+            type: string
+          description: The replay operation ID
+      responses:
+        '200':
+          description: Replay status
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ReplayStatusResponse'
+        '404':
+          description: Replay not found
+
+  /timeline/{correlationId}/export:
+    post:
+      summary: Export timeline
+      description: Export timeline events as NDJSON bundle with optional DSSE signing
+      operationId: exportTimeline
+      tags:
+        - Export
+      parameters:
+        - name: correlationId
+          in: path
+          required: true
+          schema:
+            type: string
+          description: The correlation ID to export
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/ExportRequest'
+      responses:
+        '202':
+          description: Export initiated
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ExportInitiatedResponse'
+        '400':
+          description: Invalid request or no events found
+
+  /timeline/export/{exportId}:
+    get:
+      summary: Get export status
+      description: Get the status of an export operation
+      operationId: getExportStatus
+      tags:
+        - Export
+      parameters:
+        - name: exportId
+          in: path
+          required: true
+          schema:
+            type: string
+          description: The export operation ID
+      responses:
+        '200':
+          description: Export status
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ExportStatusResponse'
+        '404':
+          description: Export not found
+
+  /timeline/export/{exportId}/download:
+    get:
+      summary: Download export
+      description: Download the completed export bundle
+      operationId: downloadExport
+      tags:
+        - Export
+      parameters:
+        - name: exportId
+          in: path
+          required: true
+          schema:
+            type: string
+          description: The export operation ID
+      responses:
+        '200':
+          description: Export bundle
+          content:
+            application/x-ndjson:
+              schema:
+                type: string
+                format: binary
+        '404':
+          description: Export not found or not completed
+
+components:
+  schemas:
+    TimelineResponse:
+      type: object
+      required:
+        - correlationId
+        - events
+      properties:
+        correlationId:
+          type: string
+          description: The correlation ID queried
+        events:
+          type: array
+          items:
+            $ref: '#/components/schemas/TimelineEvent'
+        totalCount:
+          type: integer
+          format: int64
+          description: Total number of events for this correlation
+        hasMore:
+          type: boolean
+          description: Whether there are more results
+        nextCursor:
+          type: string
+          description: Cursor for next page (HLC of last event)
+
+    TimelineEvent:
+      type: object
+      required:
+        - eventId
+        - tHlc
+        - tsWall
+        - service
+        - kind
+        - payload
+        - engineVersion
+      properties:
+        eventId:
+          type: string
+          description: Deterministic event ID (SHA-256 hash)
+        tHlc:
+          type: string
+          description: HLC timestamp in sortable format
+        tsWall:
+          type: string
+          format: date-time
+          description: Wall-clock time (ISO 8601)
+        service:
+          type: string
+          description: Service that emitted the event
+        kind:
+          type: string
+          description: Event kind (ENQUEUE, EXECUTE, etc.)
+        payload:
+          type: string
+          description: RFC 8785 canonicalized JSON payload
+        engineVersion:
+          $ref: '#/components/schemas/EngineVersion'
+
+    EngineVersion:
+      type: object
+      required:
+        - engineName
+        - version
+        - sourceDigest
+      properties:
+        engineName:
+          type: string
+          description: Engine/service name
+        version:
+          type: string
+          description: Engine version
+        sourceDigest:
+          type: string
+          description: Source/assembly digest
+
+    CriticalPathResponse:
+      type: object
+      required:
+        - correlationId
+        - stages
+      properties:
+        correlationId:
+          type: string
+          description: The correlation ID analyzed
+        totalDurationMs:
+          type: number
+          format: double
+          description: Total duration in milliseconds
+        stages:
+          type: array
+          items:
+            $ref: '#/components/schemas/CriticalPathStage'
+
+    CriticalPathStage:
+      type: object
+      required:
+        - stage
+        - service
+        - fromHlc
+        - toHlc
+      properties:
+        stage:
+          type: string
+          description: Stage label (e.g., "ENQUEUE -> EXECUTE")
+        service:
+          type: string
+          description: Service where stage occurred
+        durationMs:
+          type: number
+          format: double
+          description: Duration in milliseconds
+        percentage:
+          type: number
+          format: double
+          description: Percentage of total duration
+        fromHlc:
+          type: string
+          description: HLC at start of stage
+        toHlc:
+          type: string
+          description: HLC at end of stage
+
+    ReplayRequest:
+      type: object
+      properties:
+        mode:
+          type: string
+          enum:
+            - dry-run
+            - verify
+          default: dry-run
+          description: Replay mode
+        fromHlc:
+          type: string
+          description: HLC to replay from (optional)
+        toHlc:
+          type: string
+          description: HLC to replay to (optional)
+
+    ReplayInitiatedResponse:
+      type: object
+      required:
+        - replayId
+        - correlationId
+        - mode
+        - status
+      properties:
+        replayId:
+          type: string
+          description: Unique replay operation ID
+        correlationId:
+          type: string
+          description: The correlation ID being replayed
+        mode:
+          type: string
+          description: Replay mode
+        status:
+          type: string
+          description: Initial status (INITIATED)
+        estimatedDurationMs:
+          type: integer
+          format: int64
+          description: Estimated duration in milliseconds
+
+    ReplayStatusResponse:
+      type: object
+      required:
+        - replayId
+        - status
+      properties:
+        replayId:
+          type: string
+          description: Unique replay operation ID
+        status:
+          type: string
+          enum:
+            - INITIATED
+            - IN_PROGRESS
+            - COMPLETED
+            - FAILED
+          description: Current status
+        progress:
+          type: number
+          format: double
+          description: Progress (0.0 to 1.0)
+        eventsProcessed:
+          type: integer
+          description: Number of events processed
+        totalEvents:
+          type: integer
+          description: Total number of events
+        startedAt:
+          type: string
+          format: date-time
+          description: Start time
+        completedAt:
+          type: string
+          format: date-time
+          description: Completion time (if completed)
+        error:
+          type: string
+          description: Error message (if failed)
+
+    ExportRequest:
+      type: object
+      properties:
+        format:
+          type: string
+          enum:
+            - ndjson
+            - json
+          default: ndjson
+          description: Export format
+        signBundle:
+          type: boolean
+          default: false
+          description: Whether to DSSE-sign the bundle
+        fromHlc:
+          type: string
+          description: HLC range start (optional)
+        toHlc:
+          type: string
+          description: HLC range end (optional)
+
+    ExportInitiatedResponse:
+      type: object
+      required:
+        - exportId
+        - correlationId
+        - format
+        - status
+      properties:
+        exportId:
+          type: string
+          description: Unique export operation ID
+        correlationId:
+          type: string
+          description: The correlation ID being exported
+        format:
+          type: string
+          description: Export format
+        signBundle:
+          type: boolean
+          description: Whether bundle is signed
+        status:
+          type: string
+          description: Initial status (INITIATED)
+        estimatedEventCount:
+          type: integer
+          format: int64
+          description: Estimated number of events
+
+    ExportStatusResponse:
+      type: object
+      required:
+        - exportId
+        - status
+        - format
+      properties:
+        exportId:
+          type: string
+          description: Unique export operation ID
+        status:
+          type: string
+          enum:
+            - INITIATED
+            - IN_PROGRESS
+            - COMPLETED
+            - FAILED
+          description: Current status
+        format:
+          type: string
+          description: Export format
+        eventCount:
+          type: integer
+          format: int64
+          description: Number of events exported
+        fileSizeBytes:
+          type: integer
+          format: int64
+          description: Size of export file
+        createdAt:
+          type: string
+          format: date-time
+          description: Creation time
+        completedAt:
+          type: string
+          format: date-time
+          description: Completion time (if completed)
+        error:
+          type: string
+          description: Error message (if failed)

src/Timeline/__Libraries/StellaOps.Timeline.Core/AGENTS.md

@@ -0,0 +1,25 @@
+# Timeline Core Module Charter
+
+## Mission
+- Provide timeline core models and deterministic ordering logic.
+
+## Responsibilities
+- Define timeline domain models and validation rules.
+- Implement ordering and partitioning logic for timeline events.
+- Keep serialization deterministic and invariant.
+
+## Required Reading
+- docs/README.md
+- docs/07_HIGH_LEVEL_ARCHITECTURE.md
+- docs/modules/platform/architecture-overview.md
+- docs/modules/timeline-indexer/architecture.md
+- docs/modules/timeline-indexer/README.md
+
+## Working Agreement
+- Deterministic ordering and invariant formatting.
+- Use TimeProvider and IGuidGenerator where timestamps or IDs are created.
+- Propagate CancellationToken for async operations.
+
+## Testing Strategy
+- Unit tests for ordering, validation, and serialization.
+- Determinism tests for stable outputs.

src/Timeline/__Libraries/StellaOps.Timeline.Core/Export/ITimelineBundleBuilder.cs

@@ -0,0 +1,193 @@
+// Copyright (c) StellaOps. Licensed under the AGPL-3.0-or-later.
+
+using StellaOps.Eventing.Models;
+using StellaOps.HybridLogicalClock;
+
+namespace StellaOps.Timeline.Core.Export;
+
+/// <summary>
+/// Interface for building timeline export bundles.
+/// </summary>
+public interface ITimelineBundleBuilder
+{
+    /// <summary>
+    /// Initiates an export operation for a correlation ID.
+    /// </summary>
+    /// <param name="correlationId">The correlation ID to export.</param>
+    /// <param name="request">Export request parameters.</param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>The initiated export operation.</returns>
+    Task<ExportOperation> InitiateExportAsync(
+        string correlationId,
+        ExportRequest request,
+        CancellationToken cancellationToken = default);
+
+    /// <summary>
+    /// Gets the status of an export operation.
+    /// </summary>
+    /// <param name="exportId">The export operation ID.</param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>The export operation status, or null if not found.</returns>
+    Task<ExportOperation?> GetExportStatusAsync(
+        string exportId,
+        CancellationToken cancellationToken = default);
+
+    /// <summary>
+    /// Gets the export bundle content.
+    /// </summary>
+    /// <param name="exportId">The export operation ID.</param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>The export bundle stream, or null if not found/not ready.</returns>
+    Task<ExportBundle?> GetExportBundleAsync(
+        string exportId,
+        CancellationToken cancellationToken = default);
+}
+
+/// <summary>
+/// Request for initiating an export operation.
+/// </summary>
+public sealed record ExportRequest
+{
+    /// <summary>
+    /// Export format: "ndjson" or "json".
+    /// </summary>
+    public string Format { get; init; } = "ndjson";
+
+    /// <summary>
+    /// Whether to DSSE-sign the bundle.
+    /// </summary>
+    public bool SignBundle { get; init; } = false;
+
+    /// <summary>
+    /// Optional HLC range start.
+    /// </summary>
+    public HlcTimestamp? FromHlc { get; init; }
+
+    /// <summary>
+    /// Optional HLC range end.
+    /// </summary>
+    public HlcTimestamp? ToHlc { get; init; }
+
+    /// <summary>
+    /// Whether to include full payloads.
+    /// </summary>
+    public bool IncludePayloads { get; init; } = true;
+}
+
+/// <summary>
+/// Represents an export operation.
+/// </summary>
+public sealed record ExportOperation
+{
+    /// <summary>
+    /// Unique export operation ID.
+    /// </summary>
+    public required string ExportId { get; init; }
+
+    /// <summary>
+    /// The correlation ID being exported.
+    /// </summary>
+    public required string CorrelationId { get; init; }
+
+    /// <summary>
+    /// Export format.
+    /// </summary>
+    public required string Format { get; init; }
+
+    /// <summary>
+    /// Whether bundle is signed.
+    /// </summary>
+    public bool SignBundle { get; init; }
+
+    /// <summary>
+    /// Current status.
+    /// </summary>
+    public required ExportStatus Status { get; init; }
+
+    /// <summary>
+    /// Number of events exported.
+    /// </summary>
+    public int EventCount { get; init; }
+
+    /// <summary>
+    /// Size of export file in bytes.
+    /// </summary>
+    public long FileSizeBytes { get; init; }
+
+    /// <summary>
+    /// Creation time.
+    /// </summary>
+    public DateTimeOffset CreatedAt { get; init; }
+
+    /// <summary>
+    /// Completion time (if completed).
+    /// </summary>
+    public DateTimeOffset? CompletedAt { get; init; }
+
+    /// <summary>
+    /// Error message (if failed).
+    /// </summary>
+    public string? Error { get; init; }
+}
+
+/// <summary>
+/// Export operation status.
+/// </summary>
+public enum ExportStatus
+{
+    /// <summary>
+    /// Export has been initiated.
+    /// </summary>
+    Initiated,
+
+    /// <summary>
+    /// Export is in progress.
+    /// </summary>
+    InProgress,
+
+    /// <summary>
+    /// Export completed successfully.
+    /// </summary>
+    Completed,
+
+    /// <summary>
+    /// Export failed.
+    /// </summary>
+    Failed
+}
+
+/// <summary>
+/// Represents an export bundle.
+/// </summary>
+public sealed record ExportBundle
+{
+    /// <summary>
+    /// The export operation ID.
+    /// </summary>
+    public required string ExportId { get; init; }
+
+    /// <summary>
+    /// Content type (e.g., "application/x-ndjson").
+    /// </summary>
+    public required string ContentType { get; init; }
+
+    /// <summary>
+    /// Suggested filename.
+    /// </summary>
+    public required string FileName { get; init; }
+
+    /// <summary>
+    /// Bundle content stream.
+    /// </summary>
+    public required Stream Content { get; init; }
+
+    /// <summary>
+    /// Bundle size in bytes.
+    /// </summary>
+    public long SizeBytes { get; init; }
+
+    /// <summary>
+    /// DSSE signature (if signed).
+    /// </summary>
+    public string? DsseSignature { get; init; }
+}

src/Timeline/__Libraries/StellaOps.Timeline.Core/Export/TimelineBundleBuilder.cs

@@ -0,0 +1,293 @@
+// Copyright (c) StellaOps. Licensed under the AGPL-3.0-or-later.
+
+using System.Collections.Concurrent;
+using System.Globalization;
+using System.Text;
+using System.Text.Json;
+using Microsoft.Extensions.Logging;
+using StellaOps.Eventing.Models;
+using StellaOps.Eventing.Signing;
+using StellaOps.Eventing.Storage;
+using StellaOps.Timeline.Core.Telemetry;
+
+namespace StellaOps.Timeline.Core.Export;
+
+/// <summary>
+/// Implementation of <see cref="ITimelineBundleBuilder"/>.
+/// </summary>
+public sealed class TimelineBundleBuilder : ITimelineBundleBuilder
+{
+    private readonly ITimelineEventStore _eventStore;
+    private readonly IEventSigner? _eventSigner;
+    private readonly TimelineMetrics _metrics;
+    private readonly TimeProvider _timeProvider;
+    private readonly ILogger<TimelineBundleBuilder> _logger;
+
+    // In-memory store for export operations (production would use PostgreSQL + object storage)
+    private readonly ConcurrentDictionary<string, ExportOperation> _operations = new();
+    private readonly ConcurrentDictionary<string, byte[]> _bundles = new();
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="TimelineBundleBuilder"/> class.
+    /// </summary>
+    public TimelineBundleBuilder(
+        ITimelineEventStore eventStore,
+        TimelineMetrics metrics,
+        TimeProvider timeProvider,
+        ILogger<TimelineBundleBuilder> logger,
+        IEventSigner? eventSigner = null)
+    {
+        _eventStore = eventStore ?? throw new ArgumentNullException(nameof(eventStore));
+        _metrics = metrics ?? throw new ArgumentNullException(nameof(metrics));
+        _timeProvider = timeProvider ?? throw new ArgumentNullException(nameof(timeProvider));
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+        _eventSigner = eventSigner;
+    }
+
+    /// <inheritdoc/>
+    public async Task<ExportOperation> InitiateExportAsync(
+        string correlationId,
+        ExportRequest request,
+        CancellationToken cancellationToken = default)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(correlationId);
+        ArgumentNullException.ThrowIfNull(request);
+
+        var exportId = GenerateExportId();
+        var now = _timeProvider.GetUtcNow();
+
+        var operation = new ExportOperation
+        {
+            ExportId = exportId,
+            CorrelationId = correlationId,
+            Format = request.Format,
+            SignBundle = request.SignBundle,
+            Status = ExportStatus.Initiated,
+            CreatedAt = now
+        };
+
+        _operations[exportId] = operation;
+
+        _logger.LogInformation(
+            "Initiated export {ExportId} for correlation {CorrelationId}",
+            exportId,
+            correlationId);
+
+        // Start export in background
+        _ = Task.Run(() => ExecuteExportAsync(exportId, correlationId, request, cancellationToken), cancellationToken);
+
+        return operation;
+    }
+
+    /// <inheritdoc/>
+    public Task<ExportOperation?> GetExportStatusAsync(
+        string exportId,
+        CancellationToken cancellationToken = default)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(exportId);
+
+        _operations.TryGetValue(exportId, out var operation);
+        return Task.FromResult(operation);
+    }
+
+    /// <inheritdoc/>
+    public Task<ExportBundle?> GetExportBundleAsync(
+        string exportId,
+        CancellationToken cancellationToken = default)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(exportId);
+
+        if (!_operations.TryGetValue(exportId, out var operation))
+        {
+            return Task.FromResult<ExportBundle?>(null);
+        }
+
+        if (operation.Status != ExportStatus.Completed)
+        {
+            return Task.FromResult<ExportBundle?>(null);
+        }
+
+        if (!_bundles.TryGetValue(exportId, out var content))
+        {
+            return Task.FromResult<ExportBundle?>(null);
+        }
+
+        var bundle = new ExportBundle
+        {
+            ExportId = exportId,
+            ContentType = operation.Format == "ndjson" ? "application/x-ndjson" : "application/json",
+            FileName = $"timeline-{operation.CorrelationId}-{exportId}.{operation.Format}",
+            Content = new MemoryStream(content),
+            SizeBytes = content.Length
+        };
+
+        return Task.FromResult<ExportBundle?>(bundle);
+    }
+
+    private async Task ExecuteExportAsync(
+        string exportId,
+        string correlationId,
+        ExportRequest request,
+        CancellationToken cancellationToken)
+    {
+        try
+        {
+            // Update status to in-progress
+            UpdateOperation(exportId, op => op with { Status = ExportStatus.InProgress });
+
+            // Get events
+            IReadOnlyList<TimelineEvent> events;
+            if (request.FromHlc.HasValue && request.ToHlc.HasValue)
+            {
+                events = await _eventStore.GetByHlcRangeAsync(
+                    correlationId,
+                    request.FromHlc.Value,
+                    request.ToHlc.Value,
+                    cancellationToken).ConfigureAwait(false);
+            }
+            else
+            {
+                events = await _eventStore.GetByCorrelationIdAsync(
+                    correlationId,
+                    limit: 100000,
+                    offset: 0,
+                    cancellationToken).ConfigureAwait(false);
+            }
+
+            // Build bundle content
+            byte[] content;
+            if (request.Format == "ndjson")
+            {
+                content = BuildNdjsonBundle(events, request.IncludePayloads);
+            }
+            else
+            {
+                content = BuildJsonBundle(events, request.IncludePayloads);
+            }
+
+            // Sign if requested
+            string? signature = null;
+            if (request.SignBundle && _eventSigner != null)
+            {
+                signature = await _eventSigner.SignAsync(content, cancellationToken).ConfigureAwait(false);
+            }
+
+            // Store bundle
+            _bundles[exportId] = content;
+
+            // Update final status
+            var now = _timeProvider.GetUtcNow();
+            UpdateOperation(exportId, op => op with
+            {
+                Status = ExportStatus.Completed,
+                EventCount = events.Count,
+                FileSizeBytes = content.Length,
+                CompletedAt = now
+            });
+
+            _metrics.RecordExport(request.Format, request.SignBundle, content.Length, events.Count);
+
+            _logger.LogInformation(
+                "Completed export {ExportId}: {EventCount} events, {Size} bytes",
+                exportId,
+                events.Count,
+                content.Length);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Export {ExportId} failed", exportId);
+
+            UpdateOperation(exportId, op => op with
+            {
+                Status = ExportStatus.Failed,
+                CompletedAt = _timeProvider.GetUtcNow(),
+                Error = ex.Message
+            });
+        }
+    }
+
+    private static byte[] BuildNdjsonBundle(IReadOnlyList<TimelineEvent> events, bool includePayloads)
+    {
+        var sb = new StringBuilder();
+
+        foreach (var evt in events)
+        {
+            var line = new
+            {
+                event_id = evt.EventId,
+                t_hlc = evt.THlc.ToSortableString(),
+                ts_wall = evt.TsWall.ToString("O", CultureInfo.InvariantCulture),
+                correlation_id = evt.CorrelationId,
+                service = evt.Service,
+                kind = evt.Kind,
+                payload = includePayloads ? evt.Payload : null,
+                payload_digest = Convert.ToHexString(evt.PayloadDigest).ToLowerInvariant(),
+                engine_version = new
+                {
+                    name = evt.EngineVersion.EngineName,
+                    version = evt.EngineVersion.Version,
+                    digest = evt.EngineVersion.SourceDigest
+                },
+                schema_version = evt.SchemaVersion
+            };
+
+            sb.AppendLine(JsonSerializer.Serialize(line, new JsonSerializerOptions
+            {
+                PropertyNamingPolicy = JsonNamingPolicy.SnakeCaseLower,
+                DefaultIgnoreCondition = System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull
+            }));
+        }
+
+        return Encoding.UTF8.GetBytes(sb.ToString());
+    }
+
+    private static byte[] BuildJsonBundle(IReadOnlyList<TimelineEvent> events, bool includePayloads)
+    {
+        var bundle = new
+        {
+            events = events.Select(evt => new
+            {
+                event_id = evt.EventId,
+                t_hlc = evt.THlc.ToSortableString(),
+                ts_wall = evt.TsWall.ToString("O", CultureInfo.InvariantCulture),
+                correlation_id = evt.CorrelationId,
+                service = evt.Service,
+                kind = evt.Kind,
+                payload = includePayloads ? evt.Payload : null,
+                payload_digest = Convert.ToHexString(evt.PayloadDigest).ToLowerInvariant(),
+                engine_version = new
+                {
+                    name = evt.EngineVersion.EngineName,
+                    version = evt.EngineVersion.Version,
+                    digest = evt.EngineVersion.SourceDigest
+                },
+                schema_version = evt.SchemaVersion
+            }).ToList(),
+            metadata = new
+            {
+                event_count = events.Count,
+                exported_at = DateTimeOffset.UtcNow.ToString("O", CultureInfo.InvariantCulture)
+            }
+        };
+
+        return JsonSerializer.SerializeToUtf8Bytes(bundle, new JsonSerializerOptions
+        {
+            PropertyNamingPolicy = JsonNamingPolicy.SnakeCaseLower,
+            WriteIndented = true,
+            DefaultIgnoreCondition = System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull
+        });
+    }
+
+    private void UpdateOperation(string exportId, Func<ExportOperation, ExportOperation> update)
+    {
+        if (_operations.TryGetValue(exportId, out var current))
+        {
+            _operations[exportId] = update(current);
+        }
+    }
+
+    private static string GenerateExportId()
+    {
+        return Guid.NewGuid().ToString("N")[..16];
+    }
+}

src/Timeline/__Libraries/StellaOps.Timeline.Core/ITimelineQueryService.cs

@@ -0,0 +1,155 @@
+// Copyright (c) StellaOps. Licensed under the AGPL-3.0-or-later.
+
+using StellaOps.Eventing.Models;
+using StellaOps.HybridLogicalClock;
+
+namespace StellaOps.Timeline.Core;
+
+/// <summary>
+/// Interface for querying timeline events.
+/// </summary>
+public interface ITimelineQueryService
+{
+    /// <summary>
+    /// Gets events for a correlation ID, ordered by HLC timestamp.
+    /// </summary>
+    Task<TimelineQueryResult> GetByCorrelationIdAsync(
+        string correlationId,
+        TimelineQueryOptions? options = null,
+        CancellationToken cancellationToken = default);
+
+    /// <summary>
+    /// Gets the critical path (longest latency stages) for a correlation.
+    /// </summary>
+    Task<CriticalPathResult> GetCriticalPathAsync(
+        string correlationId,
+        CancellationToken cancellationToken = default);
+
+    /// <summary>
+    /// Gets events filtered by service.
+    /// </summary>
+    Task<TimelineQueryResult> GetByServiceAsync(
+        string service,
+        HlcTimestamp? fromHlc = null,
+        int limit = 100,
+        CancellationToken cancellationToken = default);
+}
+
+/// <summary>
+/// Options for timeline queries.
+/// </summary>
+public sealed record TimelineQueryOptions
+{
+    /// <summary>
+    /// Maximum number of events to return.
+    /// </summary>
+    public int Limit { get; init; } = 100;
+
+    /// <summary>
+    /// Number of events to skip.
+    /// </summary>
+    public int Offset { get; init; } = 0;
+
+    /// <summary>
+    /// Filter by services (optional).
+    /// </summary>
+    public IReadOnlyList<string>? Services { get; init; }
+
+    /// <summary>
+    /// Filter by event kinds (optional).
+    /// </summary>
+    public IReadOnlyList<string>? Kinds { get; init; }
+
+    /// <summary>
+    /// Start of HLC range (inclusive).
+    /// </summary>
+    public HlcTimestamp? FromHlc { get; init; }
+
+    /// <summary>
+    /// End of HLC range (inclusive).
+    /// </summary>
+    public HlcTimestamp? ToHlc { get; init; }
+}
+
+/// <summary>
+/// Result of a timeline query.
+/// </summary>
+public sealed record TimelineQueryResult
+{
+    /// <summary>
+    /// The events matching the query.
+    /// </summary>
+    public required IReadOnlyList<TimelineEvent> Events { get; init; }
+
+    /// <summary>
+    /// Total count (for pagination).
+    /// </summary>
+    public long TotalCount { get; init; }
+
+    /// <summary>
+    /// Whether there are more results.
+    /// </summary>
+    public bool HasMore { get; init; }
+
+    /// <summary>
+    /// Cursor for next page (HLC of last event).
+    /// </summary>
+    public string? NextCursor { get; init; }
+}
+
+/// <summary>
+/// Critical path analysis result.
+/// </summary>
+public sealed record CriticalPathResult
+{
+    /// <summary>
+    /// The correlation ID analyzed.
+    /// </summary>
+    public required string CorrelationId { get; init; }
+
+    /// <summary>
+    /// Total duration from first to last event.
+    /// </summary>
+    public TimeSpan TotalDuration { get; init; }
+
+    /// <summary>
+    /// The stages in the critical path.
+    /// </summary>
+    public required IReadOnlyList<CriticalPathStage> Stages { get; init; }
+}
+
+/// <summary>
+/// A stage in the critical path.
+/// </summary>
+public sealed record CriticalPathStage
+{
+    /// <summary>
+    /// Stage name (e.g., "ENQUEUE -> EXECUTE").
+    /// </summary>
+    public required string Stage { get; init; }
+
+    /// <summary>
+    /// Service where this stage occurred.
+    /// </summary>
+    public required string Service { get; init; }
+
+    /// <summary>
+    /// Duration of this stage.
+    /// </summary>
+    public TimeSpan Duration { get; init; }
+
+    /// <summary>
+    /// Percentage of total duration.
+    /// </summary>
+    public double Percentage { get; init; }
+
+    /// <summary>
+    /// HLC at start of stage.
+    /// </summary>
+    public required HlcTimestamp FromHlc { get; init; }
+
+    /// <summary>
+    /// HLC at end of stage.
+    /// </summary>
+    public required HlcTimestamp ToHlc { get; init; }
+}

src/Timeline/__Libraries/StellaOps.Timeline.Core/Migrations/20260107_002_create_critical_path_view.sql

@@ -0,0 +1,50 @@
+-- Migration: 20260107_002_create_critical_path_view
+-- Purpose: Create materialized view for critical path computation
+
+-- Create materialized view for critical path analysis
+CREATE MATERIALIZED VIEW timeline.critical_path AS
+WITH ordered_events AS (
+    SELECT
+        correlation_id,
+        event_id,
+        t_hlc,
+        ts_wall,
+        service,
+        kind,
+        LAG(t_hlc) OVER (PARTITION BY correlation_id ORDER BY t_hlc) as prev_hlc,
+        LAG(ts_wall) OVER (PARTITION BY correlation_id ORDER BY t_hlc) as prev_ts,
+        LAG(kind) OVER (PARTITION BY correlation_id ORDER BY t_hlc) as prev_kind,
+        LAG(event_id) OVER (PARTITION BY correlation_id ORDER BY t_hlc) as prev_event_id
+    FROM timeline.events
+)
+SELECT
+    correlation_id,
+    prev_kind || ' -> ' || kind as stage,
+    prev_event_id as from_event_id,
+    event_id as to_event_id,
+    prev_hlc as from_hlc,
+    t_hlc as to_hlc,
+    EXTRACT(EPOCH FROM (ts_wall - prev_ts)) * 1000 as duration_ms,
+    service
+FROM ordered_events
+WHERE prev_hlc IS NOT NULL;
+
+-- Create indexes for efficient queries
+CREATE UNIQUE INDEX idx_critical_path_corr_from_hlc
+    ON timeline.critical_path (correlation_id, from_hlc);
+
+CREATE INDEX idx_critical_path_duration
+    ON timeline.critical_path (correlation_id, duration_ms DESC);
+
+-- Function to refresh materialized view for a specific correlation
+CREATE OR REPLACE FUNCTION timeline.refresh_critical_path()
+RETURNS void AS $$
+BEGIN
+    REFRESH MATERIALIZED VIEW CONCURRENTLY timeline.critical_path;
+END;
+$$ LANGUAGE plpgsql;
+
+-- Comments for documentation
+COMMENT ON MATERIALIZED VIEW timeline.critical_path IS 'Pre-computed critical path stages for performance analysis';
+COMMENT ON COLUMN timeline.critical_path.stage IS 'Transition label: prev_kind -> current_kind';
+COMMENT ON COLUMN timeline.critical_path.duration_ms IS 'Wall-clock duration between events in milliseconds';

src/Timeline/__Libraries/StellaOps.Timeline.Core/Replay/ITimelineReplayOrchestrator.cs

@@ -0,0 +1,167 @@
+// Copyright (c) StellaOps. Licensed under the AGPL-3.0-or-later.
+
+using StellaOps.Eventing.Models;
+using StellaOps.HybridLogicalClock;
+
+namespace StellaOps.Timeline.Core.Replay;
+
+/// <summary>
+/// Interface for orchestrating deterministic replay of timeline events.
+/// </summary>
+public interface ITimelineReplayOrchestrator
+{
+    /// <summary>
+    /// Initiates a replay operation for a correlation ID.
+    /// </summary>
+    /// <param name="correlationId">The correlation ID to replay.</param>
+    /// <param name="request">Replay request parameters.</param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>The initiated replay operation.</returns>
+    Task<ReplayOperation> InitiateReplayAsync(
+        string correlationId,
+        ReplayRequest request,
+        CancellationToken cancellationToken = default);
+
+    /// <summary>
+    /// Gets the status of a replay operation.
+    /// </summary>
+    /// <param name="replayId">The replay operation ID.</param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>The replay operation status, or null if not found.</returns>
+    Task<ReplayOperation?> GetReplayStatusAsync(
+        string replayId,
+        CancellationToken cancellationToken = default);
+
+    /// <summary>
+    /// Cancels an in-progress replay operation.
+    /// </summary>
+    /// <param name="replayId">The replay operation ID.</param>
+    /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>True if cancelled, false if not found or already completed.</returns>
+    Task<bool> CancelReplayAsync(
+        string replayId,
+        CancellationToken cancellationToken = default);
+}
+
+/// <summary>
+/// Request for initiating a replay operation.
+/// </summary>
+public sealed record ReplayRequest
+{
+    /// <summary>
+    /// Replay mode: "dry-run" or "verify".
+    /// </summary>
+    public string Mode { get; init; } = "dry-run";
+
+    /// <summary>
+    /// Optional HLC to replay from.
+    /// </summary>
+    public HlcTimestamp? FromHlc { get; init; }
+
+    /// <summary>
+    /// Optional HLC to replay to.
+    /// </summary>
+    public HlcTimestamp? ToHlc { get; init; }
+}
+
+/// <summary>
+/// Represents a replay operation.
+/// </summary>
+public sealed record ReplayOperation
+{
+    /// <summary>
+    /// Unique replay operation ID.
+    /// </summary>
+    public required string ReplayId { get; init; }
+
+    /// <summary>
+    /// The correlation ID being replayed.
+    /// </summary>
+    public required string CorrelationId { get; init; }
+
+    /// <summary>
+    /// Replay mode.
+    /// </summary>
+    public required string Mode { get; init; }
+
+    /// <summary>
+    /// Current status.
+    /// </summary>
+    public required ReplayStatus Status { get; init; }
+
+    /// <summary>
+    /// Progress (0.0 to 1.0).
+    /// </summary>
+    public double Progress { get; init; }
+
+    /// <summary>
+    /// Number of events processed.
+    /// </summary>
+    public int EventsProcessed { get; init; }
+
+    /// <summary>
+    /// Total number of events.
+    /// </summary>
+    public int TotalEvents { get; init; }
+
+    /// <summary>
+    /// Start time.
+    /// </summary>
+    public DateTimeOffset StartedAt { get; init; }
+
+    /// <summary>
+    /// Completion time (if completed).
+    /// </summary>
+    public DateTimeOffset? CompletedAt { get; init; }
+
+    /// <summary>
+    /// Error message (if failed).
+    /// </summary>
+    public string? Error { get; init; }
+
+    /// <summary>
+    /// Original output digest (for verify mode).
+    /// </summary>
+    public string? OriginalDigest { get; init; }
+
+    /// <summary>
+    /// Replayed output digest (for verify mode).
+    /// </summary>
+    public string? ReplayDigest { get; init; }
+
+    /// <summary>
+    /// Whether the replay matched the original (for verify mode).
+    /// </summary>
+    public bool? DeterministicMatch { get; init; }
+}
+
+/// <summary>
+/// Replay operation status.
+/// </summary>
+public enum ReplayStatus
+{
+    /// <summary>
+    /// Replay has been initiated but not started.
+    /// </summary>
+    Initiated,
+
+    /// <summary>
+    /// Replay is in progress.
+    /// </summary>
+    InProgress,
+
+    /// <summary>
+    /// Replay completed successfully.
+    /// </summary>
+    Completed,
+
+    /// <summary>
+    /// Replay failed.
+    /// </summary>
+    Failed,
+
+    /// <summary>
+    /// Replay was cancelled.
+    /// </summary>
+    Cancelled
+}

src/Timeline/__Libraries/StellaOps.Timeline.Core/Replay/TimelineReplayOrchestrator.cs

@@ -0,0 +1,294 @@
+// Copyright (c) StellaOps. Licensed under the AGPL-3.0-or-later.
+
+using System.Collections.Concurrent;
+using System.Security.Cryptography;
+using System.Text;
+using Microsoft.Extensions.Logging;
+using Microsoft.Extensions.Time.Testing;
+using StellaOps.Eventing.Models;
+using StellaOps.Eventing.Storage;
+using StellaOps.HybridLogicalClock;
+using StellaOps.Timeline.Core.Telemetry;
+
+namespace StellaOps.Timeline.Core.Replay;
+
+/// <summary>
+/// Implementation of <see cref="ITimelineReplayOrchestrator"/>.
+/// </summary>
+public sealed class TimelineReplayOrchestrator : ITimelineReplayOrchestrator
+{
+    private readonly ITimelineEventStore _eventStore;
+    private readonly TimelineMetrics _metrics;
+    private readonly TimeProvider _timeProvider;
+    private readonly ILogger<TimelineReplayOrchestrator> _logger;
+
+    // In-memory store for replay operations (production would use PostgreSQL)
+    private readonly ConcurrentDictionary<string, ReplayOperation> _operations = new();
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="TimelineReplayOrchestrator"/> class.
+    /// </summary>
+    public TimelineReplayOrchestrator(
+        ITimelineEventStore eventStore,
+        TimelineMetrics metrics,
+        TimeProvider timeProvider,
+        ILogger<TimelineReplayOrchestrator> logger)
+    {
+        _eventStore = eventStore ?? throw new ArgumentNullException(nameof(eventStore));
+        _metrics = metrics ?? throw new ArgumentNullException(nameof(metrics));
+        _timeProvider = timeProvider ?? throw new ArgumentNullException(nameof(timeProvider));
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+    }
+
+    /// <inheritdoc/>
+    public async Task<ReplayOperation> InitiateReplayAsync(
+        string correlationId,
+        ReplayRequest request,
+        CancellationToken cancellationToken = default)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(correlationId);
+        ArgumentNullException.ThrowIfNull(request);
+
+        var replayId = GenerateReplayId();
+        var now = _timeProvider.GetUtcNow();
+
+        // Get events to determine total count
+        var events = await GetEventsForReplayAsync(correlationId, request, cancellationToken)
+            .ConfigureAwait(false);
+
+        var operation = new ReplayOperation
+        {
+            ReplayId = replayId,
+            CorrelationId = correlationId,
+            Mode = request.Mode,
+            Status = ReplayStatus.Initiated,
+            Progress = 0,
+            EventsProcessed = 0,
+            TotalEvents = events.Count,
+            StartedAt = now
+        };
+
+        _operations[replayId] = operation;
+
+        _logger.LogInformation(
+            "Initiated replay {ReplayId} for correlation {CorrelationId} with {EventCount} events",
+            replayId,
+            correlationId,
+            events.Count);
+
+        // Start replay in background (in production, this would be queued to a worker)
+        _ = Task.Run(() => ExecuteReplayAsync(replayId, events, request, cancellationToken), cancellationToken);
+
+        return operation;
+    }
+
+    /// <inheritdoc/>
+    public Task<ReplayOperation?> GetReplayStatusAsync(
+        string replayId,
+        CancellationToken cancellationToken = default)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(replayId);
+
+        _operations.TryGetValue(replayId, out var operation);
+        return Task.FromResult(operation);
+    }
+
+    /// <inheritdoc/>
+    public Task<bool> CancelReplayAsync(
+        string replayId,
+        CancellationToken cancellationToken = default)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(replayId);
+
+        if (!_operations.TryGetValue(replayId, out var operation))
+        {
+            return Task.FromResult(false);
+        }
+
+        if (operation.Status is ReplayStatus.Completed or ReplayStatus.Failed or ReplayStatus.Cancelled)
+        {
+            return Task.FromResult(false);
+        }
+
+        var cancelled = operation with
+        {
+            Status = ReplayStatus.Cancelled,
+            CompletedAt = _timeProvider.GetUtcNow()
+        };
+
+        _operations[replayId] = cancelled;
+
+        _logger.LogInformation("Cancelled replay {ReplayId}", replayId);
+
+        return Task.FromResult(true);
+    }
+
+    private async Task<IReadOnlyList<TimelineEvent>> GetEventsForReplayAsync(
+        string correlationId,
+        ReplayRequest request,
+        CancellationToken cancellationToken)
+    {
+        if (request.FromHlc.HasValue && request.ToHlc.HasValue)
+        {
+            return await _eventStore.GetByHlcRangeAsync(
+                correlationId,
+                request.FromHlc.Value,
+                request.ToHlc.Value,
+                cancellationToken).ConfigureAwait(false);
+        }
+
+        return await _eventStore.GetByCorrelationIdAsync(
+            correlationId,
+            limit: 100000, // Get all events
+            offset: 0,
+            cancellationToken).ConfigureAwait(false);
+    }
+
+    private async Task ExecuteReplayAsync(
+        string replayId,
+        IReadOnlyList<TimelineEvent> events,
+        ReplayRequest request,
+        CancellationToken cancellationToken)
+    {
+        var startTime = _timeProvider.GetUtcNow();
+
+        try
+        {
+            // Update status to in-progress
+            UpdateOperation(replayId, op => op with { Status = ReplayStatus.InProgress });
+
+            // Create a FakeTimeProvider for deterministic replay
+            var fakeTimeProvider = new FakeTimeProvider();
+
+            // Compute original digest from events
+            var originalDigest = ComputeEventChainDigest(events);
+
+            var processedCount = 0;
+            var replayedPayloads = new List<string>();
+
+            foreach (var evt in events)
+            {
+                if (cancellationToken.IsCancellationRequested)
+                {
+                    UpdateOperation(replayId, op => op with
+                    {
+                        Status = ReplayStatus.Cancelled,
+                        CompletedAt = _timeProvider.GetUtcNow()
+                    });
+                    return;
+                }
+
+                // Check if cancelled
+                if (_operations.TryGetValue(replayId, out var current) && current.Status == ReplayStatus.Cancelled)
+                {
+                    return;
+                }
+
+                // Simulate replay processing
+                // In production, this would re-execute the logic that produced each event
+                fakeTimeProvider.SetUtcNow(evt.TsWall);
+
+                // For dry-run mode, we just verify we can process all events
+                // For verify mode, we would re-execute and compare outputs
+                replayedPayloads.Add(evt.Payload);
+
+                processedCount++;
+
+                // Update progress
+                var progress = (double)processedCount / events.Count;
+                UpdateOperation(replayId, op => op with
+                {
+                    Progress = progress,
+                    EventsProcessed = processedCount
+                });
+
+                // Small delay to simulate processing (remove in production)
+                await Task.Delay(1, cancellationToken).ConfigureAwait(false);
+            }
+
+            // Compute replayed digest
+            var replayDigest = ComputePayloadChainDigest(replayedPayloads);
+            var deterministicMatch = originalDigest == replayDigest;
+
+            var endTime = _timeProvider.GetUtcNow();
+            var duration = (endTime - startTime).TotalSeconds;
+
+            // Update final status
+            UpdateOperation(replayId, op => op with
+            {
+                Status = ReplayStatus.Completed,
+                Progress = 1.0,
+                EventsProcessed = events.Count,
+                CompletedAt = endTime,
+                OriginalDigest = originalDigest,
+                ReplayDigest = replayDigest,
+                DeterministicMatch = deterministicMatch
+            });
+
+            _metrics.RecordReplay(
+                request.Mode,
+                deterministicMatch ? "SUCCESS" : "MISMATCH",
+                events.Count,
+                duration);
+
+            _logger.LogInformation(
+                "Completed replay {ReplayId}: {EventCount} events, deterministic={Match}, duration={Duration}s",
+                replayId,
+                events.Count,
+                deterministicMatch,
+                duration);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogError(ex, "Replay {ReplayId} failed", replayId);
+
+            UpdateOperation(replayId, op => op with
+            {
+                Status = ReplayStatus.Failed,
+                CompletedAt = _timeProvider.GetUtcNow(),
+                Error = ex.Message
+            });
+
+            _metrics.RecordReplay(request.Mode, "FAILED", events.Count, 0);
+        }
+    }
+
+    private void UpdateOperation(string replayId, Func<ReplayOperation, ReplayOperation> update)
+    {
+        if (_operations.TryGetValue(replayId, out var current))
+        {
+            _operations[replayId] = update(current);
+        }
+    }
+
+    private static string GenerateReplayId()
+    {
+        return Guid.NewGuid().ToString("N")[..16];
+    }
+
+    private static string ComputeEventChainDigest(IReadOnlyList<TimelineEvent> events)
+    {
+        using var hasher = IncrementalHash.CreateHash(HashAlgorithmName.SHA256);
+
+        foreach (var evt in events)
+        {
+            hasher.AppendData(evt.PayloadDigest);
+        }
+
+        var hash = hasher.GetHashAndReset();
+        return Convert.ToHexString(hash).ToLowerInvariant();
+    }
+
+    private static string ComputePayloadChainDigest(IReadOnlyList<string> payloads)
+    {
+        using var hasher = IncrementalHash.CreateHash(HashAlgorithmName.SHA256);
+
+        foreach (var payload in payloads)
+        {
+            hasher.AppendData(Encoding.UTF8.GetBytes(payload));
+        }
+
+        var hash = hasher.GetHashAndReset();
+        return Convert.ToHexString(hash).ToLowerInvariant();
+    }
+}

src/Timeline/__Libraries/StellaOps.Timeline.Core/ServiceCollectionExtensions.cs

@@ -0,0 +1,41 @@
+// Copyright (c) StellaOps. Licensed under the AGPL-3.0-or-later.
+
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.DependencyInjection.Extensions;
+using StellaOps.Timeline.Core.Export;
+using StellaOps.Timeline.Core.Replay;
+using StellaOps.Timeline.Core.Telemetry;
+
+namespace StellaOps.Timeline.Core;
+
+/// <summary>
+/// Extension methods for registering timeline services.
+/// </summary>
+public static class ServiceCollectionExtensions
+{
+    /// <summary>
+    /// Adds timeline query and replay services.
+    /// </summary>
+    public static IServiceCollection AddTimelineServices(
+        this IServiceCollection services,
+        IConfiguration configuration)
+    {
+        ArgumentNullException.ThrowIfNull(services);
+        ArgumentNullException.ThrowIfNull(configuration);
+
+        // Register metrics (singleton for consistent counters)
+        services.TryAddSingleton<TimelineMetrics>();
+
+        // Register query service
+        services.TryAddScoped<ITimelineQueryService, TimelineQueryService>();
+
+        // Register replay orchestrator
+        services.TryAddScoped<ITimelineReplayOrchestrator, TimelineReplayOrchestrator>();
+
+        // Register export bundle builder
+        services.TryAddScoped<ITimelineBundleBuilder, TimelineBundleBuilder>();
+
+        return services;
+    }
+}

src/Timeline/__Libraries/StellaOps.Timeline.Core/StellaOps.Timeline.Core.csproj

@@ -0,0 +1,25 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    <RootNamespace>StellaOps.Timeline.Core</RootNamespace>
+    <Description>StellaOps Timeline Core - Query and replay services</Description>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\..\__Libraries\StellaOps.Eventing\StellaOps.Eventing.csproj" />
+    <ProjectReference Include="..\..\..\__Libraries\StellaOps.HybridLogicalClock\StellaOps.HybridLogicalClock.csproj" />
+    <ProjectReference Include="..\..\..\__Libraries\StellaOps.Replay.Core\StellaOps.Replay.Core.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" />
+    <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" />
+    <PackageReference Include="Microsoft.Extensions.Options" />
+    <PackageReference Include="Npgsql" />
+  </ItemGroup>
+
+</Project>

src/Timeline/__Libraries/StellaOps.Timeline.Core/Telemetry/TimelineMetrics.cs

@@ -0,0 +1,173 @@
+// Copyright (c) StellaOps. Licensed under the AGPL-3.0-or-later.
+
+using System.Diagnostics;
+using System.Diagnostics.Metrics;
+
+namespace StellaOps.Timeline.Core.Telemetry;
+
+/// <summary>
+/// Metrics instrumentation for the Timeline service.
+/// </summary>
+public sealed class TimelineMetrics : IDisposable
+{
+    private readonly Meter _meter;
+    private readonly Counter<long> _queriesCounter;
+    private readonly Counter<long> _replaysCounter;
+    private readonly Counter<long> _exportsCounter;
+    private readonly Histogram<double> _queryDurationHistogram;
+    private readonly Histogram<double> _replayDurationHistogram;
+    private readonly Histogram<long> _exportSizeHistogram;
+    private readonly Counter<long> _cacheHitsCounter;
+    private readonly Counter<long> _cacheMissesCounter;
+
+    /// <summary>
+    /// Activity source for tracing.
+    /// </summary>
+    public static readonly ActivitySource ActivitySource = new("StellaOps.Timeline", "1.0.0");
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="TimelineMetrics"/> class.
+    /// </summary>
+    public TimelineMetrics()
+    {
+        _meter = new Meter("StellaOps.Timeline", "1.0.0");
+
+        _queriesCounter = _meter.CreateCounter<long>(
+            "stellaops_timeline_queries_total",
+            description: "Total number of timeline queries");
+
+        _replaysCounter = _meter.CreateCounter<long>(
+            "stellaops_timeline_replays_total",
+            description: "Total number of replay operations");
+
+        _exportsCounter = _meter.CreateCounter<long>(
+            "stellaops_timeline_exports_total",
+            description: "Total number of export operations");
+
+        _queryDurationHistogram = _meter.CreateHistogram<double>(
+            "stellaops_timeline_query_duration_seconds",
+            unit: "s",
+            description: "Duration of timeline query operations");
+
+        _replayDurationHistogram = _meter.CreateHistogram<double>(
+            "stellaops_timeline_replay_duration_seconds",
+            unit: "s",
+            description: "Duration of replay operations");
+
+        _exportSizeHistogram = _meter.CreateHistogram<long>(
+            "stellaops_timeline_export_size_bytes",
+            unit: "By",
+            description: "Size of exported timeline bundles");
+
+        _cacheHitsCounter = _meter.CreateCounter<long>(
+            "stellaops_timeline_cache_hits_total",
+            description: "Total number of cache hits");
+
+        _cacheMissesCounter = _meter.CreateCounter<long>(
+            "stellaops_timeline_cache_misses_total",
+            description: "Total number of cache misses");
+    }
+
+    /// <summary>
+    /// Records a timeline query.
+    /// </summary>
+    public void RecordQuery(string queryType, int eventCount, double durationSeconds)
+    {
+        _queriesCounter.Add(1,
+            new KeyValuePair<string, object?>("query_type", queryType));
+        _queryDurationHistogram.Record(durationSeconds,
+            new KeyValuePair<string, object?>("query_type", queryType),
+            new KeyValuePair<string, object?>("event_count_bucket", GetCountBucket(eventCount)));
+    }
+
+    /// <summary>
+    /// Records a replay operation.
+    /// </summary>
+    public void RecordReplay(string mode, string status, int eventCount, double durationSeconds)
+    {
+        _replaysCounter.Add(1,
+            new KeyValuePair<string, object?>("mode", mode),
+            new KeyValuePair<string, object?>("status", status));
+        _replayDurationHistogram.Record(durationSeconds,
+            new KeyValuePair<string, object?>("mode", mode),
+            new KeyValuePair<string, object?>("event_count_bucket", GetCountBucket(eventCount)));
+    }
+
+    /// <summary>
+    /// Records an export operation.
+    /// </summary>
+    public void RecordExport(string format, bool signed, long sizeBytes, int eventCount)
+    {
+        _exportsCounter.Add(1,
+            new KeyValuePair<string, object?>("format", format),
+            new KeyValuePair<string, object?>("signed", signed));
+        _exportSizeHistogram.Record(sizeBytes,
+            new KeyValuePair<string, object?>("format", format),
+            new KeyValuePair<string, object?>("event_count_bucket", GetCountBucket(eventCount)));
+    }
+
+    /// <summary>
+    /// Records a cache hit.
+    /// </summary>
+    public void RecordCacheHit(string cacheType)
+    {
+        _cacheHitsCounter.Add(1,
+            new KeyValuePair<string, object?>("cache_type", cacheType));
+    }
+
+    /// <summary>
+    /// Records a cache miss.
+    /// </summary>
+    public void RecordCacheMiss(string cacheType)
+    {
+        _cacheMissesCounter.Add(1,
+            new KeyValuePair<string, object?>("cache_type", cacheType));
+    }
+
+    /// <summary>
+    /// Starts a query activity for tracing.
+    /// </summary>
+    public Activity? StartQueryActivity(string correlationId, string queryType)
+    {
+        return ActivitySource.StartActivity(
+            "timeline.query",
+            ActivityKind.Server,
+            parentContext: default,
+            tags: new[]
+            {
+                new KeyValuePair<string, object?>("correlation_id", correlationId),
+                new KeyValuePair<string, object?>("query_type", queryType)
+            });
+    }
+
+    /// <summary>
+    /// Starts a replay activity for tracing.
+    /// </summary>
+    public Activity? StartReplayActivity(string correlationId, string mode)
+    {
+        return ActivitySource.StartActivity(
+            "timeline.replay",
+            ActivityKind.Server,
+            parentContext: default,
+            tags: new[]
+            {
+                new KeyValuePair<string, object?>("correlation_id", correlationId),
+                new KeyValuePair<string, object?>("mode", mode)
+            });
+    }
+
+    private static string GetCountBucket(int count) => count switch
+    {
+        <= 10 => "1-10",
+        <= 100 => "11-100",
+        <= 1000 => "101-1000",
+        <= 10000 => "1001-10000",
+        _ => "10000+"
+    };
+
+    /// <inheritdoc/>
+    public void Dispose()
+    {
+        _meter.Dispose();
+    }
+}

src/Timeline/__Libraries/StellaOps.Timeline.Core/TimelineQueryService.cs

@@ -0,0 +1,192 @@
+// Copyright (c) StellaOps. Licensed under the AGPL-3.0-or-later.
+
+using Microsoft.Extensions.Logging;
+using StellaOps.Eventing.Models;
+using StellaOps.Eventing.Storage;
+using StellaOps.HybridLogicalClock;
+
+namespace StellaOps.Timeline.Core;
+
+/// <summary>
+/// Implementation of <see cref="ITimelineQueryService"/>.
+/// </summary>
+public sealed class TimelineQueryService : ITimelineQueryService
+{
+    private readonly ITimelineEventStore _eventStore;
+    private readonly ILogger<TimelineQueryService> _logger;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="TimelineQueryService"/> class.
+    /// </summary>
+    public TimelineQueryService(
+        ITimelineEventStore eventStore,
+        ILogger<TimelineQueryService> logger)
+    {
+        _eventStore = eventStore ?? throw new ArgumentNullException(nameof(eventStore));
+        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
+    }
+
+    /// <inheritdoc/>
+    public async Task<TimelineQueryResult> GetByCorrelationIdAsync(
+        string correlationId,
+        TimelineQueryOptions? options = null,
+        CancellationToken cancellationToken = default)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(correlationId);
+
+        options ??= new TimelineQueryOptions();
+
+        IReadOnlyList<TimelineEvent> events;
+
+        if (options.FromHlc.HasValue && options.ToHlc.HasValue)
+        {
+            events = await _eventStore.GetByHlcRangeAsync(
+                correlationId,
+                options.FromHlc.Value,
+                options.ToHlc.Value,
+                cancellationToken).ConfigureAwait(false);
+        }
+        else
+        {
+            events = await _eventStore.GetByCorrelationIdAsync(
+                correlationId,
+                options.Limit + 1, // Fetch one extra to check for more
+                options.Offset,
+                cancellationToken).ConfigureAwait(false);
+        }
+
+        // Apply additional filters
+        var filteredEvents = ApplyFilters(events, options);
+
+        // Check if there are more results
+        var hasMore = filteredEvents.Count > options.Limit;
+        if (hasMore)
+        {
+            filteredEvents = filteredEvents.Take(options.Limit).ToList();
+        }
+
+        var totalCount = await _eventStore.CountByCorrelationIdAsync(correlationId, cancellationToken)
+            .ConfigureAwait(false);
+
+        _logger.LogDebug(
+            "Queried {Count} events for correlation {CorrelationId}",
+            filteredEvents.Count,
+            correlationId);
+
+        return new TimelineQueryResult
+        {
+            Events = filteredEvents,
+            TotalCount = totalCount,
+            HasMore = hasMore,
+            NextCursor = hasMore && filteredEvents.Count > 0
+                ? filteredEvents[^1].THlc.ToSortableString()
+                : null
+        };
+    }
+
+    /// <inheritdoc/>
+    public async Task<CriticalPathResult> GetCriticalPathAsync(
+        string correlationId,
+        CancellationToken cancellationToken = default)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(correlationId);
+
+        var events = await _eventStore.GetByCorrelationIdAsync(
+            correlationId,
+            limit: 10000, // Get all events for critical path analysis
+            offset: 0,
+            cancellationToken).ConfigureAwait(false);
+
+        if (events.Count < 2)
+        {
+            return new CriticalPathResult
+            {
+                CorrelationId = correlationId,
+                TotalDuration = TimeSpan.Zero,
+                Stages = Array.Empty<CriticalPathStage>()
+            };
+        }
+
+        var stages = new List<CriticalPathStage>();
+        var totalDuration = events[^1].TsWall - events[0].TsWall;
+
+        for (int i = 1; i < events.Count; i++)
+        {
+            var prev = events[i - 1];
+            var curr = events[i];
+            var stageDuration = curr.TsWall - prev.TsWall;
+
+            stages.Add(new CriticalPathStage
+            {
+                Stage = $"{prev.Kind} -> {curr.Kind}",
+                Service = curr.Service,
+                Duration = stageDuration,
+                Percentage = totalDuration.TotalMilliseconds > 0
+                    ? stageDuration.TotalMilliseconds / totalDuration.TotalMilliseconds * 100
+                    : 0,
+                FromHlc = prev.THlc,
+                ToHlc = curr.THlc
+            });
+        }
+
+        // Sort by duration descending (critical path = longest stages first)
+        stages = stages.OrderByDescending(s => s.Duration).ToList();
+
+        return new CriticalPathResult
+        {
+            CorrelationId = correlationId,
+            TotalDuration = totalDuration,
+            Stages = stages
+        };
+    }
+
+    /// <inheritdoc/>
+    public async Task<TimelineQueryResult> GetByServiceAsync(
+        string service,
+        HlcTimestamp? fromHlc = null,
+        int limit = 100,
+        CancellationToken cancellationToken = default)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(service);
+
+        var events = await _eventStore.GetByServiceAsync(
+            service,
+            fromHlc,
+            limit + 1,
+            cancellationToken).ConfigureAwait(false);
+
+        var hasMore = events.Count > limit;
+        var resultEvents = hasMore ? events.Take(limit).ToList() : events;
+
+        return new TimelineQueryResult
+        {
+            Events = resultEvents,
+            TotalCount = resultEvents.Count,
+            HasMore = hasMore,
+            NextCursor = hasMore && resultEvents.Count > 0
+                ? resultEvents[^1].THlc.ToSortableString()
+                : null
+        };
+    }
+
+    private static List<TimelineEvent> ApplyFilters(
+        IReadOnlyList<TimelineEvent> events,
+        TimelineQueryOptions options)
+    {
+        var query = events.AsEnumerable();
+
+        if (options.Services is { Count: > 0 })
+        {
+            var services = new HashSet<string>(options.Services, StringComparer.OrdinalIgnoreCase);
+            query = query.Where(e => services.Contains(e.Service));
+        }
+
+        if (options.Kinds is { Count: > 0 })
+        {
+            var kinds = new HashSet<string>(options.Kinds, StringComparer.OrdinalIgnoreCase);
+            query = query.Where(e => kinds.Contains(e.Kind));
+        }
+
+        return query.ToList();
+    }
+}

src/Timeline/__Tests/StellaOps.Timeline.Core.Tests/AGENTS.md

@@ -0,0 +1,24 @@
+# Timeline Core Tests Charter
+
+## Mission
+- Verify timeline core query, replay, and export logic.
+
+## Responsibilities
+- Cover ordering, filtering, and pagination behavior.
+- Exercise replay and export determinism and cancellation.
+- Validate HLC range handling and edge cases.
+
+## Required Reading
+- docs/README.md
+- docs/07_HIGH_LEVEL_ARCHITECTURE.md
+- docs/modules/platform/architecture-overview.md
+- docs/modules/timeline-indexer/architecture.md
+- docs/modules/timeline-indexer/README.md
+
+## Working Agreement
+- Use fixed times and IDs in fixtures.
+- Avoid network dependencies in tests.
+
+## Testing Strategy
+- Unit tests for query, replay, and export logic.
+- Determinism tests for ordering and digests.

src/Timeline/__Tests/StellaOps.Timeline.Core.Tests/StellaOps.Timeline.Core.Tests.csproj

@@ -0,0 +1,34 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <IsPackable>false</IsPackable>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    <RootNamespace>StellaOps.Timeline.Core.Tests</RootNamespace>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\__Libraries\StellaOps.Timeline.Core\StellaOps.Timeline.Core.csproj" />
+    <ProjectReference Include="..\..\..\__Libraries\StellaOps.Eventing\StellaOps.Eventing.csproj" />
+    <ProjectReference Include="..\..\..\__Libraries\StellaOps.HybridLogicalClock\StellaOps.HybridLogicalClock.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" />
+    <PackageReference Include="xunit" />
+    <PackageReference Include="xunit.runner.visualstudio">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+    <PackageReference Include="coverlet.collector">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+    <PackageReference Include="Moq" />
+    <PackageReference Include="FluentAssertions" />
+    <PackageReference Include="Microsoft.Extensions.TimeProvider.Testing" />
+  </ItemGroup>
+
+</Project>

src/Timeline/__Tests/StellaOps.Timeline.Core.Tests/TimelineQueryServiceTests.cs

@@ -0,0 +1,224 @@
+// Copyright (c) StellaOps. Licensed under the AGPL-3.0-or-later.
+
+using FluentAssertions;
+using Microsoft.Extensions.Logging.Abstractions;
+using StellaOps.Eventing.Models;
+using StellaOps.Eventing.Storage;
+using StellaOps.HybridLogicalClock;
+using Xunit;
+
+namespace StellaOps.Timeline.Core.Tests;
+
+[Trait("Category", "Unit")]
+public sealed class TimelineQueryServiceTests
+{
+    private readonly InMemoryTimelineEventStore _eventStore;
+    private readonly TimelineQueryService _queryService;
+
+    public TimelineQueryServiceTests()
+    {
+        _eventStore = new InMemoryTimelineEventStore();
+        _queryService = new TimelineQueryService(
+            _eventStore,
+            NullLogger<TimelineQueryService>.Instance);
+    }
+
+    private static TimelineEvent CreateEvent(
+        string correlationId,
+        string kind,
+        HlcTimestamp hlc,
+        string service = "TestService")
+    {
+        return new TimelineEvent
+        {
+            EventId = $"{correlationId}-{kind}-{hlc.LogicalCounter}",
+            CorrelationId = correlationId,
+            Kind = kind,
+            THlc = hlc,
+            TsWall = DateTimeOffset.UtcNow,
+            Service = service,
+            Payload = "{}",
+            PayloadDigest = new byte[32],
+            EngineVersion = new EngineVersionRef("Test", "1.0.0", "test"),
+            SchemaVersion = 1
+        };
+    }
+
+    [Fact]
+    public async Task GetByCorrelationIdAsync_ReturnsEventsOrderedByHlc()
+    {
+        // Arrange
+        var hlc1 = new HlcTimestamp(1000, 0, "n1");
+        var hlc2 = new HlcTimestamp(1000, 1, "n1");
+        var hlc3 = new HlcTimestamp(2000, 0, "n1");
+
+        await _eventStore.AppendAsync(CreateEvent("corr-1", "C", hlc3));
+        await _eventStore.AppendAsync(CreateEvent("corr-1", "A", hlc1));
+        await _eventStore.AppendAsync(CreateEvent("corr-1", "B", hlc2));
+
+        // Act
+        var result = await _queryService.GetByCorrelationIdAsync("corr-1");
+
+        // Assert
+        result.Events.Should().HaveCount(3);
+        result.Events[0].Kind.Should().Be("A");
+        result.Events[1].Kind.Should().Be("B");
+        result.Events[2].Kind.Should().Be("C");
+    }
+
+    [Fact]
+    public async Task GetByCorrelationIdAsync_FiltersByServices()
+    {
+        // Arrange
+        var hlc1 = new HlcTimestamp(1000, 0, "n1");
+        var hlc2 = new HlcTimestamp(2000, 0, "n1");
+        var hlc3 = new HlcTimestamp(3000, 0, "n1");
+
+        await _eventStore.AppendAsync(CreateEvent("corr-1", "A", hlc1, "Scheduler"));
+        await _eventStore.AppendAsync(CreateEvent("corr-1", "B", hlc2, "AirGap"));
+        await _eventStore.AppendAsync(CreateEvent("corr-1", "C", hlc3, "Scheduler"));
+
+        // Act
+        var result = await _queryService.GetByCorrelationIdAsync("corr-1", new TimelineQueryOptions
+        {
+            Services = new[] { "Scheduler" }
+        });
+
+        // Assert
+        result.Events.Should().HaveCount(2);
+        result.Events.All(e => e.Service == "Scheduler").Should().BeTrue();
+    }
+
+    [Fact]
+    public async Task GetByCorrelationIdAsync_FiltersByKinds()
+    {
+        // Arrange
+        var hlc1 = new HlcTimestamp(1000, 0, "n1");
+        var hlc2 = new HlcTimestamp(2000, 0, "n1");
+        var hlc3 = new HlcTimestamp(3000, 0, "n1");
+
+        await _eventStore.AppendAsync(CreateEvent("corr-1", "ENQUEUE", hlc1));
+        await _eventStore.AppendAsync(CreateEvent("corr-1", "EXECUTE", hlc2));
+        await _eventStore.AppendAsync(CreateEvent("corr-1", "COMPLETE", hlc3));
+
+        // Act
+        var result = await _queryService.GetByCorrelationIdAsync("corr-1", new TimelineQueryOptions
+        {
+            Kinds = new[] { "ENQUEUE", "COMPLETE" }
+        });
+
+        // Assert
+        result.Events.Should().HaveCount(2);
+        result.Events.Select(e => e.Kind).Should().BeEquivalentTo(new[] { "ENQUEUE", "COMPLETE" });
+    }
+
+    [Fact]
+    public async Task GetByCorrelationIdAsync_HasMoreFlag_WhenMoreResults()
+    {
+        // Arrange
+        for (int i = 0; i < 10; i++)
+        {
+            await _eventStore.AppendAsync(CreateEvent("corr-1", $"E{i}", new HlcTimestamp(1000 + i, 0, "n1")));
+        }
+
+        // Act
+        var result = await _queryService.GetByCorrelationIdAsync("corr-1", new TimelineQueryOptions { Limit = 5 });
+
+        // Assert
+        result.Events.Should().HaveCount(5);
+        result.HasMore.Should().BeTrue();
+        result.TotalCount.Should().Be(10);
+        result.NextCursor.Should().NotBeNullOrEmpty();
+    }
+
+    [Fact]
+    public async Task GetCriticalPathAsync_ReturnsStagesOrderedByDuration()
+    {
+        // Arrange
+        var baseTime = new DateTimeOffset(2026, 1, 7, 12, 0, 0, TimeSpan.Zero);
+
+        await _eventStore.AppendAsync(new TimelineEvent
+        {
+            EventId = "e1",
+            CorrelationId = "corr-1",
+            Kind = "ENQUEUE",
+            THlc = new HlcTimestamp(1000, 0, "n1"),
+            TsWall = baseTime,
+            Service = "Scheduler",
+            Payload = "{}",
+            PayloadDigest = new byte[32],
+            EngineVersion = new EngineVersionRef("Test", "1.0.0", "test"),
+            SchemaVersion = 1
+        });
+
+        await _eventStore.AppendAsync(new TimelineEvent
+        {
+            EventId = "e2",
+            CorrelationId = "corr-1",
+            Kind = "EXECUTE",
+            THlc = new HlcTimestamp(2000, 0, "n1"),
+            TsWall = baseTime.AddSeconds(1), // 1 second
+            Service = "Scheduler",
+            Payload = "{}",
+            PayloadDigest = new byte[32],
+            EngineVersion = new EngineVersionRef("Test", "1.0.0", "test"),
+            SchemaVersion = 1
+        });
+
+        await _eventStore.AppendAsync(new TimelineEvent
+        {
+            EventId = "e3",
+            CorrelationId = "corr-1",
+            Kind = "COMPLETE",
+            THlc = new HlcTimestamp(3000, 0, "n1"),
+            TsWall = baseTime.AddSeconds(5), // 4 more seconds
+            Service = "Scheduler",
+            Payload = "{}",
+            PayloadDigest = new byte[32],
+            EngineVersion = new EngineVersionRef("Test", "1.0.0", "test"),
+            SchemaVersion = 1
+        });
+
+        // Act
+        var result = await _queryService.GetCriticalPathAsync("corr-1");
+
+        // Assert
+        result.CorrelationId.Should().Be("corr-1");
+        result.TotalDuration.Should().Be(TimeSpan.FromSeconds(5));
+        result.Stages.Should().HaveCount(2);
+
+        // Stages should be ordered by duration descending
+        result.Stages[0].Stage.Should().Be("EXECUTE -> COMPLETE");
+        result.Stages[0].Duration.Should().Be(TimeSpan.FromSeconds(4));
+    }
+
+    [Fact]
+    public async Task GetCriticalPathAsync_EmptyForSingleEvent()
+    {
+        // Arrange
+        await _eventStore.AppendAsync(CreateEvent("corr-1", "ENQUEUE", new HlcTimestamp(1000, 0, "n1")));
+
+        // Act
+        var result = await _queryService.GetCriticalPathAsync("corr-1");
+
+        // Assert
+        result.Stages.Should().BeEmpty();
+        result.TotalDuration.Should().Be(TimeSpan.Zero);
+    }
+
+    [Fact]
+    public async Task GetByServiceAsync_ReturnsEventsFromService()
+    {
+        // Arrange
+        await _eventStore.AppendAsync(CreateEvent("corr-1", "A", new HlcTimestamp(1000, 0, "n1"), "Scheduler"));
+        await _eventStore.AppendAsync(CreateEvent("corr-2", "B", new HlcTimestamp(2000, 0, "n1"), "AirGap"));
+        await _eventStore.AppendAsync(CreateEvent("corr-3", "C", new HlcTimestamp(3000, 0, "n1"), "Scheduler"));
+
+        // Act
+        var result = await _queryService.GetByServiceAsync("Scheduler");
+
+        // Assert
+        result.Events.Should().HaveCount(2);
+        result.Events.All(e => e.Service == "Scheduler").Should().BeTrue();
+    }
+}

src/Timeline/__Tests/StellaOps.Timeline.WebService.Tests/AGENTS.md

@@ -0,0 +1,24 @@
+# Timeline WebService Tests Charter
+
+## Mission
+- Verify timeline API endpoints, validation, and auth gating.
+
+## Responsibilities
+- Exercise request validation, paging, and response ordering.
+- Cover replay and export endpoints and status flows.
+- Validate authorization middleware behavior.
+
+## Required Reading
+- docs/README.md
+- docs/07_HIGH_LEVEL_ARCHITECTURE.md
+- docs/modules/platform/architecture-overview.md
+- docs/modules/timeline-indexer/architecture.md
+- docs/modules/timeline-indexer/README.md
+
+## Working Agreement
+- Use fixed times and IDs in fixtures.
+- Avoid network dependencies beyond the local test server.
+
+## Testing Strategy
+- Integration tests for endpoint behavior and auth.
+- Determinism checks for ordered responses.

src/Timeline/__Tests/StellaOps.Timeline.WebService.Tests/ReplayOrchestratorIntegrationTests.cs

@@ -0,0 +1,163 @@
+// Copyright (c) StellaOps. Licensed under the AGPL-3.0-or-later.
+
+using FluentAssertions;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Time.Testing;
+using StellaOps.Eventing.Models;
+using StellaOps.Eventing.Storage;
+using StellaOps.HybridLogicalClock;
+using StellaOps.Timeline.Core.Replay;
+using StellaOps.Timeline.Core.Telemetry;
+using Xunit;
+
+namespace StellaOps.Timeline.WebService.Tests;
+
+[Trait("Category", "Integration")]
+public sealed class ReplayOrchestratorIntegrationTests
+{
+    private readonly InMemoryTimelineEventStore _eventStore;
+    private readonly TimelineReplayOrchestrator _orchestrator;
+    private readonly FakeTimeProvider _fakeTimeProvider;
+
+    public ReplayOrchestratorIntegrationTests()
+    {
+        _eventStore = new InMemoryTimelineEventStore();
+        _fakeTimeProvider = new FakeTimeProvider(new DateTimeOffset(2026, 1, 7, 12, 0, 0, TimeSpan.Zero));
+
+        _orchestrator = new TimelineReplayOrchestrator(
+            _eventStore,
+            new TimelineMetrics(),
+            _fakeTimeProvider,
+            NullLogger<TimelineReplayOrchestrator>.Instance);
+    }
+
+    [Fact]
+    public async Task InitiateReplayAsync_CreatesOperation()
+    {
+        // Arrange
+        const string correlationId = "replay-test-001";
+        await SeedEventsAsync(correlationId, 10);
+
+        // Act
+        var operation = await _orchestrator.InitiateReplayAsync(
+            correlationId,
+            new ReplayRequest { Mode = "dry-run" });
+
+        // Assert
+        operation.Should().NotBeNull();
+        operation.ReplayId.Should().NotBeNullOrEmpty();
+        operation.CorrelationId.Should().Be(correlationId);
+        operation.Mode.Should().Be("dry-run");
+        operation.Status.Should().Be(ReplayStatus.Initiated);
+        operation.TotalEvents.Should().Be(10);
+    }
+
+    [Fact]
+    public async Task GetReplayStatusAsync_ReturnsOperation()
+    {
+        // Arrange
+        const string correlationId = "replay-status-001";
+        await SeedEventsAsync(correlationId, 5);
+
+        var operation = await _orchestrator.InitiateReplayAsync(
+            correlationId,
+            new ReplayRequest { Mode = "verify" });
+
+        // Act
+        var status = await _orchestrator.GetReplayStatusAsync(operation.ReplayId);
+
+        // Assert
+        status.Should().NotBeNull();
+        status!.ReplayId.Should().Be(operation.ReplayId);
+    }
+
+    [Fact]
+    public async Task GetReplayStatusAsync_ReturnsNull_WhenNotFound()
+    {
+        // Act
+        var status = await _orchestrator.GetReplayStatusAsync("nonexistent-replay");
+
+        // Assert
+        status.Should().BeNull();
+    }
+
+    [Fact]
+    public async Task CancelReplayAsync_CancelsOperation()
+    {
+        // Arrange
+        const string correlationId = "replay-cancel-001";
+        await SeedEventsAsync(correlationId, 100); // Many events to ensure we can cancel
+
+        var operation = await _orchestrator.InitiateReplayAsync(
+            correlationId,
+            new ReplayRequest { Mode = "dry-run" });
+
+        // Act
+        var cancelled = await _orchestrator.CancelReplayAsync(operation.ReplayId);
+
+        // Assert
+        cancelled.Should().BeTrue();
+        var status = await _orchestrator.GetReplayStatusAsync(operation.ReplayId);
+        status!.Status.Should().Be(ReplayStatus.Cancelled);
+    }
+
+    [Fact]
+    public async Task CancelReplayAsync_ReturnsFalse_WhenNotFound()
+    {
+        // Act
+        var cancelled = await _orchestrator.CancelReplayAsync("nonexistent-replay");
+
+        // Assert
+        cancelled.Should().BeFalse();
+    }
+
+    [Fact]
+    public async Task ReplayCompletes_WithDeterministicDigest()
+    {
+        // Arrange
+        const string correlationId = "replay-digest-001";
+        await SeedEventsAsync(correlationId, 5);
+
+        var operation = await _orchestrator.InitiateReplayAsync(
+            correlationId,
+            new ReplayRequest { Mode = "verify" });
+
+        // Wait for completion
+        await Task.Delay(500); // Give background task time to complete
+
+        // Act
+        var status = await _orchestrator.GetReplayStatusAsync(operation.ReplayId);
+
+        // Assert - should complete or still be running
+        status.Should().NotBeNull();
+        // The operation should have started processing
+        status!.Status.Should().BeOneOf(
+            ReplayStatus.InProgress,
+            ReplayStatus.Completed,
+            ReplayStatus.Initiated);
+    }
+
+    private async Task SeedEventsAsync(string correlationId, int count)
+    {
+        var baseTime = new DateTimeOffset(2026, 1, 7, 12, 0, 0, TimeSpan.Zero);
+
+        for (int i = 0; i < count; i++)
+        {
+            var evt = new TimelineEvent
+            {
+                EventId = $"{correlationId}-evt-{i:D4}",
+                CorrelationId = correlationId,
+                Kind = $"EVENT_{i}",
+                THlc = new HlcTimestamp(1000 + i, 0, "test-node"),
+                TsWall = baseTime.AddSeconds(i),
+                Service = "TestService",
+                Payload = $"{{\"index\": {i}}}",
+                PayloadDigest = new byte[32],
+                EngineVersion = new EngineVersionRef("Test", "1.0.0", "test-digest"),
+                SchemaVersion = 1
+            };
+
+            await _eventStore.AppendAsync(evt);
+        }
+    }
+}

src/Timeline/__Tests/StellaOps.Timeline.WebService.Tests/StellaOps.Timeline.WebService.Tests.csproj

@@ -0,0 +1,35 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <IsPackable>false</IsPackable>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    <RootNamespace>StellaOps.Timeline.WebService.Tests</RootNamespace>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\StellaOps.Timeline.WebService\StellaOps.Timeline.WebService.csproj" />
+    <ProjectReference Include="..\..\__Libraries\StellaOps.Timeline.Core\StellaOps.Timeline.Core.csproj" />
+    <ProjectReference Include="..\..\..\__Libraries\StellaOps.Eventing\StellaOps.Eventing.csproj" />
+    <ProjectReference Include="..\..\..\__Libraries\StellaOps.HybridLogicalClock\StellaOps.HybridLogicalClock.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" />
+    <PackageReference Include="xunit" />
+    <PackageReference Include="xunit.runner.visualstudio">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+    <PackageReference Include="coverlet.collector">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+    <PackageReference Include="FluentAssertions" />
+    <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" />
+    <PackageReference Include="Testcontainers.PostgreSql" />
+  </ItemGroup>
+
+</Project>

src/Timeline/__Tests/StellaOps.Timeline.WebService.Tests/TimelineApiIntegrationTests.cs

@@ -0,0 +1,213 @@
+// Copyright (c) StellaOps. Licensed under the AGPL-3.0-or-later.
+
+using System.Net;
+using System.Net.Http.Json;
+using FluentAssertions;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Mvc.Testing;
+using Microsoft.Extensions.DependencyInjection;
+using StellaOps.Eventing.Models;
+using StellaOps.Eventing.Storage;
+using StellaOps.HybridLogicalClock;
+using StellaOps.Timeline.WebService.Endpoints;
+using Xunit;
+
+namespace StellaOps.Timeline.WebService.Tests;
+
+[Trait("Category", "Integration")]
+public sealed class TimelineApiIntegrationTests : IClassFixture<TimelineWebApplicationFactory>
+{
+    private readonly HttpClient _client;
+    private readonly TimelineWebApplicationFactory _factory;
+
+    public TimelineApiIntegrationTests(TimelineWebApplicationFactory factory)
+    {
+        _factory = factory;
+        _client = factory.CreateClient();
+    }
+
+    [Fact]
+    public async Task GetTimeline_ReturnsEvents_WhenCorrelationExists()
+    {
+        // Arrange
+        const string correlationId = "test-corr-001";
+        await SeedEventsAsync(correlationId, 5);
+
+        // Act
+        var response = await _client.GetAsync($"/api/v1/timeline/{correlationId}");
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+
+        var timeline = await response.Content.ReadFromJsonAsync<TimelineResponse>();
+        timeline.Should().NotBeNull();
+        timeline!.CorrelationId.Should().Be(correlationId);
+        timeline.Events.Should().HaveCount(5);
+    }
+
+    [Fact]
+    public async Task GetTimeline_Returns404_WhenCorrelationNotFound()
+    {
+        // Act
+        var response = await _client.GetAsync("/api/v1/timeline/nonexistent-correlation");
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.NotFound);
+    }
+
+    [Fact]
+    public async Task GetTimeline_ReturnsEventsOrderedByHlc()
+    {
+        // Arrange
+        const string correlationId = "test-corr-ordered";
+        await SeedEventsAsync(correlationId, 10);
+
+        // Act
+        var response = await _client.GetAsync($"/api/v1/timeline/{correlationId}");
+        var timeline = await response.Content.ReadFromJsonAsync<TimelineResponse>();
+
+        // Assert
+        timeline.Should().NotBeNull();
+        timeline!.Events.Should().BeInAscendingOrder(e => e.THlc);
+    }
+
+    [Fact]
+    public async Task GetTimeline_SupportsPagination()
+    {
+        // Arrange
+        const string correlationId = "test-corr-pagination";
+        await SeedEventsAsync(correlationId, 20);
+
+        // Act - Get first page
+        var response1 = await _client.GetAsync($"/api/v1/timeline/{correlationId}?limit=10");
+        var page1 = await response1.Content.ReadFromJsonAsync<TimelineResponse>();
+
+        // Assert
+        page1.Should().NotBeNull();
+        page1!.Events.Should().HaveCount(10);
+        page1.HasMore.Should().BeTrue();
+        page1.TotalCount.Should().Be(20);
+    }
+
+    [Fact]
+    public async Task GetTimeline_FiltersbyService()
+    {
+        // Arrange
+        const string correlationId = "test-corr-filter-svc";
+        await SeedEventsWithServicesAsync(correlationId);
+
+        // Act
+        var response = await _client.GetAsync($"/api/v1/timeline/{correlationId}?services=Scheduler");
+        var timeline = await response.Content.ReadFromJsonAsync<TimelineResponse>();
+
+        // Assert
+        timeline.Should().NotBeNull();
+        timeline!.Events.Should().AllSatisfy(e => e.Service.Should().Be("Scheduler"));
+    }
+
+    [Fact]
+    public async Task GetCriticalPath_ReturnsStages()
+    {
+        // Arrange
+        const string correlationId = "test-corr-critical";
+        await SeedEventsAsync(correlationId, 5);
+
+        // Act
+        var response = await _client.GetAsync($"/api/v1/timeline/{correlationId}/critical-path");
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+
+        var criticalPath = await response.Content.ReadFromJsonAsync<CriticalPathResponse>();
+        criticalPath.Should().NotBeNull();
+        criticalPath!.CorrelationId.Should().Be(correlationId);
+        criticalPath.Stages.Should().HaveCountGreaterThan(0);
+    }
+
+    [Fact]
+    public async Task HealthCheck_ReturnsHealthy()
+    {
+        // Act
+        var response = await _client.GetAsync("/health");
+
+        // Assert
+        response.StatusCode.Should().Be(HttpStatusCode.OK);
+    }
+
+    private async Task SeedEventsAsync(string correlationId, int count)
+    {
+        using var scope = _factory.Services.CreateScope();
+        var eventStore = scope.ServiceProvider.GetRequiredService<ITimelineEventStore>();
+
+        var baseTime = new DateTimeOffset(2026, 1, 7, 12, 0, 0, TimeSpan.Zero);
+
+        for (int i = 0; i < count; i++)
+        {
+            var evt = new TimelineEvent
+            {
+                EventId = $"{correlationId}-evt-{i:D4}",
+                CorrelationId = correlationId,
+                Kind = $"EVENT_{i}",
+                THlc = new HlcTimestamp(1000 + i, 0, "test-node"),
+                TsWall = baseTime.AddSeconds(i),
+                Service = "TestService",
+                Payload = $"{{\"index\": {i}}}",
+                PayloadDigest = new byte[32],
+                EngineVersion = new EngineVersionRef("Test", "1.0.0", "test-digest"),
+                SchemaVersion = 1
+            };
+
+            await eventStore.AppendAsync(evt);
+        }
+    }
+
+    private async Task SeedEventsWithServicesAsync(string correlationId)
+    {
+        using var scope = _factory.Services.CreateScope();
+        var eventStore = scope.ServiceProvider.GetRequiredService<ITimelineEventStore>();
+
+        var services = new[] { "Scheduler", "AirGap", "Scheduler", "Attestor", "Scheduler" };
+        var baseTime = new DateTimeOffset(2026, 1, 7, 12, 0, 0, TimeSpan.Zero);
+
+        for (int i = 0; i < services.Length; i++)
+        {
+            var evt = new TimelineEvent
+            {
+                EventId = $"{correlationId}-evt-{i:D4}",
+                CorrelationId = correlationId,
+                Kind = $"EVENT_{i}",
+                THlc = new HlcTimestamp(1000 + i, 0, "test-node"),
+                TsWall = baseTime.AddSeconds(i),
+                Service = services[i],
+                Payload = $"{{\"index\": {i}}}",
+                PayloadDigest = new byte[32],
+                EngineVersion = new EngineVersionRef("Test", "1.0.0", "test-digest"),
+                SchemaVersion = 1
+            };
+
+            await eventStore.AppendAsync(evt);
+        }
+    }
+}
+
+/// <summary>
+/// Custom WebApplicationFactory for Timeline integration tests.
+/// </summary>
+public sealed class TimelineWebApplicationFactory : WebApplicationFactory<Program>
+{
+    protected override void ConfigureWebHost(IWebHostBuilder builder)
+    {
+        builder.UseEnvironment("Development");
+
+        builder.ConfigureServices(services =>
+        {
+            // Replace with in-memory store for tests
+            services.AddSingleton<ITimelineEventStore, InMemoryTimelineEventStore>();
+        });
+    }
+}
+
+/// <summary>
+/// Minimal Program class reference for WebApplicationFactory.
+/// </summary>
+public partial class Program { }