Dashboard overhaul, compute integration (#814)

- **Frontend dashboard overhaul**: Unified compute/main dashboards into a single shared UI. Added new pages for cache, projects, metrics, sessions, info (build/runtime config, system stats). Added live-update via WebSockets with pause control, sortable detail tables, themed styling. Refactored compute/hub/orchestrator pages into modular JS.
- **HTTP server fixes and stats**: Fixed http.sys local-only fallback when default port is in use, implemented root endpoint redirect for http.sys, fixed Linux/Mac port reuse. Added /stats endpoint exposing HTTP server metrics (bytes transferred, request rates). Added WebSocket stats tracking.
- **OTEL/diagnostics hardening**: Improved OTLP HTTP exporter with better error handling and resilience. Extended diagnostics services configuration.
- **Session management**: Added new sessions service with HTTP endpoints for registering, updating, querying, and removing sessions. Includes session log file support. This is still WIP.
- **CLI subcommand support**: Added support for commands with subcommands in the zen CLI tool, with improved command dispatch.
- **Misc**: Exposed CPU usage/hostname to frontend, fixed JS compact binary float32/float64 decoding, limited projects displayed on front page to 25 sorted by last access, added vscode:// link support.

Also contains some fixes from TSAN analysis.

1 files changed, 264 insertions, 0 deletions

diff --git a/src/zenserver/sessions/httpsessions.cpp b/src/zenserver/sessions/httpsessions.cpp
new file mode 100644
index 000000000..05be3c814
--- /dev/null
+++ b/src/zenserver/sessions/httpsessions.cpp
@@ -0,0 +1,264 @@
+// Copyright Epic Games, Inc. All Rights Reserved.
+
+#include "httpsessions.h"
+
+#include <zencore/compactbinarybuilder.h>
+#include <zencore/compactbinaryvalidation.h>
+#include <zencore/fmtutils.h>
+#include <zencore/logging.h>
+#include <zencore/trace.h>
+#include "sessions.h"
+
+namespace zen {
+using namespace std::literals;
+
+HttpSessionsService::HttpSessionsService(HttpStatusService& StatusService, HttpStatsService& StatsService, SessionsService& Sessions)
+: m_Log(logging::Get("sessions"))
+, m_StatusService(StatusService)
+, m_StatsService(StatsService)
+, m_Sessions(Sessions)
+{
+	Initialize();
+}
+
+HttpSessionsService::~HttpSessionsService()
+{
+	m_StatsService.UnregisterHandler("sessions", *this);
+	m_StatusService.UnregisterHandler("sessions", *this);
+}
+
+const char*
+HttpSessionsService::BaseUri() const
+{
+	return "/sessions/";
+}
+
+void
+HttpSessionsService::HandleRequest(HttpServerRequest& Request)
+{
+	metrics::OperationTiming::Scope $(m_HttpRequests);
+
+	if (m_Router.HandleRequest(Request) == false)
+	{
+		ZEN_WARN("No route found for {0}", Request.RelativeUri());
+		return Request.WriteResponse(HttpResponseCode::NotFound, HttpContentType::kText, "Not found"sv);
+	}
+}
+
+CbObject
+HttpSessionsService::CollectStats()
+{
+	ZEN_TRACE_CPU("SessionsService::Stats");
+	CbObjectWriter Cbo;
+
+	EmitSnapshot("requests", m_HttpRequests, Cbo);
+
+	Cbo.BeginObject("sessions");
+	{
+		Cbo << "readcount" << m_SessionsStats.SessionReadCount;
+		Cbo << "writecount" << m_SessionsStats.SessionWriteCount;
+		Cbo << "deletecount" << m_SessionsStats.SessionDeleteCount;
+		Cbo << "listcount" << m_SessionsStats.SessionListCount;
+		Cbo << "requestcount" << m_SessionsStats.RequestCount;
+		Cbo << "badrequestcount" << m_SessionsStats.BadRequestCount;
+		Cbo << "count" << m_Sessions.GetSessionCount();
+	}
+	Cbo.EndObject();
+
+	return Cbo.Save();
+}
+
+void
+HttpSessionsService::HandleStatsRequest(HttpServerRequest& HttpReq)
+{
+	HttpReq.WriteResponse(HttpResponseCode::OK, CollectStats());
+}
+
+void
+HttpSessionsService::HandleStatusRequest(HttpServerRequest& Request)
+{
+	ZEN_TRACE_CPU("HttpSessionsService::Status");
+	CbObjectWriter Cbo;
+	Cbo << "ok" << true;
+	Request.WriteResponse(HttpResponseCode::OK, Cbo.Save());
+}
+
+void
+HttpSessionsService::Initialize()
+{
+	using namespace std::literals;
+
+	ZEN_INFO("Initializing Sessions Service");
+
+	static constexpr AsciiSet ValidHexCharactersSet{"0123456789abcdefABCDEF"};
+
+	m_Router.AddMatcher("session_id", [](std::string_view Str) -> bool {
+		return Str.length() == Oid::StringLength && AsciiSet::HasOnly(Str, ValidHexCharactersSet);
+	});
+
+	m_Router.RegisterRoute(
+		"list",
+		[this](HttpRouterRequest& Req) { ListSessionsRequest(Req); },
+		HttpVerb::kGet);
+
+	m_Router.RegisterRoute(
+		"{session_id}",
+		[this](HttpRouterRequest& Req) { SessionRequest(Req); },
+		HttpVerb::kGet | HttpVerb::kPost | HttpVerb::kPut | HttpVerb::kDelete);
+
+	m_Router.RegisterRoute(
+		"",
+		[this](HttpRouterRequest& Req) { ListSessionsRequest(Req); },
+		HttpVerb::kGet);
+
+	m_StatsService.RegisterHandler("sessions", *this);
+	m_StatusService.RegisterHandler("sessions", *this);
+}
+
+static void
+WriteSessionInfo(CbWriter& Writer, const SessionsService::SessionInfo& Info)
+{
+	Writer << "id" << Info.Id;
+	if (!Info.AppName.empty())
+	{
+		Writer << "appname" << Info.AppName;
+	}
+	if (Info.JobId != Oid::Zero)
+	{
+		Writer << "jobid" << Info.JobId;
+	}
+	Writer << "created_at" << Info.CreatedAt;
+	Writer << "updated_at" << Info.UpdatedAt;
+
+	if (Info.Metadata.GetSize() > 0)
+	{
+		Writer.BeginObject("metadata");
+		for (const CbField& Field : Info.Metadata)
+		{
+			Writer.AddField(Field);
+		}
+		Writer.EndObject();
+	}
+}
+
+void
+HttpSessionsService::ListSessionsRequest(HttpRouterRequest& Req)
+{
+	HttpServerRequest& ServerRequest = Req.ServerRequest();
+
+	m_SessionsStats.SessionListCount++;
+	m_SessionsStats.RequestCount++;
+
+	std::vector<Ref<SessionsService::Session>> Sessions = m_Sessions.GetSessions();
+
+	CbObjectWriter Response;
+	Response.BeginArray("sessions");
+	for (const Ref<SessionsService::Session>& Session : Sessions)
+	{
+		Response.BeginObject();
+		{
+			WriteSessionInfo(Response, Session->Info());
+		}
+		Response.EndObject();
+	}
+	Response.EndArray();
+
+	return ServerRequest.WriteResponse(HttpResponseCode::OK, Response.Save());
+}
+
+void
+HttpSessionsService::SessionRequest(HttpRouterRequest& Req)
+{
+	HttpServerRequest& ServerRequest = Req.ServerRequest();
+
+	const Oid SessionId = Oid::TryFromHexString(Req.GetCapture(1));
+	if (SessionId == Oid::Zero)
+	{
+		m_SessionsStats.BadRequestCount++;
+		return ServerRequest.WriteResponse(HttpResponseCode::BadRequest,
+										   HttpContentType::kText,
+										   fmt::format("Invalid session id '{}'", Req.GetCapture(1)));
+	}
+
+	m_SessionsStats.RequestCount++;
+
+	switch (ServerRequest.RequestVerb())
+	{
+		case HttpVerb::kPost:
+		case HttpVerb::kPut:
+			{
+				IoBuffer Payload = ServerRequest.ReadPayload();
+				CbObject RequestObject;
+
+				if (Payload.GetSize() > 0)
+				{
+					if (CbValidateError ValidationResult = ValidateCompactBinary(Payload.GetView(), CbValidateMode::All);
+						ValidationResult != CbValidateError::None)
+					{
+						m_SessionsStats.BadRequestCount++;
+						return ServerRequest.WriteResponse(HttpResponseCode::BadRequest,
+														   HttpContentType::kText,
+														   fmt::format("Invalid payload: {}", zen::ToString(ValidationResult)));
+					}
+					RequestObject = LoadCompactBinaryObject(Payload);
+				}
+
+				if (ServerRequest.RequestVerb() == HttpVerb::kPost)
+				{
+					std::string	 AppName(RequestObject["appname"sv].AsString());
+					Oid			 JobId		  = RequestObject["jobid"sv].AsObjectId();
+					CbObjectView MetadataView = RequestObject["metadata"sv].AsObjectView();
+
+					m_SessionsStats.SessionWriteCount++;
+					if (m_Sessions.RegisterSession(SessionId, std::move(AppName), JobId, MetadataView))
+					{
+						return ServerRequest.WriteResponse(HttpResponseCode::Created, HttpContentType::kText, fmt::format("{}", SessionId));
+					}
+					else
+					{
+						// Already exists - try update instead
+						if (m_Sessions.UpdateSession(SessionId, MetadataView))
+						{
+							return ServerRequest.WriteResponse(HttpResponseCode::OK, HttpContentType::kText, fmt::format("{}", SessionId));
+						}
+						return ServerRequest.WriteResponse(HttpResponseCode::InternalServerError);
+					}
+				}
+				else
+				{
+					// PUT - update only
+					m_SessionsStats.SessionWriteCount++;
+					if (m_Sessions.UpdateSession(SessionId, RequestObject["metadata"sv].AsObjectView()))
+					{
+						return ServerRequest.WriteResponse(HttpResponseCode::OK, HttpContentType::kText, fmt::format("{}", SessionId));
+					}
+					return ServerRequest.WriteResponse(HttpResponseCode::NotFound,
+													   HttpContentType::kText,
+													   fmt::format("Session '{}' not found", SessionId));
+				}
+			}
+		case HttpVerb::kGet:
+			{
+				m_SessionsStats.SessionReadCount++;
+				Ref<SessionsService::Session> Session = m_Sessions.GetSession(SessionId);
+				if (Session)
+				{
+					CbObjectWriter Response;
+					WriteSessionInfo(Response, Session->Info());
+					return ServerRequest.WriteResponse(HttpResponseCode::OK, Response.Save());
+				}
+				return ServerRequest.WriteResponse(HttpResponseCode::NotFound);
+			}
+		case HttpVerb::kDelete:
+			{
+				m_SessionsStats.SessionDeleteCount++;
+				if (m_Sessions.RemoveSession(SessionId))
+				{
+					return ServerRequest.WriteResponse(HttpResponseCode::OK);
+				}
+				return ServerRequest.WriteResponse(HttpResponseCode::NotFound);
+			}
+	}
+}
+
+}  // namespace zen