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, 60 insertions, 44 deletions

diff --git a/src/zenhttp/servers/httpasio.cpp b/src/zenhttp/servers/httpasio.cpp
index 2cf051d14..f5178ebe8 100644
--- a/src/zenhttp/servers/httpasio.cpp
+++ b/src/zenhttp/servers/httpasio.cpp
@@ -531,6 +531,8 @@ public:
 
 	std::atomic<uint64_t> m_TotalBytesReceived{0};
 	std::atomic<uint64_t> m_TotalBytesSent{0};
+
+	HttpServer* m_HttpServer = nullptr;
 };
 
 /**
@@ -949,6 +951,7 @@ private:
 	void OnDataReceived(const asio::error_code& Ec, std::size_t ByteCount);
 	void OnResponseDataSent(const asio::error_code& Ec, std::size_t ByteCount, uint32_t RequestNumber, HttpResponse* ResponseToPop);
 	void CloseConnection();
+	void SendInlineResponse(uint32_t RequestNumber, std::string_view StatusLine, std::string_view Headers = {}, std::string_view Body = {});
 
 	HttpAsioServerImpl&		 m_Server;
 	asio::streambuf			 m_RequestBuffer;
@@ -1167,6 +1170,38 @@ HttpServerConnection::CloseConnection()
 }
 
 void
+HttpServerConnection::SendInlineResponse(uint32_t		  RequestNumber,
+										 std::string_view StatusLine,
+										 std::string_view Headers,
+										 std::string_view Body)
+{
+	ExtendableStringBuilder<256> ResponseBuilder;
+	ResponseBuilder << "HTTP/1.1 " << StatusLine << "\r\n";
+	if (!Headers.empty())
+	{
+		ResponseBuilder << Headers;
+	}
+	if (!m_RequestData.IsKeepAlive())
+	{
+		ResponseBuilder << "Connection: close\r\n";
+	}
+	ResponseBuilder << "\r\n";
+	if (!Body.empty())
+	{
+		ResponseBuilder << Body;
+	}
+	auto	 ResponseView = ResponseBuilder.ToView();
+	IoBuffer ResponseData(IoBuffer::Clone, ResponseView.data(), ResponseView.size());
+	auto	 Buffer = asio::buffer(ResponseData.GetData(), ResponseData.GetSize());
+	asio::async_write(
+		*m_Socket.get(),
+		Buffer,
+		[Conn = AsSharedPtr(), RequestNumber, Response = std::move(ResponseData)](const asio::error_code& Ec, std::size_t ByteCount) {
+			Conn->OnResponseDataSent(Ec, ByteCount, RequestNumber, /* ResponseToPop */ nullptr);
+		});
+}
+
+void
 HttpServerConnection::HandleRequest()
 {
 	ZEN_MEMSCOPE(GetHttpasioTag());
@@ -1204,7 +1239,9 @@ HttpServerConnection::HandleRequest()
 										  return;
 									  }
 
-									  Ref<WsAsioConnection>	   WsConn(new WsAsioConnection(std::move(Conn->m_Socket), *WsHandler));
+									  Conn->m_Server.m_HttpServer->OnWebSocketConnectionOpened();
+									  Ref<WsAsioConnection> WsConn(
+										  new WsAsioConnection(std::move(Conn->m_Socket), *WsHandler, Conn->m_Server.m_HttpServer));
 									  Ref<WebSocketConnection> WsConnRef(WsConn.Get());
 
 									  WsHandler->OnWebSocketOpen(std::move(WsConnRef));
@@ -1241,6 +1278,8 @@ HttpServerConnection::HandleRequest()
 	{
 		ZEN_TRACE_CPU("asio::HandleRequest");
 
+		m_Server.m_HttpServer->MarkRequest();
+
 		auto RemoteEndpoint	   = m_Socket->remote_endpoint();
 		bool IsLocalConnection = m_Socket->local_endpoint().address() == RemoteEndpoint.address();
 
@@ -1378,51 +1417,24 @@ HttpServerConnection::HandleRequest()
 		}
 	}
 
-	if (m_RequestData.RequestVerb() == HttpVerb::kHead)
+	// If a default redirect is configured and the request is for the root path, send a 302
+	std::string_view DefaultRedirect = m_Server.m_HttpServer->GetDefaultRedirect();
+	if (!DefaultRedirect.empty() && (m_RequestData.Url() == "/" || m_RequestData.Url().empty()))
 	{
-		std::string_view Response =
-			"HTTP/1.1 404 NOT FOUND\r\n"
-			"\r\n"sv;
-
-		if (!m_RequestData.IsKeepAlive())
-		{
-			Response =
-				"HTTP/1.1 404 NOT FOUND\r\n"
-				"Connection: close\r\n"
-				"\r\n"sv;
-		}
-
-		asio::async_write(*m_Socket.get(),
-						  asio::buffer(Response),
-						  [Conn = AsSharedPtr(), RequestNumber](const asio::error_code& Ec, std::size_t ByteCount) {
-							  Conn->OnResponseDataSent(Ec, ByteCount, RequestNumber, /* ResponseToPop */ nullptr);
-						  });
+		ExtendableStringBuilder<128> Headers;
+		Headers << "Location: " << DefaultRedirect << "\r\nContent-Length: 0\r\n";
+		SendInlineResponse(RequestNumber, "302 Found"sv, Headers.ToView());
+	}
+	else if (m_RequestData.RequestVerb() == HttpVerb::kHead)
+	{
+		SendInlineResponse(RequestNumber, "404 NOT FOUND"sv);
 	}
 	else
 	{
-		std::string_view Response =
-			"HTTP/1.1 404 NOT FOUND\r\n"
-			"Content-Length: 23\r\n"
-			"Content-Type: text/plain\r\n"
-			"\r\n"
-			"No suitable route found"sv;
-
-		if (!m_RequestData.IsKeepAlive())
-		{
-			Response =
-				"HTTP/1.1 404 NOT FOUND\r\n"
-				"Content-Length: 23\r\n"
-				"Content-Type: text/plain\r\n"
-				"Connection: close\r\n"
-				"\r\n"
-				"No suitable route found"sv;
-		}
-
-		asio::async_write(*m_Socket.get(),
-						  asio::buffer(Response),
-						  [Conn = AsSharedPtr(), RequestNumber](const asio::error_code& Ec, std::size_t ByteCount) {
-							  Conn->OnResponseDataSent(Ec, ByteCount, RequestNumber, /* ResponseToPop */ nullptr);
-						  });
+		SendInlineResponse(RequestNumber,
+						   "404 NOT FOUND"sv,
+						   "Content-Length: 23\r\nContent-Type: text/plain\r\n"sv,
+						   "No suitable route found"sv);
 	}
 }
 
@@ -1448,8 +1460,11 @@ struct HttpAcceptor
 		m_Acceptor.set_option(exclusive_address(true));
 		m_AlternateProtocolAcceptor.set_option(exclusive_address(true));
 #else	// ZEN_PLATFORM_WINDOWS
-		m_Acceptor.set_option(asio::socket_base::reuse_address(false));
-		m_AlternateProtocolAcceptor.set_option(asio::socket_base::reuse_address(false));
+		// Allow binding to a port in TIME_WAIT so the server can restart immediately
+		// after a previous instance exits. On Linux this does not allow two processes
+		// to actively listen on the same port simultaneously.
+		m_Acceptor.set_option(asio::socket_base::reuse_address(true));
+		m_AlternateProtocolAcceptor.set_option(asio::socket_base::reuse_address(true));
 #endif	// ZEN_PLATFORM_WINDOWS
 
 		m_Acceptor.set_option(asio::ip::tcp::no_delay(true));
@@ -2092,6 +2107,7 @@ HttpAsioServer::HttpAsioServer(const AsioConfig& Config)
 : m_InitialConfig(Config)
 , m_Impl(std::make_unique<asio_http::HttpAsioServerImpl>())
 {
+	m_Impl->m_HttpServer = this;
 	ZEN_DEBUG("Request object size: {} ({:#x})", sizeof(HttpRequestParser), sizeof(HttpRequestParser));
 }