Add session log ingestion, dashboard visualization, and log forwarding sink

- Add POST/GET endpoints for session logs (/sessions/{id}/log) supporting
  raw text (newline-split) and structured JSON/CbObject with batch "entries" array
- Add in-memory log storage per session (capped at 10k entries) with pagination
- Add log panel to sessions dashboard with polling, auto-scroll, and level coloring
- Add SessionLogSink that batches log messages on a background thread and forwards
  them to the sessions endpoint via HTTP, integrated into ZenStorageServer when
  a remote sessions URL is configured

1 files changed, 161 insertions, 0 deletions

diff --git a/src/zenserver/sessions/httpsessions.cpp b/src/zenserver/sessions/httpsessions.cpp
index 6996ce5b5..f6eb77c15 100644
--- a/src/zenserver/sessions/httpsessions.cpp
+++ b/src/zenserver/sessions/httpsessions.cpp
@@ -111,6 +111,11 @@ HttpSessionsService::Initialize()
 		HttpVerb::kGet | HttpVerb::kPost | HttpVerb::kPut | HttpVerb::kDelete);
 
 	m_Router.RegisterRoute(
+		"{session_id}/log",
+		[this](HttpRouterRequest& Req) { SessionLogRequest(Req); },
+		HttpVerb::kGet | HttpVerb::kPost);
+
+	m_Router.RegisterRoute(
 		"",
 		[this](HttpRouterRequest& Req) { ListSessionsRequest(Req); },
 		HttpVerb::kGet);
@@ -315,6 +320,162 @@ HttpSessionsService::SessionRequest(HttpRouterRequest& Req)
 
 //////////////////////////////////////////////////////////////////////////
 //
+// Session log
+//
+
+static void
+WriteLogEntry(CbWriter& Writer, const SessionsService::LogEntry& Entry)
+{
+	Writer << "timestamp" << Entry.Timestamp;
+	if (!Entry.Level.empty())
+	{
+		Writer << "level" << Entry.Level;
+	}
+	if (!Entry.Message.empty())
+	{
+		Writer << "message" << Entry.Message;
+	}
+	if (Entry.Data.GetSize() > 0)
+	{
+		Writer.AddObject("data"sv, Entry.Data);
+	}
+}
+
+void
+HttpSessionsService::SessionLogRequest(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++;
+
+	Ref<SessionsService::Session> Session = m_Sessions.GetSession(SessionId);
+	if (!Session)
+	{
+		return ServerRequest.WriteResponse(HttpResponseCode::NotFound,
+										   HttpContentType::kText,
+										   fmt::format("Session '{}' not found", SessionId));
+	}
+
+	if (ServerRequest.RequestVerb() == HttpVerb::kPost)
+	{
+		m_SessionsStats.SessionWriteCount++;
+
+		if (ServerRequest.RequestContentType() == HttpContentType::kText)
+		{
+			// Raw text — split by newlines, one entry per line
+			IoBuffer		 Payload = ServerRequest.ReadPayload();
+			std::string_view Text(reinterpret_cast<const char*>(Payload.GetData()), Payload.GetSize());
+			const DateTime	 Now = DateTime::Now();
+
+			size_t Pos = 0;
+			while (Pos < Text.size())
+			{
+				size_t End = Text.find('\n', Pos);
+				if (End == std::string_view::npos)
+				{
+					End = Text.size();
+				}
+
+				std::string_view Line = Text.substr(Pos, End - Pos);
+				// Strip trailing \r
+				if (!Line.empty() && Line.back() == '\r')
+				{
+					Line.remove_suffix(1);
+				}
+
+				if (!Line.empty())
+				{
+					Session->AppendLog(SessionsService::LogEntry{
+						.Timestamp = Now,
+						.Message   = std::string(Line),
+					});
+				}
+
+				Pos = End + 1;
+			}
+		}
+		else
+		{
+			// Structured log (JSON or CbObject)
+			// Accepts a single record or an "entries" array of records
+			CbObject	   RequestObject = ServerRequest.ReadPayloadObject();
+			const DateTime Now			 = DateTime::Now();
+
+			auto AppendFromObject = [&](CbObjectView Obj) {
+				std::string	 Level(Obj["level"sv].AsString());
+				std::string	 Message(Obj["message"sv].AsString());
+				CbObjectView DataView = Obj["data"sv].AsObjectView();
+
+				Session->AppendLog(SessionsService::LogEntry{
+					.Timestamp = Now,
+					.Level	   = std::move(Level),
+					.Message   = std::move(Message),
+					.Data	   = CbObject::Clone(DataView),
+				});
+			};
+
+			CbFieldView EntriesField = RequestObject["entries"sv];
+			if (EntriesField.IsArray())
+			{
+				for (CbFieldView Entry : EntriesField)
+				{
+					AppendFromObject(Entry.AsObjectView());
+				}
+			}
+			else
+			{
+				AppendFromObject(RequestObject);
+			}
+		}
+
+		return ServerRequest.WriteResponse(HttpResponseCode::OK);
+	}
+	else
+	{
+		// GET - return log entries
+		m_SessionsStats.SessionReadCount++;
+
+		HttpServerRequest::QueryParams Params = ServerRequest.GetQueryParams();
+		uint32_t					   Limit  = 0;
+		uint32_t					   Offset = 0;
+
+		if (std::string_view LimitStr = Params.GetValue("limit"sv); !LimitStr.empty())
+		{
+			Limit = uint32_t(std::strtoul(std::string(LimitStr).c_str(), nullptr, 10));
+		}
+		if (std::string_view OffsetStr = Params.GetValue("offset"sv); !OffsetStr.empty())
+		{
+			Offset = uint32_t(std::strtoul(std::string(OffsetStr).c_str(), nullptr, 10));
+		}
+
+		std::vector<SessionsService::LogEntry> Entries = Session->GetLogEntries(Limit, Offset);
+
+		CbObjectWriter Response;
+		Response << "total" << Session->GetLogCount();
+		Response.BeginArray("entries");
+		for (const SessionsService::LogEntry& Entry : Entries)
+		{
+			Response.BeginObject();
+			WriteLogEntry(Response, Entry);
+			Response.EndObject();
+		}
+		Response.EndArray();
+
+		return ServerRequest.WriteResponse(HttpResponseCode::OK, Response.Save());
+	}
+}
+
+//////////////////////////////////////////////////////////////////////////
+//
 // WebSocket push
 //