Unix Domain Socket auto discovery (#833)

This PR adds end-to-end Unix domain socket (UDS) support, allowing zen CLI to discover and connect to UDS-only servers automatically.

- **`unix://` URI scheme in zen CLI**: The `-u` / `--hosturl` option now accepts `unix:///path/to/socket` to connect to a zenserver via a Unix domain socket instead of TCP.
- **Per-instance shared memory for extended server info**: Each zenserver instance now publishes a small shared memory section (keyed by SessionId) containing per-instance data that doesn't fit in the fixed-size ZenServerEntry -- starting with the UDS socket path. This is a 4KB pagefile-backed section on Windows (`Global\ZenInstance_{sessionid}`) and a POSIX shared memory object on Linux/Mac (`/UnrealEngineZen_{sessionid}`).
- **Client-side auto-discovery of UDS servers**: `zen info`, `zen status`, etc. now automatically discover and prefer UDS connections when a server publishes a socket path. Servers running with `--no-network` (UDS-only) are no longer invisible to the CLI.
- **`kNoNetwork` flag in ZenServerEntry**: Servers started with `--no-network` advertise this in their shared state entry. Clients skip TCP fallback for these servers, and display commands (`ps`, `status`, `top`) show `-` instead of a port number to indicate TCP is not available.

1 files changed, 34 insertions, 3 deletions

diff --git a/src/zen/cmds/top_cmd.cpp b/src/zen/cmds/top_cmd.cpp
index f674db6cd..cf2896f0f 100644
--- a/src/zen/cmds/top_cmd.cpp
+++ b/src/zen/cmds/top_cmd.cpp
@@ -2,6 +2,7 @@
 
 #include "top_cmd.h"
 
+#include <zencore/filesystem.h>
 #include <zencore/fmtutils.h>
 #include <zencore/logging.h>
 #include <zencore/system.h>
@@ -81,13 +82,29 @@ TopCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 	{
 		if ((n++ % HeaderPeriod) == 0)
 		{
-			ZEN_CONSOLE("{:>5} {:>6} {:>24}", "port", "pid", "session");
+			ZEN_CONSOLE("{:>5} {:>6} {:>24}  {}", "port", "pid", "session", "socket");
 		}
 
 		State.Snapshot([&](const ZenServerState::ZenServerEntry& Entry) {
 			StringBuilder<25> SessionStringBuilder;
 			Entry.GetSessionId().ToString(SessionStringBuilder);
-			ZEN_CONSOLE("{:>5} {:>6} {:>24}", Entry.EffectiveListenPort.load(), Entry.Pid.load(), SessionStringBuilder);
+
+			std::string SocketPath;
+			if (Entry.HasInstanceInfo())
+			{
+				ZenServerInstanceInfo Info;
+				if (Info.OpenReadOnly(Entry.GetSessionId()))
+				{
+					InstanceInfoData Data = Info.Read();
+					if (!Data.UnixSocketPath.empty())
+					{
+						SocketPath = PathToUtf8(Data.UnixSocketPath);
+					}
+				}
+			}
+
+			std::string PortStr = Entry.IsNoNetwork() ? std::string("-") : fmt::to_string(Entry.EffectiveListenPort.load());
+			ZEN_CONSOLE("{:>5} {:>6} {:>24}  {}", PortStr, Entry.Pid.load(), SessionStringBuilder, SocketPath);
 		});
 
 		zen::Sleep(1000);
@@ -121,7 +138,21 @@ PsCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 	}
 
 	State.Snapshot([&](const ZenServerState::ZenServerEntry& Entry) {
-		ZEN_CONSOLE("Port {} : pid {}", Entry.EffectiveListenPort.load(), Entry.Pid.load());
+		std::string Extra;
+		if (Entry.HasInstanceInfo())
+		{
+			ZenServerInstanceInfo Info;
+			if (Info.OpenReadOnly(Entry.GetSessionId()))
+			{
+				InstanceInfoData Data = Info.Read();
+				if (!Data.UnixSocketPath.empty())
+				{
+					Extra = fmt::format(" (unix: {})", Data.UnixSocketPath);
+				}
+			}
+		}
+		std::string PortStr = Entry.IsNoNetwork() ? std::string("-") : fmt::to_string(Entry.EffectiveListenPort.load());
+		ZEN_CONSOLE("Port {} : pid {}{}", PortStr, Entry.Pid.load(), Extra);
 	});
 }