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, 14 insertions, 14 deletions

diff --git a/src/zen/cmds/admin_cmd.cpp b/src/zen/cmds/admin_cmd.cpp
index 15e854796..034d430fd 100644
--- a/src/zen/cmds/admin_cmd.cpp
+++ b/src/zen/cmds/admin_cmd.cpp
@@ -17,7 +17,7 @@ namespace zen {
 ScrubCommand::ScrubCommand()
 {
 	m_Options.add_options()("h,help", "Print help");
-	m_Options.add_option("", "u", "hosturl", "Host URL", cxxopts::value(m_HostName)->default_value(""), "<hosturl>");
+	m_Options.add_option("", "u", "hosturl", kHostUrlHelp, cxxopts::value(m_HostName)->default_value(""), "<hosturl>");
 	m_Options.add_option("", "n", "dry", "Dry run (do not delete any data)", cxxopts::value(m_DryRun), "<bool>");
 	m_Options.add_option("", "", "no-gc", "Do not perform GC after scrub pass", cxxopts::value(m_NoGc), "<bool>");
 	m_Options.add_option("", "", "no-cas", "Do not scrub CAS stores", cxxopts::value(m_NoCas), "<bool>");
@@ -48,7 +48,7 @@ ScrubCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 		throw OptionParseException("Unable to resolve server specification", m_Options.help());
 	}
 
-	HttpClient Http(m_HostName);
+	HttpClient Http = CreateHttpClient(m_HostName);
 
 	HttpClient::KeyValueMap Params{{"skipdelete", ToString(m_DryRun)},
 								   {"skipgc", ToString(m_NoGc)},
@@ -70,7 +70,7 @@ ScrubCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 GcCommand::GcCommand()
 {
 	m_Options.add_options()("h,help", "Print help");
-	m_Options.add_option("", "u", "hosturl", "Host URL", cxxopts::value(m_HostName)->default_value(""), "<hosturl>");
+	m_Options.add_option("", "u", "hosturl", kHostUrlHelp, cxxopts::value(m_HostName)->default_value(""), "<hosturl>");
 	m_Options.add_option("",
 						 "s",
 						 "smallobjects",
@@ -258,7 +258,7 @@ GcCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 	}
 	Params.Entries.insert({"enablevalidation", m_EnableValidation ? "true" : "false"});
 
-	HttpClient Http(m_HostName);
+	HttpClient Http = CreateHttpClient(m_HostName);
 	if (HttpClient::Response Response = Http.Post("/admin/gc"sv, HttpClient::Accept(HttpContentType::kJSON), Params))
 	{
 		ZEN_CONSOLE("OK: {}", Response.ToText());
@@ -272,7 +272,7 @@ GcCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 GcStatusCommand::GcStatusCommand()
 {
 	m_Options.add_options()("h,help", "Print help");
-	m_Options.add_option("", "u", "hosturl", "Host URL", cxxopts::value(m_HostName)->default_value(""), "<hosturl>");
+	m_Options.add_option("", "u", "hosturl", kHostUrlHelp, cxxopts::value(m_HostName)->default_value(""), "<hosturl>");
 	m_Options.add_option("", "d", "details", "Show detailed GC report", cxxopts::value(m_Details)->default_value("false"), "<details>");
 }
 
@@ -297,7 +297,7 @@ GcStatusCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 		throw OptionParseException("Unable to resolve server specification", m_Options.help());
 	}
 
-	HttpClient Http(m_HostName);
+	HttpClient Http = CreateHttpClient(m_HostName);
 	if (HttpClient::Response Response = Http.Get("/admin/gc"sv, HttpClient::Accept(HttpContentType::kJSON)))
 	{
 		ZEN_CONSOLE("OK: {}", Response.ToText());
@@ -311,7 +311,7 @@ GcStatusCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 GcStopCommand::GcStopCommand()
 {
 	m_Options.add_options()("h,help", "Print help");
-	m_Options.add_option("", "u", "hosturl", "Host URL", cxxopts::value(m_HostName)->default_value(""), "<hosturl>");
+	m_Options.add_option("", "u", "hosturl", kHostUrlHelp, cxxopts::value(m_HostName)->default_value(""), "<hosturl>");
 }
 
 GcStopCommand::~GcStopCommand()
@@ -335,7 +335,7 @@ GcStopCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 		throw OptionParseException("Unable to resolve server specification", m_Options.help());
 	}
 
-	HttpClient Http(m_HostName);
+	HttpClient Http = CreateHttpClient(m_HostName);
 	if (HttpClient::Response Response = Http.Post("/admin/gc-stop"sv, HttpClient::Accept(HttpContentType::kJSON)))
 	{
 		if (Response.StatusCode == HttpResponseCode::Accepted)
@@ -358,7 +358,7 @@ GcStopCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 JobCommand::JobCommand()
 {
 	m_Options.add_options()("h,help", "Print help");
-	m_Options.add_option("", "u", "hosturl", "Host URL", cxxopts::value(m_HostName)->default_value(""), "<hosturl>");
+	m_Options.add_option("", "u", "hosturl", kHostUrlHelp, cxxopts::value(m_HostName)->default_value(""), "<hosturl>");
 	m_Options.add_option("", "j", "jobid", "Job id", cxxopts::value(m_JobId), "<jobid>");
 	m_Options.add_option("", "c", "cancel", "Cancel job id", cxxopts::value(m_Cancel), "<cancel>");
 }
@@ -384,7 +384,7 @@ JobCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 		throw OptionParseException("Unable to resolve server specification", m_Options.help());
 	}
 
-	HttpClient Http(m_HostName);
+	HttpClient Http = CreateHttpClient(m_HostName);
 
 	if (m_Cancel)
 	{
@@ -421,7 +421,7 @@ JobCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 LoggingCommand::LoggingCommand()
 {
 	m_Options.add_options()("h,help", "Print help");
-	m_Options.add_option("", "u", "hosturl", "Host URL", cxxopts::value(m_HostName)->default_value(""), "<hosturl>");
+	m_Options.add_option("", "u", "hosturl", kHostUrlHelp, cxxopts::value(m_HostName)->default_value(""), "<hosturl>");
 	m_Options.add_option("", "", "cache-write-log", "Enable cache write logging", cxxopts::value(m_CacheWriteLog), "<enable/disable>");
 	m_Options.add_option("", "", "cache-access-log", "Enable cache access logging", cxxopts::value(m_CacheAccessLog), "<enable/disable>");
 	m_Options
@@ -467,7 +467,7 @@ LoggingCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 		throw OptionParseException("Unable to resolve server specification", m_Options.help());
 	}
 
-	HttpClient Http(m_HostName);
+	HttpClient Http = CreateHttpClient(m_HostName);
 
 	HttpClient::KeyValueMap Parameters;
 
@@ -564,7 +564,7 @@ LoggingCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 FlushCommand::FlushCommand()
 {
 	m_Options.add_options()("h,help", "Print help");
-	m_Options.add_option("", "u", "hosturl", "Host URL", cxxopts::value(m_HostName)->default_value(""), "<hosturl>");
+	m_Options.add_option("", "u", "hosturl", kHostUrlHelp, cxxopts::value(m_HostName)->default_value(""), "<hosturl>");
 }
 
 FlushCommand::~FlushCommand() = default;
@@ -586,7 +586,7 @@ FlushCommand::Run(const ZenCliOptions& GlobalOptions, int argc, char** argv)
 		throw OptionParseException("Unable to resolve server specification", m_Options.help());
 	}
 
-	zen::HttpClient Http(m_HostName);
+	zen::HttpClient Http = CreateHttpClient(m_HostName);
 
 	if (zen::HttpClient::Response Response = Http.Post("/admin/flush"sv))
 	{