Compute batching (#849)

### Compute Batch Submission
- Consolidate duplicated action submission logic in `httpcomputeservice` into a single `HandleSubmitAction` supporting both single-action and batch (actions array) payloads
- Group actions by queue in `RemoteHttpRunner` and submit as batches with configurable chunk size, falling back to individual submission on failure
- Extract shared helpers: `MakeErrorResult`, `ValidateQueueForEnqueue`, `ActivateActionInQueue`, `RemoveActionFromActiveMaps`

### Retracted Action State
- Add `Retracted` state to `RunnerAction` for retry-free rescheduling — an explicit request to pull an action back and reschedule it on a different runner without incrementing `RetryCount`
- Implement idempotent `RetractAction()` on `RunnerAction` and `ComputeServiceSession`
- Add `POST jobs/{lsn}/retract` and `queues/{queueref}/jobs/{lsn}/retract` HTTP endpoints
- Add state machine documentation and per-state comments to `RunnerAction`

### Compute Race Fixes
- Fix race in `HandleActionUpdates` where actions enqueued between session abandon and scheduler tick were never abandoned, causing `GetActionResult` to return 202 indefinitely
- Fix queue `ActiveCount` race where `NotifyQueueActionComplete` was called after releasing `m_ResultsLock`, allowing callers to observe stale counters immediately after `GetActionResult` returned OK

### Logging Optimization and ANSI improvements
- Improve `AnsiColorStdoutSink` write efficiency — single write call, dirty-flag flush, `RwLock` instead of `std::mutex`
- Move ANSI color emission from sink into formatters via `Formatter::SetColorEnabled()`; remove `ColorRangeStart`/`End` from `LogMessage`
- Extract color helpers (`AnsiColorForLevel`, `StripAnsiSgrSequences`) into `helpers.h`
- Strip upstream ANSI SGR escapes in non-color output mode. This enables colour in log messages without polluting log files with ANSI control sequences
- Move `RotatingFileSink`, `JsonFormatter`, and `FullFormatter` from header-only to pimpl with `.cpp` files

### CLI / Exec Refactoring
- Extract `ExecSessionRunner` class from ~920-line `ExecUsingSession` into focused methods and a `ExecSessionConfig` struct
- Replace monolithic `ExecCommand` with subcommand-based architecture (`http`, `inproc`, `beacon`, `dump`, `buildlog`)
- Allow parent options to appear after subcommand name by parsing subcommand args permissively and forwarding unmatched tokens to the parent parser

### Testing Improvements
- Fix `--test-suite` filter being ignored due to accumulation with default wildcard filter
- Add test suite banners to test listener output
- Made `function.session.abandon_pending` test more robust

### Startup / Reliability Fixes
- Fix silent exit when a second zenserver instance detects a port conflict — use `ZEN_CONSOLE_*` for log calls that precede `InitializeLogging()`
- Fix two potential SIGSEGV paths during early startup: guard `sentry_options_new()` returning nullptr, and throw on `ZenServerState::Register()` returning nullptr instead of dereferencing
- Fail on unrecognized zenserver `--mode` instead of silently defaulting to store

### Other
- Show host details (hostname, platform, CPU count, memory) when discovering new compute workers
- Move frontend `html.zip` from source tree into build directory
- Add format specifications for Compact Binary and Compressed Buffer wire formats
- Add `WriteCompactBinaryObject` to zencore
- Extended `ConsoleTui` with additional functionality
- Add `--vscode` option to `xmake sln` for clangd / `compile_commands.json` support
- Disable compute/horde/nomad in release builds (not yet production-ready)
- Disable unintended `ASIO_HAS_IO_URING` enablement
- Fix crashpad patch missing leading whitespace
- Clean up code triggering gcc false positives

4 files changed, 946 insertions, 0 deletions

diff --git a/src/zenutil/logging/fullformatter.cpp b/src/zenutil/logging/fullformatter.cpp
new file mode 100644
index 000000000..2a4840241
--- /dev/null
+++ b/src/zenutil/logging/fullformatter.cpp
@@ -0,0 +1,235 @@
+// Copyright Epic Games, Inc. All Rights Reserved.
+
+#include <zenutil/logging/fullformatter.h>
+
+#include <zencore/intmath.h>
+#include <zencore/logging/helpers.h>
+#include <zencore/logging/memorybuffer.h>
+#include <zencore/memory/llm.h>
+#include <zencore/thread.h>
+#include <zencore/zencore.h>
+
+#include <atomic>
+#include <chrono>
+#include <string>
+
+namespace zen::logging {
+
+struct FullFormatter::Impl
+{
+	Impl(std::string_view LogId, std::chrono::time_point<std::chrono::system_clock> Epoch)
+	: m_Epoch(Epoch)
+	, m_LogId(LogId)
+	, m_LinePrefix(128, ' ')
+	, m_UseFullDate(false)
+	{
+	}
+
+	explicit Impl(std::string_view LogId) : m_LogId(LogId), m_LinePrefix(128, ' '), m_UseFullDate(true) {}
+
+	std::chrono::time_point<std::chrono::system_clock> m_Epoch;
+	std::tm											   m_CachedLocalTm{};
+	std::chrono::seconds							   m_LastLogSecs{std::chrono::seconds(87654321)};
+	std::atomic<std::chrono::seconds>				   m_CacheTimestamp{std::chrono::seconds(87654321)};
+	MemoryBuffer									   m_CachedDatetime;
+	std::string										   m_LogId;
+	std::string										   m_LinePrefix;
+	bool											   m_UseFullDate = true;
+	RwLock											   m_TimestampLock;
+};
+
+FullFormatter::FullFormatter(std::string_view LogId, std::chrono::time_point<std::chrono::system_clock> Epoch)
+: m_Impl(std::make_unique<Impl>(LogId, Epoch))
+{
+}
+
+FullFormatter::FullFormatter(std::string_view LogId) : m_Impl(std::make_unique<Impl>(LogId))
+{
+}
+
+FullFormatter::~FullFormatter() = default;
+
+std::unique_ptr<Formatter>
+FullFormatter::Clone() const
+{
+	ZEN_MEMSCOPE(ELLMTag::Logging);
+	std::unique_ptr<FullFormatter> Copy;
+	if (m_Impl->m_UseFullDate)
+	{
+		Copy = std::make_unique<FullFormatter>(m_Impl->m_LogId);
+	}
+	else
+	{
+		Copy = std::make_unique<FullFormatter>(m_Impl->m_LogId, m_Impl->m_Epoch);
+	}
+	Copy->SetColorEnabled(IsColorEnabled());
+	return Copy;
+}
+
+void
+FullFormatter::Format(const LogMessage& Msg, MemoryBuffer& OutBuffer)
+{
+	ZEN_MEMSCOPE(ELLMTag::Logging);
+
+	// Note that the sink is responsible for ensuring there is only ever a
+	// single caller in here
+
+	using namespace std::literals;
+
+	std::chrono::seconds TimestampSeconds;
+
+	std::chrono::milliseconds Millis;
+
+	if (m_Impl->m_UseFullDate)
+	{
+		TimestampSeconds = std::chrono::duration_cast<std::chrono::seconds>(Msg.GetTime().time_since_epoch());
+		if (TimestampSeconds != m_Impl->m_LastLogSecs)
+		{
+			RwLock::ExclusiveLockScope _(m_Impl->m_TimestampLock);
+			m_Impl->m_LastLogSecs = TimestampSeconds;
+
+			m_Impl->m_CachedLocalTm = helpers::SafeLocaltime(LogClock::to_time_t(Msg.GetTime()));
+			m_Impl->m_CachedDatetime.clear();
+			m_Impl->m_CachedDatetime.push_back('[');
+			helpers::Pad2(m_Impl->m_CachedLocalTm.tm_year % 100, m_Impl->m_CachedDatetime);
+			m_Impl->m_CachedDatetime.push_back('-');
+			helpers::Pad2(m_Impl->m_CachedLocalTm.tm_mon + 1, m_Impl->m_CachedDatetime);
+			m_Impl->m_CachedDatetime.push_back('-');
+			helpers::Pad2(m_Impl->m_CachedLocalTm.tm_mday, m_Impl->m_CachedDatetime);
+			m_Impl->m_CachedDatetime.push_back(' ');
+			helpers::Pad2(m_Impl->m_CachedLocalTm.tm_hour, m_Impl->m_CachedDatetime);
+			m_Impl->m_CachedDatetime.push_back(':');
+			helpers::Pad2(m_Impl->m_CachedLocalTm.tm_min, m_Impl->m_CachedDatetime);
+			m_Impl->m_CachedDatetime.push_back(':');
+			helpers::Pad2(m_Impl->m_CachedLocalTm.tm_sec, m_Impl->m_CachedDatetime);
+			m_Impl->m_CachedDatetime.push_back('.');
+		}
+
+		Millis = helpers::TimeFraction<std::chrono::milliseconds>(Msg.GetTime());
+	}
+	else
+	{
+		auto ElapsedTime = Msg.GetTime() - m_Impl->m_Epoch;
+		TimestampSeconds = std::chrono::duration_cast<std::chrono::seconds>(ElapsedTime);
+
+		if (m_Impl->m_CacheTimestamp.load() != TimestampSeconds)
+		{
+			RwLock::ExclusiveLockScope _(m_Impl->m_TimestampLock);
+
+			m_Impl->m_CacheTimestamp = TimestampSeconds;
+
+			int		  Count	  = int(TimestampSeconds.count());
+			const int LogSecs = Count % 60;
+			Count /= 60;
+			const int LogMins = Count % 60;
+			Count /= 60;
+			const int LogHours = Count;
+
+			m_Impl->m_CachedDatetime.clear();
+			m_Impl->m_CachedDatetime.push_back('[');
+			helpers::Pad2(LogHours, m_Impl->m_CachedDatetime);
+			m_Impl->m_CachedDatetime.push_back(':');
+			helpers::Pad2(LogMins, m_Impl->m_CachedDatetime);
+			m_Impl->m_CachedDatetime.push_back(':');
+			helpers::Pad2(LogSecs, m_Impl->m_CachedDatetime);
+			m_Impl->m_CachedDatetime.push_back('.');
+		}
+
+		Millis = std::chrono::duration_cast<std::chrono::milliseconds>(ElapsedTime - TimestampSeconds);
+	}
+
+	{
+		RwLock::SharedLockScope _(m_Impl->m_TimestampLock);
+		OutBuffer.append(m_Impl->m_CachedDatetime.begin(), m_Impl->m_CachedDatetime.end());
+	}
+
+	helpers::Pad3(static_cast<uint32_t>(Millis.count()), OutBuffer);
+	OutBuffer.push_back(']');
+	OutBuffer.push_back(' ');
+
+	if (!m_Impl->m_LogId.empty())
+	{
+		OutBuffer.push_back('[');
+		helpers::AppendStringView(m_Impl->m_LogId, OutBuffer);
+		OutBuffer.push_back(']');
+		OutBuffer.push_back(' ');
+	}
+
+	// append logger name if exists
+	if (Msg.GetLoggerName().size() > 0)
+	{
+		OutBuffer.push_back('[');
+		helpers::AppendStringView(Msg.GetLoggerName(), OutBuffer);
+		OutBuffer.push_back(']');
+		OutBuffer.push_back(' ');
+	}
+
+	OutBuffer.push_back('[');
+	if (IsColorEnabled())
+	{
+		helpers::AppendAnsiColor(Msg.GetLevel(), OutBuffer);
+	}
+	helpers::AppendStringView(helpers::LevelToShortString(Msg.GetLevel()), OutBuffer);
+	if (IsColorEnabled())
+	{
+		helpers::AppendAnsiReset(OutBuffer);
+	}
+	OutBuffer.push_back(']');
+	OutBuffer.push_back(' ');
+
+	// add source location if present
+	if (Msg.GetSource())
+	{
+		OutBuffer.push_back('[');
+		const char* Filename = helpers::ShortFilename(Msg.GetSource().Filename);
+		helpers::AppendStringView(Filename, OutBuffer);
+		OutBuffer.push_back(':');
+		helpers::AppendInt(Msg.GetSource().Line, OutBuffer);
+		OutBuffer.push_back(']');
+		OutBuffer.push_back(' ');
+	}
+
+	// Handle newlines in single log call by prefixing each additional line to make
+	// subsequent lines align with the first line in the message
+
+	size_t		 AnsiBytes		 = IsColorEnabled() ? (helpers::AnsiColorForLevel(Msg.GetLevel()).size() + helpers::kAnsiReset.size()) : 0;
+	const size_t LinePrefixCount = Min<size_t>(OutBuffer.size() - AnsiBytes, m_Impl->m_LinePrefix.size());
+
+	auto MsgPayload	  = Msg.GetPayload();
+	auto ItLineBegin  = MsgPayload.begin();
+	auto ItMessageEnd = MsgPayload.end();
+	bool IsFirstline  = true;
+
+	{
+		auto ItLineEnd = ItLineBegin;
+
+		auto EmitLine = [&] {
+			if (IsFirstline)
+			{
+				IsFirstline = false;
+			}
+			else
+			{
+				helpers::AppendStringView(std::string_view(m_Impl->m_LinePrefix.data(), LinePrefixCount), OutBuffer);
+			}
+			helpers::AppendStringView(std::string_view(&*ItLineBegin, ItLineEnd - ItLineBegin), OutBuffer);
+		};
+
+		while (ItLineEnd != ItMessageEnd)
+		{
+			if (*ItLineEnd++ == '\n')
+			{
+				EmitLine();
+				ItLineBegin = ItLineEnd;
+			}
+		}
+
+		if (ItLineBegin != ItMessageEnd)
+		{
+			EmitLine();
+			helpers::AppendStringView("\n"sv, OutBuffer);
+		}
+	}
+}
+
+}  // namespace zen::logging
diff --git a/src/zenutil/logging/jsonformatter.cpp b/src/zenutil/logging/jsonformatter.cpp
new file mode 100644
index 000000000..673a03c94
--- /dev/null
+++ b/src/zenutil/logging/jsonformatter.cpp
@@ -0,0 +1,198 @@
+// Copyright Epic Games, Inc. All Rights Reserved.
+
+#include <zenutil/logging/jsonformatter.h>
+
+#include <zencore/logging/helpers.h>
+#include <zencore/memory/llm.h>
+#include <zencore/thread.h>
+#include <zencore/zencore.h>
+
+#include <chrono>
+#include <string>
+#include <unordered_map>
+
+namespace zen::logging {
+
+using namespace std::literals;
+
+static void
+WriteEscapedString(MemoryBuffer& Dest, std::string_view Text)
+{
+	// Strip ANSI SGR sequences before escaping so they don't appear in JSON output
+	static const auto IsEscapeStart = [](char C) { return C == '\033'; };
+
+	const char* RangeStart = Text.data();
+	const char* End		   = Text.data() + Text.size();
+
+	static const std::unordered_map<char, std::string_view> SpecialCharacterMap{
+		{'\b', "\\b"sv},
+		{'\f', "\\f"sv},
+		{'\n', "\\n"sv},
+		{'\r', "\\r"sv},
+		{'\t', "\\t"sv},
+		{'"', "\\\""sv},
+		{'\\', "\\\\"sv},
+	};
+
+	for (const char* It = RangeStart; It != End; ++It)
+	{
+		// Skip ANSI SGR escape sequences (\033[...m)
+		if (*It == '\033' && (It + 1) < End && *(It + 1) == '[')
+		{
+			if (RangeStart != It)
+			{
+				Dest.append(RangeStart, It);
+			}
+			const char* Seq = It + 2;
+			while (Seq < End && *Seq != 'm')
+			{
+				++Seq;
+			}
+			if (Seq < End)
+			{
+				++Seq;	// skip 'm'
+			}
+			It		   = Seq - 1;  // -1 because the for loop will ++It
+			RangeStart = Seq;
+			continue;
+		}
+
+		if (auto SpecialIt = SpecialCharacterMap.find(*It); SpecialIt != SpecialCharacterMap.end())
+		{
+			if (RangeStart != It)
+			{
+				Dest.append(RangeStart, It);
+			}
+			helpers::AppendStringView(SpecialIt->second, Dest);
+			RangeStart = It + 1;
+		}
+	}
+	if (RangeStart != End)
+	{
+		Dest.append(RangeStart, End);
+	}
+}
+
+struct JsonFormatter::Impl
+{
+	explicit Impl(std::string_view LogId) : m_LogId(LogId) {}
+
+	std::tm				 m_CachedTm{0, 0, 0, 0, 0, 0, 0, 0, 0};
+	std::chrono::seconds m_LastLogSecs{0};
+	MemoryBuffer		 m_CachedDatetime;
+	std::string			 m_LogId;
+	RwLock				 m_TimestampLock;
+};
+
+JsonFormatter::JsonFormatter(std::string_view LogId) : m_Impl(std::make_unique<Impl>(LogId))
+{
+}
+
+JsonFormatter::~JsonFormatter() = default;
+
+std::unique_ptr<Formatter>
+JsonFormatter::Clone() const
+{
+	return std::make_unique<JsonFormatter>(m_Impl->m_LogId);
+}
+
+void
+JsonFormatter::Format(const LogMessage& Msg, MemoryBuffer& Dest)
+{
+	ZEN_MEMSCOPE(ELLMTag::Logging);
+
+	using std::chrono::duration_cast;
+	using std::chrono::milliseconds;
+	using std::chrono::seconds;
+
+	auto Secs = duration_cast<seconds>(Msg.GetTime().time_since_epoch());
+	if (Secs != m_Impl->m_LastLogSecs)
+	{
+		RwLock::ExclusiveLockScope _(m_Impl->m_TimestampLock);
+		m_Impl->m_CachedTm	  = helpers::SafeLocaltime(LogClock::to_time_t(Msg.GetTime()));
+		m_Impl->m_LastLogSecs = Secs;
+
+		// cache the date/time part for the next second.
+		m_Impl->m_CachedDatetime.clear();
+
+		helpers::AppendInt(m_Impl->m_CachedTm.tm_year + 1900, m_Impl->m_CachedDatetime);
+		m_Impl->m_CachedDatetime.push_back('-');
+
+		helpers::Pad2(m_Impl->m_CachedTm.tm_mon + 1, m_Impl->m_CachedDatetime);
+		m_Impl->m_CachedDatetime.push_back('-');
+
+		helpers::Pad2(m_Impl->m_CachedTm.tm_mday, m_Impl->m_CachedDatetime);
+		m_Impl->m_CachedDatetime.push_back(' ');
+
+		helpers::Pad2(m_Impl->m_CachedTm.tm_hour, m_Impl->m_CachedDatetime);
+		m_Impl->m_CachedDatetime.push_back(':');
+
+		helpers::Pad2(m_Impl->m_CachedTm.tm_min, m_Impl->m_CachedDatetime);
+		m_Impl->m_CachedDatetime.push_back(':');
+
+		helpers::Pad2(m_Impl->m_CachedTm.tm_sec, m_Impl->m_CachedDatetime);
+
+		m_Impl->m_CachedDatetime.push_back('.');
+	}
+	helpers::AppendStringView("{"sv, Dest);
+	helpers::AppendStringView("\"time\": \""sv, Dest);
+	{
+		RwLock::SharedLockScope _(m_Impl->m_TimestampLock);
+		Dest.append(m_Impl->m_CachedDatetime.begin(), m_Impl->m_CachedDatetime.end());
+	}
+	auto Millis = helpers::TimeFraction<milliseconds>(Msg.GetTime());
+	helpers::Pad3(static_cast<uint32_t>(Millis.count()), Dest);
+	helpers::AppendStringView("\", "sv, Dest);
+
+	helpers::AppendStringView("\"status\": \""sv, Dest);
+	helpers::AppendStringView(helpers::LevelToShortString(Msg.GetLevel()), Dest);
+	helpers::AppendStringView("\", "sv, Dest);
+
+	helpers::AppendStringView("\"source\": \""sv, Dest);
+	helpers::AppendStringView("zenserver"sv, Dest);
+	helpers::AppendStringView("\", "sv, Dest);
+
+	helpers::AppendStringView("\"service\": \""sv, Dest);
+	helpers::AppendStringView("zencache"sv, Dest);
+	helpers::AppendStringView("\", "sv, Dest);
+
+	if (!m_Impl->m_LogId.empty())
+	{
+		helpers::AppendStringView("\"id\": \""sv, Dest);
+		helpers::AppendStringView(m_Impl->m_LogId, Dest);
+		helpers::AppendStringView("\", "sv, Dest);
+	}
+
+	if (Msg.GetLoggerName().size() > 0)
+	{
+		helpers::AppendStringView("\"logger.name\": \""sv, Dest);
+		helpers::AppendStringView(Msg.GetLoggerName(), Dest);
+		helpers::AppendStringView("\", "sv, Dest);
+	}
+
+	if (Msg.GetThreadId() != 0)
+	{
+		helpers::AppendStringView("\"logger.thread_name\": \""sv, Dest);
+		helpers::PadUint(Msg.GetThreadId(), 0, Dest);
+		helpers::AppendStringView("\", "sv, Dest);
+	}
+
+	if (Msg.GetSource())
+	{
+		helpers::AppendStringView("\"file\": \""sv, Dest);
+		WriteEscapedString(Dest, helpers::ShortFilename(Msg.GetSource().Filename));
+		helpers::AppendStringView("\","sv, Dest);
+
+		helpers::AppendStringView("\"line\": \""sv, Dest);
+		helpers::AppendInt(Msg.GetSource().Line, Dest);
+		helpers::AppendStringView("\","sv, Dest);
+	}
+
+	helpers::AppendStringView("\"message\": \""sv, Dest);
+	WriteEscapedString(Dest, Msg.GetPayload());
+	helpers::AppendStringView("\""sv, Dest);
+
+	helpers::AppendStringView("}\n"sv, Dest);
+}
+
+}  // namespace zen::logging
diff --git a/src/zenutil/logging/logging.cpp b/src/zenutil/logging/logging.cpp
new file mode 100644
index 000000000..ea2448a42
--- /dev/null
+++ b/src/zenutil/logging/logging.cpp
@@ -0,0 +1,264 @@
+// Copyright Epic Games, Inc. All Rights Reserved.
+
+#include "zenutil/logging.h"
+
+#include <zencore/callstack.h>
+#include <zencore/compactbinary.h>
+#include <zencore/filesystem.h>
+#include <zencore/logging.h>
+#include <zencore/logging/ansicolorsink.h>
+#include <zencore/logging/asyncsink.h>
+#include <zencore/logging/logger.h>
+#include <zencore/logging/msvcsink.h>
+#include <zencore/logging/registry.h>
+#include <zencore/memory/llm.h>
+#include <zencore/string.h>
+#include <zencore/timer.h>
+#include <zenutil/logging/fullformatter.h>
+#include <zenutil/logging/jsonformatter.h>
+#include <zenutil/logging/rotatingfilesink.h>
+
+#include <chrono>
+#include <memory>
+
+namespace zen {
+
+static bool		 g_IsLoggingInitialized;
+logging::SinkPtr g_FileSink;
+
+logging::SinkPtr
+GetFileSink()
+{
+	return g_FileSink;
+}
+
+void
+InitializeLogging(const LoggingOptions& LogOptions)
+{
+	BeginInitializeLogging(LogOptions);
+	FinishInitializeLogging(LogOptions);
+}
+
+static std::terminate_handler OldTerminateHandler = nullptr;
+
+void
+BeginInitializeLogging(const LoggingOptions& LogOptions)
+{
+	ZEN_MEMSCOPE(ELLMTag::Logging);
+
+	zen::logging::InitializeLogging();
+	zen::logging::EnableVTMode();
+
+	// Sinks
+
+	logging::SinkPtr FileSink;
+
+	if (!LogOptions.AbsLogFile.empty())
+	{
+		if (LogOptions.AbsLogFile.has_parent_path())
+		{
+			zen::CreateDirectories(LogOptions.AbsLogFile.parent_path());
+		}
+
+		FileSink = logging::SinkPtr(new zen::logging::RotatingFileSink(LogOptions.AbsLogFile,
+																	   /* max size */ 128 * 1024 * 1024,
+																	   /* max files */ 16,
+																	   /* rotate on open */ true));
+		if (LogOptions.AbsLogFile.extension() == ".json")
+		{
+			FileSink->SetFormatter(std::make_unique<logging::JsonFormatter>(LogOptions.LogId));
+		}
+		else
+		{
+			FileSink->SetFormatter(std::make_unique<logging::FullFormatter>(LogOptions.LogId));	 // this will have a date prefix
+		}
+	}
+
+	OldTerminateHandler = std::set_terminate([]() {
+		try
+		{
+			constexpr int	 SkipFrameCount = 4;
+			constexpr int	 FrameCount		= 8;
+			uint8_t			 CallstackBuffer[CallstackRawMemorySize(SkipFrameCount, FrameCount)];
+			CallstackFrames* Callstack = GetCallstackRaw(&CallstackBuffer[0], SkipFrameCount, FrameCount);
+
+			fmt::basic_memory_buffer<char, 2048> Message;
+			auto								 Appender = fmt::appender(Message);
+			fmt::format_to(Appender, "Program exited abnormally via std::terminate()");
+
+			if (Callstack->FrameCount > 0)
+			{
+				fmt::format_to(Appender, "\n");
+
+				CallstackToStringRaw(Callstack, &Message, [](void* UserData, uint32_t FrameIndex, const char* FrameText) {
+					ZEN_UNUSED(FrameIndex);
+					fmt::basic_memory_buffer<char, 2048>* Message  = (fmt::basic_memory_buffer<char, 2048>*)UserData;
+					auto								  Appender = fmt::appender(*Message);
+					fmt::format_to(Appender, "  {}\n", FrameText);
+				});
+			}
+			Message.push_back('\0');
+
+			// We use direct ZEN_LOG here instead of ZEN_ERROR as we don't care about *this* code location in the log
+			ZEN_LOG(Log(), zen::logging::Critical, "{}", Message.data());
+			zen::logging::FlushLogging();
+		}
+		catch (const std::exception&)
+		{
+			// Ignore any exceptions in terminate callback
+		}
+		if (OldTerminateHandler)
+		{
+			OldTerminateHandler();
+		}
+	});
+
+	// Default
+
+	LoggerRef DefaultLogger = zen::logging::Default();
+
+	// Collect sinks into a local vector first so we can optionally wrap them
+	std::vector<logging::SinkPtr> Sinks;
+
+	if (LogOptions.NoConsoleOutput)
+	{
+		zen::logging::SuppressConsoleLog();
+	}
+	else
+	{
+		logging::SinkPtr ConsoleSink(new logging::AnsiColorStdoutSink());
+		if (LogOptions.QuietConsole)
+		{
+			ConsoleSink->SetLevel(logging::Warn);
+		}
+		Sinks.push_back(ConsoleSink);
+	}
+
+	if (FileSink)
+	{
+		Sinks.push_back(FileSink);
+	}
+
+#if ZEN_PLATFORM_WINDOWS
+	if (zen::IsDebuggerPresent() && LogOptions.IsDebug)
+	{
+		logging::SinkPtr DebugSink(new logging::MsvcSink());
+		DebugSink->SetLevel(logging::Debug);
+		Sinks.push_back(DebugSink);
+	}
+#endif
+
+	bool IsAsync = LogOptions.AllowAsync && !LogOptions.IsDebug && !LogOptions.IsTest;
+
+	if (IsAsync)
+	{
+		std::vector<logging::SinkPtr> AsyncSinks;
+		AsyncSinks.emplace_back(new logging::AsyncSink(std::move(Sinks)));
+		DefaultLogger->SetSinks(std::move(AsyncSinks));
+	}
+	else
+	{
+		DefaultLogger->SetSinks(std::move(Sinks));
+	}
+
+	static struct : logging::ErrorHandler
+	{
+		void HandleError(const std::string_view& ErrorMsg) override
+		{
+			if (ErrorMsg == std::bad_alloc().what())
+			{
+				return;
+			}
+			static constinit logging::LogPoint ErrorPoint{{}, logging::Err, "{}"};
+			if (auto ErrLogger = zen::logging::ErrorLog())
+			{
+				try
+				{
+					ErrLogger->Log(ErrorPoint, fmt::make_format_args(ErrorMsg));
+				}
+				catch (const std::exception&)
+				{
+				}
+			}
+			try
+			{
+				Log()->Log(ErrorPoint, fmt::make_format_args(ErrorMsg));
+			}
+			catch (const std::exception&)
+			{
+			}
+		}
+	} s_ErrorHandler;
+	logging::Registry::Instance().SetErrorHandler(&s_ErrorHandler);
+
+	g_FileSink = std::move(FileSink);
+}
+
+void
+FinishInitializeLogging(const LoggingOptions& LogOptions)
+{
+	ZEN_MEMSCOPE(ELLMTag::Logging);
+
+	logging::LogLevel LogLevel = logging::Info;
+
+	if (LogOptions.IsDebug)
+	{
+		LogLevel = logging::Debug;
+	}
+
+	if (LogOptions.IsTest || LogOptions.IsVerbose)
+	{
+		LogLevel = logging::Trace;
+	}
+
+	// Configure all registered loggers according to settings
+
+	logging::RefreshLogLevels(LogLevel);
+	logging::Registry::Instance().FlushOn(logging::Err);
+	logging::Registry::Instance().FlushEvery(std::chrono::seconds{2});
+	logging::Registry::Instance().SetFormatter(std::make_unique<logging::FullFormatter>(
+		LogOptions.LogId,
+		std::chrono::system_clock::now() - std::chrono::milliseconds(GetTimeSinceProcessStart())));	 // default to duration prefix
+
+	// If the console logger was initialized before, the above will change the output format
+	// so we need to reset it
+
+	logging::ResetConsoleLog();
+
+	if (g_FileSink)
+	{
+		if (LogOptions.AbsLogFile.extension() == ".json")
+		{
+			g_FileSink->SetFormatter(std::make_unique<logging::JsonFormatter>(LogOptions.LogId));
+		}
+		else
+		{
+			g_FileSink->SetFormatter(std::make_unique<logging::FullFormatter>(LogOptions.LogId));  // this will have a date prefix
+		}
+
+		const std::string StartLogTime = zen::DateTime::Now().ToIso8601();
+
+		logging::Registry::Instance().ApplyAll([&](auto Logger) {
+			static constinit logging::LogPoint LogStartPoint{{}, logging::Info, "log starting at {}"};
+			Logger->Log(LogStartPoint, fmt::make_format_args(StartLogTime));
+		});
+	}
+
+	g_IsLoggingInitialized = true;
+}
+
+void
+ShutdownLogging()
+{
+	if (g_IsLoggingInitialized && g_FileSink)
+	{
+		auto DefaultLogger = zen::logging::Default();
+		ZEN_LOG_INFO(DefaultLogger, "log ending at {}", zen::DateTime::Now().ToIso8601());
+	}
+
+	zen::logging::ShutdownLogging();
+
+	g_FileSink = nullptr;
+}
+
+}  // namespace zen
diff --git a/src/zenutil/logging/rotatingfilesink.cpp b/src/zenutil/logging/rotatingfilesink.cpp
new file mode 100644
index 000000000..23cf60d16
--- /dev/null
+++ b/src/zenutil/logging/rotatingfilesink.cpp
@@ -0,0 +1,249 @@
+// Copyright Epic Games, Inc. All Rights Reserved.
+
+#include <zenutil/logging/rotatingfilesink.h>
+
+#include <zencore/basicfile.h>
+#include <zencore/filesystem.h>
+#include <zencore/logging/helpers.h>
+#include <zencore/logging/messageonlyformatter.h>
+#include <zencore/memory/llm.h>
+#include <zencore/thread.h>
+
+#include <atomic>
+
+namespace zen::logging {
+
+struct RotatingFileSink::Impl
+{
+	Impl(const std::filesystem::path& BaseFilename, std::size_t MaxSize, std::size_t MaxFiles, bool RotateOnOpen)
+	: m_BaseFilename(BaseFilename)
+	, m_MaxSize(MaxSize)
+	, m_MaxFiles(MaxFiles)
+	, m_Formatter(std::make_unique<MessageOnlyFormatter>())
+	{
+		ZEN_MEMSCOPE(ELLMTag::Logging);
+
+		std::error_code Ec;
+		if (RotateOnOpen)
+		{
+			RwLock::ExclusiveLockScope RotateLock(m_Lock);
+			Rotate(RotateLock, Ec);
+		}
+		else
+		{
+			m_CurrentFile.Open(m_BaseFilename, BasicFile::Mode::kWrite, Ec);
+			if (!Ec)
+			{
+				m_CurrentSize = m_CurrentFile.FileSize(Ec);
+			}
+			if (!Ec)
+			{
+				if (m_CurrentSize > m_MaxSize)
+				{
+					RwLock::ExclusiveLockScope RotateLock(m_Lock);
+					Rotate(RotateLock, Ec);
+				}
+			}
+		}
+
+		if (Ec)
+		{
+			throw std::system_error(Ec, fmt::format("Failed to open log file '{}'", m_BaseFilename.string()));
+		}
+	}
+
+	~Impl()
+	{
+		try
+		{
+			RwLock::ExclusiveLockScope RotateLock(m_Lock);
+			m_CurrentFile.Close();
+		}
+		catch (const std::exception&)
+		{
+		}
+	}
+
+	void Rotate(RwLock::ExclusiveLockScope&, std::error_code& OutEc)
+	{
+		ZEN_MEMSCOPE(ELLMTag::Logging);
+
+		m_CurrentFile.Close();
+
+		OutEc = RotateFiles(m_BaseFilename, m_MaxFiles);
+		if (OutEc)
+		{
+			return;
+		}
+
+		m_CurrentFile.Open(m_BaseFilename, BasicFile::Mode::kWrite, OutEc);
+		if (OutEc)
+		{
+			return;
+		}
+
+		m_CurrentSize = m_CurrentFile.FileSize(OutEc);
+		if (OutEc)
+		{
+			// FileSize failed but we have an open file — reset to 0
+			// so we can at least attempt writes from the start
+			m_CurrentSize = 0;
+			OutEc.clear();
+		}
+	}
+
+	bool TrySinkIt(const LogMessage& Msg, MemoryBuffer& OutFormatted)
+	{
+		ZEN_MEMSCOPE(ELLMTag::Logging);
+
+		RwLock::SharedLockScope Lock(m_Lock);
+		if (!m_CurrentFile.IsOpen())
+		{
+			return false;
+		}
+		m_Formatter->Format(Msg, OutFormatted);
+		helpers::StripAnsiSgrSequences(OutFormatted);
+		size_t AddSize	= OutFormatted.size();
+		size_t WritePos = m_CurrentSize.fetch_add(AddSize);
+		if (WritePos + AddSize > m_MaxSize)
+		{
+			return false;
+		}
+		std::error_code Ec;
+		m_CurrentFile.Write(OutFormatted.data(), OutFormatted.size(), WritePos, Ec);
+		if (Ec)
+		{
+			return false;
+		}
+		m_NeedFlush = true;
+		return true;
+	}
+
+	bool TrySinkIt(const MemoryBuffer& Formatted)
+	{
+		ZEN_MEMSCOPE(ELLMTag::Logging);
+
+		RwLock::SharedLockScope Lock(m_Lock);
+		if (!m_CurrentFile.IsOpen())
+		{
+			return false;
+		}
+		size_t AddSize	= Formatted.size();
+		size_t WritePos = m_CurrentSize.fetch_add(AddSize);
+		if (WritePos + AddSize > m_MaxSize)
+		{
+			return false;
+		}
+
+		std::error_code Ec;
+		m_CurrentFile.Write(Formatted.data(), Formatted.size(), WritePos, Ec);
+		if (Ec)
+		{
+			return false;
+		}
+		m_NeedFlush = true;
+		return true;
+	}
+
+	RwLock						m_Lock;
+	const std::filesystem::path m_BaseFilename;
+	const std::size_t			m_MaxSize;
+	const std::size_t			m_MaxFiles;
+	std::unique_ptr<Formatter>	m_Formatter;
+	std::atomic_size_t			m_CurrentSize;
+	BasicFile					m_CurrentFile;
+	std::atomic<bool>			m_NeedFlush = false;
+};
+
+RotatingFileSink::RotatingFileSink(const std::filesystem::path& BaseFilename, std::size_t MaxSize, std::size_t MaxFiles, bool RotateOnOpen)
+: m_Impl(std::make_unique<Impl>(BaseFilename, MaxSize, MaxFiles, RotateOnOpen))
+{
+}
+
+RotatingFileSink::~RotatingFileSink() = default;
+
+void
+RotatingFileSink::Log(const LogMessage& Msg)
+{
+	ZEN_MEMSCOPE(ELLMTag::Logging);
+
+	try
+	{
+		MemoryBuffer Formatted;
+		if (m_Impl->TrySinkIt(Msg, Formatted))
+		{
+			return;
+		}
+
+		// This intentionally has no limit on the number of retries, see
+		// comment above.
+		for (;;)
+		{
+			{
+				RwLock::ExclusiveLockScope RotateLock(m_Impl->m_Lock);
+				// Only rotate if no-one else has rotated before us
+				if (m_Impl->m_CurrentSize > m_Impl->m_MaxSize || !m_Impl->m_CurrentFile.IsOpen())
+				{
+					std::error_code Ec;
+					m_Impl->Rotate(RotateLock, Ec);
+					if (Ec)
+					{
+						return;
+					}
+				}
+			}
+			if (m_Impl->TrySinkIt(Formatted))
+			{
+				return;
+			}
+		}
+	}
+	catch (const std::exception&)
+	{
+		// Silently eat errors
+	}
+}
+
+void
+RotatingFileSink::Flush()
+{
+	if (!m_Impl->m_NeedFlush)
+	{
+		return;
+	}
+
+	ZEN_MEMSCOPE(ELLMTag::Logging);
+
+	try
+	{
+		RwLock::SharedLockScope Lock(m_Impl->m_Lock);
+		if (m_Impl->m_CurrentFile.IsOpen())
+		{
+			m_Impl->m_CurrentFile.Flush();
+		}
+	}
+	catch (const std::exception&)
+	{
+		// Silently eat errors
+	}
+
+	m_Impl->m_NeedFlush = false;
+}
+
+void
+RotatingFileSink::SetFormatter(std::unique_ptr<Formatter> InFormatter)
+{
+	ZEN_MEMSCOPE(ELLMTag::Logging);
+
+	try
+	{
+		RwLock::ExclusiveLockScope _(m_Impl->m_Lock);
+		m_Impl->m_Formatter = std::move(InFormatter);
+	}
+	catch (const std::exception&)
+	{
+		// Silently eat errors
+	}
+}
+
+}  // namespace zen::logging