--- a/rts/Sim/Units/UnitTypes/Builder.cpp
+++ b/rts/Sim/Units/UnitTypes/Builder.cpp
@@ -5,6 +5,7 @@
 #include "Builder.h"
 #if defined(__EMSCRIPTEN__)
 #include "Game/WebbarNano.h"
+#include "Game/WebbarWorkAudio.h"
 #endif
 #include "Building.h"
 #include "Game/GameHelper.h"
@@ -963,8 +964,12 @@
 		script->StartBuilding(ClampRadPi(h - heading * TAANG2RAD), p - pitch);
 	}
 
-	if ((!silent || inBuildStance) && IsInLosForAllyTeam(gu->myAllyTeam))
+	if ((!silent || inBuildStance) && IsInLosForAllyTeam(gu->myAllyTeam)) {
+#if defined(__EMSCRIPTEN__)
+		webbarWorkAudio::Record(this, pos, 0);
+#endif
 		Channels::General->PlayRandomSample(unitDef->sounds.build, pos);
+	}
 
 	return inBuildStance;
 }
--- a/rts/Sim/Units/UnitTypes/Factory.cpp
+++ b/rts/Sim/Units/UnitTypes/Factory.cpp
@@ -4,6 +4,7 @@
 #include "Factory.h"
 #if defined(__EMSCRIPTEN__)
 #include "Game/WebbarNano.h"
+#include "Game/WebbarWorkAudio.h"
 #endif
 #include "Game/GameHelper.h"
 #include "Game/WaitCommandsAI.h"
@@ -207,6 +208,9 @@
 	curBuildDef = nullptr;
 
 	if (losStatus[gu->myAllyTeam] & LOS_INLOS) {
+#if defined(__EMSCRIPTEN__)
+		webbarWorkAudio::Record(this, buildPos, 1);
+#endif
 		Channels::General->PlayRandomSample(unitDef->sounds.build, buildPos);
 	}
 }
--- a/rts/Sim/Units/Unit.cpp
+++ b/rts/Sim/Units/Unit.cpp
@@ -5,6 +5,7 @@
 #include "Unit.h"
 #ifdef __EMSCRIPTEN__
 #include "Game/WebbarCloakEvents.h"
+#include "Game/WebbarWorkAudio.h"
 #endif
 #include "UnitHandler.h"
 #include "UnitDefHandler.h"
@@ -108,6 +109,7 @@
 {
 #ifdef __EMSCRIPTEN__
 	webbarCloakEvents::Forget(id);
+	webbarWorkAudio::Forget(id);
 #endif
 	RECOIL_DETAILED_TRACY_ZONE;
 	assert(unitMemPool.mapped(this));
--- a/rts/Game/WebbarBrowser.h
+++ b/rts/Game/WebbarBrowser.h
@@ -44,6 +44,7 @@
 #include "WebbarWeapons.h"
 #include "WebbarShields.h"
 #include "WebbarCloak.h"
+#include "WebbarWorkAudio.h"
 
 static bool WebbarSupports(const UnitDef* def)
 {
@@ -156,6 +157,7 @@
 	}, packet.data(), packet.size());
 	PublishWebbarShields();
 	PublishWebbarCloak();
+	webbarWorkAudio::Publish();
 	PublishWebbarWorld();
 	PublishWebbarResurrection();
 }
--- /dev/null
+++ b/rts/Game/WebbarWorkAudio.h
@@ -0,0 +1,63 @@
+/* This file is part of the Spring engine (GPL v2 or later), see LICENSE.html */
+#pragma once
+
+#include <algorithm>
+#include <cmath>
+#include <cstdint>
+#include <cstring>
+#include <vector>
+#include <emscripten.h>
+#include "Game/GlobalUnsynced.h"
+#include "Sim/Misc/GlobalSynced.h"
+#include "Sim/Units/Unit.h"
+#include "Sim/Units/UnitDef.h"
+#include "Sim/Units/UnitHandler.h"
+
+// Read-only cues at the original sound callsites, not inferred nano activity.
+// Local ownership narrows native LOS admission. Never inspect hidden targets,
+// consume simulation RNG or change build power, scripts, commands or resources.
+namespace webbarWorkAudio {
+struct Event {
+	uint32_t id, frame, unit, definition;
+	float position[3];
+	uint32_t kind;
+};
+static_assert(sizeof(Event) == 32);
+inline std::vector<Event> pending;
+inline uint32_t nextID = 0, dropped = 0;
+
+inline void Record(const CUnit* unit, const float3& position, uint32_t kind)
+{
+	if (unit->isDead || unit->team != gu->myTeam || gs->frameNum < 0 ||
+		!std::isfinite(position.x) || !std::isfinite(position.y) || !std::isfinite(position.z)) return;
+	if (pending.size() >= 1024) { ++dropped; return; }
+	if (++nextID == 0) ++nextID;
+	pending.push_back({nextID, uint32_t(gs->frameNum), uint32_t(unit->id), uint32_t(unit->unitDef->id),
+		{position.x, position.y, position.z}, kind});
+}
+
+inline void Forget(int unitID)
+{
+	pending.erase(std::remove_if(pending.begin(), pending.end(), [unitID](const Event& event) {
+		return event.unit == uint32_t(unitID);
+	}), pending.end());
+}
+
+inline void Publish()
+{
+	std::vector<Event> events;
+	for (const auto& event: pending) {
+		const CUnit* unit = unitHandler.GetUnit(event.unit);
+		if (unit == nullptr || unit->isDead || unit->team != gu->myTeam || unit->unitDef->id != int(event.definition) ||
+			event.frame > uint32_t(gs->frameNum) || uint32_t(gs->frameNum) - event.frame > 6) continue;
+		events.push_back(event);
+	}
+	pending.clear();
+	const uint32_t header[] = {0x31414257, uint32_t(gs->frameNum), uint32_t(events.size()), dropped};
+	dropped = 0;
+	std::vector<uint8_t> packet(sizeof(header) + events.size() * sizeof(Event));
+	std::memcpy(packet.data(), header, sizeof(header));
+	if (!events.empty()) std::memcpy(packet.data() + sizeof(header), events.data(), events.size() * sizeof(Event));
+	MAIN_THREAD_EM_ASM({ if (Module['webbarWorkAudio']) Module['webbarWorkAudio'](HEAPU8.slice($0, $0 + $1).buffer); }, packet.data(), packet.size());
+}
+}