--- a/experiments/RecoilWasm/rts/Game/WebbarBrowser.h
+++ b/experiments/RecoilWasm/rts/Game/WebbarBrowser.h
@@ -62,6 +62,7 @@
 #include "WebbarResurrection.h"
 #include "WebbarNano.h"
 #include "WebbarSkirmish.h"
+#include "WebbarPlacement.h"
 #include "WebbarWorld.h"
 #include "WebbarTerrain.h"
 #include "WebbarTerrainFixture.h"
@@ -83,15 +84,15 @@
 	if (!catalogSent) {
 		catalogSent = true;
 		if (std::getenv("WEBBAR_NETWORK") != nullptr) { static WebbarNetworkResult result; }
-		MAIN_THREAD_EM_ASM({ if (Module['webbarProtocol']) Module['webbarProtocol'](8, 1023 /* restore | shields | cloak | resurrection | native work effects | area resurrection | manual launch | capture | smart trajectory | energy conversion */); });
+		MAIN_THREAD_EM_ASM({ if (Module['webbarProtocol']) Module['webbarProtocol'](9, 8191 /* restore | shields | cloak | resurrection | native work effects | area resurrection | manual launch | capture | smart trajectory | energy conversion | geothermal | selectability | build restrictions */); });
 		MAIN_THREAD_EM_ASM({
 			if (Module['webbarIdentity']) Module['webbarIdentity']($0, $1, $2, $3);
 		}, gu->myPlayerNum, gu->myTeam, gu->myAllyTeam, int(gu->spectating));
 		for (const UnitDef& def: unitDefHandler->GetUnitDefsVec()) {
 			if (!WebbarSupports(&def)) continue;
 			MAIN_THREAD_EM_ASM({
-				if (Module['webbarCatalog']) Module['webbarCatalog']($0, UTF8ToString($1), $2, $3, $4, $5, $6, $7, $8, $9, $10, $11);
-			}, def.id, def.name.c_str(), def.cost.metal, def.cost.energy, def.buildTime, def.xsize * SQUARE_SIZE, def.zsize * SQUARE_SIZE, def.IsBuilderUnit(), def.IsFactoryUnit(), def.IsExtractorUnit(), !def.IsImmobileUnit(), def.CanDamage());
+				if (Module['webbarCatalog']) Module['webbarCatalog']($0, UTF8ToString($1), $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12);
+			}, def.id, def.name.c_str(), def.cost.metal, def.cost.energy, def.buildTime, def.xsize * SQUARE_SIZE, def.zsize * SQUARE_SIZE, def.IsBuilderUnit(), def.IsFactoryUnit(), def.IsExtractorUnit(), !def.IsImmobileUnit(), def.CanDamage(), def.needGeo);
 			for (const auto& option: def.buildOptions) {
 				const UnitDef* target = unitDefHandler->GetUnitDefByName(option.second);
 				if (!WebbarSupports(target)) continue;
@@ -139,9 +140,9 @@
 		if (Module['webbarEconomy']) Module['webbarEconomy']($0, HEAPF32.slice($1 >> 2, ($1 >> 2) + 10).buffer);
 	}, gs->frameNum, economy);
 	const auto units = WebbarUnits();
-	struct Record { uint32_t id; float progress; uint32_t queued; int32_t command; uint32_t target; float metal, energy; uint32_t transporter, cargo; };
-	static_assert(sizeof(Record) == 36);
-	const uint32_t header[] = {0x34534257, uint32_t(gs->frameNum), uint32_t(units.size()), 0};
+	struct Record { uint32_t id; float progress; uint32_t queued; int32_t command; uint32_t target; float metal, energy; uint32_t transporter, cargo, selectionFlags; };
+	static_assert(sizeof(Record) == 40);
+	const uint32_t header[] = {0x35534257, uint32_t(gs->frameNum), uint32_t(units.size()), 0};
 	std::vector<uint8_t> packet(sizeof(header) + units.size() * sizeof(Record));
 	std::memcpy(packet.data(), header, sizeof(header));
 	size_t offset = sizeof(header);
@@ -152,7 +153,7 @@
 		const auto& queue = unit->commandAI->commandQue;
 		const bool owned = unit->team == gu->myTeam;
 		const Record record = {uint32_t(unit->id), unit->buildProgress, owned ? uint32_t(queue.size()) : 0, (!owned || queue.empty()) ? 0 : queue.front().GetID(),
-			(owned && target) ? uint32_t(target->id) : 0xffffffff, owned ? unit->resourcesMake.metal : 0.0f, owned ? unit->resourcesMake.energy : 0.0f, unit->GetTransporter() ? uint32_t(unit->GetTransporter()->id) : 0xffffffff, owned ? uint32_t(unit->transportedUnits.size()) : 0};
+			(owned && target) ? uint32_t(target->id) : 0xffffffff, owned ? unit->resourcesMake.metal : 0.0f, owned ? unit->resourcesMake.energy : 0.0f, unit->GetTransporter() ? uint32_t(unit->GetTransporter()->id) : 0xffffffff, owned ? uint32_t(unit->transportedUnits.size()) : 0, (owned && unit->noSelect) ? 1u : 0u};
 		std::memcpy(packet.data() + offset, &record, sizeof(record)); offset += sizeof(record);
 	}
 	MAIN_THREAD_EM_ASM({
@@ -217,7 +218,7 @@
 		} else {
 			for (uint32_t i = 0; i < order.count; ++i) {
 				const CUnit* unit = unitHandler.GetUnit(order.units[i]);
-				if (unit != nullptr && unit->team == gu->myTeam && !unit->isDead && std::find(ids.begin(), ids.end(), unit->id) == ids.end())
+				if (WebbarSelectable(unit) && std::find(ids.begin(), ids.end(), unit->id) == ids.end())
 					ids.push_back(unit->id);
 			}
 			Command command(order.kind, uint8_t(order.options & SHIFT_KEY));
@@ -365,7 +366,9 @@
 						for (const auto& option: unit->unitDef->buildOptions) if (option.second == def->name) return false;
 						return true;
 					});
-					if (ids.empty()) {
+					if (WebbarBuildRestriction(def->id) != nullptr) {
+						status = 9;
+					} else if (ids.empty()) {
 						status = 8;
 					} else if (order.kind == 1003) {
 						command = Command(-def->id); // one unit per click; SHIFT means five to a native factory
--- a/experiments/RecoilWasm/rts/Game/WebbarWorld.h
+++ b/experiments/RecoilWasm/rts/Game/WebbarWorld.h
@@ -6,6 +6,8 @@
 static void PublishWebbarWorld()
 {
 	if (gs->frameNum % 15 != 0) return;
+	PublishWebbarGeothermal();
+	PublishWebbarBuildRestrictions();
 	constexpr uint32_t grid = 256;
 	std::vector<float3> contacts;
 	for (const CUnit* unit: unitHandler.GetActiveUnits())
--- /dev/null
+++ b/experiments/RecoilWasm/rts/Game/WebbarPlacement.h
@@ -0,0 +1,66 @@
+/* This file is part of the Spring engine (GPL v2 or later), see LICENSE.html */
+#pragma once
+
+#include "Lua/LuaRulesParams.h"
+
+// api_build_blocking publishes the original gadget's current per-team reasons.
+// Read that decision instead of duplicating map/option rules or calling synced
+// AllowCommand from a local preview.
+static const std::string* WebbarBuildRestriction(int definition)
+{
+	if (gu->spectating || !teamHandler.IsValidTeam(gu->myTeam)) return nullptr;
+	const auto& params = teamHandler.Team(gu->myTeam)->modParams;
+	const auto it = params.find("unitdef_blocked_" + std::to_string(definition));
+	if (it == params.end() || !(it->second.los & LuaRulesParams::RULESPARAMLOS_PRIVATE_MASK)) return nullptr;
+	const auto* reason = std::get_if<std::string>(&it->second.value);
+	return reason != nullptr && !reason->empty() ? reason : nullptr;
+}
+
+static void PublishWebbarBuildRestrictions()
+{
+	if (gu->spectating || !teamHandler.IsValidTeam(gu->myTeam)) return;
+	std::vector<uint32_t> words;
+	for (const UnitDef& def: unitDefHandler->GetUnitDefsVec()) {
+		if (!WebbarSupports(&def)) continue;
+		const auto* reason = WebbarBuildRestriction(def.id);
+		if (reason == nullptr) continue;
+		words.push_back(def.id);
+		words.push_back(uint32_t(reinterpret_cast<uintptr_t>(reason->c_str())));
+	}
+	MAIN_THREAD_EM_ASM({
+		if (!Module['webbarBuildRestrictions']) return;
+		const words = HEAPU32.subarray($0 >> 2, ($0 >> 2) + $1);
+		const entries = [];
+		for (let i = 0; i < words.length; i += 2) entries.push([words[i], UTF8ToString(words[i + 1])]);
+		Module['webbarBuildRestrictions']($2, $3, entries);
+	}, words.data(), words.size(), gs->frameNum, gu->myTeam);
+}
+
+// Local presentation/admission only. The original gadgets own noSelect and
+// the original build-square checks own geothermal placement and occupancy.
+static bool WebbarSelectable(const CUnit* unit)
+{
+	return unit != nullptr && unit->team == gu->myTeam && !unit->isDead && !unit->noSelect;
+}
+
+static bool WebbarGeoVisible(const CFeature* feature)
+{
+	return feature != nullptr && !feature->deleteMe && feature->def->geoThermal && feature->IsInLosForAllyTeam(gu->myAllyTeam);
+}
+
+static void PublishWebbarGeothermal()
+{
+	struct GeoRecord { uint32_t id; float x, y, z; };
+	static_assert(sizeof(GeoRecord) == 16);
+	std::vector<GeoRecord> vents;
+	for (const int id: featureHandler.GetActiveFeatureIDs()) {
+		const CFeature* feature = featureHandler.GetFeature(id);
+		if (!WebbarGeoVisible(feature)) continue;
+		vents.push_back({uint32_t(id), feature->pos.x, feature->pos.y, feature->pos.z});
+	}
+	const uint32_t header[] = {0x31474257, uint32_t(gs->frameNum), uint32_t(vents.size()), 0};
+	std::vector<uint8_t> packet(sizeof(header) + vents.size() * sizeof(GeoRecord));
+	std::memcpy(packet.data(), header, sizeof(header));
+	std::memcpy(packet.data() + sizeof(header), vents.data(), vents.size() * sizeof(GeoRecord));
+	MAIN_THREAD_EM_ASM({ if (Module['webbarGeothermal']) Module['webbarGeothermal'](HEAPU8.slice($0, $0 + $1).buffer); }, packet.data(), packet.size());
+}