Hint for upgrading units

core/src/mindustry/game/EventType.java

@@ -17,6 +17,7 @@ public class EventType{
     //events that occur very often
     public enum Trigger{
         shock,
+        cannotUpgrade,
         openConsole,
         blastFreeze,
         impactPower,

core/src/mindustry/ui/fragments/HintsFragment.java

@@ -81,6 +81,8 @@ public class HintsFragment{
             }
         });
 
+        Events.run(Trigger.cannotUpgrade, () -> events.add("cannotupgrade"));
+
         Events.on(ResetEvent.class, e -> {
             placedBlocks.clear();
             events.clear();
@@ -186,6 +188,7 @@ public class HintsFragment{
         generator(() -> control.input.block == Blocks.combustionGenerator, () -> ui.hints.placedBlocks.contains(Blocks.combustionGenerator)),
         rebuildSelect(() -> state.rules.defaultTeam.data().plans.size >= 10, () -> control.input.isRebuildSelecting()),
         guardian(() -> state.boss() != null && isSerpulo() && state.boss().armor >= 4, () -> state.boss() == null),
+        cannotUpgrade(() -> ui.hints.events.contains("cannotupgrade"), () -> false),
         factoryControl(() -> !(state.isCampaign() && state.rules.sector.preset == SectorPresets.onset) &&
             state.rules.defaultTeam.data().getBuildings(Blocks.tankFabricator).size + state.rules.defaultTeam.data().getBuildings(Blocks.groundFactory).size > 0, () -> ui.hints.events.contains("factorycontrol")),
         coreUpgrade(() -> state.isCampaign() && state.rules.sector.planet == Planets.serpulo && Blocks.coreFoundation.unlocked()

core/src/mindustry/world/blocks/units/Reconstructor.java

@@ -223,6 +223,7 @@ public class Reconstructor extends UnitBlock{
                 if(!upgrade.unlockedNowHost() && !team.isAI()){
                     //flash "not researched"
                     pay.showOverlay(Icon.tree);
+                    Events.fire(Trigger.cannotUpgrade);
                 }
 
                 if(upgrade.isBanned()){