autoheal split from autotarget; it's fairly different.

OpenRa.Game/OpenRa.Game.csproj

@@ -172,6 +172,7 @@
     <Compile Include="Traits\AttackBase.cs" />
     <Compile Include="Traits\AttackInfo.cs" />
     <Compile Include="Traits\AttackTurreted.cs" />
+    <Compile Include="Traits\AutoHeal.cs" />
     <Compile Include="Traits\AutoTarget.cs" />
     <Compile Include="Traits\BelowUnits.cs" />
     <Compile Include="Traits\Building.cs" />

OpenRa.Game/Traits/AutoHeal.cs

@@ -0,0 +1,64 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+namespace OpenRa.Game.Traits
+{
+	class AutoHeal : ITick
+	{
+		public AutoHeal(Actor self) { }
+
+		void AttackTarget(Actor self, Actor target)
+		{
+			var attack = self.traits.WithInterface<AttackBase>().First();
+			if (target != null)
+				attack.ResolveOrder(self, new Order("Attack", self, target, int2.Zero, null));
+		}
+
+		float GetMaximumRange(Actor self)
+		{
+			return new[] { self.Info.Primary, self.Info.Secondary }
+				.Where(w => w != null)
+				.Max(w => Rules.WeaponInfo[w].Range);
+		}
+
+		bool NeedsNewTarget(Actor self)
+		{
+			var attack = self.traits.WithInterface<AttackBase>().First();
+			var range = GetMaximumRange(self);
+
+			if (attack.target == null)
+				return true;	// he's dead.
+			if ((attack.target.Location - self.Location).LengthSquared > range * range + 2)
+				return true;	// wandered off faster than we could follow
+			if (attack.target.Health == attack.target.Info.Strength)
+				return true;	// fully healed
+
+			return false;
+		}
+
+		public void Tick(Actor self)
+		{
+			if (!self.IsIdle) return;
+
+			var attack = self.traits.WithInterface<AttackBase>().First();
+			var range = GetMaximumRange(self);
+
+			if (NeedsNewTarget(self))
+				AttackTarget(self, ChooseTarget(self, range));
+		}
+
+		Actor ChooseTarget(Actor self, float range)
+		{
+			var inRange = Game.FindUnitsInCircle(self.CenterLocation, Game.CellSize * range);
+
+			return inRange
+				.Where(a => a.Owner == self.Owner)	/* todo: one day deal with friendly players */
+				.Where(a => Combat.HasAnyValidWeapons(self, a))
+				.Where(a => a.Health < a.Info.Strength)
+				.OrderBy(a => (a.Location - self.Location).LengthSquared)
+				.FirstOrDefault();
+		}
+	}
+}

units.ini

@@ -569,7 +569,7 @@ LongDesc=Elite commando infantry, armed with \ndual pistols and C4.\n  Strong vs
 [MEDI]
 Description=Medic
 Voice=MedicVoice
-Traits=Unit, Mobile, RenderInfantry, AttackBase, TakeCover, Infantry, AutoTarget
+Traits=Unit, Mobile, RenderInfantry, AttackBase, TakeCover, Infantry, AutoHeal
 LongDesc=Heals nearby infantry.\n  Strong vs Nothing\n  Weak vs Everything