🐛 wildcard relations were removed early

Author: krispya

packages/core/src/relation/relation.ts

@@ -1,4 +1,5 @@
 import { $internal } from '../common';
+import { Entity } from '../entity/types';
 import { trait } from '../trait/trait';
 import type { Schema, Trait } from '../trait/types';
 import type { World } from '../world/world';
@@ -75,6 +76,28 @@ export const getRelationTargets = (
 	return targets;
 };
 
+export const hasRelationToTarget = (
+	world: World,
+	entity: Entity,
+	target: RelationTarget
+): boolean => {
+	const ctx = world[$internal];
+	const traits = ctx.entityTraits.get(entity);
+	if (!traits) return false;
+
+	for (const trait of traits) {
+		const traitCtx = trait[$internal];
+		if (
+			traitCtx.isPairTrait &&
+			traitCtx.pairTarget === target &&
+			traitCtx.relation !== Wildcard
+		) {
+			return true;
+		}
+	}
+	return false;
+};
+
 export const Pair = <T extends Trait>(relation: Relation<T>, target: RelationTarget): T => {
 	if (relation === undefined) throw Error('Relation is undefined');
 	if (target === undefined) throw Error('Relation target is undefined');

packages/core/src/trait/trait.ts

@@ -2,7 +2,7 @@ import { $internal } from '../common';
 import type { Entity } from '../entity/types';
 import { getEntityId } from '../entity/utils/pack-entity';
 import { setChanged } from '../query/modifiers/changed';
-import { getRelationTargets, Pair, Wildcard } from '../relation/relation';
+import { getRelationTargets, hasRelationToTarget, Pair, Wildcard } from '../relation/relation';
 import { incrementWorldBitflag } from '../world/utils/increment-world-bit-flag';
 import type { World } from '../world/world';
 import type {
@@ -229,14 +229,13 @@ export function removeTrait(world: World, entity: Entity, ...traits: Trait[]) {
 			// Check if entity is still a subject of any relation or not.
 			if (world.query(Wildcard(entity)).length === 0) {
 				ctx.relationTargetEntities.delete(entity);
-
-				// TODO: cleanup query by hash
-				// removeQueryByHash(world, [Wildcard(eid)])
 			}
 
-			// Remove wildcard to this target for this entity.
+			// Remove wildcard to this target for this entity if no other relations to this target exist.
 			const target = traitCtx.pairTarget!;
-			removeTrait(world, entity, Pair(Wildcard, target));
+			if (!hasRelationToTarget(world, entity, target)) {
+				removeTrait(world, entity, Pair(Wildcard, target));
+			}
 
 			// Remove wildcard relation if the entity has no other relations.
 			const relation = traitCtx.relation!;

packages/core/tests/relation.test.ts

@@ -232,4 +232,29 @@ describe('Relation', () => {
 		expect(person.has(Likes(apple))).toBe(false);
 		expect(person.has(Likes(banana))).toBe(false);
 	});
+
+	it('should keep wildcard trait when removing one of multiple relations to the same target', () => {
+		const Likes = relation();
+		const Fears = relation();
+
+		const person = world.spawn();
+		const dragon = world.spawn();
+
+		// Person both likes and fears the dragon
+		person.add(Likes(dragon));
+		person.add(Fears(dragon));
+
+		// Wildcard(dragon) query should find person
+		expect(world.query(Wildcard(dragon))).toContain(person);
+
+		// Remove only the Likes relation
+		person.remove(Likes(dragon));
+
+		// Person should still fear the dragon
+		expect(person.has(Fears(dragon))).toBe(true);
+		expect(person.has(Likes(dragon))).toBe(false);
+
+		// Wildcard(dragon) should still find person because Fears(dragon) remains
+		expect(world.query(Wildcard(dragon))).toContain(person);
+	});
 });