From a4bff58a99f6d689385e5ea692f10f0c9ace2d0d Mon Sep 17 00:00:00 2001
From: TaylorLeLievre <jackrabbit5567@gmail.com>
Date: Sun, 25 Aug 2024 12:22:19 -0400
Subject: [PATCH 1/3] Fix merge conflicts

---
 src/phases/return-phase.ts        | 3 +++
 src/phases/switch-summon-phase.ts | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/phases/return-phase.ts b/src/phases/return-phase.ts
index 19c73816b36..a85017fbedd 100644
--- a/src/phases/return-phase.ts
+++ b/src/phases/return-phase.ts
@@ -1,4 +1,5 @@
 import BattleScene from "#app/battle-scene";
+import { applyPreSwitchOutAbAttrs, PreSwitchOutAbAttr } from "#app/data/ability.js";
 import { SpeciesFormChangeActiveTrigger } from "#app/data/pokemon-forms";
 import { SwitchSummonPhase } from "./switch-summon-phase";
 
@@ -8,6 +9,8 @@ export class ReturnPhase extends SwitchSummonPhase {
   }
 
   switchAndSummon(): void {
+    this.lastPokemon = this.getPokemon();
+    applyPreSwitchOutAbAttrs(PreSwitchOutAbAttr, this.lastPokemon);
     this.end();
   }
 
diff --git a/src/phases/switch-summon-phase.ts b/src/phases/switch-summon-phase.ts
index 525f74e896f..5b3d2f560d8 100644
--- a/src/phases/switch-summon-phase.ts
+++ b/src/phases/switch-summon-phase.ts
@@ -18,7 +18,7 @@ export class SwitchSummonPhase extends SummonPhase {
   private doReturn: boolean;
   private batonPass: boolean;
 
-  private lastPokemon: Pokemon;
+  protected lastPokemon: Pokemon;
 
   /**
      * Constructor for creating a new SwitchSummonPhase

From 1fc34d862f6fed7093b166cdb034249e0e8c6b11 Mon Sep 17 00:00:00 2001
From: NightKev <34855794+DayKev@users.noreply.github.com>
Date: Sun, 25 Aug 2024 11:08:15 -0700
Subject: [PATCH 2/3] Remove `.js` from import

---
 src/phases/return-phase.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/phases/return-phase.ts b/src/phases/return-phase.ts
index a85017fbedd..d126f4f5d6b 100644
--- a/src/phases/return-phase.ts
+++ b/src/phases/return-phase.ts
@@ -1,5 +1,5 @@
 import BattleScene from "#app/battle-scene";
-import { applyPreSwitchOutAbAttrs, PreSwitchOutAbAttr } from "#app/data/ability.js";
+import { applyPreSwitchOutAbAttrs, PreSwitchOutAbAttr } from "#app/data/ability";
 import { SpeciesFormChangeActiveTrigger } from "#app/data/pokemon-forms";
 import { SwitchSummonPhase } from "./switch-summon-phase";
 

From c9cda53724f990cffac7b1f0c49fe91dd93c5d9a Mon Sep 17 00:00:00 2001
From: NightKev <34855794+DayKev@users.noreply.github.com>
Date: Sun, 25 Aug 2024 11:35:57 -0700
Subject: [PATCH 3/3] Add regression test

---
 src/test/abilities/delta_stream.test.ts | 50 +++++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 src/test/abilities/delta_stream.test.ts

diff --git a/src/test/abilities/delta_stream.test.ts b/src/test/abilities/delta_stream.test.ts
new file mode 100644
index 00000000000..0482d7f7b37
--- /dev/null
+++ b/src/test/abilities/delta_stream.test.ts
@@ -0,0 +1,50 @@
+import { Moves } from "#app/enums/moves";
+import { Species } from "#app/enums/species";
+import { WeatherType } from "#app/enums/weather-type";
+import { Abilities } from "#enums/abilities";
+import GameManager from "#test/utils/gameManager";
+import { SPLASH_ONLY } from "#test/utils/testUtils";
+import Phaser from "phaser";
+import { afterEach, beforeAll, beforeEach, describe, expect, it } from "vitest";
+
+describe("Abilities - Delta Stream", () => {
+  let phaserGame: Phaser.Game;
+  let game: GameManager;
+
+  beforeAll(() => {
+    phaserGame = new Phaser.Game({
+      type: Phaser.HEADLESS,
+    });
+  });
+
+  afterEach(() => {
+    game.phaseInterceptor.restoreOg();
+  });
+
+  beforeEach(() => {
+    game = new GameManager(phaserGame);
+    game.override
+      .battleType("double")
+      .enemyAbility(Abilities.BALL_FETCH)
+      .enemyMoveset(SPLASH_ONLY)
+      .enemySpecies(Species.MAGIKARP)
+      .moveset([Moves.SPLASH])
+      .starterForms({
+        [Species.RAYQUAZA]: 1
+      });
+  });
+
+  it("no longer applies after transition from double to single battle", async () => {
+    await game.startBattle([Species.FEEBAS, Species.RAYQUAZA]);
+
+    expect(game.scene.arena.weather?.weatherType).toBe(WeatherType.STRONG_WINDS);
+
+    game.move.select(Moves.SPLASH);
+    game.move.select(Moves.SPLASH, 1);
+    await game.doKillOpponents();
+    game.override.battleType("single");
+    await game.toNextWave();
+
+    expect(game.scene.arena.weather?.weatherType).toBeUndefined();
+  });
+});