Port field moves from the menu, SEL with Select, and moving Pokémon in Bill's PC

Field moves chosen in the party menu run their original checks and the
ROM's from-menu scripts (Cut, Surf, Strength, Flash, Whirlpool, Waterfall,
Sweet Scent), and Softboiled and Milk Drink share HP. SEL registers a key
item that Select then uses, replacing the Key Items shortcut, and Bill's
PC moves Pokémon between the party and every box.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/game/scripts/pc.ts

@@ -1,14 +1,23 @@
 import type { RomReader } from "../rom/reader";
 import type { PokemonData } from "../rom/pokemon";
-import { ENGINE_FLAGS, PC, RAM } from "../rom/profile";
+import { ENGINE_FLAGS, MENU, PC, RAM } from "../rom/profile";
 import { receiveItem, removeFromSlot, type ItemSlot } from "../party/bag";
-import { BOX_NAME_PATTERN, PARTY_LENGTH } from "../party/pokemon";
 import {
+  BOX_NAME_PATTERN,
+  PARTY_LENGTH,
+  type PartyMon,
+} from "../party/pokemon";
+import {
+  MONS_PER_BOX,
   NUM_BOXES,
+  bufferMon,
   currentBox,
   depositMon,
   receivePCItem,
+  restorePP,
+  toBoxMon,
   withdrawnMon,
+  type BoxMon,
 } from "../party/storage";
 import { readString, readText, type TextContext } from "./text";
 import type { MartEntry, ScriptEffect, ScriptState } from "./interpreter";
@@ -422,15 +431,128 @@ export class PcSession {
       if (choice === BILLSPC_WITHDRAW) yield* this.withdrawMons();
       else if (choice === BILLSPC_DEPOSIT) yield* this.depositMons();
       else if (choice === BILLSPC_CHANGE_BOX) yield* this.changeBox();
-      else if (choice === BILLSPC_MOVE)
-        yield {
-          kind: "notice",
-          text: "Moving Pokémon between boxes is not ported yet.",
-        };
+      else if (choice === BILLSPC_MOVE) yield* this.movePKMNMenu();
       else return;
     }
   }
 
+  // ------------------------------------------------ MOVE PKMN W/O MAIL
+
+  /** BillsPC_MovePKMNMenu: refused while a party Pokémon holds MAIL
+   * (IsAnyMonHoldingMail), then StartMoveMonWOMail_SaveGame's question. The
+   * native session saves by itself, so no save messages follow. */
+  private *movePKMNMenu(): Gen {
+    const r = this.host.reader;
+    const mail = new Set<number>();
+    for (let p = MENU.MailItems; r.byte(p) !== 0xff; p++) mail.add(r.byte(p));
+    if (this.state.party.some((mon) => mail.has(mon.item)))
+      return yield* this.print(PC["BillsPC_MovePKMNMenu.PCMonHoldingMailText"]);
+    const ok = yield { kind: "yesno", pages: this.pages(PC.MoveMonWOMailSaveText) };
+    if (ok) yield* this.moveWithoutMail();
+  }
+  /** wBillsPC_LoadedBox: 0 is the party, 1-14 the boxes. */
+  private loadedBox(box: number): (PartyMon | BoxMon)[] {
+    return box ? this.state.storage.boxes[box - 1] : this.state.party;
+  }
+  private loadedBoxName(box: number) {
+    return box
+      ? this.boxName(box - 1)
+      : this.string(PC["BillsPC_BoxName.PartyPKMN"]);
+  }
+  /** Choose the party or a box (left and right in the original). */
+  private *chooseLoadedBox(prompt: string, selected: number): Gen<number> {
+    const boxes = Array.from({ length: NUM_BOXES + 1 }, (_, box) => box);
+    return yield* this.menu(
+      [prompt],
+      boxes.map((box) => this.loadedBoxName(box)),
+      boxes.map((box) => `${this.loadedBox(box).length}/${box ? MONS_PER_BOX : PARTY_LENGTH}`),
+      selected,
+    );
+  }
+  /** _MovePKMNWithoutMail: choose a Pokémon in the party or a box, MOVE it
+   * (STATS shows it) and choose where it goes; the list is presented per
+   * box instead of with left and right. */
+  private *moveWithoutMail(): Gen {
+    const data = this.host.data;
+    const choose = this.string(PC.PCString_ChooseaPKMN),
+      where = this.string(PC.PCString_MoveToWhere),
+      cancel = this.string(PC["BillsPC_RefreshTextboxes.CancelString"]),
+      options = this.strings(PC["_MovePKMNWithoutMail.MenuData"] + 2, 3);
+    let loaded = this.state.storage.current + 1;
+    for (;;) {
+      const from = yield* this.chooseLoadedBox(choose, loaded);
+      if (from < 0) return;
+      loaded = from;
+      const list = this.loadedBox(from);
+      const index = yield* this.menu(
+        [`${this.loadedBoxName(from)}\n${choose}`],
+        [...list.map((mon) => mon.nickname), cancel],
+        this.monDetails(list),
+      );
+      if (index < 0 || index >= list.length) continue;
+      const action = yield* this.menu([this.string(PC.PCString_WhatsUp)], options);
+      if (action === 1) {
+        const mon = list[index];
+        yield {
+          kind: "stats",
+          mon: from ? bufferMon(data, mon as BoxMon) : structuredClone(mon as PartyMon),
+        };
+        continue;
+      }
+      if (action !== 0) continue;
+      // BillsPC_CheckMail_PreventBlackout, even within the party.
+      if (!from && !(yield* this.partyMonMayLeave(index))) continue;
+      // Where: a box, then the position to insert before.
+      for (;;) {
+        const to = yield* this.chooseLoadedBox(where, from);
+        if (to < 0) break;
+        const destination = this.loadedBox(to);
+        const position = yield* this.menu(
+          [`${this.loadedBoxName(to)}\n${where}`],
+          [...destination.map((mon) => mon.nickname), "▶"],
+          this.monDetails(destination),
+          destination.length,
+        );
+        if (position < 0) continue;
+        // BillsPC_CheckSpaceInDestination
+        if (
+          to !== from &&
+          destination.length >= (to ? MONS_PER_BOX : PARTY_LENGTH)
+        ) {
+          yield* this.placeString(this.string(PC.PCString_TheresNoRoom));
+          continue;
+        }
+        yield* this.placeString(
+          this.string(PC["MovePKMNWithoutMail_InsertMon.Saving_LeaveOn"]),
+          10,
+        );
+        this.insertMon(from, index, to, position);
+        loaded = to;
+        break;
+      }
+    }
+  }
+  /** MovePKMNWithoutMail_InsertMon: remove, then insert before `position`
+   * (one earlier when moving down the same list, .CheckTrivialMove). A
+   * boxed Pokémon joining the party gets CalcBufferMonStats' full HP;
+   * InsertPokemonIntoBox restores the PP. */
+  private insertMon(from: number, index: number, to: number, position: number) {
+    const data = this.host.data;
+    const source = this.loadedBox(from);
+    const [moved] = source.splice(index, 1);
+    if (from === to && index < position) position--;
+    if (to) {
+      const stored = from ? (moved as BoxMon) : toBoxMon(moved as PartyMon);
+      restorePP(data, stored);
+      this.state.storage.boxes[to - 1].splice(position, 0, stored);
+    } else
+      this.state.party.splice(
+        position,
+        0,
+        from ? bufferMon(data, moved as BoxMon) : (moved as PartyMon),
+      );
+  }
+
   /** BillsPC_CheckMail_PreventBlackout for a party Pokémon: the last one,
    * or the last that has not fainted, stays. No MAIL exists yet. */
   private *partyMonMayLeave(index: number): Gen<boolean> {