Entry 103

The party in a field: members join and leave the running fights

2026-09-25worldbattletest

Filescrates/piney-world/src/field_world.rscrates/piney-game/src/area_host.rscrates/piney-game/src/area.rscrates/piney-game/src/session/event11.rscrates/piney-world/examples/world_probe.rstools/test_party_rs.pydocs/engine/field-walk.md

Outside the towns, party_add and party_remove fell to the event host's default, which does nothing. So did the field UI's AddMember, DelMember and TransferOut requests. Event 11 hit this first: at the end of the church its tail runs party_remove 15, and BlackRose stayed in the party.

What the game does

The same functions run as in Mac Anu (field-game.md):

• ccParty::AddMember (gcmn 0x0059ce80): the first slot whose memberID is -1 gets inviteSpc(id) (0x005a08e0).
  • For a registered id, inviteSpc sets the registry's partyFlag to 1.
  • If the character is built, its own flag (+0xe0 bits 14-16) changes too: -2 turns recallFlag on, -1 clears recall and becomes 1, and 0 becomes 1.
  • It returns the character pointer. When that is null, the slot's memberChar is 0, memberID stays -1 and AddMember returns -1.
• ccParty::DelMember (0x0059cf60) acts only on slots above 0 whose memberID is not -1. It sets memberChar to 0 and calls disbandSpc (0x005a0f50): the registry's flag becomes 0, and the character becomes -2 with recall off if it was recalled, else -1. Then memberID is -1 and num goes down by 1.
• expulsionSpc (0x005a1070) is just DelMember(CheckMemberID(registry[listNum].id)).

The port

party.rs's Spcs already had all of these for the town.

Party changes. FieldWorld now has party_add, party_remove and transfer_out. They run these functions over the fights' characters (with_party, the BattleChars adapter). After a change, Combat::set_party rebuilds the fights' ccPartyManager from memberID. A member who leaves drops out of the fights, the panels and the AI's party. One who joins is back in.

Who calls them.

• area_host.rs routes cases 77 and 78 to them. party_add also sets the new slot's menu face, as the town's host does.
• area.rs answers AddMember, DelMember(slot) (as party_remove -slot) and TransferOut for a party handle.

A dismissed leaver. When the fellow task lets a leaver go (partyFlag -2 and act 14 set exitFlag), the game's ccThFellow02 calls expulsionSpc and deletes the character. The port now does the same after each combat frame (fellows_gone):

• Spcs::expulsion with the character's flag, which also frees the registry slot unless it is still a member;
• the character dropped from the fights' members and cast.

Checked

• Against the game. tools/test_party_rs.py runs AddMember, DelMember and expulsionSpc natively in eemu, with inviteSpc, disbandSpc and CheckMemberID beneath them. It uses 600 random registries and parties and the characters' whole +0xe0 words, with one to five calls each. The world_probe's new party request runs the same calls on Spcs.
  • Compared: each return, the registry's ids and flags, memberChar, memberID, num, and each character's partyFlag and recallFlag.
  • None differ. The adds return slots 1 and 2 and -1, and 235 of the runs change the registry's flags.
• The session. event_11_church_ends_with_blackrose_out plays event 11 from the join through the church. It checks:
  • BlackRose is in the party on the holy ground;
  • party_remove 15 leaves her registry flag 0 and her character's flag -1, with the party without her;
  • the party the field hands back to the session is without her;
  • take_unported() is empty.
• The workspace's tests, clippy, fmt and the docs check also pass.