Expedition: party lobby + invites (pre-run only)

[3CordGuy]

Summary

Brings the expedition mode to feature parity with quests for party assembly. The server has accepted party: string[] since day one; this PR adds the client lobby + invite plumbing on top, gated to pre-run only (no parachuting in once the picker has chosen a node).

Design

Polymorphic shell vs. fork: Forked LobbyView → ExpeditionLobbyView. The quest lobby's WS chat, ready toggle, position picker, reinforcement mode, lock toggle, and force-start don't apply to expeditions — extracting a polymorphic shell would have meant either threading a noisy capability matrix through every render branch or producing a shell that's barely shorter than the fork. The fork is ~600 lines, mirrors the visual identity (drawer, chip styles, gold action button), and stays readable.

expeditions.status enum vs. separate column: Reused status with a new 'lobby' value. The existing column has no CHECK constraint (just TEXT NOT NULL DEFAULT 'active'), and getActiveExpeditionForCharacter already had the right shape — extended its WHERE to IN ('active','lobby') so the mutex query naturally includes lobbies.

Mutex semantics: Membership rows in active_expedition_membership are inserted at accept-time for invitees, not at lobby-creation time. This means a pending invite doesn't block the invitee from being invited to other expeditions — exactly the behavior we want for an invite that hasn't been agreed to. If two lobbies try to grab the same character, the second /accept loses the SQLite UNIQUE-constraint race, reverts to pending, and returns 409. The creator's slot is reserved immediately on /start_with_party.

Migration (0068)

ALTER TABLE expedition_party
  ADD COLUMN invite_status TEXT NOT NULL DEFAULT 'accepted';
CREATE INDEX idx_expedition_party_char_invite
  ON expedition_party(character_id, invite_status);

DEFAULT 'accepted' back-fills the existing rows from /api/expedition/start (which insert auto-joined party members) so the column is meaningful for the lobby flow without rewriting history.

Routes added

Route	Behavior
POST /api/expedition/start_with_party	Creates lobby-state expedition, creator auto-accepted
GET /api/expedition/lobby	Caller's pending lobby + roster + my_invite_status
POST /api/expedition/:id/invite	Creator-only; pre-checks mutex
POST /api/expedition/:id/accept	Invitee accepts; closes mutex race
POST /api/expedition/:id/decline	Invitee removes their row
POST /api/expedition/:id/begin	Creator: refuses if any invite pending; regenerates map with accepted party signature
POST /api/expedition/:id/cancel	Creator: deletes lobby entirely

Also: POST /api/expedition/:id/pick defensively closes a stale lobby (creator only, no pending invites) instead of soft-locking. The canonical path is always /begin then /pick.

Test coverage

packages/db/src/expedition-lobby.test.ts (10 tests):

• Lobby creation: status 'lobby', creator auto-accepted, single membership row
• Mutex blocks duplicate creator and cleans up the orphan expedition row
• Invite inserts a pending row without a membership row (key invariant)
• Accept flips status + reserves membership
• Accept reverts to pending and throws ExpeditionMembershipConflictError when invitee is already elsewhere
• Decline removes the row entirely
• countPendingExpeditionInvitees reflects pending/accepted transitions
• getLobbyExpeditionForCharacter returns the lobby for both creator (accepted) and invitee (pending); returns null after /pick
• getExpeditionParty filters to accepted only
• deleteExpeditionLobby cascades party + membership; refuses non-lobby rows

Existing tests updated to include the new column (back-compat default makes them pass either way).

494 tests passing locally (462 core + 32 db).

Constraints respected

• No wrangler deploy; PR is draft
• wrangler.jsonc untouched
• Local migration applied via db:migrate:local; remote migration NOT run

Test plan

• In dev, start expedition from town → lobby drawer appears
• Click + Invite Player → roster of teammates not already in lobby
• Invite a teammate → they see the drawer with pulse on their session
• Teammate accepts → JOINED pill replaces INVITED
• Begin Expedition only enabled when no pending invites
• Begin Solo works (no invites, single-member lobby)
• Cancel deletes the lobby; refresh shows clean town
• Decline removes self from the lobby; creator's roster updates within 5s
• Invite an already-busy teammate → friendly 400 with target_in_expedition
• Try to /pick before /begin → 400 (or implicit close if creator with no pending)

🤖 Generated with Claude Code