Add Basic group alliance preview to lobby

game/engine.ts

@@ -752,7 +752,7 @@ import {
 } from './advisors';
 import { isAlliedShipmentVisit, makeBasicAlliedShipment, quoteBasicAlliedShipment, basicAlliedShipmentHasWitness,
   type BasicAlliedShipment } from './allied-separation';
-import { answerCoalitionAdmission, beginCoalitionAdmission, coalitionAllies, coalitionGroups, coalitionOf,
+import { answerCoalitionAdmission, beginCoalitionAdmission, coalitionAllies, coalitionGroups, coalitionOf, emptyCoalitionState,
   leaveCoalition, CoalitionAllianceError, type CoalitionState, type CoalitionTransition } from './coalition-alliance';
 import { coalitionBattleBeneficiary } from './coalition-battle-preparation';
 import { createCoalitionWormProtection, currentCoalitionWormAlly, decideCoalitionWormProtection,
@@ -1448,7 +1448,9 @@ type RicheseAllyOffer = {
   payer: string;
 };
 export type Game = {
-  /** Unexposed group-alliance integration state; absent in existing games. */
+  /** Explicit incomplete Basic group preview; absent in legacy games. */
+  coalitionPreview?: 'three' | 'three-short' | 'unlimited';
+  /** Group-alliance integration state; absent in ordinary existing games. */
   coalitionState?: CoalitionState;
   coalitionEscrow?: CoalitionEscrowState;
   coalitionWormProtection?: CoalitionWormProtectionFrame;
@@ -5804,6 +5806,8 @@ function twoPlayerRule<T>(operation: () => T): T {
 function twoPlayerControllersIntegrity(g: Game): void {
   requireRule(g.shortAllianceVictory === undefined || typeof g.shortAllianceVictory === 'boolean',
     'The optional alliance victory setting must be true or false.');
+  requireRule(g.coalitionPreview === undefined || ['three', 'three-short', 'unlimited'].includes(g.coalitionPreview),
+    'Invalid group-alliance preview setting.');
   if (g.twoPlayerControllers === undefined) return;
   const seats = g.players.map(player => player.id);
   twoPlayerRule(() => {
@@ -10881,6 +10885,12 @@ function startModules(state: Game): Game {
 }
 /** Public consistency only; each module's genuine initializer validates its own envelope. */
 function baseStartProfileBlock(g: Game): string | null {
+  if (g.coalitionPreview && g.status === 'lobby' &&
+      (g.advanced || g.expansions.length > 0 || g.players.length < 3 ||
+       !g.players.every(p => CLASSIC_FACTIONS[p.faction] === true) || g.twoPlayerControllers ||
+       g.shortAllianceVictory || g.techTokens || g.strongholdCards || g.homeworlds ||
+       g.nexusCards || g.discoveryEnabled || g.leaderSkills || g.ecazTreachery || lobbyModulesSelected(g)))
+    return 'The group-alliance preview needs at least three classic factions, Basic rules, and no expansion decks, other optional modules, two-person setup or separate short-alliance setting.';
   if (g.status === 'lobby' && (g.moritaniAssassinatePreview || g.moritaniAssassinate))
     return 'Separate development profiles cannot be enabled by a normal start.';
   if (g.status === 'lobby' && (g.leaderSkills || g.ecazTreachery))
@@ -10945,7 +10955,7 @@ function requireFreshBaseRuntime(g: Game) {
   const configuration = new Set<keyof Game>(['code', 'version', 'host', 'players', 'playerPositions',
     'advanced', 'expansions', 'log', 'botsPending', 'botNextActionAt', 'techTokens', 'strongholdCards',
     'homeworlds', 'nexusCards', 'discoveryEnabled', 'leaderSkills', 'ecazTreachery', 'lobbyOptions', 'kullDefaultPolicy',
-    'twoPlayerControllers', 'shortAllianceVictory']);
+    'twoPlayerControllers', 'shortAllianceVictory', 'coalitionPreview']);
   const keys = [...new Set([...Object.keys(g), ...Object.keys(fresh)])] as (keyof Game)[];
   requireRule(keys.every(key => configuration.has(key) ||
     JSON.stringify(g[key]) === JSON.stringify(fresh[key])),
@@ -10982,6 +10992,8 @@ function start(g: Game, advancedPreview = false): Game {
     'Start with unused Stronghold Cards before assigning ownership.');
   requireFreshBaseRuntime(g);
   initializeSetup(g);
+  if (g.coalitionPreview) g.coalitionState = emptyCoalitionState(
+    g.coalitionPreview === 'three' ? undefined : g.coalitionPreview);
   if (advancedPreview) g.advancedPreview = true;
   return g;
 }
@@ -16278,9 +16290,8 @@ function allianceQuestionWindow(g: Game): boolean {
 function unsettledPromises(records: readonly {fulfilled?: boolean; released?: boolean}[] | undefined): boolean {
   return !!records?.some(record => !record.fulfilled && !record.released);
 }
-/** Group negotiation is deliberately unexposed until its other alliance
- * mechanics are integrated. This narrow profile keeps existing pair games
- * and unrelated commitments on their original paths. */
+/** The incomplete group preview and staged fixtures retain this narrow profile;
+ * existing pair games and unrelated commitments keep their original paths. */
 function coalitionNexusAvailable(g: Game): boolean {
   return g.coalitionState !== undefined && g.status === 'playing' &&
     g.phase === 1 && !!g.nexus && !g.spiceWindow && !g.spiceResolution &&
@@ -44695,6 +44706,18 @@ function applyActionInner(
       log(g, `${p.name} ${action.enabled ? 'enabled' : 'disabled'} the provisional two-person, four-faction setup. Human readiness was cleared.`);
       return g;
     }
+    if (t === 'coalitionPreview') {
+      requireRule(id === g.host && Object.keys(action).every(key => key === 'type' || key === 'variant') &&
+        (action.variant === 'off' || action.variant === 'three' || action.variant === 'three-short' || action.variant === 'unlimited'),
+      'Only the host may choose a group-alliance preview option.');
+      const variant = action.variant === 'off' ? undefined : action.variant;
+      if (variant === g.coalitionPreview) return g;
+      if (variant) g.coalitionPreview = variant;
+      else delete g.coalitionPreview;
+      g.players.forEach(player => (player.ready = !!player.bot));
+      log(g, `${p.name} changed the unfinished group-alliance preview. Human readiness was cleared.`);
+      return g;
+    }
     if (t === 'shortAllianceVictory') {
       requireRule(id === g.host && typeof action.enabled === 'boolean' &&
         Object.keys(action).every(key => key === 'type' || key === 'enabled'),
@@ -47056,6 +47079,7 @@ export function viewGame(state: Game, id: string, now?: number) {
     factionSwap: g.factionSwap ?? null,
     twoPlayerControllers: g.twoPlayerControllers ?? null,
     shortAllianceVictory: g.shortAllianceVictory === true,
+    coalitionPreview: g.coalitionPreview ?? 'off',
     controlledFactionSeats: g.twoPlayerControllers
       ? g.players.filter(player => g.twoPlayerControllers!.controllers.some(controller =>
           controller.seats.includes(id) && controller.seats.includes(player.id)))